Report of the Committee on - NFPA€¦ · Wayne Geyer, Steel Tank Inst., IL [M] Robert ... Part I...

Report of the Committee on

Tank Leakage and Repair Safeguards

Joyce A. Rizzo, Chair Lexicon Environmental Assoc., Inc., PA [SE]

Charles T. Alsup, duPont Co., WV [U] Gary T. Austerman, Burns & McDonnell Engr Co., MO [SE] Larry Beasley, Robert and Co., GA [SE] Jon V. Brannan, Underwriters Laboratories Inc., IL [RT] Paul E. C, alderwood, Everett Fire Dept., M A [ E ] Wayne Geyer, Steel Tank Inst., IL [M] Robert G. Hauzie, Hancor Inc., OH [M] Kenneth D. Latdmer, Star Enterprise (Texaco), CA. [U]

Rep. NFPA Industrial Fire Protection Section George S. Lomax, Heath Consultants Inc., PA[M]

Rep. Int'l Assn. of Tank Testing Professionals Dennis Moss, Provo City Fire Dept., lIT [E] James W. Naylor, Westinghouse Savannah River Co., SC [U] Ronald H. Pritchard, Pittsburg Tank & Tower Co., Inc., KY [M] John F. Rekus, John F. Rekus & Assoc., Ltd., MD [SE]

Rep. American Industrial Hygiene Assn./Confined Spaces Committee

Robert N. Renkes, Petroleum Equipment Inst., OK [M] Thomas M. Riddle, Tank Construction & Service Co., Inc., IN [IM] James IL Rocco, BP Oil Co., OH [U]

Rep. American Petroleum Inst. Adam M. Selisker, Northampton Twp. Fire Dept., PA [El Robert P. Siegel, 3M Co., MN [U] Robert Stegall, Huntsman, TX [M] David R. Wiley, U.S. Environmental Protection Agency, DC [E] Edward J. Willwerth, Atlantic Environmental & Marine Services,

Inc., MA [SE] Rep. Marine Chemists Assn. Inc.

Alternates

John H. Bagnall, Burns & McDonnell Engr Co., MO [SE] (Alt. to G. T. Austerman)

Leslie Blaize, Belay Inc., OR [SE] (Alt. to E.J. Willwerth)

Lorri Grainawi, Steel Tank lnsL, IL [M] (Alto to W. Geyer)

Staff Liaison: David G. Trebisacci

Committee Scope: This Committee shall have primary responsibility for documents on safeguarding against fire, explosion, and health hazards associated with entry, cleaning and repair of tank systems and methods for detecting, controlling, and investigating releases that could cause these hazards.

This list represents the membership at the time the Ca~,nmittee was balloted on the text of this edition. Since that time, changes in the membership ma 3 have occurred. A key to classifications is found at the front of this book.

The Report of the Technical Committee on Tank Leakage and Repair Safeguards is presented for adoption in 4 parts.

Part I of dais Report was prepared by the Technical Committee on Tank Leakage and Repair Safeguards, and proposes for adoption a complete revision to NFPA 326-1993, Standard Procedures for the Safe Entry of Underground Storage Tanks. NFPA 326-1993 is published in Volume 6 of the 1998 National Fire Codes and in separate pamphlet form.

This document when adopted will be retitled NFPA 326, Standard for the Safeguarding of Tanks and Containers for Entry, Cleaning, or Repair.

Part I of this Report has been submitted to letter ballot of the Technical Committee on Tank Leakage and Repair Safeguards, which consists of 22 voting members. The results of the balloting, after circulation of any negadve votes, can be found in the report.

Part II of this Report was prepared by the Technical Committee on Tank Leakage and Repair Safeguards, and proposes for adoption a withdrawal to NFPA 327-1993, Standard Procedures for Cleaning or Safeguarding Small Tanks and Containers Without Entry. NFPA 3x27-1993 is published in Volume 6 of tile 1998 National Fire Codes and in separate pamphlet form.

Part II of this Report has been submitted to letter ballot of the Technical Committee on Tank Leakage and Repair Safeguards, which consists of 22 voting members. The results of the balloting, after circulation of any negative votes, ran be found in file report.

Part III of this Report was prepared by the Technical Committee on Tank Leakage and Repair Safeguards, and proposes for adoption a withdrawal to NFPA 328-1992, Recommended Practice for the Control of Flammable and Combustible Liquids and Gases in Manholes, Sewers, and Similar Underground Structures. NFPA 328-1992 is published in Volume 11 of the 1998 National Fire Codes and in separate pamphlet form.

Part Il l of this Report has been submitted to letter ballot of the Technical Committee on Tank Leakage and Repair Safeguards, which consists of 22 voting members. The results of the balloting, after circulation of any negative votes, can be found in the report.

Part IV of this Report was prepared by the Technical Committee on Tank Leakage and Repair Safeguards, and proposes for adoption a complete revision to NFPA 329-1992, Recommended Practice for Handling Underground Releases of Flammable and Combustible Liquids. NFPA 329-1992 i s published in Volume 11 of the 1998 National Fire Codes and in separate pamphlet form.

Part IV of this Report has been submitted to letter ballot of the Technical Committee on Tank Leakage and Repair Safeguards, which consists of 22 voting members. The results of tile balloting, after circulation of any negative votes, ran be found in the report.

This document when adopted will be redesignated NFPA 329, Recommended Practice for Handling Releases of Flammable and Combustible Liquids and Gases.

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N F P A 3 2 6 - - A 9 9 R O P

PART 1

(Log #CP3) 326- 1 - (1-3 Bonding , Combust ib le Gas Indicator, Lower F lammable Limit (LFL), Unstable Liquid) : Accept SUBMITTER: Technica l Commi t t ee on Tank Leakage and Repair Safeguards R E C O M M E N D A T I O N : Revise the defini t ions in Chapter 1 to read as follows:

Bonding. The p e r m a n e n t j o i n i ng o f metallic parts to form an electrically conduct ive pa th tha t will ensure electrical cont inui ty a n d the capacity to conduc t safely any cu r r en t likely to be imposed.

Combust ib le Gas Indicator. An i n s t r u m e n t tha t samples air and indicates whether the re are combust ib le vapors present . Some uni ts may indicate the percentage of the lower explosive limit of the a i r /gas mixture.

Lower F lammable Limit (LFL). T ha t concent ra t ion of a combust ib le material in air below which ignition will no t occur. Also known as the Lower Explosive Limit (LEL) Mixtures below this limit are said to be "too lean."

Unstable Liquid. A liquid that , in the pure state or as commercia l ly p r o d u c e d or t ranspor ted , will vigorously polymerize, decompose , u n d e r g o condensa t ion reaction, or become self- reactive u n d e r condi t ions of shock, pressure, or t empera ture . SUBSTANTIATION: The Commi t t ee reviewed the defini t ions in this s tandard, and the above were changed to conform to the preferred defini t ions as listed in the NFPA Glossary of Terms. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE T O VOTE: 22 VOTE ON C O M M I T T E E ACTION:

AFFIRMATIVE: 19 ABSTENTION: 1 NOT RETURNED: 2 Geyer, Lat t imer

EXPLANATION O F ABSTENTION: WILEY: I abstain because I am no t familiar e n o u g h with the

issues to appropr ia te ly vote otherwise.

(Log #10) 326- 2 - (1-3 Certified Marine Chemis t (New)): Reject SUBMITTER: Rober t H. Walker, Ill, Mar ine Chemis t Service, Inc. R E C O M M E N D A T I O N : Add the following new definit ion:

Certified Mar ine Chemist . The ho lder of a valid certificate issued by the National Fire Protect ion Association. es tabl ishine the persgn 's qualif icat ions to de t e rmi ne whe the r work and inspect ions covered by this s tandard can be u n d e r t a k e n with safety. S U B S T A N T I A T I O N : Providing this defini t ion shou ld ,aid those industr ies who seek addi t ional in format ion regard ing NFPA's qualif ication intent . Add ing dais def ini t ion would also be consis tent with the purpose beh ind its inclusion in NFPA 306. Note: mos t of the words in this def ini t ion were pa raphrased f rom NFPA 306. COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: T he Commi t t ee Rejec ted this proposal because it felt tha t to include a definit ion for one conf ined space a tmosphe re test ing safety professional would be too exclusive. The d o c u m e n t migh t in effect become too limiting, by omi t t ing many o ther professionals who are capable o f doing the testing. NUMBER OF COMMITTEE MEMBERS ELIGIBLE T O VOTE: 22 VOTE ON COMMITT E E ACTION:


EXPLANATION OF ABSTENTION: WILEY: See my Explanat ion of Abstent ion on Proposal 326-1

(Log #CP3). WILLWERTH: This r e c o m m e n d a t i o n should be Accepted. This

p roposed d o c u m e n t is wi thout reference to t ra ined and exper ienced individuals dlat the inexper ienced owner, or owner with l imited h u m a n resource,s or owner seeking a third party expert ise for liability reasons, or the author i t ies having jur isdic t ion can turn to guide t h e m t h rough this potentially very dange rous process. An NFPA Certif icated Mar ine Chemis t is such an individual and shou ld be inc luded as part of the s tandard, or at very least referred to in the appendix .

(Log #11 ) 326- 3 - (1-3 Certify, in Writing (New)): Reject SUBMITTER: Rober t H. Walker, i11, Marine Cilemist Service. h~c R E C O M M E N D A T I O N : Add rite following new defiuiUou:

Certify. in Writing. A formal, written d o c u m e n t or certificate issued bv a Oualified Person in the form and m a n n e r prescribed by this s tandard. It states the condi t ions that the Oualified Person found at the t ime of insnect ion a n d conta ins a nartial list of the S tandard Safety Designat ions na raohrased f rom-NFPA 326. S U B S T A N T I A T I O N : Providing this defini t ion should fulfill the same in ten t of inc lud ing a certificate defini t ion in NFPA 306. Note: some of the words used in this defini t ion were paraphrased from NFPA 306. COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: T h e Commi t tee Rejected this proposal because it felt that the language in Section 6-1 addresses the proposal adequate ly enough . NUMBER OF COMMITTEE MEMBERS ELIGIBLE T O VOTE: 92 VOTE ON COMMITTEE ACTION:



(Log #CP3).

(Log #12) 326- 4 - (1-3 Qualified Person) : Reject SUBMITTER: Robert H. Walker, III, Marine Chemis t Service. InCh R E C O M M E N D A T I O N : Revise defini t ion to read:

"Qualified Person.* A person des ignated in writing such .Ls NFPA Certified Marine Chemist , who is capable, by educat ion, exper ience or specialized training, of per forming specified tasks,...". S U B S T A N T I A T I O N : Without specifying whom shotfld designate (in writing), and their level of educat ion, exper ience or specialized training, industr ies chosen persons may not mee t NFPA's intent. This could be ser ious since occupat ions related to NFPA 326 are extremely dange rous and cur ren t exper ience levels ex tcnd down to h igh school graduates and non-gradua tes with only minutes (i.e., literally less than 1 hr) of in-house training. If the qualifications are in t ended to be subjective (such as in paragraph 8-4, p. 22, in which definitive qualifications are no t requi red to internally inspect a tank after cleaning), t hen there is no reason to even specify a Qualified Person. If the opposi te is true, t hen men t io n in g "NFPA" and "Certified Marine Chemist" would help d isseminate NFPA's intent. If the opposite is trne, ~ NFPA does no t want to limit industr ies ' choice, the phrase "such as NFPA Certified Marine Chemist" could be used. COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: The Commi t tee Rejected dtis proposal. It felt that to modify the defini t ion of the Qualified Person to include ,an NFPA Certificated Marine Chemis t as an example of one conf ined space a tmosphe re test ing sa£ety professional, it would be too exclusive. The d o c u m e n t would become too limiting, and would by defaul t omit many other

ofessionais who may be capable of do ing the testing. BER OF COMMITTEE MEMBERS ELIGIBLE T O VOTE: 22

VOTE ON COMMITTEE ACTION: AFFIRMATIVE: 19 ABSTENTION: 1 NOT RETURNED: 2 Geyer, Lat t imer

EXPLANATION OF ABSTENTION: WiLEY: See my Explanat ion of Abstent ion on Proposal 326-1

(Log #CP3).

(Log #13) 326- 5 - (1-3 Qualified Person) : Reject SUBMITTER= Robert H. Walker, III, Mar ine Chemis t Service, Inc. R E C O M M E N D A T I O N : Revise defini t ion to read:

"Qualified Person.* . . .and certify, in writine, utilizin~ a s tandardized certificate such as the NFPA Marine Chemis t Certificate, tha t certain activities such as entry and ho t work, may proceed in safety us ing the Standard Safety Designat ions in this s tandard." SUBSTANTIATION: Without specifying the form of file written certification, variations are b o u n d to be exper ienced t h r o u g h o u t industry. Tbis can lead to confusion. By m e n t i o n i n g said

296

N F P A 3 2 6 1 A 9 9 R O P

certificate, m o r e control over form s tandardiza t ion (and thus, less confus ion) will be achieved. Also, s ince NFPA 306 is re fe renced in NFPA 326, and since said certificate has a partial list of the same Standard Safety Designat ions pa raphrased f rom NFPA 306, the Marine Chemis t Certificate is a logical and model choice. COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: T h e Commi t t ee Rejected this proposal because of t he fact that in the land-side tank and conf ined space operat ions, there are many fo rms and certificates that are used by industry. Those opera t ions are requi red to conform to OSHA regulations, but certificates vary widely in format . The Commi t t ee did not want to m a n d a t e a "certificate" of any s tandard form, ,and did not want to specifically men t i on any type of certificate by name, with the i n h e r e n t risk of file s tandard becoming exclusive or too l imiting in its requi rements . NUMBER OF COMMITI 'EE MEMBERS ELIGIBLE T O VOTE: 22 VOTE ON C O M M I T T E E ACTION:



(Log #CP3).

(Log #4) 326- 6 - (4-1.2): Accept SUBMITTER: Peter R immel , Marine Chemis ts & Test ing Co , Inc.

I R E C O M M E N D A T I O N : Revise text as follows: ". . .former p rodnc t storage has been el iminated or is no t capable

of regenera t ion toabove permissible exposure levels." SUBSTANTIATION: Con t inued testing is required if the concern is for toxic levels above PEL's more than safe levels which may be genera ted below or to the PEL. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE T O VOTE: 22 VOTE ON C O M M I T T E E ACTION:

AFFIRMATIVE: 20 NOT RETURNED: 2 Geyer, Lat t imer

(Log #14) 326- 7 - (4-1.3): Reject SUBMITTER: Rober t H. Walker, IIl, Marine Chemis t Service, Inc. R E C O M M E N D A T I O N : Revise text to read:

4-1.3 A Oualified Person -lzer-sosm. S U B S T A N T I A T I O N : Consis tency should be mainta ined. This addi t ion will accompl ish consistency. COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: The Commi t t ee rejected this proposal becanse it felt tha t test ing does no t have to be l imited to being pe r fo rmed by a Qualified Person. T he use of tile work

erson " here is generic. BER OF COMMITTEE MEMBERS ELIGIBLE T O VOTE: 22

VOTE ON C O M M I T T E E ACTION: AFFIRMATIVE: 17 ABSTENTION: 3 NOT RETURNED: 2 Geyer, Lat t imer

EXPLANATION OF ABSTENTION: REKUS: Section 4-1.3 addresses personnel responsible for testing

~ otentially hazardous a tmosphe re s within tanks and containers . he proposal sugges ted chang ing the test related to the individual

responsible for pe r fo rming these tests f rom "persons" to "qualified person."

The commit tee ' s decision to Reject "...this proposal because it felt that testing does no t have to be l imited to be ing pe r fo rmed by a Qualified Person..." is perp lex ing since it suggests tha t the commit tee feels that is is no t necessary restrict testing to being pe r fo rmed only by individuals who by educat ion, exper ience or specialized t ra ining are capable of pe r fo rming the task.

The commit tee ' s s t a t emen t that use of tile word person in this context is "generic" creates fu r the r ambigui ty by implying that any person, (i.e., a gener ic person) n o t a pe r son who by educat ion, exper ience or specialized t ra ining is capable of pe r fo rming the task, can make die tests and m e a s u r e m e n t s st ipulated by NFPA 3260

As evidenced by the r equ i rements of Sections 2-2.2, 5-2.1.4.1, 5- 2.1.4.2, 5-2.2.1, 5-2.2.6, 5-2.4.1, 6-2.1.2, 6-2.1.3, 6-2.4.1, 6-2.4.2, 6- 2.4.3, 6-2.4.4, 6-2.5.1, 6-2.5.2, and 6-2.5.3, NFPA 326 relies extensively on the results obta ined f rom a tmospher ic mon i to r ing to establish an acceptable level of risk.

Since the reliability of any test data is highly d e p e n d e n t on the individual mak ing tile measu remen t , it would seem reasonable and p r u d e n t to assure that individuals who make these m e a s u r e m e n t

possess both the knowledge and skills necessary to assure that the m e a s u r e m e n t s are reliable and valid.

Due to the large n u m b e r of variables associated with air moni tor ing , a significant degree of professional j u d g m e n t is requi red to obtain mean ingfu l results. Even if an individual is t ra ined in the use of an ins t rument , knows how to in terpret its readings, and knows its l imitations - as required by Section 4-1..$ - that pe r son may still lack the requi red professional j u d g m e n t .

Based on my background, educa t ion and exper ience, and cons ider ing the degree of emphas i s placed on air mon i to r ing by NFPA 326, 1 feel that no t st ipulat ing that testing be pe r fo rmed by a "qualified person" results in acceptable risk be ing posed to workers, dye fire service communi ty , and the public.

WILEY: See my Explanat ion of Abstent ion on Proposal 326-1 (Log #CP3)o

WILLWERTH: This r e c o m m e n d a t i o n should be Accepted. Tes t ing shou ld never be allowed by anyone not exper ienced with both the ins t rumenta t ion and procedures covered by the proposed s tandard. These qualities are inc luded in the defini t ion of the Qualified Person in this p roposed s tandard.

(Log #15) 326- 8 - (4-1.3): Reject SUBMITTER: Robert H. Walker, 111, Marine Chemis t Service, Inc. RECOMMENDATION: Revise text to read:

"4-1.3 . . .and its l imitations, such as NFPA Certified Marine Chemist". S U B S T A N T I A T I O N : Without specifying whom shou ld cont inue testing, and their level of educat ion, exper ience or specialized training, industries ' chosen persons may not mee t NFPA's intent. This could be serious s ince occupat ions related to NFPA 326 are extremely dange rous and cur ren t exper ience levels ex tend down to h igh school g radua tes and non-graduates with only minu tes (i.e., literally less t han 1 hr) of in-house training. If no qualifications are in t ended (such as unde f ined "Persons", tha t is, no t even a Qualified Person) , t hen there is no reason to specify any kind of training, etc. If the opposite is true, t hen m e n t i o n i n g "NFPA" and "Certified Mar ine Chemist" would help d isseminate NFPA's intent. If the opposi te is true, bu t does not want to limit industries ' choice, the phrase "such ~.s a NFPA Certified Marine Chemist" could be used . COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: The Commi t t ee Rejected this propos,'d. It felt that to modify Section 4-1.3 to include an NFPA Certificated Marine Chemis t as an example of one conf ined space a tmosphe re test ing safety professional, it would be too exclusive° The d o c u m e n t would become too limiting, and would by defaul t omi t many o ther professionals who may be capable of do ing the testing. NUMBER OF COMMITTEE MEMBERS ELIGIBLE T O VOTE: 22 VOTE ON COMMITTEE ACTION:



(Log #CP3).

(Log #CP6) 326- 9 - (4-1.4): Accept SUBMITTER: Technical Commi t t ee on Tank Leakage and Repair Safeguards R E C O M M E N D A T I O N : An an Appendix i tem 4-1.4 to read:

"an appropr ia te calibration gas m e a n s a calibration gas that has a certified accuracy of + or - 5 percent ." S U B S T A N T I A T I O N : The Commi t t ee felt dais was necessary in order to conform with In s t rumen t Society of America r e c o m m e n d a t i o n s . COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE T O VOTE: 22 VOTE ON COMMITTEE ACTION:



(Log #CP3).

297

NFPA 326 - - A99 ROP

(Log #5) 326- 10 - (5-2.2.3): Accept in Principle SUBMITTER: Peter R immel , Marine Chemis ts & Test ing Co., Inc. RECOMMENDATION: Revise text as follows:

"The iner t gas shall be in t roduced into the tank or conta iner t h rough a pipe or hose ex tend ing to a po in t ~c.~r "..~.z ~ ' ~ m cf P:c "..-~.P. cr cc .~m'aer az ~ r :;;?-7 f rom ~ near as nossible to the por t ion of the tank where repairs or o the r activities will be conducted . Samol in~ of the internal a t m o s n h e r e shall be m a d e at one or more ooints as far away f rom die location where the iner t ga~ is in t roduced to assure tha t the ent ire tank is below m a x i m u m nermissible 0-2 levels reoui red by this s tandard. T he inert gas shall be introduced. . ." S U B S T A N T I A T I O N : It is preferable to in t roduce the inert gas as close to the work area as is practical. By do ing this, the lowest a m o u n t of residual 0 2 will exist at the area of greatest danger , the area where the ho t work is taking place. By us ing this p rocedure , the safest condi t ion can be assured. COMMITTEE ACTION: Accept in Principle. COMMITTEE STATEMENT: T he Commi t tee a g r e e d to Accept in Principle this proposal . T h e Commi t t ee feels that the p rocedure written in 5-2.2.3 is preferable to ensure that the ent ire tank or conta iner is proper ly inerted. With respec t to sampl ing , the n u m b e r a n d Iocadon of sampl ing points is addressed in 4-1.5. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMIT T E E ACTION:

AFFIRMATIVE: 20 N O T RETURNED: 2 Geyer, Lat t imer

(Log #1) 326- 11 - (5-2.2.5): Accept SUBMITTER: Martin H. Finkel, Environmenta l Safety & Health of Alaska RECOMMENDATION: Revise text as follows:

".. .area for rapid c-~pc:'=*5~: subl iqlat ion." S U B S T A N T I A T I O N : Solid CO 2 does no t evaporate; it sublim0,tes f rom the solid to the gaseous form directly. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:


(Log #CP7) 326- 12 - (Chapter 6): Accept SUBMITTER: Technica l Commi t tee on Tank Leakage and Repair Safeguards R E C O M M E N D A T I O N : Revise Chapte r 6 as shown in the draft shown a t the end o f this report . SUBSTANTIATION : T h e Commi t t ee felt tha t chan~es were necessary in the des ignat ions is o rder to be in c o m p h a n c e with 29 CFR 1910.146, as well as indus t ry practice. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 V O T E ON C O M M I T T E E ACTION:


EXPLANATION O F ABSTENTION: WILEY: See my Explanat ion of Abstent ion on Proposal 326-1

(Log #CP3). WILLWERTH: This r e c o m m e n d a t i o n shou ld be Rejected° The

p roposed revision o f Chapte r 6 includes sanc t ion ing p rocedures tha t would allow hot work directly on the steel shell of gasol ine storage tazak, for example , with an explosive a t mosphe re above the liquid gasol ine in the tank to be repaJred. This no t only leaves unacceptab le marg ins of safety, it defies c o m m o n sense for a fire protec t ion s tandard . See NFPA 306. Also, see my Explanat ion of Abstent ion on Proposal 326-16 (Log #CP2).

(Log #16) 326- 13 - (6-1(a)): Reject SUBMITTER: Rober t H. Walker, III, Mar ine Chemis t Service, Inc. RECOMMENDATION: Revise text to read:

"6-1 A Qualif ied Pe r son . such as a NFPA Certified Marine shall inspect.., and certify, in writing,

s tandardized certificate such as the NFPA Marine Chemis t Certificate. that..." S U B S T A N T I A T I O N : Capital letters indicate a dried position and emphas i s .

Reasons for o ther underscores o f NFPA Certified Marine Chemis t and NFPA Mar ine Chemis t Certificate have been previously substant ia ted. COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: T h e Commi t tee Rejected this proposal. It felt tha t to modify Section 6-1 to include an NFPA Certificated Marine Chemis t as an example of one confined space a t m o s p h e r e test ing safety professional, would be too exclusive. Th e Commi t t ee appl ied the same r e a s o n i n g to the r e c o m m e n d a t i o n for the use of a "s tandard certificate." T h e d o c u m e n t would become too limiting, and would by defaul t omi t many o ther professionals who may be capable of do ing the testing, as well as the many forms of certificates permi t ted for use. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:



(Log #CP3).

(Log #6) 326- 14 - (6-2.6.2): Accept SUBMITI'ER: Peter R immel , Mar ine Chemis ts & Test ing Co., Inc.

I R E C O M M E N D A T I O N : Revise text as follows: ".. .and shall be cleaned ~= =uc. t'. a m-~'::.c= == to. prc- 'cat =p:a-k~ ~:

glag f rom ~ c ~ t -vc=k ~pcr:.'.2:.:.: f rom bc!z.g ~ : r c : ; : ~r ~ rcppc~ into..?.'..~zr pc.~!c.z.z ~.f =.tzz =pz.ze. a sufficient dis tance in all direct ions inc luding below the area of the ho t work so that sparks Or slag will no t d rop or be thrown into unc l eaned areas of the

The area shall be cleaned to meet.. ." S U B S T A N T I A T I O N : The presen t writing is unclear and ambiguous . The re is no cause and effect between how a space is c leaned and where the slag or sparks may go at some later time. The c leaning crew is gone du r ing the ho t work, and canno t prevent the sparks f rom go ing anywhere. The in tent of dais is u n c h a n g e d , but the verbiage now spells ou t the ex ten t of c leaning pr ior to approval for ho t work. (The original is f rom NFPA 306 which also mus t be changed in the future.) C O M M r U r E E ACTION: Accept. NUMBER OF COMMITrEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMI'I~I'EE ACTION:

AFFIRMATIVE: 19 ABSTENTION: 1 N O T RETURNED: 2 Geyer, Latf imer

EXPLANATION OF ABSTENTION: WILEY: See my Explanat ion o f Abstent ion on Proposal 326-1

(Log #CP3).

(Log #20) 326- 15 - (6-2.6.3): Reject SUBMITTER: EdwardJ . Wiliwerth, Mar ine Chemis t Assn. R E C O M M E N D A T I O N : Revise text to read:

6-2.3.2 Hot work shall be permi t ted to be pe r fo rmed on tanks or conta iners partially filled with water. The surface level of the water shall be main ta ined at a m i n i m u m of 0.9 m (3 ft) above the area where the ho t work is being per formed. |lq addit ion, the vaoor soace above the water level mus t be less than 10 oercent of the LEL. S U B S T A N T I A T I O N : The draft l anguage would allow ho t work on the outs ide of a vessel that could conta in an explosive a tmosphere above the water level. T h o u g h ho t work conduc ted below the level of t he water would prevent ignition, mistakes in establ ishing tile level of the water, or changes in the water level migh t result in an explosion. The p roposed change , used in the mar ine industry, establishes a more adequa te marg in of safety. COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: T h e Commi t tee Rejected this

roposai because it felt it is contrary to the defini t ion of Limited ot Work Allowed. See Section 6-1 of the full text of NFPA 326

which follows. Industry m e m b e r s repor ted tha t ho t work is rout inely pe r fo rmed on tanks in which the vapor space above the liquid is no t less than 10 pe rcen t of the LEL (for example , ho t tapping) . The proposal is contrary to the defini t ion of Limited Hot Work Allowed.

2 9 8

N F P A 3 2 6 - - A 9 9 R O P

NUMBER OF COMMrITEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 17 ABSTENTION: 3 NOT RETURNED: 2 Geyer, Lattimer

EXPLANATION OF ABSTENTION: REKUS: This proposal, which suggested adding a requi rement

that "...the vapor space above the water level must be less than 10 percent of the LEL...," was Rejected because it was viewed as being "...contrary to the definit ion of Limited Hot Work Allowed..." and because some "...industry members repor ted that ho t work is routinely performed on tanks in which the vapor space above the liquids is not less than 10 percent of the LEL..."

First, I believe that the suggested proposal is consistent with the definition of "Limited H o t W o r k Allowed," but it does require an additional precaution aimed at increasing the margin of safety.

Second, without taking exception to these industry members ' experience, I believe that if the experience of the maritime industry were examined, we would f ind things to be very different. Specifically, I believe that such an evaluation would reveal a considerable incident record with respect to unp lanned fires and deflagrations in containers where the vapors space were no t considered to be a hazard. Moreover, it is likely that many of these events may have been prevented if the vapor space had been limited to less than 10 percent of the LEL.

Given the vagaries of human nature and industrial work practices, I do not believe that it is reasonable and p ruden t to allow vapor space a tmospheres to exceed 10 percen t of the LEL.

In this light, and based on my background, education and expertise, I believe that not limiting the vapor space to a level less than 10 percent of the LEL is likely to result in situations where unacceptable risk might be posed to workers, the fire service community, and the public.

WILEY: See my Explanation of Abstention on Proposal 326-1 (Log #CP3).

WILLWERTH: This recommenda t ion should Accepted in that it is used in NFPA 306, the oldest s tandard covering similar activities on marine steel product storage and transportat ion vessels, and ensures adequate margins of safety for the covered procedures. NFPA 306 also has a newly accepted standard safety designation of Safe for Limited Hot Work (the inspiration for the language in dais proposed standard) that still includes dais restriction.

(Log #CP2) 326- 16- (6-2.7.3): Accept SUBMITTER: Technical Commit tee on Tank Leakage and Repair Safeguards RECOMMENDATION: Revise 6-2.7.3 to read:

"Hot work shall be permit ted on tanks or containers that are partially filled with J j _ ~ . The surface level of the liquid shall be maintained at a min imum of 0.9 m (3 ft) above the area where the hot work is being performed." SUBSTANTIATION: The Commit tee felt that water should not be the only liquid specified for this operation. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 16 NEGATIVE: 1 ABSTENTION: 3 NOT RETURNED: 2 Geyer, Lattimer

EXPLANATION OF NEGATIVE: SIEGEL: Willie I agree that there are liquids, o ther than water,

wlfich would provide safe condit ions when working on a partially filled tank, I do not agree that this is the case with ~ liquid. There are some petroleum products, and certainly other hazardous substances, for wlfich dais would not be a safe practice.

If the intent of the proposal is to allow work on a tank without emptying and cleaning it and then refilling with water, then the propert ies of the stored liquid for which this is allowed should be specified. Tiffs may include the flash point or f lammable liquid class, physical propert ies of the liquid, o ther hazards associated with the product, etc.

Considering the wide range of materials stored in tanks, allowing dais practice in all cases does not adequately protect the employees, facility, or community. EXPLANATION OF ABSTENTION:

BRANNAN: Lack of technological expertise. WILEY: See my Explanation of Abstention on Proposal 326-1

(Log #CP3).

WILLWERTH: This recommendat ion should be Rejected in that it will allow hot work directly on the outside a tank with flammable or combustible product in it, even if the vapor space above the product was in the middle of the explosive range. The only safety margin would be inaccurately establishing the liquid level in the tank and holding the hot work to below the level of the flammable or combustible product in the tank. NFPA 306, the oldest standard covering similar activities on marine steel product storage ,and transportat ion vessels, does not allow dais practice with good reason: there is a history of failures in the safety of the allowance of this practice that forced its prohibi t ion from accepted since 1980.

(Log #7) $26- 17- (7-2.3): Accept SUBMITTEI~ Peter Rimmel, Marine Chemists & Testing Co., Inc. RECOMMENDATION: Revise text as follows:

"ff no way exists, an opening.. .shall be cut i~ in to the tarik. The section to be..." SUBSTANTIATION: Grammar correction which now agrees with 7-4.1. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 20 NOT RETURNED: 2 Geyer, Lattimer

(Log #CP5) 326- 18- (7-3.2): Accept SUBMITTER: Technical Commit tee on Tank Leakage and Repair Safeguards RECOMMENDATION: Add a s tatement to 7-3.2 to read:

"where natural ventilation is inadequate to control vapors, cont inuous mechanical ventilation shall be used while the space is occupied." SUBSTANTIATION: Some tanks do not have natural ventilation because of their location or configuration. For example, natural ventilation is not effective in an underground tank. CoMMrFrEE ACTION: Accept. NUMBER OF COMMITrEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITI 'EE ACTION:


EXPLANATION OF ABSTENTION: WILEY: See my Explanation of Abstention on Proposal 326-1

(Log #CP3).

(Log #8) 326- 19- (8-2.2): Accept SUBMITTER: Peter Rimmel, Marine Chemists & Testing Co., Inc.

I RECOMMENDATION: Add the following text: "Selection of a cleaning procedure shall take into consideration

the chemical nature and characteristics of the residue=, and characteristics o f the new material to be stored in the tank." SUBSTANTIATION: Some cleaning agents, if left in the storage tanks, may be incompatible with the new product to be placed into the tank, and this must be considered when tank cleaners choose cleaning products. (Ex: Dregs of an acid wash to eliminate one product would be very harmful to an organic product next put into the tank or piping.) COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:


(Log #3) 326- 20 - (A-I-2 (New)): Reject SUBMITrER: Martin H. Finkel, Environmental Safety & Health of Alaska RECOMMENDATION: Add tile following."

Training of Testin~ Personnel. At a minimum, a course such as the Shlnvard Comneten t Person

course taught bv the NFPA is r ecommended . SUBSTANrrlATION: This gives industry some guidance as to the level o f training considered adequate for persons conduct ing tests inside tanks or containers, and supports other NFPA program a r e a s .

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N F P A 3 2 6 1 A 9 9 R O P

COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: T he Commi t t ee Rejected this proposal because it felt tha t to men t i on any one specific t ra ining p rogram by n a m e may serve to exclude o ther qualif ied mad capable t ra ining p rograms that are offered to industry by organizat ions o ther than NFPA. NUMBER OF COMMIT17EE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMIT T E E ACTION:


(Log #2) 326- 21 - (A-l-3): Reject SUBMITTER: Martin H. Finkel, Environmenta l Safety & Health of Alaska RECOMMENDATION: Add the following text:

"Examnles of such persons include NFPA Certificated Marine

S U B S T A N T I A T I O N : Since dais is an NFPA standard, men t i on of professionals certificated by NFPA for precisely this type of e~dua t ion is no t only appropr ia te to give indust ry a guide for the level of qualification required, bu t lends suppo r t to o ther NFPA progrmn areas. COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: T h e Commi t t ee Rejected dais proposal because it felt that to include a r e c o m m e n d a t i o n for one conf ined space a t m o s p h e r e test ing safety professional would be too exclusive. The r e q u i r e m e n t would be too limiting, and omit many o ther professionals who may be capable of do ing the testing. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:


EXPLANATION O F ABSTENTION: WILEY: See my Explanat ion of Abstent ion on Proposal 326-1

(Log #CP3). WILLWERTH: This r e c o m m e n d a t i o n shou ld be Accepted.

T h o u g h the commi t tee stated tha t "a r e c o m m e n d a t i o n for one conf ined space a t m o s p h e r e test ing professional would be too exclusive", the commi t tee has rejected all professionals sugges ted without a t t empt ing to p roduce or include a comple te list. It rejected a comprehens ive list provided as a p roposed append ix addit ion. Also, see my Explanat ion of Abstent ion on Proposal 326- 24 (Log #19). It is unc lear why the commi t tee would a t t empt to shield the inexper ienced owner, or owner with l imited h u m a n resources, or owner seeking a third party exper t for [iabUity reasons, or author i t ies hav ing ju r i sdmt ion f rom expert ise tha t would guide t h e m t h r o u g h this potentially very dange rous process. NFPA Certificated Marine Chemis ts are clearly the best t ra ined to do so, bu t the commi t t ee has rejected the comprehens ive list inc luded in r e c o m m e n d a t i o n 326-24, neutral iz ing m u c h of the potential value o f the s tandard for the pe t ro leum storage conunun i ty and the authori t ies having jur isdict ion. It is in the best interests of the user of this d o c u m e n t to have a list of such expertise, even if possibly imperfec t or incomplete . It is, after all, in tile append ix of the d o c u m e n t and not mandatory. Should others be worthy of be ing inc luded on such a list, they can be added at a later date, at least allowing considerat ion o f the proven individuals on the p roposed list.

(Log #17) 326- 22 - (A-l-3): Accept in Part SUBMITTER: Rober t H. Walker, 111, Marine Chemis t Service, Inc. R E C O M M E N D A T I O N : Revise text to read:

"...selection of .Qualified Persons shou ld be..." "...aspects of the _Qualified Pe r sons educat ion. . ." "...within the scope of this s tandard. A NFPA Cert if ied Marine

Chemis t meets the in ten t of this requ i rement" . SUBSTANTIATION: Reasons for underscores previously substant ia ted. COMMITTEE ACTION: Accept in Part. COMMITTEE STATEMENT: T h e Commi t tee agreed to Accept in Part this proposal, and capitalized the words "Qualified Person" wherever they appear in the s tandard. The Commi t t ee did not agree to accept the r e c o m m e n d a t i o n of inclusion o f the reference to an NFPA Certified Mar ine Chemist , because to do so would the make the d o c u m e n t potentially restrictive, or too limiting, and migh t serve to exclude others who may be capable of pe r fo rming conf ined space a tmospher ic testing.

NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: VOTE ON COMMITTEE ACTION:


EXPLANATION ( IF ABSTENTION: WILEY: See my Explanat ion of Abstent ion on P~oposal 326-1

(Log #CP3).

22

(Log #18) 326- 23 - (A-l-g): Reject SUBMITTER: J o h n E Rekus, Riderwood, MD RECOMMENDATION: Revise text to read:

A-l-3 Individuals possessing the skills and exper ience necessary to act as qualif ied persons may be employees of the tank owner or third parties such as Certified Industrial Hygienists. Certified Safety Professional or Certified Marine Chemists . [the under l ined port ion is an addit ion] S U B S T A N T I A T I O N : None. COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: The Commi t tee Rejected dfis

roposal. It felt tha t to include a reference to Certified Industrial ygienists or NFPA Certificated Marine Chemis ts as examples of

conf ined space a tmosphe re test ing safety professionals would be too exclusive. The d o c u m e n t would become too limiting, and would by defaul t omi t m a n y o ther professionals who may be capable of do ing the testing. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:

AFFIRMAT WE: 18 ABSTENTION: 2 NOT RETURNED: 2 Geyer, Lat t imer


(Log #CP3). WILLWERTH: This r e c o m m e n d a t i o n sbould be Accepted. See

my Explanat ion of Abstent ion on Proposal 326-21 (Log #2).

(Log #19) 326- 24 - (A-l-3): Accept in Principle in Part SUBMrrTER: EdwardJ . Willwerth, Marine Chemis t Assn. RECOMMENDATION: R e c o m m e n d the following ,as subst i tut ion text for Appendix material:

A-I-3 Qualified Person. The t ra ining and exper ience of workers selected to act as Qualified Persons mus t be sufficient to accurately assess the condi t ion o f the tank and correctly apply the Standard Safety Designat ions in this s tandard. In the majority of instances in refineries, chemical plants and in many storage terminals where they are deal ing with the safety of their own employees, tile Qualified Person will be an employee of tile facility, tank or conta iner owner.

In some instances, however, it may be the preference or in the best interests of tl~e tank or conta iner owner to have a third party act as Qualified Person. (For example , when a terminal hires an outside tank c leaning company to prepare a tank for outside mechanica l contractors) . When selecting or reviewing the credenti :ds of a third party Qualified Persons in such a situation~ there are several factors that should be of concern to the tank or conta iner owner:

exper ience with the design, funct ion a n d operat ion of the tank or conta iner types inspected.

o exper ience with the physical, chemical and hazardous propert ies of the materials previously stored.

* exper ience with the industrial activities to be applied widun the tank or container.

o exper ience with the ins t rumenta t ion and inspect ion techniques used in de t e rmin ing the tested criteria associated with the Standard Safety Designations.

o familiarity with applicable indust ry and federal safety s tandards and guidel ines m e n t m n e d in this s tandard.

* (if no t an employee of the tank owner) possession of professional and general liability insurance .

The re are several sources of third party exper ts who may successfully serve as third-party Qualif ied Persons, in alphal)etical order by designat ion:

* Amer ican Pe t ro leum Insti tute Certified Aboveground Storage Tank Inspectors [recognized for expert ise in aboveground storage tank design, s t ructure, funct ion , and opera t ion as it relates to API Standard 653, Tank Inspect ion, Repair, Alterat ion an d Recons t ruc t ion Contact: Amer ican Pe t ro leum Institute,

300

N F P A 3 2 6 ~ A 9 9 R O P

Aboveground Storage Tank Inspector Certification Program, 1220 L Street, NW, Washington, DC 20005 tel: (202) 682-8161.

American Board of Industrial Hygiene Certified Industrial Hygienists [especially t rained in assisting with recognition, evaluation and control of exposure to potentially toxic materials 3reviously stored in the vessel or used during work in the tank. and in eliminating or controll ing o ther common workplace stresses. Contact: PUnerlcan Board of Industrial Hygiene, 6015 West St., Josepb, Suite 102, Lansing, Micbigml 48917-3980 tel: (517)321- 2638.]

o National Fire Protection Association Certificated Marine Chemists [especially training in dealing with fire and explosion prevention and hot work safety involving storage vessels, and in assisting with recognition, evahmtion and control of exposure to potentially toxic materials previously stored in the vessel or used during work in the tank. Contact Information: National Fire Protection Association, Marine Field Service, ! Batterymarch Park, Quincy, Massachusetts, 02269 tel: (617) 984-7499.]

o Board Certified Safety Professionals [especially trained and exper ienced to create or develop procedures, processes, standards, specifications, and systems to achieve optimal control or reduction of the hazards and exposures which may harm people, property, a n d / o r the environment. Contact: Board of Certified Safety Professionals, 208 Burwash Avenue, Savoy, Illinois 61874 tel: (217 359-9263. ] SUBSTANTIATION: The safety of confined space entry in potentially dangerous spaces is now federally regulated (29 CFR 91910.148). API estimates that 85 to 95 percent of America's one- million aboveground storage tanks are in facilities that must use outside labor (contractors) to clean and repair them. Those facilities unable or unwilling to accept responsibility for acting as qualified persons for subcontractors and outside labor are given no guidance or resources toward f inding third-party qualified persons in the draft document . The proposed text gives those seeking third-party expertise those resources. COMMITTEE ACq'ION: Accept in Principle in Part. COMMITTEE STATEMENT: The Committee agreed to Accept in Principle in Part this proposal. After extensive and thoughtful deliberations, the Committee felt that the first two paragraphs of the proposal are adequately addressed within A-I.3. The inclusion of any list or source of third party experts, even in an Appendix and regardless of how complete it may seem, would still be too limiting or exclusive, and may serve to exclude o ther individuals who may be trained and exper ienced in performing atmospheric testing in confined space. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 17 ABSTENTION: 3 NOT RETURNED: 2 Geyer, Latfimer

EXPLANATION OF ABSTENTION: REKUS: This proposal pertains to providing source information

to interested individuals who might want to secure the services of a third party to act as a "qualified person."

Considering the complex nature of both NFPA 326 and related standards such as the OSHA permit-required confined space standard as well ,as the responsibility imposed on "qualified persons," it seems almost a public disservice not to provide third party source information to interested individuals.

While I am sensitive tO members concerns about appear ing to be "°..too limiting or exclusive..." the proposal is neutral in tone and imparts no sense of limitation or any hint of exclusivity. Ahbougb it is clearly impor tant that NFPA not appear to be offering an endorsemen t in this context, it is equally clear that consideration must also be given to what acdon will result in the greater public good°

Based on my background, education and experience, I believe that the benefits to the public interest derived from making third party source information available would far outweigh the committee 's concerns that such information might be too fimiting or exclusive.

WILEY: See my Explanation of Abstention on Proposal 320-t (Log #CP3),.

WILLWERTH: This recommendat ion should be Accepted in its entirety. See my Explanation of Abstention on Proposal 326-2; (Log #2). The Committee rejects suggestions for limiting recommendat ions for one safety professional on one hand and reiects recommendat ions for all recognized safety professionals on the other for the same reason. Clearly they are not interested in assisting the safety of dtis process for any user of the proposed standard.

(Log #CP4) 326- 25 - (A-4-1.1): Accept SUBMITTER: Technical Commit tee on Tank Leakage and Repair Safeguards RECOMMENDATION: Add an Appendix item A-4-1.1 to read:

"it is r ecommended that continuous moni tor ing be performed inside the tank or container when personnel are inside." SUBSTANTIATION: Commit tee feels that cont inuous monitor ing must take place in some instmaces, in accordance with 29 CFR 1910.146. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE T() VOTE: 22 VOTE ON COMMITTEE ACTION:



(Log #CP3).

(Log #9) 326- 26 - (A-4-3.1): Accept in Principle SUBMITTER: Peter Rimmel, Marine Chemists & Testing Co., l nc RECOMMENDATION: Revise text ,as follows:

"Where concentrat ion of oxygen in a tank or container is less dmn about g.L~ percent by volume..." SUBSTANTIATION: Oxygen readings inhibit accurate LEL readings at concentrat ions as high as 12 to 14 percent. The 5 percent figure stated is too low to fit the discussion as it continues m the paragraph. COMMITTEE ACTION: Accept in Principle. COMMITTEE STATEMENT: The Commit tee agreed to Accept in Principle this proposal, and the language in A-4.3.1 was changed to reflect the concept that low oxygen concentrat ion may inhibit accurate LEL readings. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:



(Log #CP3).

(Log #CP1 ) 326- 27 - (Entire Document) : Accept SUBMITTER: Technical Commit tee on Tank Leakage and Repair Safeguards

I RECOMMENDATION: Completely revise NFPA 326, Standard Procedures for the Safe Entry of Underground Stowage Tanks, 1993 edition and include port ions of NFPA 327, Standard for Cleaning of Safeguarding Small Tanks and Containers Without Entry which is being withdrawn. SUBSTANTIATION: The Commit tee felt that much of the material contained in NFPA 327 was repetitive of the subject matteJ in NFPA 526. The Commit tee also condensed many topics in NFPA 327 for incorporat ion into NFPA 326. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:



(Log #CP3).

301

N F P A 3 2 6 1 A 9 9 R O P

N F P A 326

S t a n d a r d f o r the S a f e g u a r d i n g o f T a n k s a n d C o n t a i n e r s f o r Entry, C lean ing , o r R e p a i r

1999 Edi t ion

NOTICE: An as te r i sk (*) f o l l owing t h e n u m b e r or l e t t e r d e s i g n a t i n g a p a r a g r a p h i nd i ca t e s t h a t e x p l a n a t o r y m a t e r i a l on d i e p a r a g r a p h can be f o u n d in A p p e n d i x A.

I n f o r m a t i o n on r e f e r e n c e d p u b l i c a t i o n s can be f o u n d in C h a p t e r 9 a n d A p p e n d i x B.

F o r e w o r d

E x t r e m e cau t i on m u s t be used w h e n work is p e r f o r m e d on a t a n k or a c o n t a i n e r t h a t h o l d s or has h e l d f l a m m a b l e , combu s t i b l e , o r o t h e r h a z a r d o u s subs tances . T h e s a m e c a u t i o n a p p l i e s to t anks or c o n t a i n e r s d l a t c o n t a i n vapors r e l a t e d to t he subs t ances t h a t a re s t o r e d or were p rev ious ly s t o r e d in t he t a n k or c o n t a i n e r . Before any work is p e r f o r m e d on a t a n k or a c o n t a i n e r t h a t ha s h e l d f l a m m a b l e , c o m b u s t i b l e , o r o t h e r h a z a r d o u s subs tances , the t ank or c o n t a i n e r m u s t be m a d e safe . T h e r e f o r e , i t is i m p o r t a n t d l a t d ie p e r s o n s c o n d u c t i n g f i le w o r k h a v e a t h o r o u g h u n d e r s t a n d i n g of t he f o l l o w i n g :

1-2.2 Such p r o c e d u r e s sha l l ~ e r m i t repa i r , h o t work, or o t h e r work t h a t m i g h t c rea t e a p o t e n t i a l n re , exp los ion , or o t h e r hazard .

I-3 Units .

1-3.1 Met r ic un i t s o f m e a s u r e m e n t in th i s s t a n d a r d are in a c c o r d a n c e wi th t he m o d e r n i z e d m e t r i c sys tem knowr~ as the I n t e r n a t i o n a l System of Llnits (SI).

1-3.2 If a va lue for m e a s u r e m e n t as p r o v i d e d in t i l ls s t a n d a r d is fo l lowed by an e q u i v a l e n t va lue in o t h e r uni ts , t he f irst s t a ted ~ d u e is to be r e g a r d e d as t he r e q u i r e m e n t . A g iven e q u i v a l e n t value m i g h t be an a p p r o x i m a t i o n .

1-4 Def in i t i ons . For d i e p u r p o s e of th is s t anda rd , d i e fo l lowing t e r m s sha l l have d~e m e a n i n g s g iven below.

A d j a c e n t Spaces . T h o s e spaces in a l l d i r e c t i o n s f rom subjec t space , i n c l u d i n g all po in t s o f con tac t , c o m e r s , d i agona l s , decks, t a n k tops, a n d b u l k h e a d s .

A p p r o v e d . * A c c e p t a b l e to the a u t h o r i t y h a v i n g j u r i s d i c t i o n .

A u t h o r i t y H a v i n g J u r i s d i c t i o n . * T h e o r g a n i z a t i o n , office, or i nd iv idua l r e s p o n s i b l e for a p p r o v i n g e q u i p m e n t , an in s t a l l a t ion , or a p r o c e d u r e .

B o n d m T h e p e r m a n e n t j o i n i n g of me ta l par t s to f o r m an (a) C h a r a c t e r i s t i ~ of d i e s u b s t a n c e t h a t is s t o r ed or was , ." ~: . . . . x.. ," ! . . . . . . ". • "ou ~ • - _ _ ~ . • e l e c t n c a u y c o n o u ~ h a m m a t v~u e n s u r e e lec t r i ca l c o n t i n u i t y Drew sly s t o r e o in m e t a n k or c o n t m n e r . : . , ~ . .

" " a n d t he c a p a c l ~ 6 c : ' ~ u c t safe ly any c u r r e n t l ikely to be imposed .

(b) P o t e n t i a l h e a l t h a n d safety r isks a s soc i a t ed widl t he work to ~ _ . ~ . " . f ~ ' ~ . . . . . . . . . . . be c o n d u c t e d t ~ o m o u s t f l ~ G~lg,~!t~cator . An i n s t r u m e n t t h a t s a m p l e s a i r a n n

i n d i c a t ~ t l ~ . a r e a n y c o m b u s t i b l e vapors p resen t . S o m e un i t s It~ka~tate th c rage of t he lower exp los ive l imi t of the (e) P r o p e r p r o c e d u r e s fo r s a f e g u a r d i n g t h e t a n k or c o n t a i n e r . i ts ~ d ~ ~ ~ . . . ~

p r i o r to c o n d u c t i n g t he work aar . . . ~ m i x t u r e . :-'~..-'.#~" ~ . 4 ~ , . ~ ~.~.,.~ • .:~:" . . . .

• • • .~g~" " "n dev ine t h a t is i n t e n d e d to c o n t a i n a n a c c u m u l a t a o n A l t h o u g h d l e r e is a wide r a n g e of work t h a t is p e r f o r m e d on a ". ~ ~ x ~ . . . . . . . . . • ., . , , .~ ~, t • , o I llaZ~-t~.t~uff~unstances t l l a t is t oo smal l t o r n u m a n en t ry or n a s a hang o r c o n t a i n e r , u u s s t a n a a r o p r o v t a e s m e haste p r o c e o u r e s - - ~ 7 . ,

n e c e - to safe-- a r d a t a n k o r ~ :onta iner - r i o t to e n t r y or c a p a c l r ~ l g ~ t can be ef fecuvely a n d safely c l e a n e d w i t h o u t h u m a n y gu V ~ ~ ... p e r f o r m i n g work• T h e s teps to s a f e g u a r d a t a n k or c o n t a i n e r a re "~:~:!$-..::::,. '~S:'~s d e s c r i b e d in th i s d o c u m e n t in a log ica l o r d e r T h e r e f o r e , the u s e r :~"~-'.~':~.. -"-$~::" is e n c o u r a g e d to rev iew the e n t i r e c l o c u m e n t be fo re p r o c e e d i n g "% ":~.: .~. .~bl,~;-~'Gas (Flammal~le V a p o r s ) . Any s u b s t a n c e t h a t exists In

.., - - ,. . . . .--.'.: tx~_-xtmmans s ta te a t n o r m a t a t m o s p n e n c t e m p e r a t u r e a n n o re s su re wire s a l e g u a r t u n g a c u v m e s . -.~ ..r.:.---.,~.-~.m=.- . . . r • ::4.'-x,, "~<,~ad t [ ~ is c a p a b l e of b e i n g i g n i t e d a n d b u r n e d w h e n m i x e d with

. ~-.:.-'..'~, ~:s . . . . . . d i e ro e r ro o r t i ons of a~r ox en or o t h e r ox id i ze r Th i s s t a n d a r d d o e s n o t c o n t a i n all o f d i e de ta i l s nece~'td'.'-":...::'~.:'.-'i ~':.-'~. P P P P ' Yg ' " . . . . . . . • ~. ,!:.'~- ,.:~. ~-~ p e r f o r m the a c t i v m e s d e s c r i b e d in th i s d o c u m e n t . A I ~ f ~:; : ~ " Sub . . . .

. . . . . " :* .'..~x.~- "-';.~, ~ t H a z a r a o u s s t ance . A s u b s t a n c e t l la t is c a p a b l e o f c r e a t i n g r e f e r e n c e d o u b h c a u o n s t h a t of fer i n f o r m a t i o n relat~."~:.~os#~... '~.?.!~ . . . . . . : ? .~ . . . . . . . . . . . . . ~ . . . . . . . . . . . . . ~ : ~ . ~ " "-'.~..¢.~ h a r m to p e o p l e , m e e n w r o n m e n t , or p rope r ty , l i l e oanl~ers may a c n w u e s is I u r m s u e o in LAlaoter ~ a n n ~DDenu lx D. ....~+.~x..~., x:.:::::-~-%, . . . . . . . . . .~ . .

.. ~ . .x.~,~- a r i se f r o m b u t a re n o t h m i t e d to tox ic i ty r eacuv i ty i gmub ih ty , or • .:~'. ~.q, .f-::::::=~-- . . . . . C h a p m r 1 G e n e r a l Prove" • " ~ g . ~ . . . ~,.~ ~. "::->X~:?.~ ..:,~.~ c o r r o s m t y . A. hazardous , s u b s t a n c e i n c l u d e s c o m b u s u b l e a n d

~ ~ ! ~ ~-"-:~ f l a m m a b l e hqu lds , a n d f l a m m a b l e gases.

1-1.2" Th i s s t a n d a r d sha l l n o t a p p l y to t a n k veh ic le s or t a n k cars; tanks , b u n k e r s , o r c o m p a r t m e n t s on sh ips or b a r g e s or in a sh ipyard ; gas p l a n t e q u i p m e n t o r gas d i s t r i b u t i o n sys tems for n a t u r a l o r m a n u f a c t u r e d gas; o r c o m p r e s s e d a n d l i q u e f i e d gas cy l inders .

1-1.$* T h i s s t a n d a r d sha l l n o t a p p l y to h o t t a p p i n g .

1-1.4" Th i s s t a n d a r d sha l l n o t a p p l y to t he e n t r y of a t a n k t h a t c o n t a i n s an i n e r t a t m o s p h e r e .

1-2 P u r p o s e .

1-2.1 This s t a n d a r d sha l l p r o v i d e m i n i m u m p r o c e d u r e s fo r d i e f o l l o w i n g :

(a) T i l e safe o p e n i n g , ent ry , a n d c l e a n i n g o f a t a n k or c o n t a i n e r d l a t h o l d s or h e l d f l a m m a b l e , c o m b u s t i b l e , o r o t h e r h a z a r d o u s s u b s t a n c e vapors , gases , l iqu ids , o r so l ids

(b) T h e safe r e m o v a l o f f l a m m a b l e , c o m b u s t i b l e , o r o t h e r h a z a r d o u s s u b s t a n c e vapors , l iqu ids , gases , o r so l ids f r o m smal l t anks or con t a ine r s , a n d s a f e g u a r d i n g t h e s e vessels by o t h e r m e a n s

o p e r a t i o n s t h a t c r ea t e h o t m e t a l sparks or sur faces f r o m f r i c t ion or i m p a c t .

I n e r t Gas. Any gas d l a t is n o n f l a m m a b l e , non reac t i ve , a n d n o n c o n t a m i n a t i n g .

lner thag. A t e c h n i q u e by w h i c h t h e a t m o s p h e r e by wh ich a t a n k or c o n t a i n e r is r e n d e r e d n o n i g n i t i b l e or n o n r e a c t i v e by d i e a d d i t i o n o f a n i n e r t gas.

L iqu id . Any m a t e r i a l t h a t has a f lu id i ty g r e a t e r t h a n t h a t of 300 p e n e t r a t i o n a s p h a l t w h e n t e s t ed in a c c o r d a n c e wi th ASTM D 5, Standard T~t Method for Penetration of Bituminous Materials. W h e r e n o t o t h e r w i s e i den t i f i ed , t h e t e r m //qu/d sha l l m e a n bo th f l a m m a b l e a n d c o m b u s t i b l e l iquids .

(a) Combustible Liquid. A l i q u i d t h a t has a c lo sed -cup f lash p o i n t t h a t is a t or above 37.8°C (100°F) . C o m b u s t i b l e l i qu id s sha l l be s u b d i v i d e d as fol lows:

1. Class II l i q u i d s s i ta l l i n c l u d e t h o s e l i qu ids h a v i n g c losed-cup f lash po in t s a t o r above $7.8°C (IO0°F) a n d be low 60°C (140°F) .

2. Class I l i a l i qu id s s i lal l i n c l u d e those l i qu id s h a v i n g c losed- c u p f lash p o i n t s a t o r above 60°C (140°F) a n d be low 93.4°C (~00°F) .

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N F P A 3 2 6 - - A 9 9 R O P

3. Class IIIB liquids shall include those liquids having flash points above 95.4~C (200°F).

(b) Flammable Liquid. A liquid having a dosed-cup flash point below 37.8°C (100~F) and having a Reid vapor pressure not exceeding 2068.8 mm Hg (40 psia) at $7.8°G (100°F) as de te rmined by ASTM D $23, Standard Test Method for Vapor Pressure of Petroleum Products (Reid Method). Flammable liquids shall be subdivided as follows:

1. Class IA liquids shall include those liquids having closed-cup flash points below 22.8°C (73°F) and boiling points below 37.8°C (100°F).

2. Class IB liquids shall include those liquids having closed-cup flash points below 22.8°C (73°F) and boiling points at or above 37.8°C (100°F).

3. Class IC liquids shall include those liquids having closed-cup flash points at or above 22.8°C (7~,°F).

Lower Flammable Limit (LFL). That concentrat ion of a combustible material in air below which ignition will no t occur° Also known as the lower explosive limit (LEL). Mixtures below this limit are said to be "too lean."

Oxygen Monltor. A device that is capable of detecting, measuring, and moni tor ing concentrat ions of oxygen in the atmosphere.

Purging. The process of displacing vapors or gases from an enclosure or confined space.

Qualified Person.* A person designated in writing wbo is capable, by education, experience, or specialized training, of performing specified tasks; of recognizing the potential hazards of those tasks; of recognizing any other unsafe conditions in a confined space; of specifying the necessary control and protective action to ensure for worker safety;, and who is knowledgeable of the procedures described in this standard. A qualified person may be called upon to inspect a tank or space and certify, in writing, that certain activities, such as entry and hot work, may proceed in safety using the designations in this standard.

Shall. Indicates a mandatory requirement .

Should. Indicates a recommenda t ion or that which is ady~se~.~ but not required. . -s-:-'-'!::'~ ~-".-:~i~,

.~:.~:~ ::x:.::: w " - "i~.~:~ ;.~.::v Standard. A document , tile main text of h~ch co~only.:.L..%?..: ....

mandatory provisions using the word "shall" to indi~te?::-:."~i~"..;:~:#::~':::~i ' suitable fc requirements and which is in a form generally . . . . ~;i~:.'.-':.'ii:...

mandatory reference by ano ther s tandard or ¢ ~ r a d ~ # : : into law. Nonmandatory provisions shall b,g..:~t~"~catecI'x~. . appendix, footnote, or fine-print note a n . ~ e not to I~ j~ns td a part o f the requirements of a standard~-'Y;'~.~:.: " ~

Standby Person. A person trained in e m e r g e ~ . s c u e ~ ?' procedures and who is assigned to remain on t h , ~ ' E ~ e of die confined space and to be in communicat ion with ' ~ e working inside.

Static Electricity. The electrification of materials through physical contact and separation and the various effects that result f rom the positive and negative charges so formed, particularly where they constitute a fire or explosion hazard.

Tank. A stationary or portable device that is in tended to contain an accumulat ion of hazardous substances that is large enough to allow human entry.

Toxicity. The quality or degree a substance is harmful to humans.

Toxic Materials, Gases, or Vapors. Any material whose propert ies contain the inheren t capacity to produce injury to a biological system. This is d e p e n d e n t on concentrat ion, rate, method, and site of absorption.

Unstable o r R e a c t i v e Materials. A liquid that, in the pure state or as commercially produced or t ransported, will vigorously polymerize or decompose or will become self-reactive under condit ions of shock, pressure, or temperature . V a p o r . The evaporated phase of a substance that is normally a liquid at room tempera ture and pressure.

Work. Activities per formed on tanks and containers in accordance with this document ; including, but no t limited to, safeguarding,

%

repair, hot work, cleaning, change of service, maintenance, inspect ion, and transportation.

2-1 General. C h a p t e r 2 B a s i c P r e c a u t i o n s

2-1.1 Work on tanks or containers that hold or have held hazardous substances shall be per formed only by personnel who unders tand the associated hazards. All personnel shall be sufficiently trained to safely carry out file necessary operations.

2-1.2 The characteristics of a hazardous substance and the a tmosphere of a tank or container shall be determined. Tanks or containers shall no t be worked on until information concerning the specific hazards of that substance has been obtained and safe procedures have been established.

CAUTION: The following shall be considered when these procedures are established:

(a) All compar tments of a mul t icompar tment tank or container

(b) Annular (interstitial) space of a secondary containment- type tank or container

(c) Vapor seals (d) Under tank floors, all types of pontoons m~d pipe supports (e) Any other areas where vapors or residues c~m be trapped

,6~:-:::.. 2-1.3 An appro~'~"?"~. .rmit(s) shall be obta ined, if required by the authority ~ g j u ~ s d i c t i o u .

.~:.':ii"-=:...=~.~:s::~. 2-1.4 . T a . ~ r c o " ~ e r s that contained unstable or reactive materi~i*~.~. : .not I ~ on until information is obtained on

~ni~:~l~ ' rocedu~ ~ precautions shall be required for :.O...r.k~.O on

safe , ~ ~i..:.~ecial t h . ~ l e c .t~..n of n o n r e a ~ e cleaning materials.

$ - l . ~ a t ~ - c o n t a i n e r contents shall be vented to a safe location. Befol ~ is started on tanks or containers , any pressure shall be reduce, : ? ~ s p h e r i c pressure.

} ~ 7mf~pprooP:iat:tSotehPSSl~lolub :sutakbse~ntOeprOtect personnel from

2-1.8 If chemicals are used for t iming or cleaning a tank or container, protective equipment shall be used in order to gnard against possible injury. When using a proprietary cleaning solution, the manufacturer 's instruct ions shall be followed.

2-2 Ignition Concerns. This section shall apply to tanks or contmners that hold or have held f lammable or combustible liquids, gases, or vapors.

2-2. I Prior to conduct ing any activities outl ined in this standard, die area shall be safeguarded from all sources of ignition for a minimum distance of 7.6 m (25 ft) in all directions. Barricades and warning signs reading "FLAMMABLE - - NO SMOKING" shall be provided and placed in accordance with the requirements of the authority having jurisdiction. T h e n die area shall be tested for tile

~{ esence of f lammable or combustible gases, liquids, or vapors. le actual distance of the area shall be de te rmined by the qualified

person based on the potential for ignition around the tank or container.

2-2.2 Any equipment that is capable of providing a source of ignition shall not be permit ted within file area o f the tank or container until the tank or container and the area a round dae tank or container have been tested and found to be safe.

2-2.$ Information on working on tanks or containers that have held nitrocellulose, pyroxylin solutions, nitrates, chlorates, perchlorates, peroxides, and other materials that contain enough oxygen to suppor t combustion in an otherwise iner ted a tmosphere shall be obtained before cleaning operat ions begin.

2-2.4 Appropriate fire-fighting equipment shall be provided in the a r e a .

2-2.5" Adequate precautions shall be taken to prevent the accumulation and discharge of static electricity.

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2-2.6 Any electrical e q u i p m e n t used shall be suitable for Class I, Group D, Division 1 hazardous (classified) locations, as de f ined in NFPA 70. National Electrical Codeqg.

2-~.7 Any e q u i p m e n t that m i gh t provide a source of ignit ion shall no t be permi t ted within the vicinity of a tank or conta iner tha t is being cleaned until the area has been tested and found to be vapor free.

Chapter 3 Preparat ion for Safeguarding

3-1 Lockout /Tagout .

3-1.1 All electrical circuits that supply power to pumps or o ther e q u i p m e n t connec ted to file tank or container , or o ther energy sources tha t are a potential hazard to workers in the a rea o f the hank or container , shall be d i sconnec ted and locked out or tagged out, or bo th , per 29 CFR 1910.147, "The control of hazardous energy ( Iockout / tagout ) . "

3-1.2 Where there is a need to test, posi t ion, or activate e q u i p m e n t by temporar i ly removing the lock or tag, or both, a p rocedure shall be developed and i m p l e m e n t e d to control potential hazards to the workers.

3-3.3 Valves shall no t be relied on to prevent the flow of materi,'fl unless a locked and tagged double-valve block and bleed a r r a n g e m e n t is provided.

Chapter 4 Tes t ing Procedures

4-1 General Procedures.

4-1.1" To de te rmine tha t an atmos.phere is suitable tor entry within the t,ank or container, in an excavauon, and in tile area a round the tank or container , tests for f lammable , combust ib le , or o ther hazardous subs tance vapors shall be made with an appropr ia te i n s t rumen t as follows:

(a) Before entry or re-entry (b) Before beg inn ing al terat ions or repairs (c) Before and du r ing any welding, cutting, or hea t ing

opera t ions (d) Frequent ly du r ing the course o f the work (e) After c leaning the interior o f each tank or conta iner to

de te rmine that the c leaning p rocedures have been effective (f) Af ter any industrial process or activity has been in t roduced

into the tank or conta iner that could change the a tmosphe re within the tank or conta iner

3-1.3 Any removal of locks, tags, or o ther protective measures shall CAUTION: Tanks or conta iners that have held liquids with high be done in accordance with 29 Ca~R 1910.147, "Tbe control of flash points c ~ o m e hazardous du r ing cutt ing and welding hazardous energy ( Iockout / tagout ) . " operat ions . .~y~" ::~6~,.

~!~... -.

~1.4 Lockout or tagout, or both, o f equ ipmen t , systems, and 4-1.2 C o n ~ . t i n g for toxicity shall no t be required if processes shall be conf i rmed p rmr to pe r{ormmg work on the tank p r e~ous tC~:t~ag m ~ e s tha t toxicity associated wlth fo rmer or container , producz.~(.~2~:" ~ h a s " ' ~ el~Ininated or is incapable of

r e g e . l ~ ' ~ l ~ b o v e p e ' : ~ l e exposure levels. 3-2 Removal of Flammable, Combustible, or Other Hazardous .-.':i;: .:.:::~ ~:'::~::~ Subs tances , Liquids , or Gases . .@. ' :~i-~pe~.s responsit] 'e for testing shall be t ra ined in the use of

i ~ i l e ~ " ~ , in terpre ta t ions of its readings, and its limitations. 3-2.1 As m u c h hazardous subs tance , water, and sed imen t as 3:.'5.~.i:i: practical shall be removed f rom the tank or container . This shall ~.: .... 4-1.4" ~ i i ~ : , h a l l be done us ing a properly calibrated include the removal of l iquids or gases f rom any internal piping, "iiii~ti.:-.:i~i-.:,:,.instrnment%~e i n s t rumen t shall be calibrated with t h e traps, and s tandpipes . All p iping or similar conveyances for "f.:~:7::::~:ii!~.l~t':.~jp..riat.~alibration gas. In verifying the calibration of the f lammable , combus t ib le , or o ther hazardous substances connec ted "iii::i:: t . ~ i ~ i ' u m e n t a t i o n , the concen t ra t ion of calibration gases shall to tile hank o r con ta ine r shall be dra ined , f lushed, or isolate~..:...lf ::~ii:...:-~J~iqclu~:'~t least one poin t above and one poin t below those reactivity and solubility are no t a concern , a small q u a n t i ~ i ~ e r :'-:iiii~i atmo~"~theric concent ra t ions used as criteria to make decisions shall be permi t ted to be p u m p e d into the tank or c o n ~ r t o ' ~ a t ':.:!i~.'..uz~:~olving the in tended work ( that is entry requir ing greater than any r ema in ing liquid f rom a low spot so tha t it can h ¢ i i ~ p e d ; ~ : . ...... -.-::. ~f$]~'~5 percent oxygen, hot work below 10 percent LEL or inerted f rom the tank or container . ":::+"%!Iii: :. :ii!if:;:::::"':~.-i~i~::b.tmosphere requi r ing less tb:m 8 percent oxygen). Tile cal ibrat io .

"::??.'~i~i~i.. ""::'~i~ ~:: of the i n s t r u m e n t shall be cbecked before each day's use. The 3-2.2* Where f lammable or combust ib le l iqui~ . . .~ ,g~.es ai~?:~.g]d . i n s t r umen t shall be properly mainta ined. or have been held in a tank or container , e . . . ~ s i o t " ' ~ or ~:"%:~#" driven p u m p s shall be used. P u m p m o t o ~ 0 d suct]o"/{~.ses s ~ ] l 4-1.5 Tile n u m b e r a n d location of sampl ing points shall be be bonded to the tank or conta iner to p~#.g~:s ta t ic ele(.~..~ity " de t e rmined based on the size and conf igurat ion of the tank or ign idon hazards. ":~i~?;i~:i~ ~!~ conta iner so as to provide a representat ive de te rmina t ion of tile

~'~:~::~ . . . . . . i]':"::" a tmosphe re in the tank. . . . . . ~:~:i~.~::~......:::."

3-2.3 All hqnlds rmsea tes sohd res,dues, and v a ~ i : f f i a t are . . . . . . . . . . . . . . _ ' . . . ' . . . . • ~:x-~:- . q - z l e S t l n g f o r o x y g e n b o n t e n t , w h e n c t e t e r m m m g o x y g e n

generatec~ as a result o t tlaese o e a m n g anta sme~uar.c~ng procectures conte as for nito " a - " co " r ' ' be" " n t mo rm tang or n t ame tha t ts m ur ea shall be disposed of proper ly in accordance wit~a t[{'e appropr ia te ' g g P g regulatory requi rements , with iner t gas, a properly calibrated portable oxygen moni to r shall

be used.

3-2.4 As W remain ing residue in the tank tha t is incapable of being removed as descr ibed above shall be permi t ted to remain until proper tank entry can be made. (See Chapter 7for tank ent~ requirements. )

3-3 Isolation.

CAUTION: W h e n pu rg ing a tank or conta iner with an inert g:Ls, a combust ib le gas indicator migh t not give a correct reading. Since the objective with inert gas purg ing is to dilute the oxygen concent ra t ion to a poin t below a certain safe value, an oxygen indicator shall be used.

3-3,1 Tile tank or conta iner shall be isolated f rom all supply and dispensing piping systems, ff the tank or conta iner on which work is to be pe r fo rmed is equ ipped with a manifo ld vent, vapor recovery system, fill line, s iphon assembly, or o ther me thods of connec t ion to o ther tanks or containers , necessary measures shall be taken to isolate that tank or conta iner f rom all o ther tanks or containers . All p iping tha t is capable of p roduc ing a hazard shall be d isconnected , p lugged , or blanked off.

3-3,2 The vents for the tank or conta iner on which work is to be pe r fo rmed shall be isolated f rom tile vents of o ther hanks or containers that migh t still be in service. A separate , t emporary vent for the hank being en te red shall be provided, if necessary.

4-3 Test ing for Flammable Vapors.

4 6 . 1 " Vapor concent ra t ions shall no t exceed 10 percent of the lower f lammable limit. All work shall be s topped immediate ly when the f lammable vapors exceed 10 percen t of the lower f lammable limit. The source of the vapor release shall be located and control led.

4-3.2 Any e q u i p m e n t tha t m igh t provide a source of ignition shall no t be permi t ted within the vicinity of a tank or conta iner that is being cleaned unti l tile a rea has been tested a n d fou n d to be vapor free.

43.3 Dur ing ventilation or air purg ing of any tank or container, the f lammable vapor concent ra t ion of the eff luent shall be tested several t imes du r ing the ventilation or purg ing process.

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N F P A 3 2 6 - - A 9 9 R O P

45 .4* If an educ tor air mover pe r fo rms the purging, the eductor shall create a vacuum tha t draws air t h r o u g h at least one tank or conta iner open ing and discharges t h rough ano t he r opening . Tes t ing for f l ammable vapors shall be conduc ted with a combust ib le gas indicator with its p robe inser ted into the probe hole provided in the side o f the eductor . Tes t ing for f l ammable vapor concent ra t ions shall be pe r fo rmed .with the educ tor on and tightly secured to the tank or conta iner ' s fill tube. A reading o f 10

~ ercen t or less o f the lower f l ammable limit shall be obta ined efore the tank or conta iner is considered safe for igni t ion sources.

4-3.5* If an air blower per forms die purging, the blower shall force air into the tank or conta iner t h rough a t least one tank or conta iner open ing and discharge t h r o u g h a n o t h e r opening . Tes t ing for f l ammable vapor concen t ra t ions shall be pe r fo rmed with a combust ib le ~ indicator with its probe placed in the tank or conta iner ' s thscharge opening . W h e n a reading o f 10 percen t or less of the lower f l ammable l imit is obtained, the air blower shall be shu t off. ff readings in the tank or conta iner are taken th rough the fill opening , any fill tube tha t ex tends into die tank or conta iner shall be removed. T h e air blower shall be immedia te ly t u r n e d on after die last test in the tank or container , a n d the tank or conta iner ' s vent open i ng shall be tested.

4-3.6 W h e n test ing a tank or conta iner for ho t work, any indicat ion of f l ammable gas or vapor shall require rec leaning or fu r ther sa feguard ing of the vessel by one of the med lods descr ibed in dlis s tandard prior to pe r fo rming any ho t work.

4-4* Testing for Toxic Vapors and Gases.

Hazardous subs tances shall be tested for with appropr ia te ins t rumenta t ion to de t e rmine if any toxic materials are p resen t and to de t e rmine tile level o f dlose toxic materials.

Guidance regard ing m a x i m u m acceptable levels of hazardous subs tances shall be found in the OSHA Material Safety Data Sheet (MSDSy, OSHA 29 CaVR 1910.1000 Subpar t Z; o ther OSHA subs tance specific s tandards; t he ACGIH Threshold Limit Values (TL V) for Chemical Agents; Physical Agents and Biological Exposure Indices;, a n d the NIOSH Pocket Guide to Chemical Hazards. Assistance in selecting an appropr ia te test ing p rocedure shall be obta ined f rom tile approprmte regulatory agency, or a safety and hea l th professional.

Chapter 5 Control or

5-1 General.

5-1.1 Flammable vapors in a t ank t to be displaced or pu rged witil air, caution in Section 8-5)~ T h e m e t h o d the tank or conta iner on which wo~

5-1.2 F lammable or combust ib le li ad jacent to or within the space con hazardous subs tances shall be removed or control led prior to proceeding. These spaces shall include, bu t no t be l imited to, interstitial spaces, co lumns , floats, hollow structures , f loat ing roofs, pon toons , and tank floors.

5-1.$ Other hazardous subs tance vapors tha t are no t f lammable or combust ible , bu t tha t have adverse effects on h u m a n heal th shall be control led pr ior to proceeding. Many of the m e t h o d s identified in this section shall apply to the control of these o t h e r hazardous subs tance vapors. T h e hazardous substances a n d the appropr ia te me thods for the control of these vapors shall be identified prior to proceeding .

5-1.4 Pr ior to removing vapors f rom a tank or container, the appropr ia te regula t ions shall be consul ted to identify any specific r equ i rements for hand l i ng or d ischarg ing o f vapors or liquids while conduc t ing the activities descr ibed in this chapter .

5-1.5 If a tank is located indoors or in a conf ined area, such as unde r a building, measures shall be taken to prevent the accumula t ion of f l ammable or toxic vapors within tile building.

5-2 Removal of Flammable Vapors.

5-2.1 Displacement with Air.

5-2.1.1 Where open ings of sufficient size are available, ,air movers tha t do no t prowde an ignit ion source shall be a t tached so that air is drawn th rough or p u m p e d into one open ing ,and discharged t h r o u g h a n o t h e r open ing a sufficient dis tance away to allow cross ventilation in the tank. ff open ings canno t a c c o m m o d a t e ,an air mover, the tank or conta iner shall be thoroughly purged to remove f l ammable vapors by in t roduc ing air tha t will circulate th rough tile tank or conta iner and be d i scharged to the outside. Precaut ions shall be taken to remove all ignit ion sources f rom the area because tile concent ra t ion o f vapor in air in the tank or conta iner has the potential to pass t h rough the f lammable range before a safe a tmosphe re is obtained. An effective bond shall be main ta ined between the air mover and the tank or conta iner tha t is he lng cleaned.

5-2.1.2" Precaut ions shall be taken to e l iminate the possibility of static electric discharge du r ing gas-freeing procedures .

5-2.1.$ Where purg ing a tank with air, the air pressure in tile tmik shall no t exceed the allowable m a x i m u m design pressure for the tank. To prevent excess air pressure, the vent line shall be checked to make certain it is f ree o f blockages, obstruct ions, or traps. All discharges or vent ing to tile a tmosphe re du r ing the purg ing activity shall be at a m i n i m u m of ~.7 m (12 ft) above the g r o u n d surface and away f rom any areas that migh t contain sources of ignition.

5-2.1.4 Displacement of tire tank or conta iner a tmosphe re with air shall be accompl i shed by one o f the following methods .

tsd (a) A n e g a t i v ~ ' . ~ ' r e ~ e or vacuum is used to pull ou i e air into the tank or c ~ e r us ing an eductor air mover or o ther equipment~.,.~Wh . ~ x ~ i n g this m e t h o d the connec t ion between tile eductor ~ . ~ e ~ conta iner shall be airtight. To die extent p o s s i b ~ ~ j ~ . ~ r . a A l : ¢ n t h rough the tank or container to a l l o ~ e cross v ' ~ o n and removal. All e q u i p m e n t shall b ~ o p e f l ~ ¥ b o n d e d to ~ v e n t the genera t ion of static electric

(b) '"~.~.~sitive pressure or diffused air blower is used to push :..::!,~:,. outside ~ t . ~ e tank or container . If fill tubes that extend into :~-'.',.-'.-;.-N.~e tank o ~ t a i n e r are to be used as the air supply point, the

% : " " : ~ . ,.o.~.~e fill tube tha t ex tends into the tank or conta iner shall ~i!~.. ~ to e n h a n c e diffusion of air into tile tank or container.

~ ~,-The,.'-'~ a~feghashall be supplied, f rom a compressor. . or blower that has i: been checked for dehvery of clean air tha t ts free of f l ammable or : ! i ~ c vapors. The air-diffusing pipe shall be properly b o n d ed to 0!i~l'event the genera t ion of static electric charges.

5-2.2" Displacement with Inert Gas (Inerting). Individuals directly in charge o f any work to be pe r fo rmed on a tank or conta iner shall be thorough ly familiar with tile l imitations and characterist ics of the iner t gas being used. T h e oxygen con ten t shall be mon i to red f requent ly and ma in ta ined at less than 8 percent or 50 percent of the oxygen concent ra t ion requi red to suppor t combus t ion , whichever is less, du r ing the entire per iod that work is in progress. (The procedures for inerting are specified in 5-2. 2.1 through 5-2.2. 7. )

5-2.2.1 All open ings in the tank or conta iner shall be securely closed, except for the access open ing and vent.

5-2.2.2 The iner t gas shall be in t roduced into the tank or container t h rough a pipe or hose that extends to a poin t near the bot tom of the tank. This point shall be as far away as possible f rom the por t ion of the tank Miere repairs or o ther activities will be conduc ted in order to allow for un i fo rm reduct ion of oxygen in the tank or container . The iner t gas shall be in t roduced into the tank with considerat ion for the internal s t ructure o f tile tank or conta iner to allow for distr ibution o f the iner t gas t h r o u g h o u t the tank or container . Any metal c o m p o n e n t s of the e q u i p m e n t used to in t roduce the inert gas shall be bonded to the tank or container. All spaces to be iner ted shall be sufficiently intact to retain the iner t ing med ium.

5-2.2.3 W h e n in t roduc ing iner t gas u n d e r pressure, low pressure shall be used in order to reduce d~e genera t ion of static electricity.

5-2.2.4 When carbon dioxide is used, portable carbon dioxide fire ext inguishers shall no t be used as the source of the iner t gas. When solid carbon dioxide is used, it shall be c rushed and dis t r ibuted evenly over the greatest possible area for rapid subl imat ion .

5-2.2.5* T h e oxygen con ten t shall be measured directly by meafis of an oxygen momtor . If carbon dioxide is used, the oxygen percentage shall be permi t ted to be calculated f rom the percentage

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N F P A 3 2 6 ~ A 9 9 R O P

of carbon dioxide in the tank or container measured by means of a carbon dioxide indicator.

5-2.2.6* A sign shall be posted conspicuously that warns of the hazard of inert gas and forbids entry into the tank during the inert ing process.

5-2.2.7 When work is completed and prior to entry into the tank, inert ing media shall be removed to achieve an oxygen concentrat ion in accordance with 6-2.1. If inert ing media is to remain in the tank, the tank shall be secured and a sign shall be posted in accordance with 5-2.2.6.

5-2.3 Displacement with Water.

5-2.3.1 If the flammable, combustible, or other hazardous substance that was previously contained is known to be readily displaced by or easily soluble in water, then the removal of vapors shall be permit ted to be accomplished by completely filling the tank or container with water and draining, repeat ing the operation .as necessary to eliminate the f lammable a tmosphere .

5-2.3.2 Removal of vapors shaU also be permit ted to be accomplished by completely filling the tank or container with water. If this method is used, the tank or container shall remain filled with water. Extreme care shall be taken to eliminate any vapor spaces by providing proper venting or by properly posit ioning the tank or container during the filling operation.

5-2.3.3 All liquids, rinseates, solid residues, and vapors that are genera ted as a result o f these cleaning and safeguarding procedures shall be disposed of properly in accordance with the appropria te regulatory requirements .

CAUTION: Water shall not be used for the removal of vapors if it will adversely react with the flammable, combustible, or other hazardous substance previously conta ined in the tank or container.

5-2.4* Displacement with Steam. Displacement with steam shall be accomplished by introducing steam into the tank or container th rough a pipe that is inserted through an open ing and bonded to the tank or container or by connect ing a steam hose direcfly.,+~+one of the vessel nozzles. The rate of supply of steam shall be. ~ t to exceed tile rate of condensat ion so that the whole ~ r :~: container is heated close to the boiling point of w a t ~ t a ~ + : container shall be s teamed long enough to vaporize+6r ~ ~ : ~ removal of the residues from all port ions of the walls (sl~ ' ! i ~ d

a tmosphere in t h ~ ~ ~ heads). When testing the l ' ~ . . t h a combustible gas indicator, the tank or co allt to cool until excess water vapor has c o n d ~ e d , or the"'~ pie

filled v ~ i u m chlot~ e or be drawn through a drying tube " ~ " " o ther drying agent to keep water vapor i ron ~"~¢~ing the .... ~,.-'.~:. ~:: instrument. "-~-~,~:~.

CAUTION: Displacement with steam can g e n e S ' s t a t i c electric charges. :-:Y"

Chapter 6 Inspection and Certification of Tanks and Containers

6-1 General. Once the procedures in Chapters 2 through 5 have been followed as applicable, a c)ualified person shall inspect a tank or container and certify, in writing, that certain activities such as entry or ho t work, or both, can proceed using the designations in dais secdon. The certification shall include a descript ion of the work to be per formed and the criteria for maintaining safe condit ions during the work. Conf ined space entry permits and hot work permits are examples of certifications.

6-2 Designations. The following designations shall be consistent with 29 CFR 1910.146, "Permit-required confined spaces."

6-2.1 Enter Without Restrictions. This designation means that in die tank or space so designated the following shall apply.

(a) The oxygen con ten t shall be at least 19.5 percent and not greater than 23.5 percent by volume.

(b) Tile LFL shall be less than 10 percent.

(c) Any toxic gases or vapors related to the hazardous substances, coatings in the tank, or inert ing media shall be within the permissible concentrat ions.

(d) The residues or materials associated with the work shall not produce gases or vapors above the permissible concentrat ions while maintained as specified by the certification.

I f any of the condit ions in (a) th rough (d) are no t met, allen tile space shall not be designated "enter without restrictions."

6*2.2 No Entry Allowed. This designation means that in tile tank or space so designated, personnel shall not be authorized to enter.

6-2.$ Enter with Restrictions. This designation means that in the tank or space so desi.gnated, entry for work shall be cont ingent upon proper protective equipment , clothing, or time, as applicable, as specified by the certification.

6-2.4 Enter with Special Precautions. If any of file following conditions exist, the qualified person shall designate the precautions necessary for entry.

(a) Oxygen content less than 19.5 percent

(b) Concentrat ion of f lammable vapors less than 10 percent LEL

(c) Atmospheric concentrat ion of any toxic substance at a level that will impair the ability to serf-rescue

(d) Any other a tmospher ic condit ion that is immediately dangei-ous to life and health

(e) At workers

that results in tile enguffment of

6 - 2 . 5 H This designation means that in a tank, .ip designated the following shall apply.

Shall be at or below 23.5 percent by

(b) ~ , .{~EL shall be less than 10 percent . --:~.~ ..:.. ~ % . w . .

~:.(c) T h e : ~ u e s , scales, or preservatave coatings shall be ~ d g . ~ c i e n d y to prevent the spread of fire, and shaU not be ~ ' p r o d u c i n g an oxygen concentrat ion that is greater than ~3.5 # ~ e n t or an a tmospheric concentrat ion of f lammable gases or vapors above 10 percent of tile LFL in the presence of the hot ii!~a..xg...~tk while maintained as directed by the certification.

(d) Flammable or combustible liquids or gases found in spaces that are adjacent to of within the space that contain or have conta ined hazardous substances shall be removed or controlled as spedf ied by the certification.

If any of the conditions in (a) through (d) do not exist, then the space shall not be designated "hot work allowed."

6-2.6 Hot Work Not Allowed. This designation means that in the tank or space so designated, hot work shall not be authorized by the cerlJfieation.

6-2.7 Limited Hot Work Allowed. This designation means that in a tank, at tached piping, or a space so designated die following shall apply.

(a) Tanks or spaces with residues or preservative coatings whose flash point is 180°F (82.2°C) or greater and that are free of flowing residues or coadngs shall be permit ted to be partially cleaned for limited hot work. The qualified person shall verify the flash point of the residues prior to issuing the certification.

(b) To prevent the spread of fire, an area shall be cleaned a sufficient distance in all directions, including below the area of the hot work, so that sparks or slagwill not drop or be thrown into uncleaned areas of the space. Tile area shall be cleaned to meet the requirements of the standard safety designation "hot work allowed." A fire watch shall not be used in lieu of cleaning to establish a safe condition. The nature, location, and extent of the hot work shall be listed on the qualified person 's certification.

(c) H o t work shall be permit ted on tanks or containers that are partially filled with liquid. The surface level of the water sh,'dl be maintained at a min imum of 0.9 m ($ ft) above the area where the hot work is being performed.

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N F P A 326 - - A99 R O P

(d) A portion(s) of the tank shall meet the requirements of 6-2.5. The nature or type of hot work shall be limited or restricted.

This designation shall include a statement that describes the exact location of the hot work, the nature and type of the hot work, and the limitations or restrictions of the hot work.

6-2.8 lnerted. This designation means that a tank, attached piping, or a space so designated shall meet the criteria specified in 5-2.2. This designation shall include a statement thatdescribes the inerdng media used and its final disposition.

Chapter 7 Procedures for Access and Entry of Tanks

7-1 General.

7-1.I Prior to performing any work, flammable vapors shall be removed from the tank in accordance with the procedures outlined in Chapter 5.

7-1.2 Testing for an atmosphere that is suitable for enu-y shall be conducted in accordance with Chapter 4.

7-1.$ Any other hazards that have been identified for the material(s) previously stored shall be appropriately monitored.

7-2 Access to Tanks.

7-2.1 If excavation is necessary to gain access to the tank, the access pit shall be of sufficient size to allow entry and exit from the tank and to comply with applicable OSHA regulations. Personnel shall be familiar with all applicable procedure, such as those established by the U.S. OccupationalSafety ,,an_d Health . ,. Administration in 29 CFR 1926, Subpart P, Excavations.

7-2.2 l f a manway exists, the bolts and rid shall be removed.

7-2.$ If no manway exists, an opening of sufficient size to allow entry and exit from the tank and to comply with applicable OSHA regulations shall be cut into the tank. The section to be removed shall be marked, and a hole shall be drilled with an air-driven drill at one corner of the section using a lubricating material to reduce friction, heat, and possible sparks. After the hole is drilled, h.tank atmosphere shall be tested to verify a safe atmosphere byj~l the me te rp robe at least 61 a n (24 in.) into the driiledJltl$h location of the opening in the tank shall be p e r m i t t e ~ e by the in terna l structore of the tank.

7-2.4 For tanks that contain a flammable or ~ t l l ~ e ~ atmosphere, the tank shall be cut using a n . . ~ l r i v e ~ r snipper, using a lubricating material to r e ~ e f r ic t ion~]~ and to prevent possible sparks. Prior to ~ cu~ t h e ~ dl be supported to prevent its falling into t h e y t

7-3 Tank Entry.

7-3.1 Before entering tanks, personnel shall be fan ar with the applicable procedures described in API 2015, Safe Entry and Cleaning of Petroleum Storage Tanks; AP1 2217, Gu/dd/nfs for Confined Space Work in the Petroleum Indusb3; ANSI Zl17.1, American National Standard Safe) Rsquimamts for Co,drool Spaces; NIOSH C~iteria for a Par.mnmemtai Standard for Working in Confined Space; and the OSHA Code of Faleral Regulations, Title 29, Part 1910.146, "Permit-required confined spaces."

7-3.2 The vent line shall remain clear and unobsuucted to allow continuous ventilation. All other lines and openings shall be plugged or capped off to keep liquids or vapors from entering the tank. if natural ventilation is inadequate to control vapors, continuous mechanical ventilation shall be used while the space is occupied.

7-3.3 Additional precautions shall be taken if the tank is perforated such that liquids or vapors that might be present in the soll could re-enter the tank through the perforation.

7-4 Closing the Tank Access Opening. If an access opening has been cut into the tank, the opening shall he closed, either temporarily or permanently, depending on the disposition of the tank.

Chapter 8 Cleaning Tanks and Containers

8-1 General. The procedures outlined in Chapters 2 through 5 shall be followed to the extent applicable to the tank or container to be cleaned. If indoor cleaning is necessary, ventilation shall be sufficient m prevent the accumulation of flammable vapors inside a building.

8-2 Purpose and Extent of Cleaning. Where cleaning is necessary in preparation for hot work, change in service, or for other purposes, the procedures in this section shall apply.

8-2.1 Cleaning in Preparation for Hot Work. Cleaning of a tank or container prior to hot work shall remove flammable vapors and liquids or solid residues that might release additional flammable vapors.

8-2.2 Cleaning for Change in Service. Cleaning of a tank or container for chan~e in service shall remove residues that could contaminate or be incompatible with new material in die tank or container. Selection of a cleaning procedure shall take into consideration the chemical nature and characteristics of the residue and the characteristics of the new material to be stored in the tank.

8 - 2 . 3 0 e a n i n g for Other Purposes. Other activities where cleaning a tank or container is necessary shall include transportation or storage, routine m~Qtenance, repairs, and internal inspection. Selection o f a clfe~l~id~rocedure shall take into consideration the activity to be cj~ucte'd~', the intended use of the tank or container, and the chen/ l~lBmd nhvsical Dronerties of the material stored.

8-5 ~ l ~ f I t . e d i h l Liauids and Solids.

of Ii

or solid r~['due accumulation on the bottom of the f~emoved and placed in approved containers. Removal ~lid residues shall include removing all visible

I f i t i~pfnpossible to remove all l iquid or solid residues that ~ v a p o r s to reoccur during work m because residues can ~ c / ~ [ ' a p p e d behind heavy scale or rust and not be easily ~letect~ m additional precautions shall be taken.

~ Cleaning lns l~ct ion. After it is cleaned, the tank or container II be inspected internally to determine the effectiveness of such

cleaning. Containers or tanks that are not entered shall be visually inspected using appropriate methods, taking care to avoid inhalation of harmful vapors that might still be present. If examination shows that the tank or container is not clean, the cleaning procedure shall be repeated.

8-5* Cleaning Methods. The following methods shall be permitted to be used:

(a) Abrasive blasting (b) Low-pressure water (triple rinse) (c) High-pressure water blasting [172,250 to 275,600 kPa (25,000

to 40,000 psi) ] (d) High-pressure steam (e) Special cleaning agents (solvents, degreasers, neutralizing

agents, or emulsifiers) (f) Physical removal such as vacuum, shovel, or absorbants

CAUTION: Steam cleaning, use of special cleaning agents, or high-pressure water blasting might result in the generation of static electric charges.

Where abrasive blasting is to be used, a thin or pitted tank or container shell can be damaged or perforated.

Chapter 9 Referenced Publications 9-1 The following documents or portions thereof are referenced within this standard as mandatory requirements and shall be considered part of the requirements of this standard, The edition indicated for each referenced mandatory document is file current edition as of the date of the NFPA issuance of this standard. Some of these mandatory d o c u m e n ~ m i g h t also be referenced in this standard for specific informational purposes and, therefore, are also listed in Appendix A.

307

N F P A 3 2 6 - - A 9 9 R O P

9-1.1 N F P A P u b l i c a t i o n . National Fire Protection Association, 1

Batterymarch Park, P.O. Box 9101, Quincy, MA 02269-9101.

NFPA 70, National Electrical Code ~, 1996 edition.

9-1.2 Other P u b l i c a t i o n s .

9-1.2.1 ACGIH Publication. An~erican Conference of Covernmental Industrial Hygienists, 1330 Kemper Meadow Drive, Cincinnati, OH 45240-1634.

Threshold Limit Values (TLV) for Chemical Agent; Physical Agents and Biological Exposure Indices, 1997.

9-1.2.~ ANSI Publication. American National Standards Institute, 1430 Broadway, New York, NY 10018.

ANSI Z117.1, American National Standard Safety Requirements for Confined Spaces, 1989.

9 - 1 . 2 . 3 A P I P u b l i c a t i o n s . American Petroleum Institute, 1220 L

Street, NW, Washington, DC 20005.

API 2015, Safe Entry and Cleaning of Petroleum Storage Tanks, 1994.

API 2217A, Guidelines -[or (~nfined Space Work in the Petroleum

A-I-I.4 For information on working in an inert atmosphere, see AP1 2217A, Guidelines/or Work in Inert Confined Spaces in the Petroleum Industry.

A-I-4 Approved. The National Fire Protection Association does not approve, inspect, or certify any installations, procedures, equipment , or materials; nor does it approve or evaluate testing laboratories. In de te rmin ing the acceptability of installations, procedures, equipment , or materials, the authority having jurisdiction may base acceptance on compliance with NFPA o~ other appropria te standards. In tl~e absence of such standards. said authority may require evidence of proper installation, procedure, or use. The authority having jurisdiction may also refer to the listings or labeling practices of an organization that is concerned with product evaluations and is dins in a position to de te rmine compliance wid) appropr ia te standards for the current product ion of hsted items.

A-I-4 Authority Having Jurisdict ion. The phrase "authority having jurisdict ion" is used in NFPA documents in a broad manner , since jurisdictions and approval agencies vary, as do their responsibilities. Where public safety is primary, the authority having jurisdiction may be a federal, state, local, or other regional depa r tmen t or individual such as a fire chief; fire marshal; chief of a fire prevention bureau, labor depar tment , or health department; building official; electrical inspector; o r others having stanltory aud~orit'/. For insurance purposes, an tnsurauce inspection

Industry, 1987. depar tment , rating .bureau, or other insurance company representative m ~ . , . t h e authority having jurisdiction. In many

9-1.2.4 ASTM Publications. American Society for Testing and circumstances, ~-6"~i~"~i~erty owner or his or her designated agent Materials, 100 Barr Harbor Driver, West Conshohocken, PA 19428- ,assumes the r.~ii'.~., the andlority having jurisdiction: at government 2959. i n s t a l l a t i o n . . ~ l e ; : ~ m a n d i n g officer or departmental official may

be the atltfi~aty b ' ~ , j u r i s d i c t i o n . ASTM D 5, Standard Test Method .[or Penetration of Bituminous ,~?::.."::~'~ "::ii~i#~i~ " .....

MatenaI.L 1986. A-I .~#i"~ua|]:l~ted Perso~ii~i~signation or selection o1 qualified p ~ n s s~.ould be done: :~ ensure that the designations are

ASTM D 323, Standard Test Method for Vapor Pressure of Petroleum . ~ l y ~ e d to the':~nspected tank or container. Selection of Products (Reid Method) 1990. q u a I [ ~ i i ~ e ~ n s should include careful consideration of those

• ? - -- - -25~'~" " ' " " J d aspectS~ --'.t.he qualified person s educauon, expermnce, at 9-1.2.5 U.S. Government Pubheatmns. U.S. Government Printing :::+. s p e c m h z ~ i . ~ n g necessary to recogmze unsafe c o n d m o n s Office, Washington DC 204O2. ":~,:.,~b.ecifv ~ control me~...res, and ensure the protection of

% " " : : : ~ e l , ~ r k i n g in or near the tanks and contai nets witbi n the NIOSH Criteria for a Recommended Standard Jbr Working in Confined ::i~!:. ,~:~..':.~i.'~iis standard.

Spaces. .s.-ii#i~:~iiiiii~!iii:~ ':'iiiii"~: Individuals possessing tide skills and exper ience necessary to act :L~

OSHA, Code of Federal Regulations, Title 29, Part 1910:,~6, "Pe"t-'~it- "!::ii~:.~lified persons might be employees of d~e tank owners, required confined spaces." . : : i ~ : . . . . ::~'~..::¢i:i ...... :~i::...:ii~ 6ntract°rs, or third parties.

OSHA, Code of Federal Regulations, Title 29, Part 1.910.14'~Jji~[~e "~'~-':: When selecting or reviewing tide credentials of qualified persons, control of hazardous energy (lockout/tagout)~$:'.::%i..%:i::~. ":".iiiiii!i~:: . . . . . . there are several factors that should be considered, including the

.~:~:'::" . . . . . . ::~i-".::: "::!!::::i!i~¥ ~:: fo l lowi ng: OSHA, Code of Federal Regulations, Title ...~...~]part 192ff~j~. par.l~':P; (a) Experience with the design, funct ion and operat ion of the

'Excavations." :ii'i:'~:%~iiii:~ "%ii " tank or container types ~i~.~:i:~ ~:i: (b) Experience with the physical, chemical, and hazardous

Appendix A Explanatory M a ~ . . . . ::~!':'::" propert ies of the materials previously stored ~iiiii~..:;:.:.-..'ii!i:;" - ( c ) Experience with the industrial activities to be performed

Appendix A zs not a part of the requirements of this ..~. f4 docunwnt within or on d~e tank or container but ts included for informational purposes only. This c~'pendix contains (d) Experience with the instrumentat ion and inspection explanator~ material, numbered to correspond'with the applicabb; text techniques used in de termining the testing criteria ,~ssociated with paragraphs°

A-l- l . l The procedures in this s tandard can apply to pressurized tanks or containers that have been taken out of service and have bad dleir operat ing pressure reduced to a tmospheric pressure and vented.

A-I-I.2 Procedures for making some of the vessels listed in 1-1.2 safe are covered separately in the following publications:

(4) AGA, Pur~ng Principles and Practices (b) ANSI ZII7.1, American National Standard Safet?t Requirements for

Confined Spaces ( c ) API 1631, Interior Lining of Underground Storage Tanks (d) API 2013, Cleaning Mobile Tanks in Flammable or Combustible

Liquid Service (e) API 2015, Safe Entry and Cleaning of Petroleum Storage Tanks (f) NFPA 306, Standard for the Control of Gas Hazards on Vessels (g) NLPA 631, Entry, Cleaning, Interior Inspection, Repair, and

Lining of Underground Storage Tanks (h) OSHA, Code of FederalRegulations, Title 29, Part 1910.146,

"Permit-required confined spaces"

A-I-I.3 Procedures [or ho t tapping are covered separately in API 2201, Procedures for Welding or Hot Tapping on Equipment in Service.

the designations (e) Familiarity with applicable industry, tederal, state, aud Ioc;d

safety standards and guidelines referenced in this standard

A-2-2.5 For information on tile accumulation and discharge of static electricity, see API 2003, Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents, and NFPA 77, Recommended Practice on Static Electricity.

A-$-2.2 For information on static electricity ignition hazards, see API 2003 Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents, a n d N F P A 77, Recommz'nded Practice on ,Static Electricity.

A-4-1.1 It is r e commended that cont inuous moni tor ing be per formed inside the tank or container when personnel are itJside.

A-4-1.4 An appropriate calibration gas means a c~dibration gas that has a certified accuracy of + 5 percenL

A-4-8.1 Testing the interior o f a tank or container for tim presence of ignitable concenn'at ions of f lammable gas or vapor is the most impor tant phase of the cleaning procedure and determines whether additional cleaning is needed. Most combustible gas indicators measure the concentrat ion of vapor present as a

308

N F P A 3 2 6 - - A 9 9 R O P

percentage of t h e lower f lammable limit. W hen a tank or conta iner is oxygen deficient, the reading migh t be in error . It is essential that those us ing the indicator be well t ra ined in its use and calibration and tha t the i n s t rumen t is in good opera t ing condit ion. Calibration should be done in accordance with the manufac tu re r s ' instruct ions.

A-4-3.4 If an air mover is used to exhaus t a tank or container , the discharge f rom the air mover should be di luted with air used in the device. The results of any tests made at this poin t will be indicative of the change in the vapor concent ra t ion inside the vessel and, when the desired low concent ra t ion is reached, the condi t ion of the tank or conta iner itself can be checked at appropria te points.

A-4-3.5 See A-4-3.4.

B-I.I NFPA Publications. National Fire Protect ion Association, 1 Bat terymarch Park, P.O. Box 9101, Quincy, MA 02269-9101.

NFPA 69, Standard on Explosion Prevention Systems, 1997 edition.

NFPA 77, Recommended Practice on Static Electricity, 1993 edition.

NFPA 306, Standard for the Control of Gas Hazards on Vessels, 1997 edit ion.

B-I.2 O the r Publications.

B-I.2.1 AGA Publications. Amer ican Gas Association, 1515 Wilson Boulevard, Alexandria, VA 22209.

A-4-4 Many hazardous substances s tored in tanks and containers, or used in c leaning or repair ing them, ~'m have adverse effects on h u m a n health.

A-5-2.1.2 For more informat ion, see API 2003, Protection Against nitions Arising Out of Static, Lightning, and Stray Currents, and

PA 77, Recomrm'nded Practice on Static Electricity. See also, NFPA 69~ Standard on Explosion Prevention S'~stems.

A-5-2.1.4(b) For informat ion on u n d e r g r o u n d storage tanks, s t ructure , see API 1604, Closure of Underground Petrolm~m Storage Tanks.

Purging Principles and Practices, 2nd edition.

B-1.2.2 ANSI Publication. Amer ican National Standards Institute, 1430 Broadway, New York, NY 10018.

ANSI Z117.1, Arnertcan National Standard Safety Requirements fo* Confined Spaces, 1989.

B-1.2.5 API Publlcadons. Amer ican Pe t ro leum Institute~ 1220 L Street, NW, Washington, DC 20005.

API 1604, Closure.of Underground Petroleum Storage Tanks, 1996o ....:~...'~':~..:.

A-5-2.2 lner t lng is a m e a n s of safeguarding a tank or conta iner by API 1631, Int.~.{y TSt~.~.g of Underground Storage Tanks, 1992. reduc ing the oxygen con ten t to the poin t where combus t ion canno t ~-:~.:.--.-, take place• API 2 0 0 3 , e . ~ . f o t ~ . Against Ignitions Arising Out of Static,

Examples of iner t gases c o m m o n l y used are carbon dioxide, L i g h t n i n ~ : ' ~ St~!~.~..rrents, 1991. n i t rogen argon he l ium flue Izases that mee t the oxygen criteria - ' ~ " - % : " ""~Ii~ -"" and m~xtures of these gases. ~ 'hese can be ob tmned m cyhnders APJ.(.~'| 3, ~ a n m g l ! ,~ 'Y lPanks ~n Flammable or Combustzble Ltqmd and in tank t rucks. Carbon dioxide can ,also be obta ined in solid S ~ 1~.+.1. ~'.:::" ~:...~ . . . . . . . . . fo rm. .~'.:', .:?.!,:: ?.~:~!::..

" A ~ i ~ ? : ' + ~ ' ~ Entry and Cleaning of Petroleum Storage Tanks, 1994. A-5-2.2.5 The oxygen concentra t ion can be de t e rmined us ing the ~ following calcnlat ion :~::::,, API 20~!~g~..~ion Hazards Involved in Abrasive Blasting of

: i i~ i~ .~:~t .mospher~age Tanks in Hydrocarbon Service, 1982o ":?i:. "~:"~.:~;~::-:~-. x~:"

_ 100 - - O~ C O 2 :i~i~i. '~~"~i.l. "" i?'Procedures or Weldin or Hot Ta in on ui en in % 0 = ~ x 2 0 8 .. . . . . . i ~ . ~ g t~ g Eq pm t " . . . :!~-'.:: ...':~'~er v i c~:I 9 9 5. 1 O0 .:.:.-'.-.:-.-~-~~i-'!~:.-.:~.. ::~" ",-"

. . . . . . . . . . . . . :-(~:e. N!!! % , ~ I 2217A, Guidelines for Work in Inert Confined Spaces in the a-a-z.z.o apeclat p r ecau tmns are necessary to wor~ it!:.~ifang ~ii:: .. "!~trnleu~n I~.4~,¢t~o 1qR'7 conta in ing an iner t a tmosphe re . These activities a r e . : 6 ~ : ~ t~!:Ni~*[!~::.:. ":~:.:¢'* . . . . . . . . . . . . . . ~ . . . . . . . scope of this s tandard and the qu..alified person shou ld ' ~ . . t the"%ii:~iii:~;; 11-1.2.4 NLPA Publication. National Leak Preventiot, Associat io, . appropr ia te re terences prior to allowing entry t~..~i..~,tank O~N~ 7685 Fie ds ~'rtel l~o~a C i n c ; ~ a t l n t 4 av~gal conta iner that contains an inert atmosphere..::.:?::::' "~::"?':-~i%::. '::':.i~i~ii:".'~:i:~ ~::"

. . . . ~ : . . "::-"~!ii~i?, ..:;iii~::" NLPA 631, Entry Cleaning• Interior Insl~ection ReOair and Linintr A-5-2.4 For more t m o n n a u o n on s tauc . g ~ c claargeg~i~e ':" or U n d ~ o u ~ d ~[ora~- "r~,~', loo~ ~ ' - - ' ,Section 4 2 7 of API 2 0 1 5 . . Safe Ent y~ r 3 an~ C~uw~g of ... "~ ~'s . . . . . . e,° :~'r . . . . . Storage..Tanks, and NFPA 77, mc~mmended Pra~..::io.n Sta~: B-1.2.5 UoS. Gove rnmen t Publications. U•S. Gove rn m en t Printing z~tectrtctt~

' ' '%~'.'!::::...::i#: Office, Washington, DC 20402.

A-8-5 See Section 4.7.2 of API 2015, Safe Entry and~beaning of NIOSH Pocket Guide to Chemical Hazards, 1997. Petroleum Storage Tanks. for appropr ia te safeguards.

For informat ion on abrasive blasting, see API 2027, Ignition Hazards Involved in Abrasive Blasting of Atmospheric Storage Tanks in HTdrocarbon Service.

A p p e n d i x B R e f e r e n c e d P u b l i c a t i o n s

B-I Tile following d o c u m e n t s or por t ions the reof are re ferenced within this s tandard for informat ional purposes only and are thus not cons idered par t of the requ i rements of this s tandard unless ,also listed in Chapter 9. T he edit ion indicated here for each reference is the cu r ren t edit ion as of the date of the NFPA issuance of this s tandard.

OSFIA, Code of Federal Regulations, Title 29, Part 1910, 1000, Subpar t Z, Air Contaminants .

OSHA, Code of Federal R~,~;ulations, Title 29, Part 1910.146. "Permit- required conf ined spaces?

OSHA, Material Safety Data Sheet (MSDS).

3 0 9

N F P A 3 2 7 / 3 2 8 / 3 2 9 1 A99 R O P

PART !1 PART III

(Log #CP1) 327- 1 - (Entire Document): Accept SUBMITTER: Teclmical Committee on Tank Leakage and Repair Safeguards

I RECOMMENDATION: The Committe proposes to withdraw NFPA 327, Standard Procedures for Cleaning or Safeguarding Small Tanks and Containers Without Entry. SUBSTANTIATION: Portions of NFPA 327 have been incorporated into the proposed complete revision of NFPA 326, Standard Procedures for the Safe Entry of Underground Storage Tanks. See full text of NFPA 326 as shown at the end of NFPA 326 proposals. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS EHGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:


(Log #CP1) 328- 1 - (Entire Document): Accept SUBMITTER: Technical Committee on Tank Leakage and Repair Safeguards RECOMMENDATION: The Committe proposes to withdraw NFPA 328° Recommended Practice for the Control of Flammable and Combustible Liquids and Gases in Manholes, Sewers, and Similar Underground Structures, 1992 edition. SUBSTANTIATION: Portions of NFPA 328 have been incorporated into the proposed complete revision of NFPA 329, Recommended Practice for Handling Underground Releases of Flammable and Combustible Liquids. See full text of NFPA ~29 as shown at the end of NFPA 329 proposals. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 20 NOT RETURNED: 2 Geyer, IA~tfimer

(Log #1) 327- 2- (3-3.4): Reject Note: This Proposal appeared as Comment 327-6 which was held

from the Annual 93 TCD on Proposal 327-22. SUBMITTER: James G. Gallup, P.E., CSP, RoifJeusen & Assoc., Inc. RECOMMENDATION: Delete the following text:

$-3.4 ~ . . . . . . ng ~ ~ n . . . . . . . . . . . . . . v . . . . . . . . . . . . e, . . . . . . . . . . . . . . . . . . . . . . . . . . ~. P o r t a b l e c a r b o n d m x l d e . . ° SUBSTANTIATION: We know of no feasible means to reduce the pressure of carbon dioxide flow to eliminate a static charge° COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: The Committee rejected this

roposal due to the fact that NFPA 327 is being withdrawn. owever, the Committee has addressed a similar concern in tbe

proposed complete revision to NFPA $26 (See Chapter 5-2.2.4 of the full text of NFPA 326 following the NFPA 326 proposals.) NUMBER OF COMMrlq'EE MEMBERS ELIGIBLE T O VOTE: 22 VOTE ON COMMITTEE ACTION:


EXPLANATION OF ABSTENTION: WILEY: For this, I abstain because 1 am not familiar enough with

the issues to appropriately vote otherwise.

(Log #2) 327- 3- (3-3.7): Reject Note: This Proposal appeared as Comment 327-7 wlfich was held

from the Annual 93 TCD on Proposal 327-22. SUBMITTER: James G. Gallup, P.E., C, SP, RolfJensen & Assoc., Inc. RECOMMENDATION: Delete the following words from 3-3.7:

• . . of inhalation of inert gas !f pzrtJz! e:'.try !: pc::ilz!c." SUBSTANTIATION: This is the only reference to partial entry. The scope of the revised standard does not permit entry. COMMITTEE ACTION: Reject. COMMITTEE STATEMENT: The Committee rejected rials

roposal due to the fact the at NFPA 327 is being withdrawn. owever, all references to "partial entry" have been deleted in the

complete revision to NFPA $26. (See the full text of NFPA 326 at the end of the NFPA 326 proposals). NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:


PART IV

(Log #CP2) 329- 1 - (1-2 (New)): Accept SUBMITTER: Technical Committee on Tank Leakage and Repair Safeguards

[ RECOMMENDATION: Add a defintiions section (1-2) to Chapter SUBSTANTIATION: The Committee felt a definitions section was necessary for this Recommended Practice to identify key terms used throughout the text. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMITTEE ACTION:

AFFIRMATIVE: 20 NOT RETURNED: 2 Latdmer, Selisker

(Log #CP1) 329- 2 - (Entire Document): Accept SUBMITrER: Technical Committee on Tank Leakage and Repair Safeguards RECOMMENDATION: Completely revise NFPA 329, Recommended Practice for Handling Underground Releases of Flammable and Combustible Liquids, 1992 edition and include

ortions of NFPA $28, Recommended Practice for the Control of ammable and Combustible Liquids and Gases in Martholes,

Sewers, and Similar Underground Structures which is being withdrawn. SUBSTANTIATION: The Committee has determined that a significant portion of NFPA 328 is either outdated or repetitious , t the material content of NFPA 329. Those portions of NFPA 328 that remain valid and informational have been included in tile complete revision of NFPA 829 .as shown at the end of this report. COMMITTEE ACTION: Accept. NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 22 VOTE ON COMMrVrEE ACTION:

AFFIRMATIVE: 20 NOT RETURNED: 2 Lattimer, Selisker

310

N F P A 3 2 9 ~ A 9 9 R O P

NFPA 329

Recommended Practice for Handling Releases of Flammable and Combustible Liquids and Gases

1999 Edition

NOTICE: An asterisk (*) following the n u m b e r or letter des ignat ing a paragraph indicates tha t explanatory material on the paragraph can be f o u n d in Append ix A.

Informat ion on referenced publ icat ions can be found in Chapte r 8 and Appendix F.

Foreword

Releases of f l ammable and combust ib le liquids and gases can result f rom Ieaks in tanks or lines, surface spills, or h u m a n error. Generally, the a m o u n t of liquid or gas tha t is lost is small and can be dissipated by evaporat ion or otherwise ,assimilated. However, because of the physical and chemical characteristics of many f l ammable and combust ib le l iquids or gases, it is possible tha t a release can find its way into a subsurface structure, such as a basement , utility condui t , sewer, or well. Whe the r or not an immedia te hazard exists d e p e n d s on a n u m b e r of factors, such as die a m o u n t of liquid or gas released, where it is found , how it is

1-1.4" The condi t ion created by the releases o f liquids and vapor~ in subsurface sm~ctures can be g rouped into two classes: (1) f l ammable and (2) i ~ u r i o u s to life. The latter condi t ion results f rom the toxic or su~oca t ing propert ies o f the gases or vapors. Some of these liquids and gases fall into both classes. While dais publ icat ion deals primari ly with the f lammable limits associated with liquids and gases, some of which are listed in Appendix A, addit ional precaut ions migh t be requi red to protect against hea l th hazards. An example is benzene; its dange rous brea th ing concent ra t ion is only a small fract ion of the lower f lammable limit (LFL).

1-1.5 The responsibility for p roper hand l ing of a suspected release of f l ammable and combust ib le liquids and gases, or a potential hazard f rom such a release, will be shared by various individuals, organizations, and regulatory agencies. The successful hand l ing of these problems will d e p e n d on the best possible cooperat ion between them. This r e c o m m e n d e d practice is in tended for the informat ion of all organizat ions and persons involved. Owaaers, operators, or o thers becoming aware of a hazardous condi t ion should notify tlae fire depar tment , police, or o ther proper anthority.

1-1.6 The National Fire Protect ion Association does not, by the publicat ion o f this r e c o m m e n d e d practice, r e c o m m e n d action that ts no t in compl iance with applicable laws and regula t ions arid shou ld not be considered as do ing so. Users of this r e c o m m e n d e d confined~ and possible sources of ignition. practice shou ld c.Qnsult all applicable federal, state, and local laws

Because a f l ammable or combust ib le liquid tha t is u n c o n f i n e d in ,and r e g u l a t i o n s f i ~ c i a l l y with respect to any applicable repor t ing the subsurface can move f rom place to place, any indication that reqmremen~'.:~il such liquids have escaped into the subsurface mus t be considered ..S:-~iS:, as a potential , if no t immedia te , hazard. T he probability of an 1.9 IIoFC~]~lnn~'-":'~:. ~- explosion or fire within a subsurface space d e p e n d s on two factors: . _ ~..~....:~.~. . . . . . . .-.:~?..:, (1) the a tmosphe re mus t contain a mixture of f lammable vapor ~ ..::::¢:~::::":::~" " ~ ! : : : : " . . . . . . ,, and air within the f lammable rarme and (2) there mus t be a ~.o~r the purpose ot ~ r e c o m m e n o e a pracnce, the toliowmg

. . . . . . . . . s s "" have the ¢heanin given below coinc ident source of ignition. T h e severity of an individual .... ~ ~ : gs . explosion or fire and its consequences d e p e n d s on various factors. " ~ . :~ '~ ' : " '% . . . .

Aut Havan ur l sd lc tmn The organlzauon office or The possibility tha t any one explosion migh t result in a major ~ g J " • " " , , . . . . . . . . . ho :~ ~l . . . . . . . . . . . . ~ i nd iv i~ : :¢es l~ons ib l e for approvimz e q u i p m e n t an installation or

~ . , : . : . a p r o c e ~ This r e c o m m e n d e d practice will provide regulatory officials, fire ::~."~:~::... ........ ~ . . . .

The p e r m a n e n t o m m g of meta lhc parts to form an authori t ies, contractors, and owners of subsurface s t ructures "-': ~ g " J . , ;A . . . . . . . . . h l ~ . ; . . . . h 4 ~ n . . . . ~.to ~ a . ~ t . . o.:t.,o :: ..~::" e l ec~ca l ly conductive pa th tha t wall ensure electrical cont inui ty ~qtl']d's~a~l~l"g~-sesti'Ja't'mi'g'ht"be~o'un"~l i ' n " s u ~ b s u ~ a c e " s ~ . ; a n d '~i:. and¢the capacity to conduc t safely any cur ren t likely to be imposed. o ther a r e a s . - - - ~ i ~ i : "?':::--/

• ":~ii~:~ ~!" ..2.:~::" Combus t ib le Gas Indicator. An i n s t rumen t that samples air and ~ "-':i~:.....-'.:.:....::..~!i~i'::.'-'~"-~-:.:J~!~:~:!*i::.:!:~:::" indicates whe the r the re are combust ib le vapors p resen t Some units

Chapter 1 General Provisions ":'%~i!i:i~ ............... :':::::::::*:" may indicate the percentage of the lower explosive limit of the a i r - ,..... ~:~ d ~ ?".'~i.'.:~ i~ii'-'.~i:i:-. ~::~i!ii~-!:: ...... gas mixture .

1-1 Scope. ....:~i~. "::!.:-:..'~-..".".;:: -.::" Container . A device that is in tended to contain an accunmla t ion • ::"::::'Zs~.':.:ii~:= " ~ of hazardous substances that is too small for h u m a n entry or has a

1-1.1 Tiffs r e c o m m e n d e d practice p rov ides"~opr ia te i i : '~ne thods capacity that can be effectively and safely cleaned without h u m a n for r e spond ing to fire and explosion hazards r~ '~ : '~g . :~ 'om the entry. release of a f l ammable or combust ib le liquid, g,~"~".?'~r~zapor that might migrate to a subsurface structure. Althoughf~is Flammable Gas (F lammable Vapors). Any subs tance that exists in r e c o m m e n d e d practice is i n t ended to address only these fire and the gaseous state at normal a tmospher ic t empera tu re and pressure explosion hazards, o ther author i t ies shou ld be consul ted regarding the envi ronmenta l and heal th impact and o ther hazardous condi t ions of such releases.

1-1.2 This r e c o m m e n d e d practice outl ines opt ions for de tec t ing and investigating the source of a release, for mit igat ing the fire and explosion hazards resul t ing f rom the release, and for tracing the re leased liquid back to its source. These opt ions are not in t ended to be, nor shou ld they be considered to be, all-inclusive or manda to ry in any given si tuation, ff better or more appropr ia te alternative me thods are available, they should be used.

1-1.$ The procedures out l ined in this r e c o m m e n d e d practice can apply to hazardous subs tances o ther t han f l ammable and combust ib le liquids tha t migh t have adverse h u m a n hea l th effects. However, the physical characterist ics of the hazardous subs tance released m u s t be unde r s t ood before taking any action. It shou ld be recognized tha t o ther authori t ies, such as federal or state hazma t personnel , shou ld be consul ted regard ing the env i ronmenta l and heal th impact and o ther hazardous condi t ions o f these substances. Guidance regard ing m a x i m u m acceptable levels of these substances can be found in the Material Safe~ Data Sheet (MSDS); OSHA 29 CFR 1910.1000 Subpar t Z; o ther OSHA substance specific s tandards; the A C G I H Threshold Limit Values (TL V) for Chemical Agents; Physical Agents and Biological Exposure lndic.es: and the NIOSH Pocket Guide to Chemical Hazards.

and tha t is capable of be ing igni ted and bu rned when mixed with the proper propor t ions of air, oxygen, or o ther oxidizer.

Hazardous Substance. A subs tance that is capable of creat ing h a r m to people, the env i ronment , or property. The dangers may arise f rom but are no t l imited to toxicity, reactivity, ignitibility, or corrosivity. A hazardous subs tance inc ludes combust ib le ,and f lammable liquids and f l ammable gases.

Hot Tapping. The t echn ique of welding and drilling on in-service tanks or conta iners that contain f lammable , combustible, or o ther haza rdous substances .

Hot Work. Any work that is a source of ignition, inc luding open flames, cut t ing and welding, spark ing of electrical equ ipmen t , gr inding, buffing, drilling, chipping, sawing, or o ther similar opera t ions tha t create ho t metal sparks or surfaces f rom friction or impact .

Inert Gas. Any gas that is nonf l ammable , nonreactive, and noncon tamina t ing .

lnert lng. A techn ique by which the a tmosphe re by which a tank or conta iner is r ende red nonigni t ib le or nonreact ive by die addit ion of an inert gas.

311

N F P A 3 2 9 ~ A 9 9 R O P

Liquid. Auy material daat has a fluidity greater than that of 300 penet ra t ion asphal t when tested in accordance widl ASTM D 5, Standard Test Method for Penetration of Bituminous Materials. Wbere not otherwise identified, the term liquid shall mean both f l ammable and combust ib le liquids.

(a) Combustible Liquid. A liquid having a closed-cup flash point at or above 37.8°C (100°F). Combust ib le liquids shaU be subdivided as follows.

1. Class II liquids sball inc lude those liquids having closed-cup flasl~ points at or above 37.8°C (100°F) and below 60°C (140°F).

2. Class IIIA liquids shall inc lude those liquids having closed- cup flash points at or above 60°C (140°F) and below 93A°C (200°F).

3. Class IIIB liqnids shall inc lude those liquids having flash points above 93.4°C (200°F).

(b) Flammable Liquid. A liquid having a closed-cup flash poin t below 37.8°C (100°F) and having a Reid vapor pressure not exceeding 2068.8 m m Hg (40 psia) at 37.8°C (100°F) as de t e rmined by ASTM D 323, Standard Test Method for Vapor Pressure of Petroleum Products (Reid Method). H a m m a b l e liquids shall be subdivided as follows.

1. Class IA liquids shall include daose liquids having closed-cup flash points below 22.8°C (73°F) arid boil ing points below 37.8°C (100°F).

2. Class IB liquids shall include those liquids having closed-cup flash points below 22.8°C (73°F) and boiling points at or above 37.8°C (100°F) o

3. Class IC liquids shall inc lude those liquids having closed-cup flash points at or above 22~8°C (73°F).

Lower F lammable Limit (LFL). T ha t concent ra t ion of a combust ib le material in air below which ignit ion will no t occur. Also known as the lower explosive limit (LEL). Mixtures below this

Toxic Materials, Gases, or Vapors. Any material whose propert ies contain the i nhe ren t capacity to produce injury to a biological system. This is d e p e n d e n t on concentra t ion, rate, me thod , and site of absorpt ion.

Unstable or Reactive Materials. A liquid that, in the pure state or ms commercial ly p roduced or t ranspor ted, will vigorously polymerize or decompose or will become self-reactive u n d e r condi t ions of shock, pressure, or t empera ture .

V a p o r . Tile evaporated phase of a subs tance that is normally a liquid at room tempera tu re and p re~ure .

Volatile Liquid• A liquid that evaporates readib' :it normal t empera tu re and pressure.

Work. Activities pe r fo rmed on tanks and conta iners in accordat~ce with this document ; including, but not l imited to, s:ffeguarding, repair, ho t work, cleaning, change of service, main tenance . inspect ion, and t ransportat ion.

Chapte r 2 Sources o f F lammable and Combus t ib le Liquids and Gases

2-1 General.

2-1.1 * H a m m a ~ - - : ~ n d combust ib le liquids and gases are common ly stg.....~d arid hand led in locations flint are immediate ly adjacent t o . : ~ t u r e s , facilities, and people. F lammable and combust!. . l~ he ta''':::~..~, inc lude chemicals, c leaning fluids, motor gasoline~Z~l.iesel ~ - ~ . . a n d beat ing oil. Motor gasoline is the most wide.!~'.{~e':i:l of the~:~. .~.kls, and is c o m m o n l y s tored u n d e r g r o u n d at...~rvice stations an~i'i'~i~her vehicle fuel ing operat ions. F lammable .~..cofi:~.'~.ustible g a s ~ include natural gas, p ropane , sewage gases,

.... ~ ~ n t ~ e s . ..:.:.:.:.:-:..

limit are said to be "too lean." 2 - 1 . 2 " : : ~ m . ~ b l e vapors in subsurface s t rnctures can result f rom a

Oxygen Monitor . A device capable of de tec t ing and measur ing :%1"~:-'.-:.-.,. release ~ i~ f f l ammab le or combust ib le liquid. Examples of these :~U:.:~-iiii~i~!;r:.-.ejeases i#/!lude c leaning solvents and c o m p o u n d s washed down

concent ra t ions of oxygen in the a tmosphere . :!ii. " : ' . : . -~ i : .by industrial and domest ic users and a surface release that

Purging. Tile process of displacing vapors or gases f rom an ":'i<.::: :s:" carl "~ ' ter a sewer or drain. A release can also result f rom damage enclosure or conf ined space° ..::i::~{iiiiiii!}i:: "~i~. to t,4nks, containers, and lines, for example , f rom corrosion,

:ii:. s tructural failure, excavation in the area, or fire° ..::Y "?i:!:i:i- . .... Qual i f ied Person, A person, who by possession of ~ g o g n i ~ d ~]":f"

de,~ree certificate nrofessional s tandin~ or skill a~'d ~ . ~:-:-:i:~:'-:::::~:-'::.':::::::::::~::':" 2-1.3 If a f l ammable or combust ib le liquid or gas is present in the ~ , , , 1 ~ ~ , ~ . .x .%.~: . . .~&:> ' : : : : :~ : : ' : i : : : : : : - : : - : : : - . . . . . . e e as o s ted soft as mi bt be roduced by deca)qng or anic mat ter there ~s knowledge training, and xperi nce, b d e m n tra tl:t~!~bility ........ , g P • g ,

t~ clo.ql wit{~ n rnh l em s a¢¢OClatoA tn the suhi,-ct.:~ra~a~r t h o ' : ~ k k nr some likelihood tha t it will oene t ra te an adiacent subsurface tt'~e~)~oiecS v" . . . . . . . . . . . . . . . . . . . . ~::S:':'~'~"'~2ii~i~:[ "~ "-'::.~'~÷ii~":": s'~ s tructure. Particular attenti 'on sbould be p~dd to landfill sites

~ ..:::':iii:~ "":'{ii!~i!: )::°" developed by the deposi t ing of garbage and trash. Gas fi'om dlis Se l f -Conta lned Breath ing Apparatus . ~ " X ~ b l e resp i"~ory source, primarily me thane , m igh t no t have art odor.

device des igned to protect the wearer f rom a."~-"~uygen-d~'!icient or o ther haza rdous a tmosphere . It suppl ies a resl~. l~Je ~ o s p h e r e 2-1.4 Hammab le gases or vapors can en ter conduits , sewers, that is e i ther carried on in or gene ra ted by t h e ' ~ a t u s and is dra ins or basemen t s because subsurface s t ructures cons t ruc ted of ~.4 . . . . ~1 . . . . c ,i. e ~ . en t ~'Zi . . . . e~t i . :s ~?~:;"~e a with a c emen t concrete brick or vitreous tile generally are not built to l l l l l l ~ [ J ~ l | U K ~ l l l * ~ 1 l l | * J . | | | O | I o i l * / l t , J | l | | | I I • I L I t ~ - ~ I t l r l ~ ~ 1 , ' • ~

- s ov S e a Hea be Impervmus to ases or va ors Gases or va ors can en ter the full-face mask and i appr ed by dae U . . Min S~e ty nd lth . g . .P • P n a at u e O auo I S subsurface secuons of b m l d m s t h r o u g h cracks or a r o u n d any Adminis t ra t io nd the N ional lnst i t t for c c u p " na afety g

and Heakh .

Standby Person . A person who is ass igned to remain on the ouLside of the conf ined space ,and to be in commun i ca t i on with those working inside.

Static Electricity. The electrification of materials t h rough physical contact and separat ion and tile various effects that result f rom tile positive and negative charges so formed, particularly where they consti tute a fire or explosion hazard.

Subsur face Structure. Subsurface s t ructures include manho le s , sewers, utility condui ts , observat ion wells, s torm drains, vaults, water lines, tirol gas dis t r ibut ion systems, electric l ight and power conduits , t e l ephone and te legraph commun i ca t i on lines, street- l ight ing conduits , police and fire signal systems, traffic signal lines, refr igerat ion service lines, s team lines, pe t ro l eum pipelines, subways, runnels , and the subst ructura l areas of bui ldings such as basements and parking garages.

Tank. A stationary or portahle device tha t is i n t ended to conta in an accumula t ion of haza rdous substances that is large enough to allow Imman entry.

Toxicity. The quality or degree a subs tance is ha rmful to humans .

u n d e r g r o u n d condui ts tha t pene t ra te the subs t ruc ture walls or floors.

2-2 Sources o f Ignition°

2-2.1 The possibility of ignit ion of f l ammable gases or vapors that migh t collect in subsurface s t ructures is l imited by certain f imdamen ta l condit ions. The vapor mus t be mixed with sufficient air to make a f lammable mixture or it mus t be escaping into air at a poin t where a f lammable mixture can be created. Heat of sufficient intensity to ignite the particular a i r -vapor mixture involved mus t be p resen t at the place where a f lammable mixture exists. Such heat migh t be caused by an open flame, an electric arc or spark, or o ther ho t surface°

2-2.2 The f lammable limits of some gases and vapors that have been found in subsurface s t ructures are listed in Appendix B. Flammable mixtures are fo rmed when the concent ra t ion of these gases and vapors in air is between the lower and uppe r limits shown.

2-2.3 Potential sources o f ignit ion can be encoun te red in everyday operat ions. Little control can be exer ted over these sources of ignition when f lammable vapors are escaping from or into subsurface structures. Such sources of ignition include open

3 1 2

N ~ A 3 2 9 1 A 9 9 R O P

flames, furnace pilot lights, au tomot ive and o ther internal combus t ion engines , tar pots, and smoking.

9-2.4 Static electricity can be a source of ign idon and its accumula t ion is general ly greatest in an a t m o s p h e r e of low humidity. The hazard appears when static accumula tes to die extent where a spark discharge occurs. Static electricity can be genera ted when a liquid u n d e r pressure escapes f rom a p i p e at ltigh velocity. Particles of dust, scale, or rust, or liquid droplets inside tile pipe can become heavily charged with static when blown out by gas or vapor and, if they imp inge on an electrically isolated body, the body will accumula te the charge and a spark discharge c a r l o c c u r .

Chapter 3 Initial Response

3-1 Indicators of a Release. A release of f lammable or combust ible liquids or gases can be indicated by physical discovery or by indicat ions of a potential release.

3-1.1 A release of f l ammable or combust ib le liquids or gases can be indicated by physical discovery in the following:

(a) Normally inhabi ted subsurface s t ructures such as basements , subways, ~md tunne l s

(b) O the r subsurface s t ructures such as manholes , sewers, utility conduits , observation wells, and similar subsurface structures near tanks

(c) Groundwater (d) Drinking water supplies (e) Surface water (f) Seepage f rom the eardl

3-1.2 Indicat ions of a potential release of f l ammable or combust ib le liquids, gases, or vapors can be de tec ted by the following:

(a) Evidence of a spill (b) Failure of a t ightness test (c) Moni tor ing e q u i p m e n t (d) Loss of inventory (e) Presence of water in a tank (f) Odors

3-2.4.1 If liquids, gases, or vapors within or above the f lammable range are found in a building, the buildinl~ should not be entered. Evacuation of bui ld ing occupants , at least m areas that were exposed, should be ordered. Const ruct ion and layout as well as occupancy are factors to be cons idered in order ing evacuation.

3-2.4.2 If liquids, gases, or vapors are f ound in tunne ls or subways, t~tffic shou ld be s topped until qnalified personnel de te rmine that there is no danger of explosion, fire, or heal th hazards.

3-2.5 Eliminating Sources of Ignition.

3-2.5.1 Smoking or o ther sources of ignition should not be permi t ted in areas where f lammable or combust ib le liquids, gases, or vapors have been discovered. Lights and o ther electrical switches should no t be tu rned on or off, and power cords shou ld not be removed f rom oudets . Any such action can create a spark that is capable o f ignit ing f l ammable gases or vapors. Use only those switches located well away f rom the area to d i sconnec t electrical power. This migh t require tha t the electric utility effect a remote cutoff.

3-2.5.2 After the presence of f l ammable or combust ible liquids, gases, or vapors has been verified in a bui lding or subsurface structure~ d ie electlical and gas services to the bui lding or s tructure, where possible and feasible, should be d i sconnec ted or shu t off outside the structure. Shut t ing off the gas service outside of the bui ld ing rexnoves the fuel f rom pilot lights and gas burners ,

..:.:-:.

which could b..e:..:;~t~ces of ignition.

3-2.6 Ente.li~i."..~.e Area.

3-2.6.[::..y~ enter:i~i:'.a..rea in which there is an u n d e t e r m i n e d con.~tB'f~.uon of st"~.-...~cflknown gas or vapor is to risk die p..~ibil~ty of fire or e ~ l o s i o n . F lammable gases or vapors in a

~ o ( ~ . g . . o n d u i t migh t no t originate f rom f lammable liquids. They " ' ~ . . ~ : ~ o r s f rom overheated insulation, sewer-generated gases, fuel " ~ , or industrial gases. Consequent ly , special ins t ruments ,

. equlpffi~,,azs..kills, and procedures (conf ined space entry) might be ::iiii~.-'~.:::::.., ' necessm:~iii~e guidance of tile utility owning and operat ing the ":~ii[':':'-~i. ty sb6uld be solicited and followed. Entry should n o t be made

::i . . . . : : ~ i " ~ gas or vapor concent ra t ion has been checked with at, "::i; ........ app~:pr ia te i n s t rumen t as indicated in 3-2.3.

...... ~.:.-:~i!i~:~::. ....

3-2 initial Response to Physical Discovery.

3-2.1 Depend ing on tile c i rcumstances of p h ~ i : . ~ ' . s c o v ~ i ~ i i : : . condi t ions can exist where there migh t be a . : # ~ ' ~ r i ~ ! ~ a r d " ~ l f f e or property, and immedia te steps s h o u l d . ~ L a k e n t o ' ~ ( ~ e c t t ~ public f rom the dange r of explosion a n f f ~ : "!ii~i

-::!:~:!~.~: ..'::.:.

3-2.2 For un inhab i t ed structures, those direct'~i~..~...po . ~ b l e for the facility involved shou ld be contacted: the m u n i c ~ j , ~ i t a r y d e p a r t m e n t or highway or street d e p a r t m e n t for s ~ t r s ; tile electrical or t e l ephone or gas companies ' eng inee r ing depa r tmen t s for conduit . Normally, the ma i n t enance and eng inee r ing depa r tmen t s of such organizat ions will be well equ ipped to take care of the situation. Police, if needed , can be asked to keep the pnblic clear of the dange r areas° Tile fire d e p a r t m e n t migh t be n e e d e d to assist in fire control and purging. Those involved with facilities that store and hand le f l ammable and combusdble liquids that migh t be the source of the problem should offer all possible assistance.

3-2.3 The presence of f lammable gases or vapors in a bui lding or subsurface s t ructure is general ly repor ted because of an odor. However, smell canno t be relied on to de te rmine tile type of gas or vapor or its concent la t ion . Tile use of an appropr ia te instrument~ such as a combust ib le gas indicator or photoioniza t ion detector, is required to de te rmine the presence and ex ten t of a f lammable gas or vapor concentra t ion.

3-2.4 No one shou ld en te r areas where f l ammable or combust ib le liquids, gases, or vapors have been discovered except as descr ibed in Section 3-3.

.::;:;;*'"'":¢;;i-::"..::-'!i! ":~!::...$-9.6.2 An addit ional life hazard migh t exist because of toxic gases ,~.~. . . : . : . : .:.~.,- . . - . . ' ~

• ..::~i~i~i~iii .... ii!:! ;::::" or vapors or insufficient oxygen. If these c o n d m o n s are suspe "ted, " ":::',iiii~iii-::....::~."~i}!i!i!ii~!ii~i!::~iii!i~ili:.:::" ins t ruments to detect toxic gases or vapors or insufficient oxygetl

.................... :" should be used.

3-2.6.3 The appropr ia te i n s t rumen t shou ld be used f requent ly to de te rmine file gas or vapor concent ra t ions in tile affected area. Where gas or vapor concent ra t ions are above 50 pe rcen t of the lower f lammable limit, everyone within the affected area mus t be evacuated. The area should be ventilated to remove or reduce the f lammable gas or vapors and thus reduce the fire or explosion hazard. As soon as the f lammable gas or vapor has been reduced below 50 percen t of file lower f lammable limit, entry can be made to locate and el iminate the source of gas or vapor. Self-contained brea th ing appara tus shou ld be worn when en ter ing the affected a r e a ~

3-2.6.4 Natural ventilation provided by open ing doors and windows and removing m a n h o l e covers or o ther accesses might be adequate to remove vapors f rom tile affected area. G r o u n d e d mechanical exhaus t ventilating e q u i p m e n t migh t be required to remove vapors f rom all areas, particularly f rom low, conf ined spaces. Fans driven by motors tha t are approved for Class 1, Group D locations, hand-dr iven fans, or air eductors can be used to remove vapors (seeFigure 3-2.6.4). Sources of ignit ion near the exhaus t outlets shou ld be el iminated. Open ings for free entry of fresh air should be provided, but air should never be forced into the area. A water hose with the nozzle set in a spray pat tern can be used for ventilating the area if it is set in a window and discharges outwardly.

3 1 3

N F P A 3 2 9 - - A 9 9 R O P

Window opening V / / to areas to be

A~ay~suc~ai~out-- ~/~ Ik ~a~uat~d n'v'r"°'\ Eliminate sources ~ I _ ] ~l~ ~ 1

_. _"-/,,NL inlets elsewhere

3-2.11.1 If the entire surface of tile water is covered, or fl~ere are large pools in the order of 20 ft (6 m) or more across, a fire hazard does exist. If large a m o u n t s of vapor are being genera ted , the wind direct ion shou ld be checked and all sources of ignit ion within at least 100 ft (30 m) downwind of the source shou ld be removed. It is unlikely tha t vapors will be in the f lammable range far ther than 100 ft (30 m) away. However, if large a m o u n t s are revolved, an d the air is relatively still, an appropr ia te i n s t rumen t shou ld be used to de te rmine tile ex ten t of the hazardous area. Its use is desirable in any event if f l ammable liquids are involved°

3-2.11.2 Normally, the only effective means to stop furd~er accumula t ion is to f ind tile source of the release and stop it. Dikes or dams migh t need to be const ructed t o p r e v e n t fi ir ther spreading of the liquids or of con tamina t ed water. Floating booms can be used on flowing water to hold d~e con tamina t ing liquid. (See Chapters 6 and 7).

3-2.1 !,3 Once the source of f l ~ n m a b l e or combust ible liquids is s t opped , removal can be accompl i shed by evaporation, normal dispersal, di lut ion, collection with adsorbents , sk imming devices. or f i l tering devices. (See Chapter 7for details.)

F i g u r e 3 - 2 . 6 . 4 E x h a u s t v e n t i n g ° 3-3 Initial Response to Indicat ions o f a Potential Release.

3-2.7 The genera t ion of sewer gas can be s topped or s ignif icandy reduced by f lushing the sewer or condui t with water°

3-3.1 An inventory loss, water in tanks, failure of a r ightness test. or o ther monitoring~ e q u i p m e n t indicat ions do no t directly indicate a hazard o f fire a .~?: '~plosion. The immedia te vicinity should be

3-2.8 When tile a rea has been m a d e safe for entry, it can be checked for ...~..~'signs o f escaping liquid. If any exist, tile examined to de t e rmine the source of the f lammable or p r o c e d u r e s . . : : ~ i~or initial response to physical discovery should combust ib le liquids, gases, or vapors, ff file place or places of ent ry be follow...O$[~#~.£opriate. (See Section 3-2.) Otherwise, the of the liquid, gases, or vapors can be de te rmined , appropr ia te steps p rocedu '~s o f C ' f i ~ r s 5, 6, and 7 should be followed. shou ld be taken to seal t h e m off. Un t r apped drains, dry traps, ....:~S,>.:.. "~ "...:~:~!:..:'?•:........ pipes, or o ther open ings t h r o u g h floors or founda t ions are 3-$.~-~"" Tile act ions r e d ' m e n d e d in Cbapter 7 should be t'olh,wc,:l c o m m o n sources o f liquid gas or vapor entry. Any gas pipes in the .,.,2, ' . . . . ~ " il'

. . . . . ec" " t" ~ ' bl . . . . . , t ~ [ e r e l~..evloence o r a sp t. a rea s u t u r e oe cn xea ne t t a m m a e gas or vapor m~gnt be tuet "::'"%:::.:.:~!:, ..:.:~:S:. gas. If this appears to be the source tile gas c o m p a n y shou ld be "::~::~iiii~ "~ ....... called.. "::::'~-:.~i'~::. Chapte r 4 Searching for the Source

:::::::.... ''~?~i~.~:,..~ 3-2.8.1 If vapor is en te r ing th rough a dra in or collection pipe, it :~i~.':-%~':~:~::.. ":i~."'!::" migh t be because the trap is dry. ~ l l i n g the trap with water is an ~!:: " ~ e n . e f a L effective means of blocking fu r the r gas or vapor entry. '::'!~ , 7 " " ~ : "

.~i:i:~-.-.::. !~i~" 4-1.1rAfter all t he necessary precaut ions have been taken to mitigate 3-2.8.2 The na ture of seepage migh t be such tha t it c a ~ i i v '~- fire and explosion hazards, the nex t most impor tan t step is to effectively s topped f rom inside the structure. In this ~ , an ~:}# iiiii:":{ocate the source of the f l ammable or combust ib le liquid and in tercept ing hole or t rench, holes for pumps , or w d ~ " ~ . t s ~::~....:.:.:.:.:...:...":" prevent any fur ther release. used outs ide tile con tamina ted s t ructure, between it ancT:i~i':*'::::::::;:~::::~iiii:iii!~::" s t tspected source . . . . . ~.~..:::... '"~i:.:. .... 4-1.2 Generally, the source of tile liquid will be relatively near the

..::!::::"~::::::::~::~:.~iiii~::~ ""~: : : : location where u n c o n f i n e d liquid or vapor has been discovered. 3-2.8.3* When seepage is de tec ted in a se .~ r , tile so~.C...sbot.~]~l be However, liquids c~m travel h u n d r e d s of feet or even miles located by backtracking with a p p r o p r i a t ( ~ ' ~ u m e n t s . ~ 0 o i n t s of u n d e r g r o u n d th rough porous soil or rock, d l rough t renches filled entry to the sewer system are l imited in n u ~ , ? n t e r c e ~ i o n of tile with porous material, a longs ide pipes or conduits , or in sewer leak can be achieved by use of t renches, well ~:$..fi, or y~ll points, pipes. Consequendy , file location f rom which a released liquid

• . . "':~::i~iii~:::;."::~" . migh t have or iginated can be remote and extensive and can include 3-2.8.4 If entry o f hqmd, .g~, or vapor !.n.to .the c o ~ m t o r sewer ts many facilities that hand le and store f lammable or combust ib le to be s topped, a n d the inside of t he facthty ts not 'accessthle, tile liquids. Also, the source of the release migh t be an a b a n d o n e d area a longside tile facility shou ld be p robed or drilled to de t e rmine the extent of its exposure to the sa tura ted soil. The exposed area should be uncovered and the facility should be sealed f rom tile outside.

3-2.9 Liquid seepages of water will of ten be more of a problem, because o f pollut ion, t han an explosion or fire hazard. However, until the source of tile f l ammable or combust ib le liquid is f ound arid s topped and all liquid and vapor are safely removed, the re is a potential hazard of explosion or fire°

3-2.10 When f l ammable or combust ib le liquids are f o u n d in well water, p u m p i n g shou ld be s topped and any source of igni t ion a r o u n d well houses and water s torage tanks shou ld be avoided until vapor concent ra t ions are checked. Electrical power outside any well house or similar trap tbat migh t collect vapors f rom the well or s tored water shou ld be d isconnected .

3-2.11 Where f lammable or combust ib le liquids are f o u n d on snrface water or emerg i ng f rom the earth, f l ammable vapor concen t ra t ions can develop in di tches or collection points. Normally, tile a m o u n t of f l ammable or combust ib le liquid found on die surface water will be in such a thin layer that it will no t create a fire hazard. This is the case where the liquid is dispersed into small bubbles or pools, or where a s h e e n is visible on the surface of the water.

u n d e r g r o u n d s torage tank. If a check of potential sources adjacent to or within several h u n d r e d feet of the discovery is no t conclusive, t hen tile investigation should be e x p a n d e d to include other potential sources in the general a rea o f tile discovery. Some potential sources inc lude the following:

(a) Automotive service stations, both retail and private (b) Automotive garages or dealc, rsbips (c) Fleet opera t ions such as taxicab companies , municipal

garages, dairies, and bakeries (d) Contractors or e q u i p m e n t dealers who store fi~els on their

p remises (e) Motor hlel and beat ing fuel distr ibutors (f) Cleaning establ ishments , inc luding dry cleaners (g) Industrial and chemical process plants (h) Airports and mar inas (1) U n d e r g r o u n d pe t ro l eum or gas t ransmiss ion lines (j) Any a b a n d o n e d tanks tha t s tored f lammable or combust ible

liquids in the past (k) Any o ther proper ty on which f lammable or combust ible

liquids are or can be s tored

4-1.3 Efforts shou ld be made to secure informat ion on g roundwate r flow pat terns f rom the regional U.S. Geological Survey (USGS) office, local public works depar tments , or similar agencies. Search efforts shou ld be init iated up-gradient f rom the leak.

3 1 4

N F P A 3 2 9 1 A 9 9 R O P

4-1.4" A map of the area shou ld be obta ined or sketched, each facility shou ld be marked on the map, and ,all the informat ion that is obta ined shou ld be recorded• Well-organized, accurate da ta will prove invaluable in subsequen t efforts to solve the p rob lem (see Appendix C).

4-1.5 Teams shou ld be organized as necessary to conduc t the search. O n e efficient m e t h o d is to assign a two-person team to each specific zone on the map. O n e o f the team m e m b e r s should represen t the local public authority, T he search shou ld begin with the neares t and mos t obvious potential sources ,and work out f rom the point of discovery, moving uphill , up-gradient of g roundwater flow, or ups t r eam of sewer or condui t flows.

4-1.6 Often the source can be found by incluiry or simple inspection. The p rocedure out l ined in Sectaon 4-2 should be followed. If an obvious or very likely source is no t f ound within several hours , it is t hen advisable, while the pr imary search cont inues , to begin test ing the closest and mos t probable sources, such as equ ipmen t , u n d e r g r o u n d storage tanks, or u n d e r g r o u n d piping, for concealed points of release•

4-2 Search Procedure.

(b) T h e areas a r o u n d fill pipes where liquid is t ransferred f rom tank vehicles to s torage tanks should be checked for signs of spillage. Saturated or da rkened soil, s ta ined concrete, or dis integrated asphal t indicates that repeated spills migh t have occurred and liquid accumula ted u n d e r g r o u n d .

(c) The areas a r o u n d above-ground tanks shou ld be checked for similar signs of leakage.

(d) All exposed piping should be checked for signs of leaks. (e) Dispensing e q u i p m e n t shou ld be checked for leaks. A

combust ib le gas indicator should be used when checking dispensers of the type used at automot ive service stations. The cover of the d ispenser should be opened jus t e n o u g h to insert the indicator probe into the area benea th the dispenser . Op en in g the cover wide migh t provide e n o u g h ventilation to dilute any vapors present and give a reading low e n o u g h to indicate dtat there is no leak. If the vapor concent ra t ion indicates a potential release, the d ispenser cover shou ld he removed and the piping, valves, an d fitt ngs should be inspected for signs of leaks. The dispensing nozzle and hose should also be checked.

(f) If a remote p u m p i n g uni t is used, its hous ing or pit should be checked with a combust ib le gas indicator before opening. The unit cma then be opened for inspection.

(g) Automotive repair areas should be cbecked for signs of w,xste liquids being d u m p e d into inappropr ia te floor dra ins or sumps.

. : : ~ : : ~ ":'%i..":.'~.~. . . . . 4-2.2* The following ques t ions shou ld be . ~ d 6~:~I~cilit~/'-'.:;~i?.'!;:" operators in the area of the search. ,~i~'-'.~ ::~-':':.-".':"~-?.::: J""

• . ':': . , : ~ . . . . ':@ (a) Has the re been a spill du r ing loading B i~ . ' ~ load t@ (b) Is any storage or hand l ing e q u i p m e n t l e ~ t ~ o r ~ a s there

been a leak? ~'~;*~" (c) Is there evidence of excavations or repairs thj~ migh t have

d a m a g e d u n d e r g r o u n d facilities? (See Appendix D). (d) Has there been any ma i n t enance on pipes, tanks, or o ther

(e) The barrels o f a n y f i r e hydrants in the area should be

e q u i p m e n t tha t migh t have resul ted in a release? (e) Has there been any odor or o the r signs of liquids in areas

where there shou ld no t be? (f) Are inventory and use records kept? Do they show any

indicat ion of a release? (g) Has water been f o u n d in any u n d e r g r o u n d storage system? (11) Is there any knowledge of an acc ident tha t migh t have

released l iquids f rom a tank vehicle, container , or storage tank? A check with local law e n f o r c e m e n t agencies is useful here. T h e age of u n d e r g r o u n d facilities should be considered. If subsequen t tests are made, older e q u i p m e n t m i gh t be suspect.

(i) Have any problems been encoun t e r ed du r ing p u m p i n g and liquid transfer?

4-2.3 If inquiry fails to disclose a n y p o t e n t i a l source, each premises owner or opera tor should be a s k e d f o r cooperat ion in checking equ ipmen t . If an opera tor refuses because he or she is no t the owner, t hen permiss ion should be obta ined f rom the owner. If necessary, local governmenta l officials can help to secure such coopera t ion .

4-2.4 The following gu idance shou ld be helpful in checking equ ipmen t .

(a) On-site leak detec t ion e q u i p m e n t shou ld be inspected for p roper opera t ion and for indications of a leak.

checked. (f) Nearby excavations and s teep cuts or natural slopes down-

g rad ien t f rom the potential source should be checked for signs of l iquid.

4-2.6 D u m p i n g or spill ing f l ammable or combust ib le liquids into sewers or on the g r o u n d migh t be a violation of state or federal law and should be repor ted to the proper authori t ies immediately.

4-2.7 Small spills do occur inadvertent ly and migh t appear to be larger t han they reali x are. A small a m o u n t o f liquid (one cup of fuel, for example) spdled on to a wet pavemen t will spread over a relatively large area. Small spills that spread out over a large area will disstpate rapidly and are no t likely sources of u n d e r g r o u n d contaminat ion . T h e signif icant releases are large spills and repeated small spills that can flow to points o f access into subsurface s t ructures or porous soils and t h e n reach the groundwate r table.

4-3 Procedures to Verify the Source.

4-3.1 Once an obvious source or sources have been found and the fu r ther release of liquid has been s topped, fu r ther search efforts can be temporar i ly suspended . It now shou ld be d e t e r m i n e d if each identif ied source is, in fact, the actual source of the release. While removal and protective measures are taken, the flow of the liquid, the a m o u n t of liquid, and the vapor concent ra t ions at those locations where the prob lem exists shou ld be moni to red an d recorded• If a distinct and con t inuous decrease occurs, t h en it can be as sumed that the source of the release has been identified. The decrease migh t no t occur immediately; it might , in fact, take days or weeks for liquid tlaat has accumula ted u n d e r g r o u n d to be removed or to dissipate. Refer to Chapter 6 for f i t r ther informat ion

3 1 5

N F P A 3 2 9 - - A 9 9 R O P

on es t imat ing the t ime requi red for a decrease to occur at the mon i to r ed point.

4-3.2 If ,after a reasonable length of t ime the flow of liquid to the affected area does no t stop or show a defini te decrease, fu r the r investigation shou ld be conduc ted s imul taneously us ing the two p rocedures descr ibed below.

(a) Release detect ion tests shou ld be conduc ted on any liquid storage or hand l ing system in the vicinity of the affected area. (See Chapter 5.)

(b ) T h e path o f the l iquid u n d e r g r o u n d shou ld be t raced f rom its po in t of discovery to the s o u r c e . T r a c i n g will de te rmine the actual ex t en t of the release, its direct ion o f flow, and any o ther potential. (See Chapter 6.)

Chapter 5 Release Detection for Storage Tank Systems

5-1 General.

5-1.1 All da ta previously ga the red shou ld be reviewed to de te rmine the mos t efficient m e t h o d or m e t h o d s of testing. The re are several me thods descr ibed in dais chapter tha t can reveal a leak prior to conduc t ing a t i ghmess test. If one of these pre l iminary techniques

mon i to r ing releases and should serve as one of the first areas checked to see if a release has occurred. If submers ible turbine p u m p s are used to p u m p the liquid, they are located in a s u m p above the tank. A visual check of the s u m p area is also an impor tan t check point.

5-2.2 Checking Above-Ground Tank Systems. The informat ion obta ined f rom the search p rocedures described in Chapter 4 shou ld be reviewed. In particular, the following should be rioted.

(a) The m e t h o d of filling tanks. Above-ground tanks are normally f l i e d by pressurized pumps . In addi t ion to tile i tems noted for u n d e r g r o u n d tanks, spills f rom overfills can also be observed near normal and emergency vent open ings and a round the tank itself.

(b) It is no t unusua l for water to be p resen t at the bot tom of bulk s torage tanks due to condensa t ion and deliveries. Since g roundwate r is normal ly below the b o t t o m of an above-ground tank, the presence of water is no t necessarily reflective of a leak in the bo t tom of the tank.

(c) Any evidence of founda t ion or suppor t se t t l ement a round tank systems. Past or recent work on the tanks or a t tached piping and any sign of work that migh t have damaged the tank or iLs fittings.

(d) The age of the facility. (e) The location and flow of liquid f o u n d u n d e r g r o u n d by gas

does no t reveal the source of a suspected leak, it c anno t be sensors or visual inspect ion. A release de tec ted at a mon i to r ing conc luded tha t the liouid-handlint~ swtem is tight. But the well usually indicates tha t a s ignif icant release has occurred. possibility of quickly s~)lving the pr~obl" em will often warrant the (t) A b o v e - g r o ~ . . t a n k systems often require a.spill prevent ion limited effort involved before a t ightness test or o ther release control & cou.~erni 'easure plan, SPCCP, as requi red by Title 40 detec t ion m e t h o d is under t aken . For addit ional details on the CFR 112 " P . ~ t i o n o f Env i ronment . ' . T h e plan should be latest test ing and release de tec t ion methods , indus t ry publ icat ions checked ~ . ~ i ~ e . c o r . d s and for spec,fic . r ecommenda t ions on and officials shou ld be consul ted, how s u c l ~ ~ e ins t ructed to con tmn spdls.

(g) .~. .~datory c "ffli~J r..ecords, the type of tank gauge system, and 5-1.2 Regardless of the p rocedures involved, l iquid-handl ing w h ~ . ~ r Oae gauge ~¢:.~".~'t,.~peradon. With large above-ground tanks, e q u i p m e n t should be evaluated in a m a n n e r tha t is as close as . ~ . v o l ~ e of the ta~.[ makes a rehable ,.assessment of.t,~ank integrity. possible to normal opera t ing condit ions. Excessive pressures or - : : ~ t g . ~ e n t o r y recorcts or gauge reanmgs, more CllIIiCnlL (3e,? tests by nonrepresenta t ive liquids m i gh t indicate a leak where none the'~?luib.s m 5-2.4.)

o (h ther the tank system includes s e c u n d ~ co n t a in m en t exist or migh t conceal leaks tha t d exist. For example , perforat ion ~ : ~ . t h e . . " . , y ," . of a tank shell migh t no t be de tec ted due to impermeab le backfill, '-'.-"i!'~: .... A b o v e . ~ tanks and piping of ten mcor.porate secondary the water table, sludge, or rust plugs, all of which can inhibi t : ~ n .t~nmj//~iL C o n t a i n m e n t areas normally include a port for release of tile p roduc t f rom the tank. :':: .... ~ g j f i g releases and sbou ld be one of the first areas checked to

::~:. x:.-:-~::'see:~+'release has occurred. Some tank systems migh t not have • 5:., secofidary c o n t a i n m e n t u n d e r the tank bot tom. However, many

5-2 Action Prel iminary to Release Detection or T i g h t n ~ g . ~!~ large above-ground tanks have been retrofi t ted with release ..<~i . . . . ~#! :!i~..'.-~revention barriers such as secondary steel bot toms or liners.

5-2.1 Checking Underground Tank Systems. The fl~O~ti~:x:...,:.~::::::. -~ obta ined f rom file search p rocedures descr ibed in Chalf f~ .~i ''~''~':'~-%'~-'" , . . . . . . . . . . . . . . :.:.. " :3-i:.z, ~ n e c g m r! m ~ terns. shou ld be revtewed. In parucular , the f o l l o w t ~ ~ e d , g P g ys

,,.x~: ~ : _ . . ~ ' - ' ~ : ~ : ~ : !

(a) The m e t h o d of filling tanks. D a m a g ~ ' f i l l ~ o r l y ) i 5 2.3.1 For pmpmg systems, the following shou ld be checked:

(b) Any evidence of g r o u n d se t t l ement a round tanks and-any sign of work tha t migh t have damaged the tank or its fittings.

(c) History o f past or recen t work on the tanks or a t tached piping.

(d) Tile presence of excessive a m o u n t s of water in the u n d e r g r o u n d tmak and any history of past water removal. (De te rmined by water-finding paste on the gange stick.) If possible, it should be d e t e r m i n e d whe the r the water increases du r ing per iods of heavy rainfall and remains cons tan t or d imin ishes du r ing dry spells. Also, if possible the dep th of the water table should be de t e rmi ned by checking a mon i t o r i ng well in

. the hnmedia te tank area. Any accessible open ings shou ld be checked to de te rmine whe the r water is en te r ing t h rough a loose cap. The surface area a r o u n d vent lines shou ld be checked for evidence that water migh t be en te r ing by this route (s tanding water over vent lines could be the source) . Vent open ings shou ld be checked to ensure tha t there is protect ion against rainwater in t rus ion.

(e) The age of the facility. (f) The location and flow of liquid f o u n d u n d e r g r o u n d by gas

sensors or visual inspection. A release de tec ted at a mon i to r ing well usually indicates tha t a significant release has occurred.

(g) Inventory control records, the type of tank gauge system, and whether the gauge was in opera t ion shou ld be checked. (See the procedures in 5-2.4.)

(h) It shou ld be d e t e r m i n e d tha t the system includes secondary con ta inment . Tanks and p ip ing of ten incorpora te secondary con ta inment . C o n t a i n m e n t areas normal ly include a port for

se t t lement , tha t m igh t have d a m a g e d piping or pipe suppor ts (d) Deteriorated asphal t paving or distressed vegetation that

indicates a spill or solvent act ion of liquids or vapor (e) Evidence of abandoned , capped, or d i sconnec ted piping,

such as u n u s e d d i spens ing islands or o ther u n u s e d ancillary facilities

(f) In-line leak detect ion devices for p roper operat ion and evidences of a release

(g) Type o f u n d e r g r o u n d pip ing and corrosion control system (h) Pipe integrity test records

5-2.3.2 Checking Suction Piping.

(a) If tile p u m p used in moving the liquid is above g ro u n d and the supply pipe operates u n d e r vacuum or suction, certain p u m p i n g cbaracteristics will indicate ei ther a leaking check valve (Jl a leaking pipe. Air enters tile pipe th rough a leaking check valve or t h rough a pipe leak ,as liquid drains back into the tank. The

~ resence of dais air is indicated by the action of the p u m p in tile rst few seconds of operat ion after an idle period. If file p u m p is

equ ipped with a mete r and cos t /quan t i ty display device, such ,as is found in a gasol ine service station, p u m p i n g of air migh t be indicated by "skipping" of the vo lume display, a ratt l ing sound in the pump , or erratic liquid flow due to mixing of air and liquid. Ano the r indicat ion is overspeed of the p u m p when first tu rned on, followed by slowing of the p u m p as it begins to move liquid. A

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N F P A 3 2 9 - - A 9 9 R O P

third indication is "churning" of the pump, that is, running but not moving liquid at all.

(b) If any of the preceding condit ions indicate a leak in the suction line, the check valve should be inspected first. Some check valves are located close to the pump inlet, others are mounted in the underg round pipe jus t above the tank, and some are installed on the end of tile suction stub inside the tank. Some of these valves located in die pipe above the tank can be inspected and repaired from rite surface of rile g round th rough a special extractor mecbanism installed with the valve. If the valve is inside rile tank, it might be necessary to dig down to the tank to check rite valve or disconnect and seal off d ie pipe for a Iwdrostatic pressure test.

(c) Generally, digging down to the check valve or tank should be delayed until other, more easily per formed surface tests have failed to reveal the leak. If there is any doubt that the check valve seats dghdy, it should be repaired, replaced, or sealed off. Then the pumping test should be repeated and, if air is still enter ing the suction line, it can be assumed that the pipe is leaking unde rg round and it should be exposed for inspection. Digging should be done carefully to avoid any damage to file pipe that might make it impossible to verify whether a leak actually existed prior to excavation.

(d) If the pump does not exhibit symptoms of a leak, as described above, but there is still reason to suspect a pipe leak, or if a complete system check has been per formed and it is now necessary to isolate and check the piping system, individual pipe runs can be isolated and pressure tested hydrostatically,

5-3.2.1 Automatic Tank Gauging. If tile tank is equipped with an automatic tank ganging system that has a "leak test" mode, a leak test should be conducted in accordance with file manufacturer 's operat ing instructions. Automatic tank gauging equipment should be capable of detect ing a leak rate at least as low as 800 ml / l t r (0.2 gal /hr ) from any port ion of the tank that routinely contains product , with a probability of detect ion of 0.95 and a prohability of false alarm of 0.05.

5-3.9.2 Inventory Reconciliation Analysis. If inventory records have been analyzed by quantitative statistical methods, tile analysis should be examined for indications of a probable televise, assuming that the data can be analyzed conclusively.

5-3.2.3 Manual Tank Gauging. For tanks of 3785-L (1000-gal) capacity or less, manual tank gauging can be used, if tile liquid level measurements are taken at the beginning and end of a period that is at least 36 hours long and during which no liquid is added or removed from the tank. (See Appendix E.)

5-$.2.4 Tank Systems Equipped with Secondary Containment. If the tank system is of double wall construction or is installed with a secondary conta inment system, the interstitial space moni tor point or the well(s) located within the secondary conta inment area. whichever is applicable, should be checked for the indication of a release.

5-3.2.5 Vapor o~.-.(~roundwater Monitoring Wells. If vapor or 5-2.4 Checking Inventory Records. groundwater ..~"ni~Bring wells have been installed in the tank

system e x c a ~ . n area, they should be checked for file indication 5-2.4.1" A carefifl check of inventory records will be very helpful in of a r e l e ~ de te rmin ing the course of fur ther investigation. (See Appendix E). ~ . , % . , [ ' ; ~ . . . . . . . . . .

uu.x.,.~.~...'~mocts ~ . ~ , [ ~ approvea oy m e mcm regutatory agency.

5-2.4.2 A check should be made to be sure that a loss of inventory , ~g~ . . ~ = , ovegrounct ~aorage l a n k .~ystems is not due to one of rile followin , AI~!. .

t.-,I Me ,~,~ th ~,e nnt fly " ecl 5 - 3 ~ . ~ m i l a l Inspection. An external visual inspection of the tank , . . . . . . t_.~ _.at . . . . . co r rec_ , cahbrat . . . . . . . . . . . . (b') Contract ion due to lower te•mperatures . sys ten 'g .~ .u to tm per tormen. (c) Theft ~:-".~-'. ~ ....

• ~X~.'g~: $.$.2 T ~ k Systems Equipped with Secondary Containment A (d) Use of a conversion chart that does not conform to actual ~::. , .::~.~!k~'3:: . . . . . . . . . . . . . " --...tank mefr . . . . . . nmetrv, :~':~ "~ :~ ' -~ . . : : . ~,m pecuon ot m e seconytary conta inment area snoul(l De

(e) Malfimctioning automatic tank gauging probe ~ : j " p e " ~ e d . • e.~$~!..,

• " :::"" "~""~& "<'-~k The interstitial space moni tor point or tile well(s) located within ~2.4.$ Evidence of inventory loss strongly ~mphes that..~*;ie ~ i ~ ¢ e has been found but subsequent checks to determin...~x.~, t h e ~ s s ~ f h e secondary conta inment area, whichever is applicable, should has occurred should be made before definite c o n c l ~ ~ : " : " be checked for the indication of a release. drawn. Any loss that is partially or totally explained b ~ i ~ " : : : " ' * : listed in 5-2.4.2 cannot be considered as c o n ~ d e n f l ~ . ~ t ~ Tile leak detect ion ports, if present, should be checked. the site in question is not the only sour c e . ~ ' ~ f f e n f W " incorrect or inadequate. Unless ano the rA .~ rce is fo ".d~..and/ 5-$.8.$ Vapor or Groundwater Monitoring Wells. If vapor or considered to be groundwater moni tor ing wells have been installed in die tank a satisfactory solution ~ p r o b l e m , ~ ' ~ l e r tests should be pe r fo rmed to draw definite c o n c ~ ~ : system area, they s h o u l d b e checked for rile indication of a release.

5-3 Release Detection Methods. ~.-

5-3.1 With the information from the search procedures of Chapter 4 as a basis, the techniques described in this section can be used in a logical process of elimination. The following should be considered when applying release detect ion methods.

(a) Means mad methods of release detect ion should be installed, maintained, and operated in accordance with the manufacturer 's r e c o m m e n d e d procedures. Personnel utilizing these methods should be properly trained in their use and operat ion. Proper documenta t ion of procedures and results should be provided.

(b) As applicable, methods of release detect ion should comply with applicable local, state, and federal environmental regulations and be documen ted with respect to accuracy,

(c) If a release is indicated by any of the described methods, fur ther investigation may be required by ei ther confirmatory testing (see Section 5 4 ) or the tracing techniques described in Chapter 6, whichever is most appropriate•

5-3.2 Underground Storage Tanks.

Additional information regarding r e c o m m e n d e d procedures is provided in EPA/5S0/UST-89 1012, Detecting Leaks: Successful Methods Step-by.Step.

5-4 Testing.

5-4.1 Underground Tank Systems.

5-4.1.1 If tile release detection methods described in Section 5-3 are not available or do not yield conclusive identification of the source of a release, testing of rile piping or tank, or both, might be necessary. The test procedures should detect a leak anywhere in the complete underground storage and handl ing system unless o ther information has eliminated some port ion of the system from the search. Certain test methods might allow additional product to be released from rile system or might cause structural damage to file tank or piping dur ing the test. Where it is reasonable to assume that a leak exists, the effects on safety and environment should be considered when de te rmin ing which test method to use.

5-4.1.2 The following should be considered when applying testing methods.

(a) Means and methods of testing should be per formed in accordance with the manufacturer ' s r e commended procedures. Personnel utilizing these methods should be properly trained. Proper documenta t ion of procedures and results should be provided.

(b) Methods of testing should comply with applicable Ioc~d, state, and federal environmental regulations and be documented with respect to accuracy.

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5-4.1.3 Both volumetric and nonvolumet r ic t ightness testing m e t h o d s can be used. Addit ional in format ion on volumetr ic and nonvolumet r ic t ightness test me t hods is provided in EPA 530/LIST- 89 1012, Detecting Leaks: Successful Methods Step-by-Step.

5-4.1.4 When volumetric t ightness testing is per formed, the m e t h o d should be capable of de tec t ing a leak of as little as 380 m l / h r (0.10 ga l /h r ) , with a probability of de tec t ion of 0.95 and a probability of false alarm of 0.05. This is a pe r fo rmance s tandard to de t e rmine die detect ion capabilities of die test ing device and procedure , The detect ion th reshold for declar ing a leak will vary based on the individual manu fac tn r e r ' s specifications.

5-4.1.5 A nonvolumet r ic t ightness test is an acceptable test for leak detection; however, it does not quant i fy a leak rate.

5-4.1.6 If the results of a t ightness test indicate dlat a leak migh t exist, e i ther appropr ia te corrective action or addit ional test ing to conf i rm the leak shou ld be per formed.

5-4.1.7 Pressure Testing.

5-4.1.7.1 Pressure Tes t ing with Air or Other Noniner t Gases.

WARNING: Pressure test ing with air or o ther non ine r t gases of tanks or p iping that contain f l ammable or combust ib le liquid is no t r e c o m m e n d e d , should no t be requi red by regula t ion or

5-4.3.2.1 Tempera ture-Level Method. The temperature-level m e t h o d measures the liquid level accurately and compensa tes for the rmal expans ion or contract ion us ing a vertical array of t empera tu re sensors to compensa t e for vertical the rmal gradients. A leak is indicated by a d rop in tile t empera tu re -compensa ted level.

5-4.3.2.2 Mass -Measurement Method. The mass -measurement m e t h o d measures die pressure act ing near die bo t tom of die tank. The pressure cor responds to the mass above the measur ing point and shou ld be i n d e p e n d e n t of liquid level changes caused by thermal expans ion .

5-4.3.3 Tracer Gas Testing. This m e t h o d involves adding a tracer gas to the s torage system and then test ing for its presence outside the s torage system.

5-4.$.4 Pressure T e s d n g with Inert Gases. Inert gases can be used for the purpose of de tec t ing a leak for both tank and piping systems. The pressure exer ted by both the p roduc t and the inert gas should no t exceed the limits r e c o m m e n d e d by the tank manufac ture r . The use of pressure- l lmit ing devices is required in this application.

5-4.3.5 Internal Inspect ion. ff warranted, an internal inspect ion of the tank should be conduc ted to evaluate the condi t ion of tbe hank interior.

CAUTION: Proper p rocedures for safe ent ry shou ld be followed. ..:::~::::.

ordinances , and shou ld be d iscouraged in practice. .....g,

5-4.1.7.2 Tes t ingwl th Inert Gases. Iner t gases can be used for tile ~ . . . ~ ! e r 6 Tracing Liquids U n d e r g r o u n d purpose of de tec t ing a leak for both tank and piping systems. The 6-1 G e n i i A ~ g h the following I~uidelines are given in an pressure exer ted by both the p roduc t and the iner t should no t no o*~tm " t e ~ . ' . J m o v " v " gas a r. t.ate o r d e ' ~ ? ortance, t h e . are not necessan l , In the exceed the limits r e c o m m e n d e d by die tank manufac turer . The o ' r ~ ] : r e ~ order for " ~ e s . T h e actual s equence of p rocedures use of pressure-l lmlt ing devices is r equ i red in this application. ~ thC~Jhoice of te~ : 'methods will d e p e n d ' o n the c i rcumstances

• • ~ ~ ' ~ . p ~ e m , in format ion ga ined f rom the pr imary search, and 5-4.1.8 Internal Inspect ion. If warranted, an internal inspect ion o t a n ~ " ~ o u k test results. It is beyond the scope of this the tank should be conduc ted to evaluate the condi t ion of die tank r e c o ' ~ . d e d practice to cover the p rob lem in all its potential interior. :~:!~:~.:-.- c o m p l e ' * ~ f I t ~ initial efforts fail to identify the source, addit ional

• : " ! i ! ! ' i ! ~ ~ . ~ m c e migh t be necessary. CAUTION: Proper p rocedures for safe ent ry Should be ":"---. " ~ : .." followed. ":: ~ " ' ~'::'.-::::: 6-2 i~'rocedure for Determining U n d e r g r o u n d Flow.

.'::::::::f':~'- :x 5-4.2 U n d e r g r o u n d Piping. ..e: :":::"%~."~ %. .

~i~i-. ! ~ -~#:-':~-2.1 Any potenual sources and pathways shou ld be no ted on a 5-4.2.1 Hydrostat ic Tes t ing o f Piping. A hydrostatiG:." i ~ ""* ":~ " " a " .f- P!~g~,9...~ ........ "" sketch of the local area. Also, any pe r t inen t geological dat: that ts ... ~ - ! ~ - : . - . . . . . is a relatively s imple test dlat can quickly indicate a leal~:-.' ~'-.'%:-." .~&ff.::::- available and the locauons of sewers, streets, condmts , s t reams. hydrostat ic test, the piping is isolated and a hyd.r:%,~d.c. I ~ e manholes , tanks, fill pipes, ven t risers, and p u m p s should be test is conduc ted at 150 percen t of the m a x i # ~ j ? teff~].-.:~...: ..... noted. Any a b a n d o n e d di tches or s t ream beds that have beetJ filled pressure of the system, but not less than a . ~ u g e p r d ~ of 3".~t8 and covered should be included. A USGS map or aerial kPa (5 psi) at the h ighes t po in t of die s ~ , T h e tesi':'j ou ld be pho tog raph can serve as a useful base. Some sources for tills ma in ta ined for a t least 10 minutes• A d ? ' o l ~ " ~ ( e s s u r e i~ licates die in format ion are as follows: possibility of a leak in the piping, and a vo l m~%~f tighli ess test shou ld be per formed. It shou ld be no ted t h a t ' ~ O ~ " l i q u i d (a) Municipal and state public works agencies, water pressure can be a t t r ibuted to die following: i.::. V depar tments , and sewer depa r tmen t s

(b) Local, state, and federal geological depa r tmen t s (a) A line leak (b) A decrease in liquid t empera tu re in the line (c) Piping distort ion dne to the liquid pressure (d) Vapor t rapped in the p ip ing

5-4.2.2 Suction Piping for Vehicle Fueling. A liquid volumetric pressure test c,'m be pe r fo rmed on a suct ion line by connec t ing to the exit por t of the air e l iminator or o ther appropr ia te fitting: This connec t ion permits pressure to be applied to the suct ion piping from the p u m p back to the check valve. In this test, the hydrostatic pressure shou ld no t exceed a gauge pressure of 103,4 kPa (15 psi) to prevent damage to tbe pump .

5-4.2.3 Where tracer or dye test ing has been approved for the product , it has the advantage of leaving the pipe system in service while die test is pe r formed.

5-4.3 Aboveground Storage Tanks.

5-4.3.1 Acoustic Emission. Acoustic emission leak detect ion technology is the l is tening for characterist ic noises created by a leak from the bo t tom of a tank. T he system operates essentially by detect ion :utd location of noise signals consis tent wifll the types of signals emit ted f rom tank bot tom leaks.

5-4.3.2 Volumetric Leak Detection. T he re are two basic forms of vohmletr ic leak detect ion, the temperature-level m e t h o d and tile m a s s - m e a s u r e m e n t me thod .

(c) Ut i l i~ companies (d) Facihty owners and local res idents (Special a t tent ion should

be given to elderly and long-t ime residents. They will often provide valuable in format ion about the area prior to its deve lopment )

6-2.2 If necessary, metal detectors should be used to locate and trace bur ied steel pipe.

6-2.3 Informat ion ga thered and plotted on the sketch up to dims poin t migh t indicate that a specific nearby facility is a very likely source. If so, tests to verify this, as descr ibed in Chapter 5, can be condueted .

6-2.4 Potential liquid flow pa ths should be checked as follows.

(a) Manholes , sewers, inlet boxes, wells, open t renches, exposed slopes and cuts, and tile like, shou ld be visually checked. Samples of water should be taken to test for the presence of f lammable or combus t ib le l iquids.

(b) A photoionizat ion detector or o ther i n s t rumen t shou ld be used to de te rmine the presence of vapors. O the r sources of vapor readings, such as natural gas lines, land fills, and sewer gas, should be considered.

(c) If checking u n d e r g r o u n d s t ructures does not give a clear indicat ion o f the di rect ion o f m o v e m e n t of tile u n d e r g r o u n d flow, a more detai led search can be conduc ted in porous backfill or pervious strata by testing for vapors in file soil.

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N F P A 3 2 9 - - A 9 9 R O P

6-2.5 When this testing has determined the probable direction from which the contamination is coming, extend the search up-gradient using these same methods to determine the next most likely source. Both sides of the direction of flow should be checked to determine its width.

6-2.7 As the problem becomes more complex, other methods of testing.and tracing might be useful as outlined in Sections 6-3 through 6-5, or other methods not described here. However, the advantages and disadvantages of each test procedure should be recognized if valid conclusions are to be reached.

6-3 Dye Tracing. The use of a dye tracer is often suggested as a means of tracing the f lowof liquid. This method involves adding a compatible dye to the storage system that is suspected as the source of the release, then seeing if the dyed liquid appears at the point of discovery. (This could take minutes, hours, or days.)

6-4 Chromatographic and Spectrographic Analysis. The cltromatograph and the spectrograph are instruments capable of detecting traces of the elements of almost any compound. For example, they can detect a trace quantity of an element that is unique to a particular method of manufacture, thus identifying the source. They can also detect the amount of the element present. This procedure only involves a small sample taken at the point of

7-1,~ Refer to safety procedures in Section $-2.

7-1.6 Before washing spilled petroleum products from street surfaces into drains or sewers (a potentially dangerous action and often an unlawful practice), other disposal means, such as soaking up the substance with sand, rags, or mops, should be considered. if, in an emergency, no alternative is available, disposal in a drain or sewer should be done only on the decision of a qualified person after appropriate public authorities have been notified.

7-2 Normally Inhabited Subsurface Structures.

7-2.1 Basements.

7-2.1.1 With very few exceptions, the quantity of flammable or combustible liquid that will be found m a basement will be relatively small, became a liquid will normally be detected before significant quantities can accumulate and additional flow can be intercepted or stopped. Where volatile liquids and their vapors are involved, thepr imary removal and disposal action is ventilation, as described in Chapter $. Small amounts of liquid that remain can be removed with commercial absorbents. Used absorbents should be placed in covered containers to prevent the further spread of vapors. Once all flammable or combustible liquids have been

discovery. These tests should be used in cases that involve complex removed, final cleanup can be accomplished by flushing out mixtures, such as petroleum liquids. However, these tests might be basement sumps and floor drains with water and washin~ down all inconclusive because some identifying component can be lost in imps . ted su .rface~kwith a b!odegradable surfactant.. Venulation and the ground or a component not originally present can be picked cbecging witl~...~_4[ltlPAI0bustible g~. indicator should be continued up from the ground or from contact with buried materials, t h r o u g h o u t ~ l e a n u p procedure.

6-5 Other Chemical Analysis. Other methods of chemical analysis 7-2.1.2 ~f~he~]~Kcases involving relatively large volumes of are available, and many ot" the same comments in Section 6-4 might volatilgll~Luids, v ~ t i o n might not sufficiently reduce the vapor apply. Examples of significant factors that can sometimes b e cong41~mfion to a~][h~wel due to the continued evaporation of determined by chemical analysis are additives and the age of the dkcd[lanImable or cot]p~stible liquid. In these cases, bail or pump contaminant. ~h~.am~t~able or coffibustible liquid into barrels, drums, or other

Cstilq~ej[~htainera or into portable tanks or tank vehicles. It might 6-6 Other Sources. if the investigation fails to locate an active be n'~][~mry to dig an interceptor trench between the source of the source of release, it is possible that the problem could be a r e s u l t , releasc-q[~ t l~ affected structure. • of an accumulation ~ o m a previous eouipment failure, spill, or ~.. ~ " improper disposal of the liquid. Exl~er]ence has indicated that ~ 1 . $ W~en nonvolatile liquids, such as fuel oils, are involved, many such residual deposits have eiisted and remained undetected ~ ~31UMbJtn is ineffective because the liquid evaporates at such a low for long periods of time before becoming large enough to make V r a t e , Absorbents should be used for thin films of flammable or their presence known. ~ ~ conibnstible liquid on water surfaces or on solid surfaces.

~ ' - ~ :~Whenev.er possible, flammable or combustible liquids should be . . . . . . . . . . ~ , . , ~ l ~ , ~ ~ ° r e m o v e d with puml3s or by bailing, if final cleanup requires ~napter • Kemovat area umposm m emm " "b . . . . . ~ ~ flushing sumps and drains and washing surfaces, local sanitation

t~omonso le taqums " ~ i ~ ' ' ~ z ~ y and environmental authorities should be consulted before flushing " ~ . such flammable or combustible liquids to sanitary sewers.

7-1 General. ~ ~ w f f " 7-2.1.4 Where vapors iu a basement are the resu i to fa re lease of a ~ h ~ . ~ . flammable or combustible liquid to the environmental media, the

7-1.1 In general, removal and disposal meth'l~[[~will d e l e d on the primary removal and disoosal action in the basement is ventilation, amount of flammable or combustible liquid r ; ~ L e d [O ¢ as described in Chapter ~. Elimination of the vapors might not be enxaronmental media (soil, ground water, or s u ~ t e r ) or possible until remediation of the affected environmental media has present in a structure or on the surface, its chemical and physical been completed, as discussed in Section 7-6. characteristics, and the area impacted.

7-1.2 The most significant chemical characteristic of a flammable or combustible liquid that is significant to methods of removal and disposal is the volatility, or abihty, of the liquid to evaporate at ambient temperatures.

7-1.2.1 Flammable liquids such as solvents, gasoline, and other volatile liquids will rapidly evaporate at ambient temperature.

7-1.2.2 Combustible liquids such as heating oils, food processing oils, and other nonvolatile liquids do not readily evaporate and will tend to remain in place for longer periods of time.

7-1.$ In general, purging a structure or enclosure of vapors of volatile liquids is primarily a matter of ventilation, while liquids are physically collected and removed.

7-1.4 The principal categories of structures or environmental media involved are the following:

(a) Normally inhabited subsurface structures, such as basements, subways, tunnels, and mines

(b) Normally uninhabited subsurface structures, such as crawl spaces, sewers, and utility runnels

(c) Surface water (d) Ground water (e) Soil

7-2.2 Subways, Tunnels, and Mines.

7-2.2.1 If only small amounts of volatile liquids are involved, ventilation alone might be adequate to permit safe entry and possibly continued use of the facility. In such cases, t he same removal and disposal methods as described previously for basements can be used. However, added precautions should be employed due to the greater potential exposure to the public and, normally, due to the greater exposure to potential ignition sources. The authority responsible for the facility, the fire department, and other public safety officials should effect a cooperative effort for maximum public safety,

7-2.2.2 Subways, tunnels, and mines will normally be more prone to underground seepage than other subterranean structures such as basemenUL Consequently, even though entry of a flammable or combustible liquid is thou.~ht to have been stopped, monitoring with a combustible gas indicator should be conunued for an extended period of time after remediation to check for recurrence.

A constant check should be maintained for at least 24 hours after remedlation has been completed, if results are negative, the check periods should be extended to an 8-, 12- or 24-hour cycle depending on the use of the facility. Subsequent checks should he cont inuedto include periods of extreme changes in groundwater

319

N F P A 3 2 9 ~ A 9 9 R O P

levels. Significant rainfall and rising groundwater can carry with it more liquid.

7-2.2.3 If a relatively large a m o u n t of f lammable or combust ible liquid is involved or if leakage cont inues , it migh t be necessary to close tire facility to tile public and su spend normal operat ions, It miglrt also be necessary to deactivate any electric lines or transit tracks in the vicinity of the seepage. Venti lat ion should be main ta ined and a collection point shou ld be provided for in tercept ing seepage and p u m p i n g it out. Only a nonspa rk ing or air-operated p u m p motor shou ld be used. The materials for proper disposal shou ld be removed.

Tire fadli ty opera tor should be consul ted to de te rmirm tire degree to which c leanup and remedia t lon are necessary. Normally, once fl lr ther entry of volatile l iquids has been stopped, such facilities can be adequately purged of vapors wifl~ reasonable periods of ventilation.

7-2.2.4 Wlrere vapors in subsud'ace s t ructures are the result of a release of f lammable or comhust ib le liquid to the envi romnenta l media, dre priorary removal and disposal act ion in tl~e subsurface s t ructure is ventilation, as described in Chapter 3. Elimination of the vapors migh t trot be possible until remedia t ion of tire ~fffected env i romnenta l media bas been comple ted , as discnsseci in Sectior~ 715

74 Normally Uninhabited Structures.

7-$A Utility Conduits°

7-3.2.2 Where vapors in sewers are the result of a release of f lammable or combust ib le liquids to tire envi ronmenta l media, the primary removal and disposal action in the sewer is ventilarion, :Ls described in Chapter 3. Elimination of the vapors might not be possible until remedia t ion of tire :fffected envi ronmenta l media has been completed , as discussed in Section 7-6.

7-4 Underground Release. A knowledge of the local geology is basic to effective removal of f l ammable or combust ible liquids or their c o m p o n e n t s f rom subsurface soils and groundwater . A geologist who is familiar with the area shou ld be consul ted before field activities are begun° Subsurface assessment will most likely be required to fu r ther def ine tile ex ten t of con tamina t ion and properly design the r emed iadon efforts. Additional informat ion can be found in API 1628, Guide to the Assessment and Remediation of Underground Petroleum Releases', and API 1629, Guide to the Assessment and Remediation of Petroleum Releases ~o Soil.

Chapter 8 Referenced Publications

8-1 Tire following d o c u m e n t s or port ions thereof are referenced within this r e c o m m e n d e d practice and should be considered as part of its r ecommenda t ions . The edit ion indicated for each referenced d o c u m e n t is die cur ren t edit ion as of the date of tire NFPA issuance of this r e c o m m e n d e d practice. Some of these d o c u m e n t s migh t also be re fe renced in this r e c o m m e n d e d pvactice for specific infor~: i t ional purposes and, therefore, are also listed in Append ix :::::::::::::::::::

...q::

8-1.1 A C ~ b l l c a t i o n o 130 Kemper Meadow Drive, Cincinnati , OH 4524~q 63'~ii.;.:iii~::..

74.1ol Removal and disposal med t ods for utility condui ts differ f rom those descr ibed for o ther sub te r ranean s t ructures previously covered for the following reasons.

(a) The a m o u n t s of f lammable or combust ib le liquids will normally be h igher because early discovery and preventive nreasures are unlikely.

(b) Access to entry points and impacted areas is usually f rom manholes , bu t such access migh t no t be available.

T h ~ l J i ' L i m i t ~....:~.-TLV) for Chemical Agents; Physical ,agents a~'Biological Exposu~?::lndices, 1997.

"::'8-:~i,~::~:~!i~-ublications. Amer ican Pe t ro leum Institute, 122(I L SL NlA/~!-~hington, DC 20005.

r{[Ji?.:3 ..... API 1 ~: . ' .~uide to the Assessment and Remediation of Undergr ..... d "~::i::7:i;ii::i::::iiiiii!~,..tT...qteum.5~eleases, Second Edition, 1996.

"!:%::-::" A151~i!:]'629, Guide to the Assessment and Remediation of Petro~,m The utility operator should be consul ted on all details of the remedia t ion effort and the proposed purg ing procedure~. : ,~ .e . :~:::. Rele'ases to Soil 1993. opera tor ' s special knowledge will be essential to selecU.'~"~'~;i!~i!iiiii: ":!i'::....:, p rocedures and techniques to be used. ..:;i{::i::!::i!. iiii.:: .:ii-:":'8-1.3 ASTM Publications, Amer ican Society for Test ing and

...... ~iiiiiiiii::....::!{i!.".-'~ili~iii#?i:i:i:i:~:~:..':::" Materials 1916 Race Street, Phi ladelphia PA 19103. 7-3.1.2 Where vapors in Ore utility condui t are the result":~:ii" ................ ::'::::::::::" release of f l ammable or combust ib le liquid t p . . ~ r o n ~ . . . * . a . . . ! .... ASTM D 5, Standard Test Method for Penetration of Bituminou.s media, ventilation of the utility condui t miglji::'be g~riate'::::.~ii::~::U Materials, 1986. Elimination of file vapors migh t not be p ~ b l e until"~Z~edi,xd~m of the ,affected env i ronmenta l med ia ha*: :13:~i isomplet~j as ASTM D 323, Standard Test Method for Vapor Pressure of Petrog~zm

:::'.!:: d iscussed in 7-4.1. ".::i.:-'~i!i~ii: . . . . ::."

7-3.2 Sewe

7-3.2.1 ()n occasion, sewers citn collect f lammable or combust ib le liquids f rom a s u r r o u n d i n g area impacted by tire liquids. It is se ldom practical to seal off all entry points into tire sewer. Conseqnent ly , removal of the f l ammable or combust ib le liquids will normal ly be a con t inu ing effort until the entire area is purged. Wbeta relatively large a m o u n t s of f l ammable or combust ib le liquid are involved, every reasonable effort should be taken to divert tire M'tected water flow to a separator.

if this is impractical, it m i gh t be possible to set up a sk imming facility or float a boom or inflated tube across some point of the s t ream flow. If tire f l ammable or combust ib le liquid is mostly on the surface of die s t ream flow, and flow is no t turbulent , significant a m o u n t s of tile liquid can be t rapped beh ind the boom and can be removed with sk immer p m n p s or absorbents . ISee Figures 7-3.2.1(a) and 7-3.2.1(b)]. Weirs can also be used in tim same way by installing drent in such a m a n n e r tha t water can flow unde rnea th , ~rapping the f lammable or combust ib le liquid beh ind the uppe r part of the weir. Weirs shou ld be used whenever possible because of dreir grea ter efficiency, particularly where tire s t ream flow exceeds 1 m / s e c (3 f t / sec) . [See Figure 7-3.2.1(c)1.

Products (Reid Method), 1990.

8-1.4 U.S. Environmental Protection Agency Publication. U.S. Environmenta l Protect ion Agency, Washington, DC 20460_

EPA 530/UST-89 1012, Detecting Leaks: Successful Methods S~ep4,~- Stq~, Novemher 1989.

8-1.5 U.S. Government Publications. U,S. Governmen t Pr int ing Office, Washington, DC 20402

NIOSH Pocket Guide to Chemical Hazards.

OSHA, Code of Federal Regulations, Title 29, Part 1910-1000, Subpar t Z

OSHA, Code of FedeTal Regulations, Title 40, Part 112, "Protection of Environment ."

OSHA, Material SaJety Data Sheet (MSDS)

32(i

N F P A 3 2 9 - - A 9 9 R O P

Contaminant and water --.---.p

/

( t

Hose to pump section

Strap to support funnel 1

w=.,,o,,.

X Funne~ ~ ~B~om or float

~ H o s e to pump section !;

s~pport s~ ,ps ~,":..;%%~:,," !i~,..~:::" U ~ ~:[-_. cou.,e..~i0,, to

t... ~ ~ ~ control pipe elevation ~ - - ~ / / / / ~ Z..-~ ,.:-.:. .:: .7 \ Oon~~ ~ ~,,-

, ~ s ~'.~lot !~l 102 mm (4 in.) plastic sewer pipe

" % , I I~om of sewer or channel

F ' ~ 7-3.2.1(a) Typical skimming installation.

Contaminate container for disposal

Perforated pipe e Supporting straps

Boom or float

Plastic foam- Polystyrene filled tube float

ter

Inflated Wood 102 mm x 102 mm tire hose (4 in. x 4 in.} or larger

Wood pole

Effective in currents up to ,9 nYsec (3 ft/sec)

Figure 7-3.2.1(b) Typical floats and booms for trapping contaminants floating on water.

321

N F P A 3 2 9 - - A 9 9 R O P

. / W i e r board (dam)

Con,=ninant-'1 I II

Wate . . ~ - - - - ~ r - " ~ ~ / A d j u s t clearance so that contaminant ~ ~ is not carried under wier board

Contam inant - - ~ . . . ; . . . . . - . . . . : . . . : . . . . . . . , . . : . - . ~ , . , . . . . . ; ; : : . . . . • . : . . . . . • - , . . ¢ - , • ...:::.;., .;-,...('...-,..:::..,..,...-,. ,-;,.-....,.......~ . .;~;...,.-: .:..

Wier board (dam)

Downstream water surface

Water f '~.

.::i?.~::.. Adjust clearance sq.:~i c:bntaminant is not carried under .... .~board

Sewer or channel Bottom -~S . . . . . ~!:'~!.~:'.:::,

When current flow exceeds .9 m/sec (3 ff/sec), contaminants # ~ be:.trapped by ~ n g a difference in upstream and downstream surface with a baffle or wier board . . . . . ;'-'~!~~ii .... ~./."i!i:::,

F i g u r e 7 - 3 . 2 . 1 ( c ) T y p i c a l i n s t a l l a t i o n o f a " ~ ; : . i n a f l o w i n g s t r e a m .

":~!.:'i'~i~::.:... A p p e n d i x A E x p l a n a t o r y M a t e r i a l !~Y::~::;~.~!~:-::::.~.. .-:"

"~ . . . . :" "~...-!,-'.'~.-'i:::" A endix A is not a part of the recommendations of this NFPA ::-::"

document but is included for ,nforma.onat purposes on O. T ~ d z x "~i: contains ex#lanatory material, numbered to correspond w i t ~ h e :::.:.'~i: :~ii::...:-" applicable text paragraphs. - ,:~-..:A.~::.. ~:.: .~'-""

" "::~i~!'!!:i::-...::~:~:~:-:.::i:K~!:i::i.5::::::::::: ::" "~i$!'~ U ":':':':':":"!:~:::~:-::?~:::" :.x~..

Table A-I-I.4 Properties of Some ~ . . . a . b l e and' :~busf ib le ~ m ~ and Gases That Have Been Found m Under~ouod S ~ o u r e s ~ 1

#..:...:~:~"-"':':~--.~ "~!Jii~i::'- F l ammab le Limits in Air " "':~!~-:: % by Volume (Watec = 1) .~!~:., -':~-'...'.-'..-'..~.

. . . . ..:::~ . .:.$:.: Specif ic Gravi ty o f Vapor Density ~ P o m t iii?: Lower Upper Lower (Air = 1)

Ace tone 4 )'::" Z15 13.0 0.8 2.00 Acetylene Gas 2.5 100.0 - - 0.90 A m m o n i a Gas 16.0 25.0 - - 0.6 Benzene 12 1.3 7,1 0.9 2.8 Butadiene Gas 2.0 12.0 - - 1.9 Butane Gas 1.6 8.5 - - 2.00 Carbon disulfide 22 1.3 50.0 1.30 2.60 C~ar ben monox ide Gas 12.5 74.0 - - 1,0 Ethane Gas 3.0 12.5 - - 1.0 Ethyl chlor ide 58 3,8 15.4 0.9 2.2 Gas oil ~ 150 0.5 5.0 <1 - - Gasoline /values "~ary for different 45 1.4 7.6 0.8 3.~-4.0

grades of gasoline) Hydrogen Gas 4.0 75.0 - - 0.1 Hydrogen sulfide Gas 4.0 44.0 - - 1.2 Kerosene 100-162 0.7 5.0 <1 - - Methane Gas 5.0 15.0 -0.6 Methyl b r o m i d e (practically Gas lif0 15.0 -3.3

nonf lammable ) Methyl chlor ide (;as 8.1 17.4 -1.8 Natural gas ~ Gas 3.8 13.0 - - - - Petroleum <O 1.1 5.9 0.6 2.5 Naph tha ~

(pe t ro leum e ther ) Propane Gas 2.1 9.5 - - 1.6 Toluene 40 1.2 7.1 0.9 3.1

' Proper t ies ot o ther f l ammable materials can be found in NFPA 325, C,u/de to Fire Hazard Properties of Flammable Liquids, Gases, and Volatile Solids. ~l'hese liquids and gases are mixtures, and their proper t ies can vary d e p e n d i n g on the composi t ion.

3 2 2

N ~ A 3 2 9 1 A 9 9 R O P

A-I-2 Authority Having Jurisdiction. The phrase "authority having jurisdiction" is used in NFPA documents in a broad manner , since jurisdict ions and approval agencies vary, as do their responsibilities. Where public safety is primary, the authority having jurisdiction may be a federal, state, local, or other regional depa r tmen t or individual suclt as a fire chief; fire marshal; chief of a hre prevention bureau, labor depar tment , or health depar tment : building official; electrical inspector; or others having statutory authority. For insurance purposes, an insurance inspection depar tment , rating bureau, or other insurance company representative may be tile authority havingjurisdlctlou. In many circumstances, the property owner or his or her designated agent • "LSSUlTleS the role of the authority bavingjurisdictlon; at government installations, the commanding officer or depar tmental official may be tile authority having jurisdiction.

A-3-2.8.3 For information on underg round petroleum releases, see APt 1628, Guide to the Assessment and Remediation of Underground Petroleum Releases.

Appendix B Examples of Sources of Flammable and Combust ible Liquids and Vapors

This appendix is not a part of the recommendations of this NFPA document but is included for informational purposes on~.

B-I Natural Gas. Natural gas originates from naturally occurring gas- or oil-bearing strata. In oil-producing and natural gas- producing areas, cracks and faults in the underlying strata or abandoned wells can permit gas to permeate the soil and enter unde rg round conduits and vaults. Within the boundaries of some cities, there are actively producing oil and gas fields and many of these underl ie developed areas, residential and industrial, where subsurface structures are not installed.

B-2 Fuel Gas. Fuel gases include natural gas, liquefied petroleum gas, coke-oven gas, coal gas, oil gas, carbureted water gas, water gas, p roducer gas, and blast furnace gas. These gases, except liquefied pet ro leum gas, have specific gravities lower than that of air so that, when they are released in a subsurface structure, they :~i will t end to rise and diffuse rather rapidly above the point of leakage. These gases, when mixed with air within certain limits, produce f lammable mixtures. Since the oxygen content of each of these gases, when not mixed with air, is usually below l . .Q:~: :cnt , they can be classed as suffocating gases. With the exc$~o/ i ;~ i~ natural gas and liquefied pet ro leum gas, they are al .s#.-~hly ~ x i c because of the higb carbon monoxide content. N a / ' u ~ ~ ~ i other fuel gases, as distr ibuted by utility companies in u d ' ~ r o u ' / i / : l pipes, are also a source of f lammable gas. T . . l ~ . ~ . f . S ar6~,~,.:.~eGt to damage caused by corrosion, electrolysi.~f~5~ucti]'W,~.~.-~.'.ure:gi.~nd adjacent excavating. Tbese causes are d i ~ e d in g r ~ . r d e ~ l in later paragraphs o f this section. ";'" -'-"~.,. ~.-":~i:. ,..%

~, ~::i -~ B-3 Refrigerant Gases. A number of c o m m o r ~ : ~ . i ~ t s , such as ammonia, methyl chloride, ethyl chloride, metl t # ~ m i d e , and ethyl bromide, have varying degrees of f lammabil i t~.~ With the exception of ammonia, all of these refrigerants are heavier than air when in the vapor phase. Therefore, if they are released in large quantities in closed spaces, they will flow downward into the lowest areas. Of these, only ammonia has a sufficiently strong odor, in dilute concentrations, to indicate its presence. Exposure to ammonia vapors can cause severe burns even at concentrat ions below the f lammable limits. Liquid ammonia is often distr ibuted through underg round street pipes for refrigeration service in the business districts of many large cities. This system of pipes is subject to tile same exposure to physical damage as fliel gas pipes and pet ro leum pipelines.

B-4 Electric Cable and Other Insulating Material Gases. This source of f lammable gas is practically limited to severely overloaded electric unde rg round circuits. A breakdown of cable insulation will produce an electric arc. If the protective fuses do not operate promptly, this electric arc will continue. The heat of the arc can, by destructive distillation of cable insulation (varnished cambric, rubber , or paper) , p roduce f lammable gases that contain hydrogen, carbon monoxide, and hydrocarbouso

B-5 Chemicals. Accidental spillage in chemical processing plants and disposal of waste chemical products th rough sewers by industrial plants are potential sources or contr ibuting causes for explosive conditions. Examples of such products are carbon disulfide and ammonia. Calcium carbide will react with water to produce tile f lammable gas acetylene.

B-6 Sewage Gases. Sewage gas results from file fermentat ion or decomposi t ion of organic matter. These gases can be produced when organic matter has settled as a solid in sewer lines as a result of flat grades, crevices, sumps, or obstructions where consistent flow of sewage is lacking, or as a result of bacterial action on wood or o ther organic material immersed in water. These flammable gases are principally methane, hydrogen sulfide, and hydrogen and, on the basis of present evidence, they seldom reach explosive concentrat ions m sewers and drains. However, when they are mixed with other f lammable liquids and gases present in sewers, explosive conditions might exist.

B-7 Petroleum Pipeline Liquids. Liquid petroleum and liquefied pet roleum gases are conveyed by pipelines installed beneath public streets mad rights-of-way. Tbese pipelines are exposed to the same sources of physical damage as fuel gas pipes, as discussed in detail later. If any of these pipelines should fail, the escaping liquids and gases can penetrate substructure walls or rise to the street surface, Liquids can be washed into drains or enter the ventilating openings in the manhole covers of subsurface structures. Escaping liquid pet roleum products can evaporate in tile ground, penetrate file surrounding ground, or enter a confined space to produce a f lammable mixture.

11-8 Electric Circuit Oil Switches and Oil-Insulated Transformers . This equ ipment is frequently installed in a street vault, and electrical failures will occasionally result in an explosion. This action of protectiv.e devices in shutt ing off current is usually very fast, a p p r o x i m ~ - , - ~ seconds or less. This has die effect of limiting file damage .~::the vault in which file failure occurs. However, w h e n the ~ ad jacent to or within a large s t r u c t u r e s u c . a,, ex plosio,~:'#tSan ........ ~ t . ~ t in heavy damage.

.:~. ~:::;. ".::'~$::.-:.. Ap.l~i~llg C B a s i c " ~ . e l p l e s and Concepts of Underground Flow

~! ~ s a ~ i x is not"'a part of the recommendations of this NFPA Only. informational purposes : ~ is included for

G1 P ~ . . , , The principal characteristic that permits liquids to enter, a d ~ u l a t e , and flow through soil or rock is porosity:, tile

~ e or.'/bids that exist between the particles that make up the soil ~ o i l , to essentially zero, as in fine, dense day. Rock almost nev.~ nas large voids, but sandstones and limestones have voids similar to a fine sand.

:'* Crystalline rocks, such as granite mad marble, are essentially impervious, but these rocks often have fractures and cracks that will permit flow. The rate of flow through rock fractures will vary from large continuous cracks that will act like a pipe to very small irregular cracks that result in flows similar to wbat would be found in fine sand.

The rate of flow through soils and rocks depends largely oil tile size of the voids, with flows ranging from 6 ft per year in fine clays to 6 ft per day in gravels. The term used to describe soils that allow flow. is p.ervious.. A very. pervious, soil will allow rapid flow of liquid while an impervmus soil will allow only very slow flow. When tile word impervious is used alone, it implies absolutely no flo~-, for example, glass is impervious to the flow of the water. It should be unders tood that porosity does not always mean a pervious condition. In order for the soil or rock to be pervious, the pores must be in terconnected. A porous rock whose pores are isolated from each other will be impervious.

C-2 Groundwater. Almost all f lammable and combustible liquids are lighter than water and will float on tile water, unless the liquid is water soluble. When these liquids escape into the ground, they will normally flow downward undl they encounte r a layer of

roundwater. Then they will move along with the groundwater. nders tanding the flow of groundwater is essential to tracing the

flow of a f lammable or combustible liquid underground .

C-$ Pores and Voids. Water is almost universally found underground at some level in soil or rock. It might be in very limited quantities and only able to dampen the soil. But when it fills all pores and voids in the soil and saturates the soil or rock up to a certain level, it becomes somewhat like water in a bucket and establishes a definite top surface, called a water table. Figure C-3(a) shows that groundwater can occur in several layers underground. A porous layer between two impervious layers might be completely filled or might be only partially filled and have its own water table. However, o ther layers must be considered,

323

N F P A 3 2 9 - - A 9 9 R O P

because, even though dlese might be very deep at one location, they can be close the surface at others. [See Figure C,-3(b).]

_ _ _ _

Dry or damp soil , Pervious soil - - l

- - W a t e r table

Soil filled with water ~ Upper layer o( groundwater

Fi!

r " Strea ( o u t l i e

Figure C-3(b) Hypothetical groundwater

C-4 Origin of Groundwater. All groundwater, with the exception of narrow bands along the seacoast, originates as rain or snowfall that seeps into the soil. As shown in Figure C-3(b), at any given location, die water might have come from precipitation on the surface immediately above or it migl~t have flowed underg round for long distances through pervious soil or rock from a point where the pervious layer "outcrops" or intercepts the surface. Of course, water from precipitation can also flow to lakes and rivers and then into underground layers.

C-5 Underground Flow. Water tends to seek its own level underground, jnst as it does on the surface. However, water flowing undergronnd will not flow as fast as on the surface because of the resistance of the soil particles. This has the effect of steepening the slope of the same water table. The water does not flow to lower levels as fast as it fills due soils at more shallow depths. The same effect is showu where a lake or odaer body of

system showing significant features.

water supplies water to the pervious soil. Expressed anotller ~ay, pressure is required to overcome the resistance to flow and the increase in elevation provides tlae necessary pressure~

C~6 Water Table. The height or elevation of the water table will depend not only on how fast die water flows out of the strata (layers), but also on how fast it is fed into the strata by rain or melting snow. When no water is being added, the water table drops, as water flows out at springs and wells and as it "wicks" through dry soil to evaporate at the surface, r6qaen water is added faster dmn it can flow out, the water table rises. This rise and fall can be several feet in a few days, as the weather changes from dry to wet and vice versa.

C-7 Summary. The following principal factors are important to tracing unconfined liquids underground~

324

N F P A 3 2 9 - - A 9 9 R O P

(a) Most f l ammable and combust ib le liquids will float on water.

(b) When u n c o n f i n e d in the g round , f l ammable and combust ible liquids will float on the top of the water table and will flow a long with it.

(c) Groundwater will flow t h rough pervious soil or rock toward lower elevations at a flow rate tha t varies f rom several feet per day to several feet per year.

(d) The top of the water ( the water table) will slope downward in the direct ion of flow.

(e) T h e water table will rise and fall (in some cases, several feet in a few days), d e p e n d i n g on the supply of rain or m e l d n g snow.

C-8 Slope. Figures C,-8(a) and (b) show the effect o f the slope of the u n d e r g r o u n d strata on the direct ion of liquid flow. The figures show identical surface condit ions, bu t differ ing subsurface condit ions. In Figures C-8(a) and (b) a four-story bui ld ing lies approximate ly midway between two streets tha t are 122 m (400 ft) apart. A 5 pe rcen t grade f rom left to r ight places the street on the r ight abou t 6.1 m (20 ft) h igher than the street on the left.

In Figure C-8(a), the u n d e r g r o u n d strata follows the general slope of the surface and g roundwate r in the sand and gravel layers shown f rom r ight to left. U n d e r these condit ions, if gasoline liquid or vapors were found in the sub-basement of the building, the source of tha t gasoline would mos t likely be f rom the service station to the right, at the h igher elevation, or f rom other tanks far ther up the hill.

In Figure G-8(b), the si tuation is such tha t the service station downhill is the mos t likely source. The water-bearing strata of sand and gravel slopes down f rom left to right, opposite to that of the surface of the ground. Groundwate r flow would also be f rom lett to r ight a n d would carry any gasoline escaping f rom the service station on the left to the sub-basement of the building.

O n e o ther condi t ion, shown in Figure C-8(a), is the effect of a rising and falling water table. Dur ing a dry season, when the water table is below the sub-basement floor of the building, gasoline floating on the water table would no t be able to en ter the sub- basement . But, as the water table rises, the gasoline will be rifted a long with it, eventually reach ing the sub-basement level. The re have been many cases where this has been the reason for the a l ternat ing appea rance and d isappearance of con tamina t ing liquid.

I,( 122 m f4OO:~:'--'b:--.. ..... "-.:'."~'~"" ..-~.x..x...x.5.;';

!l station Elevation8,5 m(28ft) o [] [] ~-~ n _ .

: :, :/..,..,.. :::.Elevation 5,2 rn (17 ft)..', i :..".;3.6 m (12 ft):' :: i,. ~: ;: ::'.i ' ..2.,-: .:.::. Sand andgravel ,' .: .:.:.,

I

.6 m (2 ft) to Down 5°/o 1.5 p (5 ~.! .,~,.....--.. .~. top so!!,

OJ

Figure C-8(.~)~.: . . : . : :~ ; ~ i - ~ _ P u n d e r g r o u n d strata on groundwater flow | .

. . . . ' : " ,3m(lft)to "'':: :Lo .. [] [] 12 ~I~.~

Se~ice Y [] [] [] ~ /topsoil

0 . " P , t - , ° , , • , . , D . . . . ° , .

D

. J , .

I

Figure C-8(b) Effects o f s lope o f u n d e r g r o u n d strata on groundwater flow II.

325

N F P A 3 2 9 ~ A 9 9 R O P

C-9 Contrary U n d e r g r o u n d Flow. Figure C-9 illustrates ano the r example of how u n d e r g r o u n d flow can be contrary to the slope of the g r o u n d above. In this case, f l ammable liquids are s tored in a tank tha t is some distance above a small body of water. From the surface, it would appea r that escaping liquid would flow into the pond. But, because tile tank is over a pervious strata that slopes away from the pond, the l iquid flows in that direction, con tamina t ing wells tha t serve bui ldings at a m u c h h igher elevation t han the tank. Note also tha t if the wells were no t present , discovery would be delayed, probably until t he release reached the g r o u n d on the o ther side of the hill. This could be several miles away.

ephone le conduit

water bearing layer

Figure C-9 Effects o f s lope o f unde rg round strata on g roundwate r flow III.

Consequent ly , the water table rises ,and falls with changes in the weather. For this example , a s sume d~at the water table is widfin 0.305 m (1 ft) of the surface dur ing wet periods, bu t falls to a Level below the bo t tom of the tank evacuation dur ing dry periods.

It is easy to see that a leak in the tank will r e suh in contaminaUng liquid collecting on the bot tom of the excavation, as if it were in an open square tank. ff rainfall raises the water table to a level above the bo t tom of the pipe t renches , t hen the con tamina ted groundwater can flow a long the pipe t renches , m u c h as it would flow th rough a pipe. By means of intersect ions with o ther t renches or with zones of more pervious fill, this con tamina ted water can spread to the adjacent buildings or to the sewer and water main trenches. Note that it will no t necessarily en te r the sewer pipe in the street. It migh t flow a long the t rench, outside of tile pipes themselves and no t appear unti l it comes to a point where it can seep into a m a n h o l e or catch basin.

Ano the r condi t ion illustrated here is the potential for the con tamina t ing liquid to move without the presence of groundwater . If a serious leak were to occur in the suct ion piping, pure liquid could flow a long the t renches.

C-11 Summary. Tile principles and concepts discussed in tiffs append ix poin t ou t the impor tance of a knowledge of the u n d e r g r o u n d soil condi t ions and sub te r ranean features when

C-10 Rising and Falling Water Table. Figures C-10(a) and (b) tracing tile m o v e m e n t of escaped liquids f rom the point of illustrate some o ther aspects of a rising and falling water table and discovery back to.:....the source. It will no t always be possible to tile ability of t r enches to behave like in te rconnec ted piping, obtain all the .~:-"~[esired, but the effort shou ld be made so tha t especially when d u g in relatively imper ious soil, t h en backtilled remediation....~.~l be successful, with a more porous material. Figure C-10(a) shows a tank ~ ' l - ' : ~ installed in an excavation dug in clay and backfilled with sand. Append.:~ D ' ~ c e s o f Damage to Storage Conta iners and Lines Product supply and vent lines are likewise in t r enches dug in clay ..~.... "%. ~i-:.::.-, and backfilled with the same material as the tank. Figure C-10(b) ~:~[J~endix is n'~.3...a~ert of the recommendatior~ of this NFPA shows the layout of a tank installed nex t to a bui lding with a ~ m e ~ . . . but is i n c l , ' f o r informatio~zl purposes onl~. basement . The water supply line to the bui ld ing is also in a t rench ~;'~~::. !iii$:. "" backfilled with sand, as is the city water main and sewer line. "D:'[~..::...~.#~i~ion. One type of corrosion affecting fits lines and Finally a low area between the buildings is filled with sand and p e t r ' O ~ pipel ines occurs when the soil composi t ion and ~ravel" - - .. r e s i s ~ . . ~ r e / s u c h that electric cur ren t f rom tile deve lopment of

" ::~.-~::.,. local acta" ".o~:'e":::e::~ells can flow readily f rom anodic areas on the pipe Sua~oforound ~ V~tli,* :'. '.. 'Z.."':~i~ce th~0ugh the soil to the cathodic areas on the same pipe.

I[ . / ~. ~ . . , ~ ~ - . 7 . ~ ~. . ? ~ h d i t i o n s can be due to the soil 's acid or alkali content ,

S a n d b a c k f i l l i n , x : ~ . ~ . - . ~ ; " : ~ . ~ : . : : . - " . . . " . . . ~ ~ . ~ . -:.!~::. hnes Is stray electric cur rents or ig inat ing f rom such sources as

: _ __ ~ , ~ _ ~ v . . . . . . :~_ :_ ^, . . . . .~ t . '~ '~ , ,_ .~ ...-~k - _a g r o u n d as a re turn conductor" stray currents f rom cross- o - "::~-:~$-:~ ~:. c o n n e c t m n s w~th o ther s t ructures carrying current ; and leakage

"::~.."..:?."::" ~ f rom foreign system cathodic protect ion rectifiers. These currents Ventline .::'::" . ~ .'~N migh t no t be destructive where they en te r the piping system, but

j t ,~ ~ ~ dra inage o f these stray currents to g r o u n d can cause corrosion at ~---2~1. ] ~ " X ~ x"l these points o f discharge.

k \ \ \ \ \ \ \ \ \ \ X l !I / / ~ ~_N - ° I | / [ 1

.~ ~," Lo.ar~a ~ ~ ~ D-3 Structural Fa,inres. The a l locauon of msuffic, en t space for b~ ~N~]""~', ~rou,wm~to.= k ] ~ the installation o f subsurface structures can result, in some

, ~ ili " ~ ~ x~ si tuations in the e n c a s e m e n t of gas and f lammable and ~,~ng ~ ;11 _ - ~ " ~ ~ .~ combust ib le liquid pipes in the walls o f ducts and subsequent ly

]~x~X\\ \ \ \ \ \ \g~lx"~ - - - ~ ~ ~ cons t ruc ted masonry vaults. Such pipes f rom vaults nt ight be

ili - " . . . . " . . . . D-4 Excavating. Contractors do ing excavation work often |ll|~ ~.. encoun t e r gas mains and f l ammable and combust ib le liquid pipes.

I Curb of street [[~ d ' ' ' ~ Even t h o u g h workers are aware of their presence, they miglat Ill " un in ten t iona l ly damage a pipe, resul t ing e i ther immediate ly or il{ ~ " - j ul t imately in a leak. Damage such as this is no t always repor ted ~1! ~ ' " and often inadequa te repairs are a t t empted by the party responsible

~___ ~ ~ ~ ~ a . for the physical damage . . . . . W , ~ - - m , T - - 7

Figure C-lO(b) T a n k ins ta l l ed n e x t to a b u i l d i n g with a b a s e m e n t .

The paren t or original soil is clay. A water table that exists in this clay will have little horizontal flow, due to the resistance of the clay.

D-5 Fire Damage. Fires in subsurface s t ructures can result in spall ing o f concrete, des t ruc t ion of protective linings, and deter iorat ion of o ther inter ior surfaces. Such damage , if extensive, can weaken the structure°

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NFPA 329 A99 ROP

A p p e n d i x E I n v e n t o r y C o n t r o l P r o c e d u r e s

This appendix is not apar t of the recommendations of this NFPA document but is inoluded for informational purposes on O.

E-I Tanks with Me te red Dispensing. For this m e t h o d to be effective, all me te r s that measu re liquid d i spensed f r o m t h e u n d e r g r o u n d system shou ld be p rope r ly cal ibrated to local s t andards fo r m e t e r cal ibrat ion or an accuracy of 5 m l / L (6 inS/5 gal) of p rodnc t s wi thdrawn. A m e t e r tha t reads significantly h ighe r than actual voh lme p u m p e d can h ide a leak. Conversely, a m e t e r that indicates less than the t rue vo lume migh t sugges t a leak where one does n o t exist.

release has occur red . T a n k liquid level m e a s u r e m e n t s are taken at t he beg inn ing a n d e n d i n g of at least a $6-hour pe r iod d u r i n g which n o l iquid is a d d e d to o r r emo v ed f r o m the tank. Level m e a s u r e m e n t s are based on an average of two consecutive gauge read ings at bo th the b e g i n n i n g a n d e n d i n g per iod. Accord ing to U.S. Env i ronmen ta l Pro tec t ion Agency regulat ions, a leak is suspec ted if the weekly or m o n t h l y s t andards exceed the values shown in Table E-2.

T a b l e E-2 S t a n d a r d D e v i a t i o n s f o r I n v e n t o r y R e c o n c i l i a t i o n

M o n t h l y S t a n d a r d N o m i n a l T a n k W e e k l y S t a n d a r d ( A v e r a g e o f F o u r

C a p a c i t y ( O n e Test) Weekly Tests) E-I . I Daily P rocedures . At tile b e g i n n i n g of each bus iness day (or (fiat) (lgal) (gal)" each shift, if p re fe r red ) , tile tank vo lume shou ld be manual ly m e a s u r e d us ing a gauge stick, or o t h e r means , and a cal ibrat ion 550 or less 10 5 char t to conver t tile tank level into gallons. Level m e a s u r e m e n t s shou ld be based o n the average o f two consecut ive stick readings. 551-1000 13 7 This gaug ing ope ra t i on shou ld be carr ied ou t with grea t care to 1001-2000 26 13 ensu re m a x i m u m accuracy. O p e n i n g me te r totalizer read ings sh ou ld also be r eco rded for each dispenser•

W h e n liquid is a d d e d to the u n d e r g r o u n d tank, file tank vo lume shou ld be g a u g e d bo th before and after tile delivery. T h e o p e r a t o r shou ld also check tile tank for p r e sence of water to the neares t 3.2

For tanks larger t han 7570 L (2000 gal), tank levels shou ld be accnrately g au g ed and r eco rded before and after any i npu t or withdrawal. To d e t e r m i n e if the s torage system is losing liquid, the o p e r a t o r sh o u ld c o m p a r e tile vo lume before an i n p u t or withdrawal with the m e a s u r e d vo lume after the previous i npu t or

• • • withdrawal This loss or gain f igure for each pe r iod of tank m m ( 1 / 8 in.) using, for example , water - f indmg paste or o t h e r . . . : . . . . . . . . . . . a p p r o p r i a t e means~ This p r o c e d u r e , however, i s n o t appl icable to ina,cuvl,ty s n o u t a o.e carr lea i o r w a m a n a c u m u m u v e variance

ma in t a ined by g the gum or sub t rac t ing the loss f r o m the water-miscible liquids. Water tha t is de tec ted s h o u l d be a c c o u n t e d . . ~ . p r e w o u s n u m r ~mce tank gaug ing er rors are corn letely for in tile inventory p r o c e d u r e s and any significant a c c u m u at ion ~ • P

• ' . r a n d o m th¢~,)" ~ould t end to cancel o u t f rom one m e a s u r e m e n t to [ that IS, g rea te r t han 12.7 m m ( 1 / 2 in.)] shou ld be p rompt ly - , -~ ~_~o . . . . . . . - - - m e next. ~t-cdtlel~ent a n a increas ing negatave or nosltlve t r ena removeu . . . . .. ~. . . ,

ind, c a t e ~ p o t ~ Z ~ . ~ i l e a k that sh o u ld be investigated.

At tile close of the bus iness day (or tile end of d ie shift), tank _ ~-:~%:': , . '~:o,.-:-: . . . . . . . . voh tme shou ld again be g a u g e d and me te r totalizer read ings .~i..~¢ ao~ltaonm m t o ~ t a o n on m e subject, see m e tot towmg: r eco rded T h e d i f fe rence be tween tile o p e n i n g and closing totalizer ..::f!?-"..'!-::-. ~::.. _ " . . . . . . . . . . .

. . . . . . . . '":'{~...¢~. :~:t:~21 tfecommenctea Yractice or l:tut~ Li uid Stoct~ Gontrot at readings is tile sales fo r tile inventory per iod. All readmtzs that are . . . . . .:..-<..P,~-.. . . . . fi q - ~ l¢,eta~.?" utlets r eco rded as par t of this p r o c e d u r e shou ld be kept in a safe location .~!~, " • -- . . -- . -. . "-:::::~:$:.

a n d re ta ined for a m i n i m u m of 1 year. Detailed ins t ruct ions ,:.~:~.~: . . . . . . . . . . :'S.--:-:-.. (b) . . . . . . its of Factors Affecting Service Stat ion Inventory c o v e n n g tank gaugang, water gauging, me te r c a h b r a u o n checks, ::.:....':!:!....'~:.::.:. ~ ~ . . . . . . . . . . . .

a n d record keeping are con ta ined in AP1 1621, Recommended -~il-'-<:;?..~i!iii~...9:..n.trol, ,~'eport p r e p a r e o for m e At-i oy tile t~acuan t so rpora tmn . Practice for Bulk Liquid Stock Control at Retail Outlets. ::': .:.~::':'::~.':.~?:.:i?:.:~..-.:.<-~" -!: ..:::: ..x..~$:..

A p p e n d L x F R e f e r e n c e d Publ ica t ions E-I.2 Dally Reconcil iat ion. Inventory reconci l ia t ion c o ~ i o f :ii:. " " " " c o m p a r i n g tile m e a s u r e d closing inventory to the b o o k . : ~ v e ~ , ::~i!::....4, . . . . . . . . . . .

. . . . . . . -.':':~- ~- ::::::"lP-i l n e iOllOWing a o c u m e n t s or por t ions u l e r e o i are reterencecl which is o b t m n e d by add ing deliveries a n d subtractiBt~:.:'~t~.les aO~ :::: . . . • ~.2"...~a : . . . . . . . . . D . . . . . # -~ '_~ ,~ z.~.:-::...<.:.: ............ ~ vo thm d n s r e c o m m e n d e d practice for in fo rmat iona l pu r pos e s only on-site usage f r o m the m ~ , ~ u , c u , . , ~ . t , , , y. L,u~ tu vat,nm.ca~..::~:?.~:~::'.i:~:!~:':!:.::3!::" . . .

. . . . . . - - • :-:..-:.:..-x: -..--...,,.~:.:-:..-¢. and a re thus no t cons idered pa r t of its r e c o m m e n d a u o n s T h e i n h e r e n t in tile process this r econc lha t lon will rarely b a ~ exactlv to the e ~ l o n a n d small daUv "over ~ or . ? . ~ f i o l i r ~ : ~ e to edit ion indicated he re for each re fe rence is tile cu r r en t edi t ion as be' exp'ected, l~'y observat ion of dally ~ varian...g~'s, '~:: '~tor~.tc i~'~'fe~!~ of tile date of tile NFPA issuance of this r ecommended . . practice. to identify t rends over time; daily f l u c t u a ~ t end to ~ e l plat . . . . . . . ,h~ ~ , ~ , ~ .~'-'~-~.-::-~-::~ ".~,.,.-.":"~" F-I . I NFPA Publicat ions. Nat ional Fire Protec t ion Associatioi~ ~. . . . . . . . . . . ~ . . . . . . . . ~..-.:..~ ~: ::.-:..'.-: . ,

"::~!~ .:.-':~ Bat terymarch Park, P.O. Box 9101 Q u m c y MA 02269-9101. --'~...-:~ ~- , , E-I.3 Inven tory Reviews. T h e ope ra to r of an t ~ r . ~ n d tank

NFPA 30 Flammable and Combustible Liquids Code 1990 edlUon system s to r ing f l ammab le or combus t ib le l i q u i d s " : ~ | d review the , " " , " " • daily inventory records once a week• The nperator.)~'hould be c o n c e r n e d with small b u t g rowing daily losses or s u d d e n NFPA 325, Guide to Fire Hazard Properties of Flammable Liquids. u n e x p l a i n e d changes f rom the establ ished pat tern . E i ther of these Gases, and Volatile Solids, 1996 edition• s y m p t o m s could indicate a potent ia l leak.

For a facility tha t s tores m o r e t han o n e variety of similar liquids ( such as a retail service s ta t ion) , t he o p e r a t o r s h o u l d c o m p a r e inventory records for the various tank systems. This will mit igate the effect of tile t empe ra tu r e - indnced er rors on the inventory account ing . Since the impac t of t e m p e r a t u r e shou ld be roughly file same, a s ignif icant d i f ference in tile inventory variance f rom one p r o d u c t to the nex t migh t indicate a leak. The first s tep in investigating this would be to check the m e t e r cal ibrat ions on the d i spense r system.

At tile end of each mon th , file o p e r a t o r shou ld again review the dally i n v e n t o r y a c c o u n t i n g a n d p e r f o r m a mond l ly reconcil iat ion. Accord ing t o U . S . Env i ronmen ta l Pro tec t ion Agency regulat ions, a leak is suspec ted if, for two consecut ive mon ths , the m o n t h l y inventory shor tage exceeds 1 p e r c e n t of the system t h r o u g h p u t plus 492 L (130 gal). The o p e r a t o r shou ld look closely to see i f the negative variance is a one- t ime f luctuat ion or if the re is a consis tent negative t r end t h r o u g h o u t tile inventory period.

E-2 Tanks Wi thout M e t e r e d D i s p e n s i n g . For these systems, tile inventory review is compl ica ted by tile fac t tha t all withdrawals can only be measu red by gaug ing tile tank. For tanks of 7570 L (2000 gal) or less, manua l hank gaug ing can be used to d e t e r m i n e i f a

NFPA 495, Explosive Materials Code, 1992 edi t ion.

F-I.2 ASTM Publicat ion. Amer ican Society for Tes t ing and Materials, 1916 Race St., Phi ladelphia , PA 19103.

ASTM D 1250-80, Pe t ro l eum M e a s u r e m e n t Tables.

17-1.$ API Publicat ions. Amer ican Pe t ro leum Institute, 1220 L St., NW, Washing ton , DC 20005.

API 1621, Recommended Practice for Bulk Liquid Stock Control at Retail Outlets, Four th Edition, 1993•

APt 1628, Guide. to the Assessment and Remediation of Underground Petroleum Releases, 1993.

"Analysis of Factors Affecting Service Stat ion Inventory Control ," r ep o r t p r e p a r e d for the APt by the Radian Corpora t ion , July 1984.

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