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. Cairo Inspection Company (CIC)

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Eng. Ibrahim Eldesoky

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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; Cairo Inspection Company (CIC)

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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; Cairo Inspection Company (CIC)

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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. Cairo Inspection Company (CIC)

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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. Cairo Inspection Company (CIC)

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UG-99(b) 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

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■ 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. Cairo Inspection Company (CIC)

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■ 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. Cairo Inspection Company (CIC)

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■ 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. Cairo Inspection Company (CIC)

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■ 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. Cairo Inspection Company (CIC)

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UG-100, Pneumatic 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. Cairo Inspection Company (CIC)

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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. Cairo Inspection Company (CIC)

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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 Cairo Inspection Company (CIC)

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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. Cairo Inspection Company (CIC)

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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. Cairo Inspection Company (CIC)

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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: Cairo Inspection Company (CIC)

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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.


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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. Cairo Inspection Company (CIC)

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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. Cairo Inspection Company (CIC)

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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 Hydrostatic Testing

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 . Cairo Inspection Company (CIC)

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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. Cairo Inspection Company (CIC)

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137.4.5 Required Hydrostatic Test Pressure 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.


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137.5 Pneumatic Testing

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. Cairo Inspection Company (CIC)

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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 onetenth of the test pressure until the required test pressure has been reached.


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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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