8.5.1 Pressure test shall be carried out after the piping finishes the installation and heat treatment and passes the non-destructive examination. Before the pressure test, the piping system within the pressure test scope shall be inspected; all construction, excluding painting and heat insulation, have been finished according to the design drawing; the installation quality shall meet the relevant requirements of design document and this code and all preparation work shall be completed before pressure test.
Examination amount: all piping and installation data within the pressure test scope.
Examination method: carrying out visual inspection and inspecting the related data.
8.5.2 Hydraulic test shall meet the following requirements:
1 Clean water shall be adopted for hydraulic test. When water may cause adverse effect on the piping or process or may damage the piping, other appropriate non-toxic liquid may be adopted. When combustible liquid medium is adopted for test, the flash point shall not be less than 50℃.
2 The hydraulic test temperature must not be close to the brittle transition temperature of metallic material.
3 The test pressure shall meet the following requirements:
1) The test pressure of above-ground steel piping and non-ferrous piping bearing internal pressure shall be 1.5 times the design pressure. The test pressure of buried steel piping shall be 1.5 times the design pressure and shall not be less than 0.4MPa.
2) When the design temperature of the piping is greater than the test temperature, the test pressure shall be calculated using the following formula and the stress under the test pressure (PT) condition of piping shall be checked. When stress beyond yield strength is generated by test pressure under test temperature, the test pressure shall be reduced to the maximum pressure not exceeding the yield strength.
T tT P
P 1.5 (8.5.2)
Where,
PT- test pressure (gauge pressure), MPa;
P- design pressure (gauge pressure), MPa;
T - permissible stress of pipe material under test temperature, MPa;
t - permissible stress of pipe material under design temperature, MPa.When
T/
t is greater than 6.5, it may be taken as 6.5.3) When the piping and equipment are tested as a system and the test pressure of the piping is equal to or less than the test pressure of equipment, the test shall be carried out according to the test pressure of the piping. When test pressure of the piping is greater than the test pressure of the equipment, the piping and equipment cannot be separated, and the test pressure of the equipment is not less than 77% piping test pressured calculated using Formula (8.5.2) in this code, the test may be carried out according to the test pressure of the equipment upon the agreement of the design or development organization.
4) For the test pressure of buried cast iron piping bearing internal pressure, when the design pressure is less than or equal to 0.5 MPa, it shall be 2 times the design pressure; when the design pressure is greater than 0.5 MPa, it shall be the design pressure plus by 0.5MPa.
5) For piping with large potential difference, the static pressure of test medium shall be counted in the test pressure. The test pressure of fluid piping shall be subject to the pressure at the highest point; the pressure at the lowest point shall not exceed the bearing capacity of the piping components.
6) For piping bearing external pressure, the test pressure shall be 1.5 times the difference of the design internal and external pressure and shall not be less than 0.2 MPa.
7) The test pressure of the inner pipe of jacket pipe shall be determined according to the internal or external design pressure, whichever is larger. Unless otherwise stated in the design document, the test pressure of the outer pipe of the jacket pipe shall be in accordance with Item 1 of 8.5.2 in this code.
4 In the hydraulic test, the pressure shall be increased gradually and maintained for 10 min after reaching the test pressure; and then the test pressure is dropped to the design pressure and maintained for 30 min; the piping is deemed as qualified if the reading of the pressure gauge does not drop and the entire piping is free of leakage.
Examination amount: complete inspection.
Examination method: carrying out visual inspection and inspecting the pressure test record.
8.5.3 During the hydraulic test of stainless steel, nickel and nickel alloy piping or piping connected with stainless steel, nickel and nickel alloy piping components or equipment, the chloride ion content in water shall not exceed 25×10-6(25ppm).
Examination amount: complete inspection.
Examination method: inspecting the water quality analysis report.
8.5.4 Pneumatic test shall meet the following requirements:
1 Dry and clean air, nitrogen or other noninflammable and non-toxic gas shall be adopted as the test medium.
2 The pneumatic test temperature must not be close to the brittle transition temperature of metallic material.
3 The test pressure of steel pipe and non-ferrous pipe bearing internal pressure shall be 1.15 times the design pressure. The test pressure of vacuum piping shall be 0.2MPa.
4 Pressure relief device shall be provided during the pneumatic test and the set pressure shall not be greater than 1.1 times the test pressure.
5 Before the pneumatic test, trial test shall be carried out with air and the test pressure should be 0.2MPa.
6 During the pneumatic test, the pressure shall be increased gradually; when the pressure rise reaches 50% of the test pressure, if no abnormal condition or leakage is discovered, the pressure shall be continued to be increased according to 10% of the test pressure stage by stage; the pressure at each stage shall be maintained for 3min till the test pressure. The pressure shall be maintained 10min at the test pressure and then is dropped to the design pressure; the piping is deemed as qualified if no leakage is discovered upon examination by foaming agent.
Examination amount: complete inspection.
Examination method: carrying out visual inspection and inspecting the pressure test record.
8.5.5 Hydraulic-pneumatic test shall meet the requirements of 8.5.4 in this code and the pressure of piping part filled with liquid shall not be greater than that specified in Sub-items 1) and 2) of Item 3 of 8.5.2 in this code.
Examination amount: complete inspection.
Examination method: carrying out visual inspection and inspecting the pressure test record.
8.5.6 It is not allowed to carry out hydraulic pressure and pneumatic test for piping at site condition; the pressure test may be replaced by non-destructive examination, piping system flexibility analysis and leakage test upon the agreement of development and design organization and shall meet the following requirements:
1 100% radiographic or ultrasonic examination shall be carried out for all circumferential and longitudinal butt welds and spiral welds; 100% penetrant or magnetic particle examination shall be carried out for other welds (connection welds between supports/hangers and piping). The acceptance criterion of non-destructive examination for welds shall meet the requirements of 8.2.1 and 8.3.1 in this code.
2 The flexibility analysis method and result of piping system shall comply with relevant current national standards.
3 Leakage test shall be carried out for piping system using sensitive gas or immersing liquid; if not specified in the design document, leakage test shall meet the following requirements:
1) The test pressure shall not be less than 105kPa or 25% the design pressure, whichever is smaller.
2) The test pressure shall be gradually increased to 0.5 times the test pressure or 170kPa, whichever is smaller; then initial examination shall be carried out, after which the
pressure shall be increased to the test pressure stage by stage gradually; in addition, at each stage, the pressure shall be maintained for an adequate time to balance piping strain.
3) The test result shall meet the requirements of 8.5.7 in this code.
Examination amount: complete inspection.
Examination method: carrying out visual inspection, inspecting the flexibility analysis result, non-destructive examination report and leakage test record.
8.5.7 The leakage test shall be carried out according to the requirements of design document and shall meet the following requirements:
1 Leakage test must be carried out for piping transmitting extremely and highly toxic medium as well as combustible medium.
2 The leakage test shall be carried out after the piping passes the pressure test, and the testing medium should be air.
3 Leakage test pressure shall be the design pressure.
4 The leakage test pressure shall be increased slowly stage by stage; when the test pressure is reached, it shall be maintained for 10min; patrol inspection shall be carried out for sealing positions such as valve packing box, connection place of flange or thread, emptying valve, exhaust valve and drain valve; the inspection shall be deemed as qualified if no leakage is discovered.
Examination amount: complete inspection.
Examination method: carrying out visual inspection with foaming agent and inspecting the leakage test record.
8.5.8 After the vacuum system passes the pressure test, 24-hour vacuum degree test shall be carried out for it according to the requirements of design document, and the rate of pressurization shall not be greater than 5%.
Examination amount: complete inspection.
Examination method: carrying out visual inspection and inspecting the vacuum degree test record.
8.5.9 If it is specified in the design document that the leakage test shall be carried out by halogen, helium, ammonia gas or other methods, it shall meet the requirements of current relevant national standards and design documents.
Examination amount: complete inspection.
Examination method: carrying out visual inspection and inspecting the leakage test record.
9 Blowing and Cleaning of Piping
9.1 Water Flushing