ASME VIII Div. 1- 6 Pressure Testing

Cairo Inspection Company

Eng. Ibrahim Eldesoky

ASNT –NDT-LEVEL III

ASME AUTHORIZED INSPECTOR

Inspection

The Certificate of Shop Inspection portion of a

Manufacturer's Data Report for the Inspector, requires him

to certify in part, the following:

■ ...to the best of my knowledge and belief, the

Manufacturer has constructed this pressure vessel in

accordance with the ASME Code, Section Viii, Division 1.

Make all Inspections required of him, plus

Such other inspections as he believes are necessary to

enable him to certify that all vessels which he authorizes to be

stamped with the Code Symbol have been designed and

constructed in accordance with the requirements of this

Division.

2 Cairo Inspection Company (CIC) Www. CIC-Egypt.com Eng. Ibrahim Eldesoky

Some but not all of the required inspections and verifications

which are defined in the applicable rules, are summarized as

follows:

verifying that the Manufacturer has a valid Certificate of

Authorization and is working to a quality control system;

verifying the applicable design calculations are available;

verifying that materials used in construction of the vessel

comply with the requirements of UG-4 through UG-14;

verifying that all welding and brazing procedures have been

qualified;

verifying that all welders, welding operators, brazers and

brazing operators are qualified;


verifying that the heat treatments, including

PWHT, have been performed;

verifying that material imperfections repaired by

welding were acceptably repaired;

verifying that weld defects were acceptably

repaired;

verifying that required NDE, impact tests and

other tests have been performed and the results are

acceptable;

making a visual inspection of the vessel to

confirm that the material identification numbers

have been properly transferred;


making a visual inspection of the vessel to

confirm there are no material or dimensional

defects;

performing internal and external inspections and

witnessing the hydrostatic or pneumatic tests;

verifying the required marking is provided and

that any nameplate has been attached to the proper

vessel;

signing the Certification of Inspection on the

Manufacturer's Data Report when the vessel, to the

best of his knowledge and belief, is in compliance

with all the provisions of this Division.


Pressure testing requirements are established by:

UG-99 Standard Hydrostatic Test

UG-100 Pneumatic Test

Pneumatic testing may only be performed when the vessels

are so designed and/or supported that they cannot be safely

filled with water;

not readily dried, used in services where traces of the testing

liquid cannot be tolerated.

A hydrostatic test shall be conducted on all vessels after:

(1) all fabrication has been completed, except for cosmetic

grinding on the base material which does not affect the

required thickness; and

(2) all examinations have been performed.


Standard hydrostatic tests are conducted at a pressure

which at every point is at least equal to:

1.3 x MAWP x lowest ratio of Stest / Sdesign

permitted stress value for the materials of which the

vessel is constructed.

Example Applying The Rules of UG-99(b)

MAWP = 375PSI @ 800° F

UG-99(b)


■ A hydrostatic test based on calculated Test pressure (3-2) may

be used under the following conditions:

Highest permissible internal pressure is determined using

nominal thickness (including corrosion allowance) of each

element of the vessel and using the allowable stress @ test

temperature;

The hydro test pressure at the top of the vessel shall be the

minimum of the calculated test pressures; multiplied by 1.3 and

reducing this value by the hydrostatic head

■ these provisions are by agreement between the user and the

Manufacturer;

■ the Inspector shall reserve the right to require the

Manufacturer or designer to provide calculations used in

determining the hydrostatic test pressure of any part of the

vessel.


■ UG-99(b) are minimum requirements, while UG-99(c) is a

special test based on calculations. Any intermediate value may

be used.

■ This Division does not specify an upper limit for hydrostatic

test pressure. However, if the hydrostatic test pressure is

allowed to exceed, either intentionally or accidentally, the value

determined as prescribed in (c) above to the degree that the

vessel is subjected to visible permanent distortion, the

Inspector shall reserve the right to reject the vessel.

■ Following the application of the hydrostatic test pressure, an

inspection shall be made of all joints and connections.

■ This inspection shall be made at a pressure not less than the

test pressure divided by 1.3.


■ Except for leakage at temporary test closures for those

openings intended for welded connections, leakage is not

allowed.

■ Leakage from temporary seals shall be directed away so as

to avoid masking leaks from other joints.

■ It is recommended that the metal temperature during the

hydrostatic test be maintained at least 30° F (17° C) above

the minimum design metal temperature, but need not exceed

120° F (48° C), to minimize the risk of brittle fracture.

■ The test pressure shall not be applied until the vessel and

it's contents are at about the same temperature.

CAUTION: a small liquid relief valve set to 1.3 times the test pressure is

recommended for the pressure test system, in case a vessel, while under

test, is likely to be warmed up materially with personnel absent.


■ Vents shall be provided at all high points of the vessel in the test

position to purge possible air pockets while the vessel is filling.

■ Before applying pressure, the test equipment shall be examined

to see that it is tight and that all low pressure filling lines and

other appurtenances that should not be subject to the test

pressure have been disconnected.

■ Vessels, except for those in lethal service [(UW-2(a)], may be

painted or otherwise coated either internally or externally, and

may be lined internally, prior to the pressure test.

■ The user is cautioned that such painting or coating may mask

leaks that would otherwise have been detected during the

pressure test.


Subject to the provisions of UG-99(a)(1) and (a)(2), a

pneumatic test prescribed in this paragraph may be used in

lieu of the standard hydrostatic test prescribed in UG-99 for

vessels:

that are so designed and/or supported that they cannot

safely be filled with water;

not readily dried, that are to be used in services where

traces of the testing liquid cannot be tolerated and the parts of

which have, where possible, been previously tested by

hydrostatic pressure to the pressure required in UG-99.

UG-100, Pneumatic test


Except for enameled vessels, the pneumatic test

pressure shall be at least equal to:

1.1 x MAWP x lowest ratio of Stest/ Sdesign

S = permitted stress value for the materials of which

the vessel is constructed.

In no case shall the pneumatic test pressure exceed 1.1

times the basis for calculated test pressure (3-2).

The metal temperature during the pneumatic test shall

be maintained at least 30 ° F (17° C) above the MDMT to

minimize the risk of brittle fracture.


The pressure in the vessel shall be gradually

increased to not more than one-half of the test

pressure;

thereafter, the test pressure shall be increased in

steps of approximately 1/10 of the test pressure

until the required pressure is reached.

After the test pressure is reached, the pressure

shall be reduced to the value equal to the test

pressure divided by 1.1 and held for a sufficient

time to permit inspection of the vessel


An indicating gage shall be connected directly to the vessel.

If the indicating gage is not readily visible to the operator

controlling the pressure, an additional gage shall be provided

where it is visible to the operator.

Dial indicating pressure gauges shall be graduated over a

range of about double the intended maximum test pressure,

but in no case shall the range be the test pressure.

less than 1 1/2 times, nor

more than 4 times the test pressure.


Digital reading pressure gages having a wider range

of pressure may be used provided the readings give

the same degree of accuracy as obtained with dial

pressure gages.

All gages shall be calibrated against a:

- standard dead weight tester, or

- calibrated master gage.

Gages shall be calibrated any time there is reason to

believe they are in error.


PG-99 HYDROSTATIC TEST

After a boiler has been completed (see PG-104), it

shall be subjected to pressure tests using water at not

less than ambient temperature, but in no case less

than 70°F (20°C).

pressures, apply to the highest point of the boiler

system. When the boiler is completed in the

Manufacturer’s shop without boiler external piping,

subsequent hydrostatic testing of the boiler external

piping shall be the responsibility of any holder of a

valid “S,” “A,” or “PP” stamp. The safety valves need

not be included in the hydrostatic test. The tests shall

be made in two stages in the following sequence:


PG-99.1 Hydrostatic pressure tests shall be applied by

raising the pressure gradually to not less than 1 1/2

times the maximum allowable working pressure as

shown on the data report to be stamped on the boiler.

Close visual inspection for leakage is not required

during this stage.

PG-99.2 The hydrostatic test pressure may then be

reduced to the maximum allowable working pressure,

and maintained at this pressure while the boiler is

carefully examined. The metal temperature shall not

exceed 120°F (50°C) during the close examination.


PG-99.4 Test Gages

PG-99.4.1 An indicating gage, visible to the operator

controlling the pressure applied, shall be connected to

the pressure parts. Hydrostatic head on the gage shall be

considered such that the required test pressure is

achieved at the top of the boiler.

PG-99.4.2 Dial pressure gages used in testing shall

preferably have dials graduated over their entire range of

about double the intended maximum test pressure, but in

no case shall the range be less than 1 ½ times that

pressure.

The spacing between graduations shall be such that the

inspector and the operator controlling the test shall be

able to determine when the required test pressure has

been applied.


137.1.5 Testing Schedule. Pressure testing shall be performed

following the completion of post weld heat treatment, required

by Para. 132, nondestructive examinations required by Table

136.4, and all other fabrication, assembly and erection

activities required to provide the system or portions thereof

subjected to the pressure test with pressure retaining capability.

137.2.6 Precautions Against Test Medium Expansion.

If a pressure test is to be maintained for a period of time during

which the test medium in the system is subject to thermal

expansion, precautions shall be taken to avoid excessive

pressure. A pressure relief device set at 1 1/3 times the test

pressure is recommended during the pressure test, provided

the requirements of paras. 137.1.4, 137.4.5, and 137.5.5 are

not exceeded.


137.3.1 Boiler External Piping. Boiler external piping [see Para.

100.1.2(A)] shall be hydrostatically tested in accordance with

PG-99 of Section 1 of the ASME Boiler and Pressure Vessel

Code. The test shall be conducted in the presence of the

Authorized Inspector.

137.4.1 Material.

When permitted by the Material Specification, a system

hydrostatic test may be performed in lieu of the hydrostatic test

required by the material specifications for material used in the

piping subassembly or system provided the minimum test

pressure required for the piping system is met.

137.4.2 Provision of Air Vents at High Points.

Vents shall be provided at all high points of the piping system

in the position in which the test is to be conducted to purge air

pockets while the component .

137.4 Hydrostatic Testing


137.4.3 Test Medium. Water shall normally be used as the

test medium unless otherwise specified by the Owner. Test

water shall be clean and shall be of such quality as to

minimize corrosion of the materials in the piping system.

Further recommended precautions on the quality of test

water used for hydro testing of austenitic (300 series) and

ferrite (400 series) stainless steels are contained in

Appendix IV, Para. IV-3.4.

137.4.4 Check of Test Equipment Before Applying

Pressure. The test equipment shall be examined before

pressure is applied to ensure that it is tightly connected. All

low-pressure filling lines and all other items not subject to

the test pressure shall be disconnected or isolated by

valves or other suitable means.


The hydrostatic test pressure at any point in the piping system

shall not be less than 1.5 times the design pressure, but shall

not exceed the maximum allowable test pressure of any no

isolated components, such as vessels, pumps, or valves, nor

shall it exceed the limits imposed by Para. 102.3.3(B). The

pressure shall be continuously maintained for a minimum time

of 10 minutes and may then be reduced to the design pressure

and held for such time as may be necessary to conduct the

examinations for leakage. Examinations for leakage shall be

made of all joints and connections. The piping system,

exclusive of possible localized instances at pump or valve

packing, shall show no visual evidence of weeping or leaking.

137.4.5 Required Hydrostatic Test Pressure


137.5.1 General.

Except for preliminary testing in accordance with Para. 137.5.4,

pneumatic testing shall not be used unless the Owner specifies

pneumatic testing or permits its use as an alternative. It is

recommended that pneumatic testing be used only when one of the

following conditions exists:

(A) when piping systems are so designed that they cannot be filled

with water

(B) when piping systems are to be used in services where traces of the

testing medium cannot be tolerated

137.5.2 Test Medium.

The gas used as the test medium shall be nonflammable and

nontoxic. Since compressed gas may be hazardous when used as a

testing medium, it is recommended that special precautions for

protection of personnel be observed when a gas under pressure is

used as the test medium.

137.5 Pneumatic

Testing


137.5.5 Required Pneumatic Test Pressure.

The pneumatic test pressure shall be not less than 1.2

nor more than 1.5 times the design pressure of the piping

system. The test pressure shall not exceed the maximum

allowable test pressure of any no isolated component,

such as vessels, pumps, or valves, in the system. The

pressure in the system shall gradually be increased to not

more than one-half of the test pressure, after which the

pressure shall be increased in steps of approximately one-

tenth of the test pressure until the required test pressure

has been reached.


The pressure shall be continuously maintained for a

minimum time of 10 minutes. It shall then be reduced

to the lesser of design pressure or 100 psig [700 kPa

(gage)] and held for such time as may be necessary to

conduct the examination for leakage. Examination for

leakage detected by soap bubble or equivalent

method shall be made of all joints and connections.

The piping system, exclusive of possible localized

instances at pump or valve packing, shall show no

evidence of leaking.


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ASME VIII Div. 1- 6 Pressure Testing

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