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1 Subject matter and scope of application: This standard specifies the requirements, methods, and evaluation criteria for pressure testing of general-purpose valves. This standard applies to the pressure testing of gate valves, globe valves, check valves, plug valves, ball valves, butterfly valves, diaphragm valves, etc. 2 Terms 2.1 Test pressure: The gauge pressure that the interior of the valve must withstand during testing. 2.2 Shell test: A pressure test conducted on the entire valve housing, which is formed by combining the valve body, valve cover, and other components. The purpose is to test the tightness of the valve body and valve cover, as well as the pressure resistance of the entire housing, including the joint between the valve body and valve cover. 2.3 Sealing test: A test to evaluate the sealing performance of the sealing surfaces between the operating parts and the valve body. 2.4 Upper seal test: A test to verify the sealing performance of the seal pair between the valve stem and the valve cover. 2.5 Test duration: The time during which the test is conducted at the test pressure. 3 Test items The pressure test items include: a. Hull test ； b. Upper seal test (valves with an upper seal structure shall undergo this test) ； c. Sealing test. 4 Test Requirements 4.1 Each valve shall undergo a pressure test before entering the factory. 4.2 Before the shell test is completed, it is not allowed to paint the valve or apply other sealant coatings; however, chemical anti-rust treatments that do not provide sealing effects and lining the valve with a lining material are permitted. For painted inventory valves, if the user’s representative requests a re-pressure test, there is no need to remove the coating. 4.3 Before the sealing test, oil stains on the sealing surface should be removed; however, a thin layer of a protective agent with a viscosity not greater than that of kerosene is allowed. For valves sealed with grease, it is permissible to apply the grease specified in the design requirements. 4.4 During the test, the valve should not be subjected to any external forces that could affect the test results. 4.5 Unless otherwise specified, the temperature of the test medium should be between 5 and 40°C. 4.6 The following test media shall be selected by the manufacturer itself, but must comply with the requirements specified in Tables 1 and 2 ； a Liquid: water (an anti-rust agent can be added), kerosene, or other suitable liquids with a viscosity not exceeding ； b Gas: air or other suitable gases. 4.7 When testing with a liquid, the gas in the valve chamber should be removed. When using gas for experiments, safety precautions should be taken. 4.8 During sealing and pressure testing, it shall be closed in the manner specified in the design. 4.9 The test pressure shall meet the specified requirements. 4.9.1 The test pressure for the shell test shall be in accordance with the provisions of Table 1. Nominal pressure PN, in MPa. Test medium: Test pressure < 0.25 for liquids; 0.1 MPa plus 1.5 times the maximum allowable operating pressure at 20°C for liquids. Note: The value of the maximum allowable operating pressure at 20°C is determined in accordance with the relevant product standards. When the relevant standards do not provide specifications, it may be determined in accordance with Appendix A (Reference). 4.9.2 The test pressure for the sealing and upper sealing tests shall be in accordance with the provisions of Table 2. Nominal inner diameter DN, mm; Nominal pressure PN, MPa. Test medium: Test pressure ≤ 80. All pressures apply to liquids or gases. The test pressure is 1.1 times the maximum allowable operating pressure at 20°C (for liquids) or 0.6 MPa (for gases). Range: 100–200; ≤5 and >5. For liquids, the test pressure is 1.1 times the maximum allowable operating pressure at 20°C. 4.9.3 The test pressure must remain constant throughout the duration of the test. 4.10 The duration of the test shall comply with the specified requirements. 4.10.1 The test duration for the housing test shall be not less than that specified in Table 3. Nominal diameter DN, mm: ≤50; 65–200; ≥250. Minimum test duration: S15601804.10.2 The test duration for the sealing and upper sealing tests shall be no less than that specified in Table 4. For the nominal diameter DN in mm, the minimum test duration is as follows: for S-seal tests, metal seals and non-metallic elastic seals – ≤50; 151; 510; 65–200; 301; 515; 250–450; 603; 020; ≥500; 120; 603; 04.10.3 The test duration must not only comply with the requirements specified in Tables 3 and 4, but also meet the requirements set by the specific leak detection methods regarding the test duration. 5 The test methods and procedures should first involve upper seal tests and housing tests, followed by seal tests. 5.1 Upper seal test: Seal the valve’s inlet and outlet, loosen the packing gland (if the valve is equipped with an upper seal inspection device that allows for reliable testing of the upper seal’s performance without loosening the packing gland, then it is not necessary to loosen the packing gland). With the valve in the fully open position, close the upper seal, fill the chamber with the test medium, and gradually increase the pressure to the test level; thereafter, inspect the performance of the upper seal. 5.2 Shell test: Seal the inlet and outlet of the valve, tighten the packing gland to maintain the test pressure, with the moving parts in a partially open position. Fill the cavity with the test medium and gradually increase the pressure to the test pressure (the check valve should be pressurized from the inlet side), then inspect the housing (including the stuffing box and the joints between the valve body and the valve cover). 5.3 The pressurization methods for the main valve types are specified in Table 5. However, for valves that specify the flow direction of the medium, pressure should be applied in accordance with the specified flow direction (except for check valves). During testing, the pressure should be increased gradually to the specified test pressure, after which the sealing performance of the sealing pair is checked. Valves – Pressurization method: Gate valves, ball valves, plug valves. These valves seal both ends of the passage; the closing element is in a slightly open position. The chamber is filled with the testing medium, and pressure is gradually increased to the specified test pressure. Then the closing element is closed, and the pressure at one end of the valve is released. The other end of the valve is also pressurized in the same way. Valves with two independent sealing pairs can also introduce a medium into the chamber between the two sealing pairs and apply pressure; check valves and diaphragm valves should apply pressure to the moving part in the direction that is most unfavorable for sealing against the valve seat. For example, for globe valves and angle diaphragm valves, the medium should be introduced and pressure applied in the direction that opens the valve disc; for butterfly valves, the medium should be introduced and pressure applied in the direction that is most detrimental to the seal. Butterfly valves with symmetric seatings can be pressurized in either direction; check valves should have the medium introduced and pressure applied in the direction that causes the valve disc to close. Evaluation criteria 6.1 Shell test: During the shell test, there must be no visible leaks at the pressure-bearing walls or at the joints between the valve body and the valve cover. The shell (including the packing box and the joints between the valve body and the valve cover) shall not suffer any structural damage. Unless otherwise specified, leakage at the packing is permitted at the shell test pressure, but no visible leakage should occur when the test pressure is reduced to the sealing test pressure. 6.2 Upper seal test: No visible leakage during the duration of the test. 6.3 Sealing test The maximum allowable leakage amount for the sealing test is specified in Table 6. The leakage amounts in Table 6 apply only to emissions into the atmosphere. Class A is suitable for non-metallic elastic-sealed valves, while Classes B, C, and D are suitable for metal-sealed valves. Among them: Class B is suitable for relatively critical valves, while Class D is suitable for ordinary valves. The maximum allowable leakage rate (grade) for various types of valves shall be in accordance with the provisions of relevant product standards. If the relevant standards do not specify otherwise, non-metallic elastic-sealed valves shall meet Class A requirements, while metal-sealed valves shall meet Class D requirements. If the user requests grade B or C, it should be specified in the order contract. Maximum allowable leakage rate for the test medium: for liquids of grades B, C, D, there shall be no visible leakage during the duration of the test, with values of 0.01×DN; 0.03×DN; 0.1×DN respectively. For gases, the values are 0.3×DN; 3×DN; 30×DN