Resource Group on Threading, Gauging, and Compounds – Winter Jan 22, 2008 Ft. Worth Report of Meeting Resource Group on Threading, Gauging, and Compounds (API C1/SC5, TG2, RG02) Jim Powers, Bill Sargent Co-Chairmen Meeting Tuesday Jan 22, 2008, 8:00 am – 12:00 pm Fort Worth, Texas The meeting began at 8:00 AM with the customary individual introductions. There were 19 voting members in attendance at the beginning of the meeting and 22 voting members or alternates from the signed attendance sheets (Refer to Attendance Roster, Attachment 1). Agenda Items Assigned by API SC5/TGOCTG RP5A3 Thread Compounds for Casing, Tubing & Line Pipe 1033a API Thread Compound Research Charge: To develop a small scale friction/galling test procedure for inclusion in API RP5A3 WG Chair: Herschel McDonald and Jack Smith W.G. Chair, Herschel McDonald gave a report. Small-scale and full-scale torque-turn curves, and resulting coefficient of friction data was reviewed. The small-scale tests were run on the assembly developed by the work group that utilizes Bellville (compression) washers to model full-scale connection make-up characteristics and a bolt force sensor to accurately measure axial load. Specially designed, strain gauged NC-46 and NC-50 tool joints were used to obtain the full-scale test data. Five trial compounds of varying composition were tested and compared to the results of a “reference” compound with well-established frictional properties. Five connection make-ups were performed for each trial compound. Make-ups with the reference compound were performed before and after each trial compound sequence to recheck the baseline conditions. The small-scale and full-scale preliminary test results were compared and discussed by the Resource Group. Although the comparisons were not as close as the group had hoped, there were close comparisons for particular compounds. Herschel explained, he had hoped that the results could have been closer (within 10%) but went on to explain the various reasons for the torque variation and the fact that trial results may predict relative friction factors for certain types of compounds not necessarily absolute values. He closed by stating that a W.G. meeting will be scheduled for February or March to discuss the results in greater detail and to come to a consensus on the need for additional testing and the continuation of the test program. One suggestion was to conduct “round robin” small-scale to full-scale testing using 2 or 3 manufacturer’s labs, to compare the repeatability of various small-scale results. Refer to Attachment 2 3063 Review of ISO 13678 - Thread Compound (ISO TC67/SC5/WG4) Charge: Revision of ISO 13678 / coordination with API RP5A3 WG Chair: Mark Mulvihill W.G.Chair Mark Mulvihill reported on the results of the W.G. meeting held Monday, Jan 21. He explained that the W.G. had started the process of resolving the individual comments, but the W.G. did not have consensus on the desired final API version of the ISO 13678 document. The W.G. could not decide if the API version of API RP5A3 (to include RP 7A1) should be an API Recommended Practice or a Specification. A straw vote was taken and the majority of the R. G. voted to adopt back ISO 13678 as a R.P. Refer to Attachment 3
Transcript
Resource Group on Threading, Gauging, and Compounds – Winter Jan 22, 2008 Ft. Worth
Report of Meeting Resource Group on Threading, Gauging, and Compounds
(API C1/SC5, TG2, RG02) Jim Powers, Bill Sargent Co-Chairmen
Meeting Tuesday Jan 22, 2008, 8:00 am – 12:00 pm Fort Worth, Texas
The meeting began at 8:00 AM with the customary individual introductions. There were 19 voting members in attendance at the beginning of the meeting and 22 voting members or alternates from the signed attendance sheets (Refer to Attendance Roster, Attachment 1).
Agenda Items Assigned by API SC5/TGOCTG RP5A3 Thread Compounds for Casing, Tubing & Line Pipe 1033a API Thread Compound Research Charge: To develop a small scale friction/galling test procedure for inclusion in API RP5A3 WG Chair: Herschel McDonald and Jack Smith W.G. Chair, Herschel McDonald gave a report. Small-scale and full-scale torque-turn curves, and resulting coefficient of friction data was reviewed. The small-scale tests were run on the assembly developed by the work group that utilizes Bellville (compression) washers to model full-scale connection make-up characteristics and a bolt force sensor to accurately measure axial load. Specially designed, strain gauged NC-46 and NC-50 tool joints were used to obtain the full-scale test data. Five trial compounds of varying composition were tested and compared to the results of a “reference” compound with well-established frictional properties. Five connection make-ups were performed for each trial compound. Make-ups with the reference compound were performed before and after each trial compound sequence to recheck the baseline conditions. The small-scale and full-scale preliminary test results were compared and discussed by the Resource Group. Although the comparisons were not as close as the group had hoped, there were close comparisons for particular compounds. Herschel explained, he had hoped that the results could have been closer (within 10%) but went on to explain the various reasons for the torque variation and the fact that trial results may predict relative friction factors for certain types of compounds not necessarily absolute values. He closed by stating that a W.G. meeting will be scheduled for February or March to discuss the results in greater detail and to come to a consensus on the need for additional testing and the continuation of the test program. One suggestion was to conduct “round robin” small-scale to full-scale testing using 2 or 3 manufacturer’s labs, to compare the repeatability of various small-scale results. Refer to Attachment 2 3063 Review of ISO 13678 - Thread Compound (ISO TC67/SC5/WG4) Charge: Revision of ISO 13678 / coordination with API RP5A3 WG Chair: Mark Mulvihill W.G.Chair Mark Mulvihill reported on the results of the W.G. meeting held Monday, Jan 21. He explained that the W.G. had started the process of resolving the individual comments, but the W.G. did not have consensus on the desired final API version of the ISO 13678 document. The W.G. could not decide if the API version of API RP5A3 (to include RP 7A1) should be an API Recommended Practice or a Specification. A straw vote was taken and the majority of the R. G. voted to adopt back ISO 13678 as a R.P. Refer to Attachment 3
Resource Group on Threading, Gauging, and Compounds – Winter Jan 22, 2008 Ft. Worth
3066 Leak Resistance Test for Thread Compounds Charge: Prepare a specification for thread compounds suitable for proper make-up and performance with connections covered by API5B WG Chair: Mark Mulvihill The W.G. Chair reviewed the data from a FEA to determine effect of coupling hoop stress when using a solid pin verses a bored out pin, modeling a 2 3/8” API 8 Round connection. The work group would like to thank Dave Mutis, Bob Sivley and Dave Mallis from Tenaris-Hydril for their work on the FEA. The results confirmed that the bored out pin will better model actual connections, and that the solid pin would result in elevated hoop stresses that would not model the normal connection. With the work complete Mark suggested the W.G. machine some parts and have them made-up. Special inserts will be used to model the worst case, or largest gap between the root and crests. Wheeling Machine volunteered to machine the couplings using the same inserts. Refer to Attachment 4 Spec 5B Threading, Gauging & Thread Inspection of Casing, Tubing and Line Pipe 2291 Leak Resistance of API BTC Connections Charge: Define a BTC connection with reliable performance for 5CT, 5B, 5B1 and 5C1. WG Chair: Brian Schwind W. G. Chair Brian Schwind reviewed past trials, 9 5/8”’ x .545 wall P110 BTC that were designed to have 5 to 7 turns of interference. He explained the need for PD type gauging and reduced clearances for the Buttress Thread thread form. The reduction in clearances would only apply to the 4 ½” – 13 3/8” size range, due to the thread compounds inability to seal even with the larger Teflon particles. He also stated that the W.G. was considering various ways to obtain the necessary turns of interference such as increased make-up turns into the J area and a possible slight reduction to the coupling PD, but preferred to keep the couplings close to current tolerances. Refer to Attachment 5 3047 Std 5B Review/Reorganization (review changes) Charge: Provide SI units in the current API 5B format WG chair: Jim Powers Jim Powers the W.G. Chair reported to the group that 5B Proof 8 had incorporated the R.G.comments. Joe Mackin, Dave Mallis and Ed Evans detailed their comments for the R.G.. There was a group discussion that provided guidance to clarify some of the drawings and figures. Lastly, the group suggested ideas to add consistency to the SI tables. Jim stated that 5B should be published before the June meeting and thanked everyone for their input. 3064 Broaden Application of SR22 Gauging Practices Charge: Evaluation of the use of SR22 gauging practices, e.g. the use of pitch diameter gauges in lieu of API solid ring and plug thread gauges. WG Chair: Dean Goodson Dean thanked the R.G. for their support for the passed “philosophy” letter ballot. He went on to explain that the ring and plugs will continue to be used to ensure interchangeability, but the PD gauging will promote better connections. A W.G. meeting is scheduled for the afternoon following the R.G. meeting to discuss the PD tolerances and review the proposed thread gauging practices. Refer to Attachment 6,7,8 & 9
Resource Group on Threading, Gauging, and Compounds – Winter Jan 22, 2008 Ft. Worth
3067 BTC and 8-Round Coupling Burr Charge: Revise the pin chamfer angle tolerance to increase coupling thread crest clearance during power make-up. WG Chair: Bill Sargent W.G. Chair Bill Sargent reported to the R.G. that the letter ballot for the chamfer tolerance change had passed and thanked the group for its input and assistance and that the change will be incorporated in the new 5B. Joe Mackin made a motion to drop the item from the agenda. The motion passed unanimously. This item will be dropped from the R.G. agenda, but will remain on the SC5 agenda. RP5C5 Procedures for Testing Casing & Tubing Connections 2314 Assessment of Prior Connection Tests Scope of WG2a:
1. Enhance Annex G of ISO 13679 to fully develop and document a process for threading manufacturers to perform a product line qualification test program.
2. Develop a process to assess previous test results to correlate the data to the requirements of ISO 13679:2002 (API RP5C5)
3. Address other areas of improvement/enhancement to ISO 13679 based on ongoing usage and review in recent years.
WG Chair: Gloria Valigura Gloria reported results of the December meeting in Houston. After significant and lengthy discussion of threader’s concerns with user requirements, consensus was obtained on all outstanding items. At the completion of the meeting, based on a straw-man vote, there was 100% support from all company representatives to move CD 13679 to Country vote. Gloria informed the R.G. that a W.G. meeting is scheduled for the afternoon following the R.G. meeting to discuss the remaining 6 items finalize the 13679 CD before its sent to ISO TC67/SC5 Chair for preparation/distribution for country vote. Refer to Attachment 10 2317 Tech Report on LTC/BTC Performance Properties and Leak Resistance Charge: Create summation of leak resistance of API LTC and BTC thread items and
compare to leak resistance for enhanced LTC (SR22) and the proposed enhanced BTC.
WG Chair: Brian Schwind Brian reported to the group that the report is complete, in draft form. Concerns of the paper’s references were discussed and it was decided that the R.G. members could have a copy of the report, but it would not be posted on the API Technical Literature website. It was explained that ISO Technical Reports require regular review and update and that Technical Paper do not. Concerns were expressed that ISO representatives should be consulted to determine if ISO uses the term “Technical Paper”. Joe Mackin made a motion to consider the item complete and drop it from the agenda. The motion passed unanimously. This item will be dropped from the R.G. agenda, but will remain on the SC5 agenda. Refer to Attachment 11
Resource Group on Threading, Gauging, and Compounds – Winter Jan 22, 2008 Ft. Worth
General 2329 Define BTC and 8-Round coupling alignment, eccentricity, and OD Charge: To ensure BTC and 8-Round coupling alignment, eccentricity, and OD dimensions create a wall thickness that does not fall below a minimum specification WG Chair: Brian Schwind The W. G. Chair reported that there is no method to guarantee a minimum wall thickness for couplings. He explained that the W.G. is considering using 90% of nominal wall thickness as minimum thickness. Brian also reviewed a spreadsheet that considered changing the 7.656” coupling OD to 7.875” to reduce the coupling hoop stresses for the heaver walls of 7” casing. John Greenip cautioned the group that the users maybe concerned with clearance issues. Lastly, Brian stated that API should issue a strong warning regarding 7” performance data and list the limits of 4 ½” to 9 5/8” casing connections that are limited by their coupling stresses. He explained that before users choose to use heaver walls in their well design, they must consider the connection strength (coupling strength) limitations. Refer to Attachment 5 Spec 7 Rotary Drill Stem Elements 7004 10424-2 Threading, and Gauging of Rotary Shoulder Threaded Connections Charge: Review the draft ISO 10424-2 as it progresses through the various ISO stages and assist in preparing USA vote/comments on the drafts. WG Chair: Tony Collins, Schlumberger Tony Collins stated the ISO 10424-2 was published in October 2007and ballot for back-adoption as API Spec 7-2 has just closed and passed and the few API comments are being addressed. Tony explained that the comments will be reviewed before publication and probably communicated to ISO as errata. Refer to Attachment 12,13 7010 Left Hand Connection Charge: Determine necessary provisions for LH versions of API threads (e.g., for top-drive application). Jack Smith to address Jack Smith reported that Samit Gokhale from T.H. Hill Co. was interested in changing the wording of the specification to state that “left hand” threads on NC connection are not prohibited because of lack of performance but because there are no master rings and plugs. Dean Goodson stated the fact that the PD gauging “philosophy” passed letter ballot that rings and plus should not be an issue. However, Jack recommended, since there has been no meeting or activity on this item, it should be dropped from the agenda. A motion was made and passed to drop from R.G. agenda. This item will be dropped from the R.G. agenda, but will remain on the SC5 agenda. 7015 Proprietary Connections on Kelly Valves Charge: Establish protocol for monogramming Kelly valves without referring to the connections, to allow non-API connections to be used WG Chair: Doyle Brinegar W.G. Chair Doyle Brinegar reported that a proposal was submitted and passed
Resource Group on Threading, Gauging, and Compounds – Winter Jan 22, 2008 Ft. Worth
ballot and is awaiting publication in 7A1. Doyle suggested we drop this item from the agenda. This item will be dropped from the R.G. agenda, but will remain on the SC5 agenda. 7018 Add NC84 Connection Charge: Establish standard for NC84 used for the larger top drive connections W.G. Chair: Bill Braman Jack Smith gave a report that the item will be discussed on Wed morning. Jack reported that National OilWell had made the request to include the NC 84 as an API product. There was a discussion of who would pay for these new master gauges and the fact that PD gauging may not be suitable for drill stem connections. Old Business New Business Item 1 Brad Bellinger from API Staff gave a report to the R.G. concerning procedures to add new state sponsored gauge certification agencies. INMETRO in Braziland Russia may be in the pipeline. He explained that Dennis Everett of NIST and Bill Woods has agreed to audit INMETRO once they choose to go forward. Brad requested that the R.G. draft a new W.I to develop a procedure for initial and follow-up audits of gauge certification agencies. Tony Collins explained that ISO 17025, 2005 edition defines “General Requirements for Comparison of Testing and Calibration Labs”. Other possibly sources are, American Association for Laboratory Accreditation, A2LA, and ANSI Z540-1-1994. Item 2 Dean Goodson suggested that 5 ¾” x 16 lb, 17.60 lb, 19.30 lb, 21.40 lb and 12 ¾” x 49.10, 57.20, 63.60 lb be included as 5B connections. There was discussion to whether these items would require unique threads or thread design already in use. For example; 5 ½” threads on 5 ¾” pipe. Dean explained if 5 ¾” and 12 ¾” are put in 5CT , we should consider putting them in 5B. Others in the R.G. stated that 13 5/8” should also be considered. It was noted that WI 2343, update 5CT tables, with these ODs is underway, W.G. Chair is S. Rekin (was C. Beck). NWI 3065; Revise RP 5B1 as a practical guideline, wait for item 3064 PD Gauging to be complete Resource Group Roster The “official R.G. Roster” was presented at the meeting and will be cleaned up before the June meeting when it will be distributed to all members. Collect Attendance Sheets - Adjourn
sargent
Text Box
Attachment 1
COMPOUND RUN-CYCLE TORQUE @ 60 ksi F.F - Torque
KK 1-1 6421-2 6001-3 600
Avg.: 614 1.10API - C 2-1 641
2-2 6642-3 665
Avg.: 657 1.20KK 3-1 600
3-2 5983-3 600
Avg.: 664 1.10API - B 4-1 572
4-2 5674-3 579
Avg.: 573 1.00KK 5-1 665
5-2 6655-3 663
Avg.: 664 1.10ZN-50 6-1 607
6-2 6186-3 630
Avg.: 618 1.02KK 7-1 664
7-2 6647-3 684
Avg.: 671 1.10API - A 8-1 489
8-2 4918-3 487
Avg.: 489 0.83KK 9-1 656
9-2 6249-3 612
Avg.: 631 1.10
SMALL-SCALE REVISED RP 7A1
sargent
Text Box
Attachment 2
COMPOUND RUN-CYCLE TORQUE @ 70 ksi F.F - Torque
KK 1 19,3002 19,700
Avg.: 19,500 1.10API - C 1 18,500
2 18,5003 19,0004 18,8005 18,800
Avg.: 18,700 1.08KK 3 19,200
4 18,400Avg.: 18,800 1.10
ZN-50 1 17,2002 17,3003 17,1004 17,0005 16,400
Avg.: 17,000 1.00KK 5 19,000
6 18,800Avg.: 18,900 1.10
API - 7A1 1 17,5002 17,1003 16,2004 17,300
Avg.: 17,000 1.02KK 7 18,200
8 18,400Avg.: 18,300 1.10
FULL-SCALE NC-46 #1
COMPOUND RUN-CYCLE TORQUE @ 70 ksi F.F - Torque
KK 1 22,5002 22,6003 22,8004 22,1005 22,4006 23,000
API 7A1 1.02ZN-50 1.02 1.00API - A 0.83 0.97API-B 1.00 1.24API-C 1.20 1.08 1.13
FRICTION FACTOR COMPARISON
TEST SPECIMEN
NC-501.10
0.90
API Item No. 3063, Thread Compounds – API Review of ISO 13678 On January 21, 2008, 30 attendees were at the ISO WG 4 meeting from 3 – 5 PM to discuss comments on DIS 13678. Closing date for the voting DIS 13678 is January 30. Most of the comments from the US were discussed at meeting but more time is needed to complete the evaluation of the US comments. In an effort to produce equivalent ISO and API documents, an extensive discussion compared API RP’s and ISO IS’s. Different ways of accomplishing equivalence were proposed but the WG could not reach a consensus. Another WG 4 meeting is planned for March 2008 to resolve remaining comments and API RP vs. ISO IS concerns. API Item No. 3066, Leak Resistance Test for Thread Compounds On January 21, 2008, 18 attendees were at the API WG 3066 meeting to discuss the FEA that was generated by Tenaris Hydril. Work was donated to the WG by Tenaris and is greatly appreciated. FEA analysis indicates that hollowed pin and coupling are best configuration for the 2 3/8” API EUE 8 round connection. WG will order test connections and meet during week ending February 8 to discuss procedure and schedule for the leak resistance tests.
sargent
Text Box
Attachment 3
sargent
Text Box
Attachment 4
1
PERFORMANCE PROPERTIESRequirements for Leak Resistance of API
Connections (BTC)
API Connection Leak ResistanceWI 2291/ WI2317
January 2008
sargent
Text Box
Attachment 5
2
Agenda: Performance Basis
WI 2329: Coupling Wall Thickness (min)Obtain consensus on minimum coupling wall (10%)
Obtain consensus on minimum 7” W (7.875” proposed)
Location of measurement for minimum coupling wall.
Discuss Performance Properties per wall toleranceAddressing Coupling Weak configurations
WI 2291: BTC Leak ResistanceDiscuss BTC Performance for SR22 type connectionObtain consensus tolerance and measurement method/ locationsObtain consensus on calculation methodCoupling PD v Makeup Position
3
WI 2329: Coupling Wall Thickness
Fig 11: coupling wall variation from grinding
99% W
101% W
tmin
4
WI 2329: Coupling Wall Thickness9-5/8, 53.5 L80 Min. Int. Yield Pressure: 7,930psi
Outside 5C3-32 mid L7 API Diameter Out. Dia. API coupling Ratio
D Regular coupling stress @ MIYP efficiency nominal 0.9 Eff Delta tin. W MIYP twall Pyield MIYP Pyield P(141)of Seal Nmin Thickness Thickness W interference Pcont MU Stress Pinternal Pc
Resolution 5: The thread pitch diameter, E8 at L8 and M8, will be the toleranced and added to API Standard 5B. Ring and/or plug gauge stand off measurements shall continue to be used without change. In case of dispute, Pitch Diameter Measurement (E8 at L8and M8) shall govern.
API STD 5B Thread Elements• Taper• Lead• Thread Height• Angle, Included (Thread Form ***)• Standoff• Thread Addendum• Thread Diameter & Ovality
Thread TaperTaper shall be defined as the change in diameter along the pitch cone of the threads. Taper is measured in inches per foot or inches per inch.API Standard 5B Table 5Taper per foot on diameter (0.750 in) +0.0625 in
-0.0312 inper inch on diameter (0.0625 in) +0.0052 in
+0.0026 in
Thread Taper Implications
• Improper application of taper tolerances promotes connection leakage.
• Incorrectly miss-matched tapers can lead to premature jump-out failures.
THREAD LEAD
Lead is defined as the distance from a point on a thread turn to the corresponding point on the next thread turn, measured parallel to the thread axis. Lead tolerances are expressed in terms of "per inch" of threads.
API Standard 5B Table 5Lead per inch ±0.003 in
cumulative ±0.006 in
8RPLEAD.DWG
6.7 PIN THREAD LEAD MEASUREMENT
Thread Lead Implications
• Improper application of lead tolerances promotes connection galling.
THREAD HEIGHT
Thread height shall be defined as the distance between the crest to root normal to the axis of the thread.Thread height is measured in thousandths of an inch.API Standard 5B Table 5Height hs and hn + 0.002 in
- 0.004 inProposedHeight hs and hn ± 0.002 in
Thread Height Implications
• Improper thread height can promote connection leakage.
Thread FormThe form of the thread is its profile in an axial plane.
ImplicationsImproper thread form promotesconnection leakage, galling and increases the potential for jump-out failure.
API Standard 5B Table 5Angle, included ± 0.0015 in
ProposedAngle, included ± 0.001 in
Thread Addendum• Thread addendum shall be defined as the
distance between the pitch line to thread crest normal to the axis of the thread.
• Thread addendum is measured in thousandths of an inch.
Proposed API Standard 5B Table 5Proposed API Standard 5B Table 5Thread addendum pitch line to crest ± 0.001 in
USS Proposed API Standard 5B Table 5USS Proposed API Standard 5B Table 5Thread addendum pitch line to crest + 0.0005 in
- 0.0015 in
8RPSHV.DWG
Thread Standoff
Thread standoff shall be defined as the relationship between the working ring/plug gage against the product threads.A+ (S1-S) on the working plug gage against the coupling, and P1 on the working ring gage against the pin thread.
API Standard 5B Table 5Standoff A See Para. 4.4 (±1p)
API Ring Gauge on API PIN Thread
API Buttress Pin and Ring Gauge
Mated API Buttress Pin and Ring Gauge
Thread Standoff Implications• Thread measurement at improper
• Measured diameters provide actual interference levels that reduce the potential for connection leakage.
API Work Item 3064 – Alternate Thread Gauging 8 Round & Buttress January 24, 2008 A Work Group meeting was held Tuesday afternoon January 22, 2008 at the winter API Conference in Fort Worth, Texas. The specific purpose of the meeting was to address the negative votes and comments on the 3064 Alternate Gauging Consensus letter ballot. Work Group leader, Dean Goodson, presented a Power Point presentation that began with a clear philosophy on the direction of the work group followed by a review of each individual thread element for proposed change by the work group and the major implications that each element has on the performance of the connection. It is the Work Group Leader’s belief that each of the Negative votes have been positively addressed. William Sargent of US Steel presented a paper that concerned documented data on the efficiency and wear of 8 Round threading inserts. The conclusion of the data indicates that a Thread Addendum tolerance of +0.0005”/-0.0015” and a thread crest radius of 0.019” ±0.001” was more efficient than a Thread Addendum tolerance of ±0.001” and a thread crest radius of 0.020” ±0.001”. The report was accepted and will be attached to this report. In as much as the 3064 Letter Ballot on Alternate Thread Gauging 8 Round and Buttress Consensus passed, work will begin to prepare the work item for acceptance letter ballot following the June 2008 API Conference in Calgary.
note: Thread Crest Radius .0185 for most tool manufThread Root Radius .0165 gives best thread depth and form (bold black font)
the design we like the best gives us the best positive depth and most negative thread form readings, like "type" a and fboth a and f give us + .0005 depth and -.0005 to -.001 form.we work to depth tolerance of + / - .002 and a form tolerance of 0 to - .003
Thread Thread Form FormCrest Root Thread Thread line line
Type Radius Radius Depth Form Inside Outsidea 0.0185 0.0165 0.0005 -0.001 -0.0005
b 0.0175 0.0185 0 -0.002 -0.001
c 0.0185 0.017 0.00025 -0.0005 -0.0005-0.0015
d 0.0175 0.0175 0 -0.0015 -0.001-0.0005 -0.002
x 0.0185 0.017 0 0 0-0.001 -0.0005
e 0.0195 0.0175 0.0005 0.00025 0
f 0.0185 0.0165 0.0005 -0.0005
sargent
Text Box
Attachment 8
Pin and Box Pitch Line to Crest is .03413 plus .0005 , -.001"Design was .0185 plus and minus .0015 .020 and .017
Pin Crest Radius Box Root Radius Gap Form Reading0.0175 0.0170 0.0005 -0.002
Depth Tolerance .001 to -.001 won't get over .00075
Form Tolerance -.0015 to .0005
Since Root is biased on deep side, crest has to be biased on tall sideChaser Tool miss trackage is detected by Positive Form readings, any plus form indicates tooth too wideUsing Crest Radius of .0185 and Root Radius of .0165, Gap would be .002Using .03413 with Tolerance of +.0005 resulting crest to root gap would be.0015Using .03413 Tolerance -.001 Gap would be .003If Form Tolerance kept to -.0015 limit, this would limit crest to .0180 and maintain .0015 gapIf Form Tolerance max limit .0005 this would limit crest radius to .020 and gap of .003
sargent
Text Box
Attachment 9
Status Report - API WI 2314 Combined Effort between API WI 2314 and ISO TC67/SC5/WG2a
January 2008
Scope of WG2a 1. Enhance Annex G of ISO 13679 to fully develop and document a process for
threading manufacturers to perform a product line qualification test program. 2. Develop a process to assess previous test results to correlate the data to the
requirements of ISO 13679:2002 (API RP5C5) 3. Address other areas of improvement/enhancement to ISO 13679 based on ongoing
usage and review in recent years. Status/Meetings
WG Chair is Gloria Valigura Pat McDonald and Ed Banker are facilitators for Items 1 and 3. Meetings
o Two half-day meetings in Scottsdale (Jan 2007) o Three half-day meetings in San Francisco (June 2007) o Manufacturers (threaders) met in August to review individual requirements of
the end users. Results were communicated to WG2a at September meeting. o In September meeting, worked to resolve outstanding action items and new
concerns. A major threader concern is testing connections close to yield as we may be in the regime of rate-depending, inelastic behavior of the alloy.
o A very productive meeting was held in December in Houston. After significant and lengthy discussion of threader concerns with user requirements, consensus was obtained on all outstanding items. At the completion of the meeting, based on a straw-man vote, there was 100% support from all company representatives to move CD 13679 to Country vote.
o Afternoon of January 22, 2008, in Ft. Worth.
Items Needed to complete CD 13679 Clause 5.11 can strain gauges be re-zeroed during bending tests? Mini-WG assigned Clause 7.3 mini-WG to report out on material behavior issues which impacts whether we
test at 90% of 95% of pipe body VME at ambient and elevated. Clause 7.3.1 Test Load Calculations – for axial load calculations, use average of measured wall
or minimum measured. (Affects whether or not Annex B needs to be updated.) Tables A.2 and A.3 Needs to be updated based on new TS-A load table (after Jan meeting) Form C.6 Needs to be updated to match new TS-A load table (after Jan meeting) Form C.7 Needs to be updated to match new TS-B load table 11 (after Jan meeting)
Go-Forward Plan By February 11, 2008 -- WG2a Chair updates appropriate text, tables and forms (see above) By February 15, 2008 -- WG2a Chair sends CD 13679 in WORD format (updated AutoCad
files sent separately) to ISO TC67/SC5 Chair for preparation/distribution of CD 13679 for Country vote.
sargent
Text Box
Attachment 10
Next Meeting – earliest in 3Q 2008 to resolve any comments resulting from Country vote
API CONNECTION LEAK PERFORMANCE: TECHNOLOGY REVIEW, PRODUCT STATUS,
Key Words: API, Computational Mechanics, reliability, test, risk, OCTG, connections, structural mechanics Abstract Connections are the single most critical component to tubular reliability for oil well design.
The criticality of connection performance is reflected in the operator failure databases, which sites twice as many connection failures as all other failure modes combined. Performance-based premium connection methodologies have successfully eliminated premium connection failures in recent years. Surprisingly, API performance based methods for connections did not exist until the end of the 1999. Furthermore, performance based methods exist only as supplemental requirements today; the standard API connection specifications remain largely unchanged from the 1950’s. Consequently, many operators do not use API connections in critical wells.
The original American Petroleum Institute (API) tubular specifications were established in the early 20th century with the intent to standardize pipe sizes and connections so that material from one mill/user could be assembled with material from other sources. The original API specifications for threaded connections did not focus specifically on leak resistance; only interchangeability. Today, the importance of connection integrity and reliable leak resistance is more widely recognized.
With few exceptions, early API connection performance evaluations (1940-1980) considered tension and leak resistance separately. However, deeper wells, particularly in the 1980’s, drove operators away from the previous empirical basis toward higher grade and larger diameter configurations under higher axial load, and failures were being experienced. To address the tension-leak resistance issue API has a number of initiatives dating back 20 years. The API Production Research Advisory Council funded a series of studies in the mid-1980s that characterized the interaction of makeup, limited dimensional variation, tension, and pressure (including load path considering the nonlinear connection system).
This technology, when combined with modern physical testing (per IS013679) and root cause analysis, has been successfully applied in the development of more reliable API connections. Although the API currently has a number of work items dealing with connections, these improvements to connection technology remain limited to API, manufacturer, and operator supplemental specifications.
1 ATT 11 API LTC Connection Report - WI2317.doc
sargent
Text Box
Attachment 11
– 2 – 20 December 2003
API CONNECTION LEAK PERFORMANCE: TECHNOLOGY REVIEW, PRODUCT STATUS,
This report opens with an introduction of the problem definition and background material, summarizes full-scale laboratory performance testing with an emphasis on Gas Pressure Testing, provides a synopsis of Finite Element Analysis, addresses reliability, variability and uncertainty issues, and ends with conclusions and recommendations. 1.0 INTRODUCTION
Tubulars are a fundamental component of well design. Tubular connections are one of the performance-limiting aspects of tubular products. The critical nature of connection performance is reflected in the Industry’s failure experience. Typically, connection failures account for up to 90% of all tubular failures. One user’s failure database, for example, cites twice as many connection failures as all other modes combined (Fig. 1). Remarkably, typical well design methodologies do not address threaded
connection performance in any detailed fashion. Rather a safety factor is applied to pipe body ratings. In contrast, API and industry supplemental methods specifically address connection performance and reliability. API SR22 has defined performance limits and specifications have been developed to ensure leak resistance of 100% API internal pressure rating with a tension design factor of 1.6.
The reliability of a tubulars system is dominated by the fact that the system consists of parts in series (please refer to Fig. 2). Consequently, obtaining a specific system reliability requires part (connection) reliability to be orders of magnitude greater than the system goal. As a useful reference Fig. 3 provides tubing retrievable Surface Controlled Subsurface Safety Valve (SCSSV) reliability. Reliability improvements have resulted in a first year
reliability of 95% (one failure in 20- in fact, SCSSV mean time to failure ranges from 25 to 100+ years). Table 1 gives a summary of connection reliability requirements to achieve a 95% string reliability, which shows that a connection reliability between 99.9% and 99.99% reliability is required for a 5,000 foot string, approximately 99.99% for a 10,000’ string, and connection reliability needs to be between 99.99% and 99.999% to obtain a 95% system reliability for a 20,000 foot string. This Table also indicates that a
Con
nect
ions
Col
laps
e
Wea
r
Brit
tle
unkn
own
1990's1980's0.00
0.100.200.30
0.400.50
0.60
0.70
ilureRate
Failure Mode
TimePeriod
Casing Field Failure History
1990's1980's
Fa
Fig. 1-Twice as many field failures occur from connections than all other failure modes combined. Connectionqualification has eliminated field failures for those qualified,however, 55% of connection failures involve APIconnections, and 45% involve unqualified proprietary.
2 ATT 11 API LTC Connection Report - WI2317.doc
– 3 – 20 December 2003
connection reliability of 95% results nearly zero string reliability. Alternately one operating company identified the acceptable risk factors of 10-2, 10-3.5, 10-5 and 10-6.5,
as given in Table 2. Referencing a 10,000 foot string, a 99.998% connection reliability (one failure in roughly 50,000 connections) is required to achieve a 10-2 string reliability, a 99.99994% connection reliability (one failure in roughly 1.5 million connections) is required to achieve a 10-3.5 string reliability, a 99.999998% connection reliability (one failure in roughly 50 million
connections) is required to achieve a 10-5 string reliability, and a 99.9999999% connection reliability (one failure in roughly 1.5 billion connections) is required to achieve a 10-6.5 string reliability.
Both the historical failure data and string reliability considerations point to the critical nature of connection reliability.
The original American Petroleum Institute (API) tubular specifications were established in the early 20th century with the intent to standardize pipe sizes and connections so that material from one mill/user could be assembled with material from other sources. The original API specifications for threaded connections did not focus specifically on leak resistance-only interchangeability. Today, the importance of connection integrity and reliable leak resistance is more widely recognized. Casing and tubing strings represent the primary environmental and safety barrier(s) for oil and gas containment. The threaded connections for these strings are one of the performance-limiting and most critical features for the tubular product.
Series Model: reliability challange / sensitive to part reliability
With few exceptions, early API connection performance evaluations considered tension and leak resistance separately. The API/USS effort to determine BTC [1] and 8-round [2] joint strength (in the 1960’s on structural capacity) remains unaltered to this day. The API adopted a shrink fit approach to leak resistance based on empirical data (no applied tension) reported by Weiner in 1967 [3]. However, deeper wells, particularly in the 1980’s, drove operators away from the previous empirical basis toward higher grade and larger diameter configurations under higher axial load, and failures were being experienced. To address the tension-leak resistance issue API has a number of initiatives dating back 20 years. The API Production Research Advisory Council funded a series of finite element studies in the mid-1980s (PRAC 84-53 [4], 85-53 [5], 86-53 [6], and 87-53 [7]) that characterized the interaction of makeup, limited dimensional variation, tension, and pressure (including load path considering the nonlinear connection system). This work was actually completed in late 1989.
In the early 1990s an API work group consisting of user and manufacturer representatives developed a performance-based connection specification for LTC (Long, Threaded and Coupled)1 connections for casing and tubing [8,9]. These new specifications were finalized in late 1990s as a Supplemental Requirement to API Specification [10]. Development of these supplemental specifications employed the PRAC 53 series Finite Element Analysis (FEA) techniques with full scale physical testing, evaluations of product specifications, inspection and gaging methods, process control, makeup and thread compound. The
Fig. 3-SCSSV reliability in terms of failure rate per year
123456
Failure Rate 0.0%
5.0%
10.0%
15.0%
20.0%
25.0%
30.0%
35.0%
Failu
re R
ate
Years in Service
SCSSV ReliabilityLCC Analysis Based on Reliability Improvement
ReliabilitymprovementI
3 ATT 11 API LTC Connection Report - WI2317.doc
– 4 – 20 December 2003
objective of this API initiative was to minimize failures, increase reliability and performance, improve delivery and decrease inventory, and minimize supplier and user life cycle cost by developing an engineered connection as an industry standard.
1.1- The cross section of an API 8-Round connection1 [11] is given in Fig. 4. The threaded region of the BTC and 8-round connection performs the dual function of transferring axial load between joints and sealing against wellbore pressures. The API threaded region forms sealing surfaces provided adequate
contact pressure is developed and root and crest clearances are sufficiently “plugged” with compound. Leaks can propagate axially or along the thread helix. Thread compound is required to seal the clearance along the thread helix. This was demonstrated experimentally.
Surface contact pressure is established during makeup. As tension is applied the load flank contact pressure increases, while the
stab flank contact pressure decreases to zero. Consequently, tension can lead to a total loss of leak resistance as a result of thread contact. Internal pressure increases stab flank contact pressure provided leak does not occur. If leak occurs then pressure penetrates the thread helix decreasing contact pressure and separating pin from coupling. The leak resistance currently defined by API in Bul. 5C3 [12] is: P = ETtNp W2 − Es
2( ) 2EsW2 (1)
The equation is derived from shrink fit cylinder approximation and is independent of thread form and pin internal diameter. The relationship is only valid in the elastic regime and does not account for the detrimental affect of tension. Poisson's effects are also not considered. In 1941, Thomas and Bartok [13] tested 8-round specimens by applying gas internal pressure and then tension until leak was obtained. This work demonstrated for the first time the importance of tension. Most of the samples leaked at tensions well below the API tension rating. Thomas and Bartok showed that power turns makeup is significant to leak resistance, and that a factor of safety of 1.6 of the API tension rating should be applied for 8-Round connections to ensure that leak resistance.
2.0 FINITE ELEMENT ANALYSIS Although the broad application of computational mechanics dates back to the 1950’s, and the first Finite
Element publication regarding API connections date back to the mid 1970s [14], it was not until the early 1980s that leak resistance was studied using the Finite Element Method. In 1984 the API funded rigorous and fundamental evaluation of leak resistance that continued for a four yeas [15]. Deeper wells of the time drove users away from the previous empirical basis toward higher grade and larger diameter configurations, and problems were being experienced. API Production Research Advisory Committee (PRAC) Projects3 evaluated many of the performance parameters and provided basic understanding of the interaction of tension on leak resistance, as well as the effect of variations in makeup, grade and load sequence. This multi-year FEA investigation was culminated in an efficient FEA program customized for the analysis of API connection performance, API-LEAK [7]. Today FEA is a mature technology for connection evaluation.
FEA provided a comprehensive understanding of the response of 8-Round and BTC connections to makeup, axial load, and pressure. Figure 5 [16] provides an example of FEA results in terms of contact pressure along the length of the threaded region as a function of load. The load path progressed from makeup to tension, and then internal pressure was applied. The
Fig 4: API 8-Round conenction
P la n eo f
S y m m e try
L in e o f A x is y m m e try
Z( l )
R a d ia l(r )
cL
C o u p lin gP in
A x ia lL o a d
A x ia l
C o u p lin g
P in
L o a d F la n k
T h re a d R o o t C le a ra n c e(F ille d w ith T h re a d C o m p o u n d )
S ta b F la n k(P la te d w ithT h re a d C o m p o u n d )
y
T h re a d C re s t C le a ra n c e(F ille d w ith T h re a d C o m p o u n d )
4 ATT 11 API LTC Connection Report - WI2317.doc
– 5 – 20 December 2003
purpose of FEA was to gain an understanding of the response of connections under operating conditions. In addition to the tension and pressure response previously presented, FEA results indicated 1) a total loss of stab flank contact pressure for nominal 13-3/8 STC connection with an axial load equal to joint strength divided by 1.6 (a common design factor) and 2) hydrotesting (capped end pressure testing) significantly overstates leak resistance as a result of the internal pressure increasing contract pressure and decreasing pin von Mises stress. Load path was shown to be significant to API connection performance, and ISO 13679 [17, 18] applies the worst-case load path for API connection evaluation.
The ability to quantitatively assess the API connection leak resistance using FEA provided the foundation for performance-based design, and represents a significant advancement in connection technology. Computational mechanics specifically provided a basis for (1) connection tolerances, (2) makeup requirements, (3) quantifying connection performance, and (4) benchmarking for empirical validation of this work.
Computational mechanics provides the basis for empirical evaluation. Specifically, the scientific objectivity of the analysis was demonstrated by consistent agreement in the results between the experimental and numerical methods used.
3.0 LABORATORY PERFORMANCE TESTING Laboratory gas pressure testing includes the Thomas and Bartok work of 1941, USS testing in the 1950s
[19, 20, 21], the Weiner work reported in 1967, DEA-5 [22] and third party testing of the 1980s [23], as well as SR22 testing in the 1990s [24]. In general this work has demonstrated that makeup and dimensional control are critical to leak resistance. The original landmark API research on leak resistance of 8-Round connections in tension was reported in 1941 based on physical testing of J55 casing2. This massive task of gas testing 64 full-scale connections represented an aggressive effort to resolve the leak resistance issue. Thomas and Bartok recommended 3 to 3-1/2 turns of power-tight makeup, and the results adequately addressed the applications of the day; primarily shallow oil wells. Their effort represented the state of the art for its time, but testing was limited to thin-wall, low strength pipe with a maximum internal pressure of 1000 psi, with tension factors greater than 1.6. This work could not address current applications for the high-pressure, higher API grade materials.
Over time, additional investigations of leak resistance were conducted by both manufacturers and
Figure 5: Example of FEA result as a function of loading
5 ATT 11 API LTC Connection Report - WI2317.doc
– 6 – 20 December 2003
operators. These efforts, however, did not affect API 8-Round connection specifications, which remained largely unchanged from the 1950’s. It is for this reason that today many operators do not use API connections in critical wells, and the operators that do employ supplemental specifications.
In the mid 1950’s United States Steel (USS) funded evaluations of leak resistance on BTC and 8-Round tubing [19, 20, 21]. USS evaluated special tolerance connections and determined that a specific makeup technique was required to seal one hundred thermal cycles at a gas pressure of 10,000 psi. These investigation included strain gaging with capped end pressure testing. The Weiner et al. work of 1967 developed the shrink-fit relationship for leak resistance that determines leak resistance based on dimensions, makeup interference, and applied pressure (given in equation 1). The Weiner work was empirically verified. Both the USS effort of the 1950s and the Weiner work of the 1960s are considered appropriate for evaluating plugging capacity, but not field applications, due to the lack of tension applied.
DEA-5 [22] and third party testing in the 1980s [23] funded further evaluations of leak resistance. Deeper wells of the time drove users away from the empirical basis of Thomas and Bartok, USS, and Weiner (high tension applications with higher grade and larger diameter configurations) and problems were being experienced. DEA-5 evaluated many of the performance parameters and provided basic contact pressure leak criterion for a 7, 29 LTC subjected to tension with gas pressure. It correlated the effect of variations in makeup on leak pressure. This investigation included Finite Element Analysis.
Third party testing correlated leak resistance, and demonstrated that a leak in a threaded connection can propagate through the thread form, plastically deform the coupling, and result in catastrophic failure via leak induced jump-out.
API Work Item 2239 was established to take the results from these previous studies and develop practical performance ratings and product specifications that would provide the next generation of API products to the Industry. This goal has been achieved through analysis and testing, as well as fundamental evaluations of product specifications, inspection and gaging methods, process control, makeup and thread compound. This SR22 connection remains interchangeable with a standard API 5B product, however.
Testing was performed and is summarized in Table 3. Testing included dimensional as well as running & handling extremes, with loading and temperature (275°F) cycling per ISO 13679. This was helpful to users in determining connection use. It is anticipated that the burden of proof requirement will vary with user or manufacturer, as will design methodology.
API Work Item 2239 testing was performed per ISO CD 13679. ISO CD 13679 evaluates a connection as an assembly and evaluates that assembly at tolerance extremes within the full range of makeup and load parameters. Full assembly testing has the advantage of evaluating the net impact of interactions of threads, seal, and other connection features on performance, as well as the effects of thread compound. Test load path and load cycling were critically evaluated to be consistent with worst-case conditions while replicating field load sequence. Repeated thermal and mechanical cycling is included to "shake down" the connection load response.
3.1- 9-5/8”, 53.5# P110 SR22 LTC Reliability Qualification Testing [25] Connections were machined and made-up to tolerance extremes with several notable observations. Galling was not indicated despite 8 to 10 power turns makeup for 9-5/8,53.5 P110. Maximum dimensional variations (within 0.001 inch) and makeup extremes (minimum 6 turns to 10 turns) were tested as depicted in Figure 5. Actual test leak pressure was 2000+ psi higher than predicted leak resistance. Testing included thermal cycling to 275°F and tension and pressure load cycling per ISO13679. API 5A3 thread compound (Best-O-Life 2000) was used for these tin plated couplings. 9-5/8,53.5 P110was considered a worst case for galling evaluation since 6 turns are required. The final 9-5/8 torque varied from 8,640 ft-lbs to 14,060 ft-lbs, and makeup position was as much as maximum position plus one turn (which resulted in 10 power turns makeup and over 11,000 ft-lbs. of torque.) Even with these final make-up parameters, the ID was checked after makeup and no drift problems were indicated.
ISO CD 13679 is divided into four Application Levels (AL). AL IV is the most severe and requires the maximum amount of testing. The procedure selected was AL II B. Testing procedures are divided into three Test Series - A, B and C. Series A test specimens undergo testing in combined axial tension, axial 6 ATT 11 API LTC Connection Report - WI2317.doc
– 7 – 20 December 2003
compression, and internal gas pressure about the Yield Envelope for the pipe or the Service Envelope for the connection, whichever is limiting. Series B tests samples in combined axial tension, axial compression, and internal gas pressure with bending optional. Series C includes thermal and mechanical cycling (at 280°F and 11,210 psi). AL III and II require a total of 10 thermal cycles and 15 mechanical cycles.
The tests emphasized extremes in makeup- minimum makeup being a concern for leak resistance, and maximum makeup being a concern for galling. The refined thread form and tin-plated coupling requirements are credited for the very repeatable assembly that was observed despite the 10 full power turns makeup. Any potential problem with oversized drifting of the pipe ends after power makeup of the coupling was eliminated by the tapered bore of the inside of the pipe end. Cyclic testing was completed without leakage, and pressure had to be increased to 119% to 139% of API internal yield pressure of the pipe to finally cause the connection to leak.
Tests to failure involved tension with increasing internal pressure to failure. The procedure was to apply
three different tension values (one tension value for each of the 3 specimens) to the maximum tension rating of 850 kips, and maintain this tension constant as internal gas pressure was increased until failure. The limit load (failure) test for Specimen #8 reached the maximum pressure of 13,351 psi of gas. The connection held pressure for 11 minutes and then End A (mill end) began to leak. Specimen #9 reached the maximum pressure of 13,420 psi and then end B (field end) began leaking.
Sample #5 reached the maximum pressure of 13,233 psi and held pressure for the 30 minute hold time. The same loads as samples #8 and #9 were then applied and held for 5 minutes each, with no leaks. The sample was then removed from the load frame, filled with water and tested in capped end pressure (no applied tension frame load). Pressure was increased in 500 psi increments using 10 minute holds starting at 13,500 psi. Maximum obtained pressure was 15,528 psi. During this hold end B (field end) began to leak at 15,198 psi at a rate of 100 cc/minute.
3.2- 5"18# P110 SR22 LTC Reliability Qualification Testing Summary [26] Fast pin taper and slow box taper dimensional variations were evaluated with makeup to minimum position (3.7 to 6 turns). Testing included thermal cycling to 275°F with tension loads exceeding joint strength divided by a factor of safety of 1.6 combined with internal pressure load cycling beyond the API internal yield pressure per ISO13679. Best-O-Life 2000 thread compound was used for these tin plated couplings.
xzz5", 18ppf P110 SR22 Test Variation in Dimensions
0.065
0.0635
0.064
0.0645
.0655
0.066
Coup
ling
Tape
r
0Acceptale dimensional Range
fast pin/ slow-box evaluated
Variation in Makeup
00.20.40.60.8
11.21.41.61.8
2
Posi
tion
(turn
s)
Acceptale Makeup Range
Figure 6: Testing to extremes in makeup and dimensions.
9-5/8" 53.5ppf P110 Dimensional Variation
0.063
0.064
0.065
0.066
0.06 0.061 0.062 0.063 0.064
Pin Taper (dimensionless)
Cou
plin
g Ta
per
9-5/8", 53.5ppf P110 Variation in Makeup
4.75
4.8
4.85
4.9
4.95
5
5.05
5.1
6 7 8 9 10
Power Turns
Mak
eup
Posi
tion
Acceptale Makeup RangeDimensional Range
7 ATT 11 API LTC Connection Report - WI2317.doc
– 8 – 20 December 2003
Figure 7: Testing to extremes in makeup and dimensions.
Yielding was not noted during assembly, and no problems were noted during makeup. Makeup included doping the pin and the coupling, which is a worse case condition for leak resistance. All specimens were subjected to 100% of the API specified joint strength prior to the evaluation of leak resistance, which is a significant overload compared to the maximum 62.5% specified joint strength service envelope load. Mechanical and thermal cyclic tests were performed with maximum tension loads of 309 kips (joint strength divided by a safety factor of 1.6) and a maximum internal pressure of 13,940 psi (nominal API internal yield pressure). Tests with an internal pressure of 13,9040 psi and a tension to 445 kip (90% of API joint strength) were then performed which is a significant overload. No leaks occurred at anytime during gas testing.
3.3- 5", 18# L80 SR22 Reliability Qualification Testing Summary [27] This extreme parameter evaluation followed the 9-5/8" test format, but included greater makeup variations (3.5 turns which is the minimum makeup requirement to 5 power turns, with final makeup beyond the allowable position stamp) and tension loads exceeding the joint strength divided by a factor of safety of 1.6 and internal pressure exceeding the pipe body internal yield pressure. Actual test leak pressure was 14,450 psi (142% MIYP) at 318,500 pounds (a tension factor- Fact of 1.1). The cyclic loading at 10,140 psi gas pressure was based on jumpout strength, which is roughly 15% greater than joint strength. API 5A2 thread compound (Shell 72732) was used for these phosphated couplings.
Leak testing was performed after the connections had undergone an extreme galling evaluation which included significant plastic deformation for the maximum makeup specimens. Excellent galling resistance was noted. API thread compound has smaller particles, and is thought to represent a worse case-plugging medium. Testing emphasized minimum makeup, which provides the minimum leak resistance configuration, with high loading. However, excessive makeup was also included for the galling evaluation of this configuration, which has the highest contact forces in the SR22 product line.
Cyclic testing proceeded without fault. No leak occurred until final destructive pressure testing when the connection leaked at 14,500 psi, which is 43% higher than nominal API pipe body internal yield pressure. No leakage was indicated during non-destructive testing as shown in Table 3. Heating was provided by the induction method. During thermal cycling, insulation was removed from the coupling and
0.061 0.0650.063 0.0650.063 0.0635
5", 18# L80 SR22Variation in Makeup
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3.5 4 4.5 5 5.5
Power Turns
Posi
tion
(turn
s)
Position Mark Range
5", 18ppf L80 SR22 Dimensional Variation
0.061
0.062
0.063
0.064
0.065
0.066
0.06 0.061 0.062 0.063 0.064 0.065 0.066
Pin Taper (dimensionless)
Coup
ling
Tape
r
Dimensional Range
Figure 9: Testing to extremes in makeup and dimensions.
8 ATT 11 API LTC Connection Report - WI2317.doc
– 9 – 20 December 2003
a light spray of water from an overhead water sprinkler accomplished cooling. Two thermocouples were attached to each coupling to measure temperature.
This test method is known as Worst Case Analysis [28] which considers the impact on desired performance of expected (i.e. reasonable) variations in part parameters. The most conservative worst case analysis calculates product performance with all parameters at their worst value. This was the approach used in these SR22 tests, and is known as the extreme value analysis. It is the easiest approach. Other approaches are root-sum-squared and Monte Carlo analysis, which consider the statistical distribution of variables, recognizing that random variations of different parts are rarely all at extreme values in the same direction and that one variation can offset another. These more realistic approaches are more difficult to perform, and are important when the penalties of designing for the extreme value are too severe to make it practical.
3.4 Thread Compound Performance Qualification- API threads form sealing surfaces provided adequate contact pressure is developed and thread clearances are sufficiently “plugged” with compound. The ability of a thread compound to perform this function must be determined on an empirical basis. Thread compound performance starts by determining proper application (weight and technique), then plugging capacity is considered. Gas testing (275ºF) is performed on 8-Round connections a 5 18 phosphate P110 LTC (20 gm API mod) test configuration is used, and for BTC a 7-5/8" 39# L-80 test configuration is used. Several reasons are given for these configurations including 1) these small diameter configurations are the highest rated and most sensitive to thread compound plugging effect (high performance / low leak path configuration), 2) it allows efficient thermal cycling and longer term test (i.e. 6 day tests), 3) it allows for monitoring compound pressure (per application).
This test was developed over a series of iterations, and was executed for the first time evaluating API modified thread compound from 15 through 21 January, and was leak tight at 10,000 psi.
Methods and have demonstrated that LTC connections can clearly seal pressures as high as 15,000 psi. Testing did not improve reliability; it simply demonstrated goal achievement. Users have successfully applied these specifications for the past 5 to 10 years in applications as high as 10,000 psi (injection). Mobile Bay A-95 No. 5 13-3/8” casing, the 9-5/8" intermediate casing string and the 4-1/2" production casing string on the Tip Top Well #77C17G in Wyoming were the first applications. These cost effective API connections were used instead of unproven connections. In applying supplemental specifications, operators and manufacturers have had the opportunity to evaluate the requirements with a keen eye that is not often available. This experience resulted in an even better specification. 4.0 RELIABILITY: VARIABILITY AND UNCERTAINTY
Engineered products are designed to perform a function by selecting component parameters that will permit successful operation of the product in an expected use environment. Variations in the part parameters or in the operating environment may degrade the desired performance.
Figure 9 shows that the variation in the performance of a part and variation in the applied load can result in an area in which the load can be greater than the performance, resulting in a failure. Since variations cannot be avoided, a number of countermeasures have been devised to assure satisfactory operation of a product when conditions deviate from nominal. Significantly, API methodology considers only the nominal conditions in assessing performance.
9 ATT 11 API LTC Connection Report - WI2317.doc
– 10 – 20 December 2003
Potential Failure
Although some particular countermeasures claim the title “robust design” (the term is a registered trademark of the American Supplier Institute), all methods of dealing with variations can help to produce robust designs. For API connections robust design has been developed through analysis and/or testing while varying connection performance parameters within design limits. Robust design starts by
understanding the physics of failure to identify the performance parameters. It was determined that the standard product API connection includes multiple root causes of failure including 1) Thread Form (eliminate root-crest contact) 2) Coupling Yield (eliminate heavy wall pipe configurations / specify coupling wall thickness 3) thread compound (no performance requirements/ improper application), 4) Tension (unloading of stab flank contact pressure not addressed), 5) Gaging (pitch diameter not measured), 6) dimensional tolerances (pitch diameter, thread lead, thread taper specification is modified for high pressure application), 7) Makeup (additional power turns quantified for each diameter and grade), 8) coupling coatings (address galling/ leak resistance). Having
identified the root cause of failures and performance parameters, the industry progressed to eliminate these failures causes, and optimize performance and cost. Any one of these parameters can lead to leak and or jump-out.
Performance
LOAD
API Thread Form allows root-crest contact given the current specified tolerances, as shown in Fig 10. Root and crest contact eliminates stab flank and load flank contact (i.e. provides a clearance), and can result
in galling. Stab flank and load flank clearance represents a leak path that thread compound is not designed to seal. Furthermore, galling involves adhesion wear and moving material from one region to another, altering (lowering / eliminating) surface contact. This violates the conditions necessary for sealing. Supplemental Requirement 22 has revised specifications for thread form to eliminate root and crest contact, thus eliminating this root cause of failure. It is recommended that API adopt this thread form standard for all 8-Round connection. Coupling overstress issues result from both inadequate API coupling
specifications as well as excessive pipe wall thickness (given the fixed coupling outside diameter). Specifically, API BTC and 8-Round coupling specifications [11] do not currently define wall thickness; only coupling outside diameter and thread diameters. This compromises performance per API 5C3 [12], resulting in decreased contact pressure and increasing coupling stress as a result of variations in wall thickness, as shown in the Figure 11 to 13.
For example, a 7 inch 32 ppf N80 LTC connection has a coupling hoop stress at the E1 location of roughly 50,000 psi (nominal 3 turns makeup), and 83,150 psi hoop stress for 5 turns (large pitch diameter pin, small pitch diameter coupling) makeup. If this configuration is subjected to 5,000 psi, the coupling hoop stress increases to 67,175 psi and 100,435 psi for 3 and 5 turns, respectively. The amount of overstress will of course be even greater for 35 ppf and 38 ppf configurations, since coupling diameter remains constant regardless of wall thickness.
Fig 9: Variation in performance and Load
Fig 10: Standard v Sr22 8-Round thread Form (mated) 0.003
earancecl , standard +0.002 to -0.004 thread height tolerance
10 ATT 11 API LTC Connection Report - WI2317.doc
– 11 – 20 December 2003
Furthermore, coupling stress can increase as dimensions move off-nominal. If the minimum coupling diameter (with an OD tolerance of +/- 1%) of 7.579 inch is considered (with perfect alignment) the stresses
level increases to 52,750 psi for 3 turns and 87,920 psi for 5 turns. A reasonable configuration is described in the Figure to the left, which includes grinding out an imperfection. The resulting makeup hoop stress is 59,480 for 3 turns makeup, and 99,135 psi for 5 turns makeup. If this configuration is subjected to an internal pressure of 5,000 psi, the coupling hoop stress will increase to 80,100 psi and 119,750 psi for 3 and 5 turns, respectively.
Since API does not specify minimum wall thickness, coupling alignment, and maximum eccentricity;
configurations with much thinner couplings and higher stress levels than discussed above can occur, and still meet API specifications.
Not only can the 7 inch 32 ppf coupling yield at makeup, but the reduced coupling wall thickness reduces thread
contact pressure, which permits leaks to occur. Coupling overstressing results in yielding (permanent
deformation) and fracture, leak and catastrophic jump-out [23]. These failure modes will occur even per nominal specification (with perfect alignment). The fact that API coupling specifications are not matched to the mating pipe wall thickness means that the coupling will eventually become overstresses as wall thickness increases [29], as is the case for the 7”, 35 ppf N80 configuration just discussed.
This is less of a problem for K55 specifications (which include only thinner wall configurations), but is particularly acute for high strength (L80 and above). 7 inch BTC is overstressed for weights in excess of 29 ppf, yet 7 inch BTC includes configurations to 38 ppf. Again, this mismatch between coupling and pipe thickness leads to overstressing,
allows for coupling yielding and fracture, which subsequently leads to leak and catastrophic jump-out. Coupling yielding can lead to significant deformation and thread jumpout. The thread height of the
API 8-Round is 0.07125 inch, consequently 2.85% strain is required to jump the thread on a 4.5 inch (assuming no pin deformation). As diameter increases the strain required to jump the thread reduces to 1.86% for 7” LTC, and to 0.68 for 20” LTC. Ductile materials can experience strains an order of magnitude greater than this. However, coupling fracture is possible as well.
Thread compound is required for lubrication to preserve surface quality as well as plug clearances to seal pressure. API threads form sealing surfaces provided adequate contact pressure is developed and root and crest clearances are sufficiently “plugged” with compound. The original work by Mayberry in the 1950s required API thread compounds to plug 10,000 psi, but no such requirement has ever been included in an API document. In fact there are many commercial compounds that cannot plug API thread
Fig 12: coupling wall variation due to ovality (in lathe chucks)
Fig 11: coupling wall variation from grinding
Fig 13: coupling wall variation due to debris on lathe chucks
tmin
Machined surface
99% W
tmin
101% W
Chuck
Machined surface
Center of Lathe Rotation
Debris
11 ATT 11 API LTC Connection Report - WI2317.doc
– 12 – 20 December 2003
clearances, these often used in proprietary connections employing conical metal seals. Significantly, although the original API thread compound specification detailed the required solids, the current specification not only fails to address leak performance, it has eliminated the solids requirement.
Proper lubrication is required to ensure surface contact pressure. Surface contact pressure is established during makeup, and poor lubrication can contribute to galling. Since galling particles are large and tend to become wedged in the thread form, contact pressure can be compromised if galling occurs during makeup. Lubrication and plugging can only be determined experimentally. A method to evaluate this was given in section 3.4.
Significantly, Section 3.4 validates the proper application of thread compound as well. Specifically, sufficient thread compound must be applied so that the thread compound solids can fill the thread clearances for plugging. For a 5”, 18 LTC connection roughly 18 grams of API 5A3 thread compound are recommended (9 grams of “green” thread compound). In the course of testing SR 22, one series of tests test series applied 10 times the amount of thread compound to fill the thread voids. Over-doping can compromise leak resistance, and in this case the connection leaked at a pressure just over the pressure rating had been applied. In over doped connections thread compound becomes trapped in the thread annulus as makeup progresses from the point of initial stabbing, through the free-running portion, to the theoretical interference condition. The trapped thread compound builds pressure as the helical volume decreases in makeup, and yielding can occur. Pressure exceeding 15,000 psi has been recorded. High thread compound pressure during over doping can plastically deform the pin, thereby nullifying radial interference. Without interference reliable leak resistance is not achieved.
Significantly, over-doping can mask poor connection configurations since it may take minutes to days for pressure to displace the thread compound (for reference, mill hydrotesting is completed in seconds). Ominously, current API documents grossly over-dope API 8-Round connections.
Tension unloading of stab flank contact [13, 31] is not addressed in current API performance properties, thus rendering them non-conservative and inapplicable for use in design and service. As previously stated, this phenomena (unloading of stab flank contact) also points to the fact that API hydrotesting is insufficient for evaluation of leak resistance in service. API recognizes a leak resistance problem, and in fact states “although leak proof at time of makeup may not always remain so after transportation, handling, and use.” This statement implies that mill hydrotesting does not correlate to field service, as independently verified by test and FEA.
API Ring and Plug gages inaccurately and indirectly evaluate the pitch diameter of the pin and coupling, respectively [30, 32, 33]. Ovality and taper affect this evaluation, and the resulting errors can be larger than the tolerance to be evaluated (please refer to Fig 10 and 11). These errors result in making the average pin diameter smaller than the measurement may indicate, while the coupling indication is larger. Small pins and large couplings result in less interference for a given makeup position, and hence lower leak resistance.
Ring and plug gaging errors can result in poor process control, since ovality is random, and ovality
effect on measurement can be large. Thus, even connections threaded to consistent and acceptable diameters (when measured in the chucks) can show significant standoff variations (which could reject parts) when inspected later. This makes the gage less practical to control size. Variations due to ovality and taper make it difficult to evaluate connection suitability for service and process control using a ring or plug gage.
Fig 14: Ring gage error due to taper
L4
Ring Gauge on a Fast Pin
L1
g
At L1, ΔE1 due to fast pin = - (L4 - L1 - g - p) x (Taperpin - 0.0625)
where p is the pitch (0.125 in/turn)
L4
Ring Gauge on a Fast Pin
L1
g
At L1, ΔE1 due to fast pin = - (L4 - L1 - g - p) x (Taperpin - 0.0625)
where p is the pitch (0.125 in/turn)
12 ATT 11 API LTC Connection Report - WI2317.doc
– 13 – 20 December 2003
The unacceptability of ring in plug gaging is well understood in other industries. The United States Department of Commerce, National Institute of Standards and Technology (letter to the Nuclear Regulatory Commission) [34] states that “(ring and plug) acceptance methods do not assure dimensional conformance with material limits specified in ASME B1, MIL-S-8879, MIL-S-7742, and Federal Standard H-28.” The United States Air force (letter to the Pentagon) [35] states “this method to be technically unacceptable for verifying screw thread dimensions”. Similarly, in the United States Department of Commerce, National Institute of Standards and Technology letters to Portsmouth Naval Shipyard [36], Aerospace Industries Association [37], and the Secretary of the Air Force [38] states that the method A (ring and Plug) is “technically incorrect and create a safety hazard”. Finally, the Massachusetts Institute of Technology [39] assessment concludes that the ring and plug “is not adequate to assure a safe and reliable threaded fastener”. Nonetheless, API specifications currently do not allow methods other than ring and plug gages with the exception of SR22 (which requires alternate gaging methods). It should be noted that a new API work item is developing alternate gaging methods to ring and plug.
Furthermore, ring and plug gages are not practivcal for use in process control. For example, a reference 0.3% ovality for 10-¾ the diameter variance is roughly 0.032 inch, which greatly overshadows the 0.006 inch (approx) tolerance in diameter for BTC. Under such circumstances, only 100% ring (or plug) gaging is sufficient to prevent rejects from entering a production stream.
Per current tolerance specifications and gaging procedures, a 7” LTC connection can be made up to nominal “power tight” position and yet still have stab flag and load flank clearance [32] (small pin, large box with maximum tapers). This ignores the ovality error.
Dimensional tolerances such as “pitch diameter” (ring and plug standoff), thread taper specification, and makeup position are not currently considered in performance properties of standard API connections. In addition to the error in ring and plug gaging just discussed, the tolerances often render product unfit for use as oil field tubing or casing. For the 7 inch LTC example, a large portion of the lack of interference is related to the ± 1-turn standoff tolerance for both pin and coupling. Given this tolerance, it is acceptable for interference to vary from –2 turns to + 2 turns for a given position. Most API LTC connections have a nominal 3 power turns makeup interference. Again, allowable variance (ie tolerances) dominate the intended dimensional target. But even makeup is nebulous per API.
API Specification 5CT Section 7.14.1, addresses “Coupling Makeup and Thread Protection” for the referenced product. Paragraph 7.14.1.1 states, “All casing couplings and regular tubing couplings… shall be screwed onto the pipe power tight…” API T1 Glossary of Oilfield Production Terminology defines power tight as “A threaded connection that has been fully made up by mechanical means using power tongs or a screw on machine”. Thus API specifications 5CT has no torque or position requirement.
API Standard 5B, Specification for Threading, Gauging, and Thread Inspection of Casing, Tubing, and Line Pipe threads and Thread Protection addresses position criteria of makeup in the second paragraph of Section 3.1.3 for the referenced product. Although API 5B has a position requirement for buttress casing (reference the second to the last sentence in paragraph two and Figure 5), no position requirement is made for any 8-Round connection. In fact, although marking requirements are cited for larger diameter product (a 3/8” equilateral triangle), the standard specifically states that “ the position of the coupling with respect to the base of the triangle shall not be a basis for acceptance or rejection”. Again, API specifications expressly refuse to define a torque or position requirement.
The need for 3 to 3-1/2 turns power makeup was based on smaller diameter J55 8-Round casing product in 1941 (please note that “power turns” has never in issued as an API requirement). With few exceptions API specifies 3 to 3-1/2 turns makeup to this day. In contrast SR 22 requires restricted
Fig 15: Ring gage error due to Ovality
Ring Gauge on an Oval Pin
E1 measured
E1 actual
E1 due to ovality = - % ovality x E1100
Ring Gauge on an Oval Pin
E1 measured
Δ
E1 actual
E1 due to ovality = - % ovality x E1100
ΔΔE1 due to ovality = - % ovality x E1100
% ovality x E1100
13 ATT 11 API LTC Connection Report - WI2317.doc
– 14 – 20 December 2003
tolerance and up to 6 turns makeup; performance was verified by test. As an observation, SR22 K-55 requires 3 to 3-1/2 turns makeup is in agreement the Thomas and Bartok work of 1941.
Taper tolerance is significant to leak resistance, galling resistance, and connection stress state, but is not addressed in standard API performance properties. In contrast, worst-case pitch diameter, taper, and makeup tolerances are evaluated in API Supplemental Requirement 22.
Coupling coatings such as phosphate and tin are used to improve address galling and leak resistance. Users and operators have found some galling problems with phosphate coating on higher-grade configurations including P110. As discussed in section 3.1 and 3.2, tin plating has been successful in terms of both galling and leak resistance. Since tin coating thickness is roughly 2.5 thousandths of an inch thick, plating also increases interference by approximately 0.005, thus improving leak resistance.
The SR22 design evaluation method is known as Worst Case Analysis which considers the impact on desired performance of expected (i.e. reasonable) variations in part parameters. This robust design (supplemental) process continued with definition of operator expectations, and how to best alter performance parameters, design and manufacture the product to meet those expectations. The most conservative worst-case analysis calculates product performance with all parts at their worst value. This was the approach used in SR22, and is known as the extreme value analysis. It is the easiest approach. Other approaches are root-sum-squared and Monte Carlo analysis, which consider the statistical distribution of variables, recognizing that random variations of different parts are rarely all at extreme values in the same direction and that one variation can offset another. These more realistic approaches are more difficult to perform, and are important when the penalties of designing for the extreme value are too severe to make it practical. 5.0 CONCLUSIONS AND RECOMMENDATIONS
Conclusions: According to operator failure databases, connections are the single most critical component to tubular reliability for oil and gas well design. The reliability of a casing string with connections is dominated by the fact that the system consists of parts in series, and that leak performance was not initially “designed in” to API connection specifications. The original American Petroleum Institute (API) tubular specifications were established in the early 20th century with the intent to standardize pipe sizes and connections so that material from one mill/user could be assembled with material from other sources. That is, the original API specifications for threaded connections did not consider leak resistance; only interchangeability. Surprisingly, API performance based-methods for connections did not exist until the end of the 1999. Furthermore, performance based methods exist only as supplemental requirements today, the standard API connection specifications remain largely unchanged from the 1950’s. Today, connection technology has matured, and includes computational mechanics, physical testing (generally per ISO 13679), and the evaluation of variability and uncertainty. These tools have identified numerous root causes of API connection failure including (1) inadequate makeup, (2) tension/load path (unloading sealing surfaces), (3) gaging errors, (4) coupling yielding, (5) thread compound issues, (6) thread form and thread taper, and (7) dimensional tolerancing. In fact, the user and manufacturer can meet all current API requirements and still have no thread seal interference (i.e. no leak resistance), thereby having a product that is not suitable for use as oilfield tubing and casing. Until recently [40, 41] the industry had applied various ad hoc supplemental specifications that were generally insufficient to ensure leak performance [33].
API supplemental Specification 22 is the result of applying this technology to each root cause of failure to develop a more reliable performance-based API LTC design. Every diameter, weight, and grade connection was analyzed at dimensional and loading extremes using a qualified and calibrated finite element program. Minimum performance grew from no leak resistance (standards 5B product) to 100% API minimum internal yield pressure for tension less than or equal to joint strength/1.6. At the end of the "reliability growth" phase (which can be executed via analysis or testing) the SR22 design was mature, and limited or no verification testing was required prior to procurement.
14 ATT 11 API LTC Connection Report - WI2317.doc
– 15 – 20 December 2003
Although previous testing quantified leak criteria, validated methods, and calibrated analysis methods, additional demonstration testing was performed. Dimensional and makeup extremes (makeup is identified as the most significant performance parameter), and combined loading to 15,000+ psi. pressure (2000 psi higher than the API pipe body yield pressure) with tension factor as low as 1.2 (versus the typical maximum tension load of joint strength divided by a safety factor of 1.6) was evaluated. Loads were typically adjusted for actual mechanical properties. The performance of the tested product exceeded the target performance when run to assembly specifications.
In SR22, gauging methods were changed, leak resistance ratings incorporate the effect of tension, makeup criteria include both torque and position aspects, and connection tolerances are improved. Through the SR22 specification, deficiencies are now addressed to provide a reliable performance-based connection that is fit for purpose. These objectives were pursued through an API work group representing joint industry input from both the manufacturer and operator communities. SR22 represents a straightforward way to obtain reliable, high performance API connections using refinements to existing technology.
Recommendations include eliminating the root causes of failure of API connections, including the currently active BTC configuration. Eliminating root causes of failure will include elimination of the ring and plug gage as a method of diameter determination, refining dimensions including thread form, qualifying thread compound performance including application, and establishing robust performance parameters.
Acknowledgments The following individuals as well as their respective companies are recognized for their support of standardization, the advancement of connection technology, and for their support of this report. These professionals exerted substantial effort, much hard work, and significant innovation to the development of new standards. These individuals and their company affiliations are as follows: Bruce Bradley, (VAM-PTS), John Casner, P.E., Ed Evans, (Grant Prideco), Rich Miller, PE, Dean Goodson, Eddie Johnson, and Mike Webber (Hunting Oilfield Services), Herschel McDonald (Jet-Lube), Pat McDonald, P.E. (Mohr Engineering Division), Dr. Mike Payne, PE and Dr. Phil Pattillo (BP), George Palyo and Bill Sargent (United States Steel), Mike Calwell (Koppell Steel), Gaylon Smith (Franks International), Dewey Allen & Jim Shelton (V&M Star), Ron Pitzer (Wheeling Machine), Jim Douglas (GageMaker), Joseph Ottaviani (Sooner Pipe), Lowell Johnson (Johnson Gage Co.), Dr. Carey Murphey (PPI Technology Services), Jim Anson, P.E. (ExxonMobil), Gloria Valigura (Shell), Jiang Wu (Chevron Texaco), Tom Asbill, P.E. (Stress Engineering Services), and Erich Klementich, P.E. (PPI Technology Services)
15 ATT 11 API LTC Connection Report - WI2317.doc
– 16 – 20 December 2003
References 1 Buttress Thread Joint Strength, W.O. Cliendinst 2 The Tensile Strength of API Round Thread Casing Joints W.O. Cliendinst June 1963 3 New Technology for Improved Connection Performance P.D. Weiner, F.D. Sewell 1967 4 Investigation of Leak Resistance of API 8-Round Connector Co. M.B. Allen, B.E. Schwind, G.R.
Wooley Enertech Engineering & Research API PRAC 84-53 Houston, Texas 5 Investigation of Leak Resistance of API 8-Round Connector Enertech Engineering & Research Co.
B.E. Schwind/ G.R. Wooley API PRAC 85-53 Houston, Texas 6 Investigation of Leak Resistance of Buttress Connector B.E. Schwind, G.R. Wooley API PRAC 86-53,
Enertech Engineering & Research Co. Houston, Texas 7 Investigation of Leak Resistance of API Casing Connectors, M.B. Allen, R.F. Mitchel, G. John, API
PRAC 86-53, Enertech Engineering & Research Co. Houston, Texas 8 API SR-17 connection technology: Perfrormance Based Connection Technology Schwind - (February
1998) Report to API. 9 API WI2239 status Report 23 JAN 1996 Mike Spanhel 10 Technical Report on SR22 Supplemental Requirements for Enhanced Leak Resistance LTCAPI Report
5TRSR22 September 2001 LTC 11 API Std. 5B, Specification for Threading, Gaging, and Thread Inspection of Casing, Tubing and Line
Pipe Threads (May 1988). 12 API Bul. 5C3, Bulletin on Formulas and Calculations for Casing, Tubing, Drill Pipe and Line pipe
Properties (July 1989). 13 Thomas, P.D., and Bartok, A.W.: "Leak Resistance of Casing Joints in Tension," paper presented at
the 1941, 22nd Annual Meeting, San Francisco, November. 14 Strain Limit Design of 13 3/8" N-80 Buttress Casing, Wooley, Christman, Crose 76-PET-82 ASME 15 New Findings on Leak Resistance of API 8-Round Connectors in Tension, Schwind Wooley Society of
Petroleum Engineers, Production Engineering, November 1989.. 16 LRFD Connection Technology: Method for Statistically Based Performance Ratings of API LTC
Connections, Schwind The IV World Congress on Computational Mechanics, July, 1998 17 ISO 13679, Petroleum and Natural Gas Industries - Testing Procedures for Casing and Tubing Connections
Recommended Practice (Jan. 1998).
18 A New International Standard for Casing/Tubing Connection Testing M.L. Payne, Schwind presented at the SPE/IADC Drilling Conference March 1999 (SPE52846)
19 USS development of gas tight BTC Aug 1958 20 USS development of gas tight BTC tubing July 1957 21 USS development of gas tight EUE tubing June 1956 22 DEA-5 23 Experimental Evaluation of 7” API Buttress and –blank- Tubular Connections, B.E. Schwind, Stress
Engineering Services, August 1990 24 Status: API WI2239 Action regarding SR22 Casner and Schwind letter to Peterson and Spanhel] 25 9-5/8”, 53.5# P110 SR22 LTC Reliability Qualification Testing 26 5"18# P110 SR22 LTC Reliability Qualification Testing Summary [26] 27 5", 18# L80 SR22 Reliability Qualification Testing Summary [27] 28 Creating Robust Designs by Anthony Coppola Selected Topics in Assurance Related Technologies
START 96-1, , Volume 3, Number 1
16 ATT 11 API LTC Connection Report - WI2317.doc
– 17 – 20 December 2003
29 Casing and Tubing Connector Stresses by Warren Schneider August 1982 SPE Journal of Petroleum Technology
30 LRFD Derived Performance of a Qualified API Connection Population, B.E. Schwind, D.W. Currington, and R.A. Miller Presented at the 27th Annual Offshore Technical Conference in Houston, Texas, May 1995.
31 Certification of 7 inLTC thread gap at nominal makeup position, Letter J.H.Myers to B.E. Schwind, May 1994
32 Caution: API Gaging Practices may be Hazardous to Your Leak Resistance T.H. Hill, R.C. Money Petroleum Engineer International, October 1989
33 The United States Department of Commerce, National Institute of Standards and Technology March 10, 1994 letter to the Nuclear Regulatory Commission
34 The United States Air force Oct 27 1992 letter to the Pentagon 35 United States Department of Commerce, National Institute of Standards and Technology June 20, 1977
letter to Portsmouth Naval Shipyard (New Hampshire) 36 United States Department of Commerce, National Institute of Standards and Technology February 7,
1992 letter to Aerospace Industries Association 37 United States Department of Commerce, National Institute of Standards and Technology, July 1, 1991
letters to the Secretary of the Air Force 38 Massachusetts Institute of Technology December 2, 1992 letter to the Johnson Gage Company 39 New Makeup Method for API Connections, J.B. Day, M.C. Moyer, A.J. Hirshberg, 1989 SPE IADC
Drilling Conference, New Orleans, LA 40 11-7/8 71.80 (0.582" wall) Q125 T1 S BTC-L Tin Drilling Casing, B.E. Schwind, P.R. Brand, D.B.
Lewis, E.F. Klementich, 33rd Annual Offshore Technical Conference in Houston, Texas, May, 2001
Proposal: Accept the 7-2 ballot attachment as the 1st edition API Spec 7-2, an adoption of ISO 10424-2. Also accept the attached Spec 7 addendum 3 to remove threading and gauging.
VotingCategory
Did Not VoteAbstainNegativeAffirmativeCommentsCompanyVoter
Proposal: Accept the 7-2 ballot attachment as the 1st edition API Spec 7-2, an adoption of ISO 10424-2. Also accept the attached Spec 7 addendum 3 to remove threading and gauging.
Proposal: Accept the 7-2 ballot attachment as the 1st edition API Spec 7-2, an adoption of ISO 10424-2. Also accept the attached Spec 7 addendum 3 to remove threading and gauging.
VotingCategory
3
API Ballot Comments and Resolution Ballot: 7-2, 1st Edition Proposal: Accept the 7-2 ballot attachment as the 1st edition API
Spec 7-2, an adoption of ISO 10424-2. Also accept the attached Spec 7 addendum 3 to remove threading and gauging.
Ballot ID: 1288
Date: January 17, 2008
1 2 3 4 5 6
Voter Name (Vote)
Clause No./ Subclause No./Annex (e.g. 3.1)
Type of Comment
Comment (justification for change) by the Voting Member Proposed change by the Voting Member
Comment Resolution
page 1 of 2 API electronic balloting template/version April 2003
Dennis Everett
NIST
(Affirmative)
10.3.1.5.2 Editorial No clear distinction between "certifying agency", which certifies new and reconditioned master gauges, and "testing agency", which I believe is the list in Annex J of labs that can perform Periodic Retest.
Add the phrase "listed in Annex J" to the end of the sentence.
Dennis Everett
NIST
(Affirmative)
10.3.2.1 Editorial Sign convention is confusing when in (b) you have all positive numbers but a negative result. This results from a plus/plus tolerance on a plug and relating it to the measured pitch diameter since the plus taper would yield a smaller diameter.
At least a note indicating why (b) is negative. Also, (c) should be -0.0003 in.
The example appears good but needs to be clear since it is a change in the way we look at taper.
David Maisch
PMC Lone Star
(Affirmative)
Section 8.4.1 Figure a) Page 25
Technical The tolerance listed for gauging of box is incorrect, it currently reads:
(S -S1 ) +0,25 (+0.10 )
(S1 -S ) -0,25 (-0.10)
David Maisch
PMC Lone Star
(Affirmative)
Section 10.3.1.3 Figure 21 Page 42
Technical The dimensions shown for the torque hammer are incorrect:
177.8 ± 3.2 (7 ±0.12) should be changed to 171.5 ± 3.2 (6-3/4 ± 1/8)
152 ± 3 (6 ± 0.1) should be changed to 152.4 ± 3.2 (6 ± 1/8)
15,88 -0,4 (.625 -0.016) should be changed to 15.9 -0,4 (5/8 -1/64)
David Maisch
PMC Lone Star
(Affirmative)
Section 10.3.1.6 Page 43
Technical The tolerance listed for the interchange standoff is incorrect, it reads ±0,1000mm (0.0396 in)
The tolerance should read ±0,102mm (0.004 in)
Doyle Brinegar Section 4 D fi iti
Editorial There are two items with the same definition. Why two i h ill d h j b?
Consolidate iinto one symbol
sargent
Text Box
Attachment 13
API Ballot Comments and Resolution Ballot: 7-2, 1st Edition Proposal: Accept the 7-2 ballot attachment as the 1st edition API
Spec 7-2, an adoption of ISO 10424-2. Also accept the attached Spec 7 addendum 3 to remove threading and gauging.
Ballot ID: 1288
Date: January 17, 2008
1 2 3 4 5 6
Voter Name (Vote)
Clause No./ Subclause No./Annex (e.g. 3.1)
Type of Comment
Comment (justification for change) by the Voting Member Proposed change by the Voting Member
Comment Resolution
page 2 of 2 API electronic balloting template/version April 2003
Smith Drilco
(Affirmative)
Definitions and symbols
items when one will do the job?
1 Item Lfp and item Tfp are both defined as "thickness of gauge fitting plate"
Doyle Brinegar
Smith Drilco
(Affirmative)
Figure 14 part a -gauging of box
Technical The standoff and tolerances are backwards
They should be (S1-S) +0.00 mm,-0.25 mm (+0.00 in,-0.010 in)
Not (S-S1) +0.25 mm,-0.00 mm (+0.010,-0.00 in)
Correct the standoff and tolerances
Doyle Brinegar
Smith Drilco
(Affirmative)
Table 9 - Footnote a
Editorial Footnote says "See Table A.5 for USC units"
Should say "See Table A.9 for USC units"
Correct the reference.
Doyle Brinegar
Smith Drilco
(Affirmative)
Figurre 20 - Working Thread Gauges
Technical Note says "(from 0.65 in to 0.38 in)"
Should say "(from 0.63 in to 0.38 in)"
Correct the error
Doyle Brinegar
Smith Drilco
(Affirmative)
Annex A Table A.1 the 1"Reg and 1 1/2" Reg Column
Technical If the gauge standoff on the Product is 0.375", the DL dimension for the 1" Reg is 1.250" and for the 1 1/2"Reg, DL is 1.637"
