Operating instructions for valve pressure testing First introduce the basic terminology of stress test Upper seal test Test of sealing performance of valve stem and bonnet seal Shell test Pressure test of the entire valve casing joined by the valve body and the valve cover. The purpose is to verify the tightness of the valve body and bonnet and the pressure resistance of the entire housing including the junction of the valve body and the bonnet. Seal test Test for inspection of sealing performance of opening and closing parts and valve body sealing pair test pressure The gauge pressure that the valve cavity should withstand during the test Test duration The duration of the test under test pressure The pressure test described in this paper is applicable to gate valves, globe valves, check valves, plug valves, ball valves, butterfly valves, diaphragm valves, etc. First, the pilot project Stress test project 1 , shell test  2 , the upper seal test (the valve with the upper seal structure should do this test)  3 , sealing test   Second, the test requirements 1. Each valve should be pressure tested before leaving the factory. 2. It is not allowed to paint the valve or use other coatings to prevent leakage before the shell test is completed, but it is allowed to carry out chemical anti-rust treatment without sealing and lining the lining valve. For lacquered stock valves, if the user representative asks to redo the pressure test, there is no need to remove the coating. 3. Before the sealing test, the oil stain on the sealing surface should be removed, but it is allowed to apply a thin layer of protective agent with a viscosity no greater than kerosene. The grease-sealed valve allows the coating of grease selected according to the design regulations. 4. The valve should not be subjected to external forces that may affect the test results during the test. 5. Unless otherwise specified, the temperature of the test medium should be between 5 and 40 °C . 6. The following test media shall be selected by the manufacturer, but shall comply with the requirements of Tables 1 and 2 . 1 , liquid: water ( can be added rust inhibitor ) , kerosene or other suitable liquid with viscosity not greater than water 2 , gas: air or other suitable gas 7. When testing with liquid, the gas in the valve chamber should be excluded. Safety measures should be taken when testing with gas 8. When performing the sealing and upper sealing test, it shall be closed in the way given by design. Nine, the test pressure should meet the requirements 1. The test pressure of the shell test is as specified in Table 1 . Note: The maximum allowable working pressure at 20 °C is in accordance with the relevant product standards. When the relevant standards are not specified, it can be determined according to Appendix A ( reference ) 2. The test pressure of the seal and the upper seal test is as specified in Table 2 . 3. The test pressure should remain unchanged for the duration of the test. X. The duration of the test shall comply with the regulations. 1. The test duration of the shell test shall be not less than the provisions of Table 3 . 2 , the duration of the test of the seal and the upper seal test shall be not less than the provisions of Table 4 . 3. In addition to the requirements of Tables 3 and 4 , the duration of the test shall also meet the requirements of the specific leak detection method for the duration of the test.  Third, test methods and steps The upper seal test and the shell test should be performed first, followed by the seal test. Upper seal test Close the valve inlet and outlet, and loosen the packing gland ( if the valve is equipped with an upper seal inspection device and can reliably check the performance of the upper seal without loosening the packing gland, then the packing gland does not have to be loosened ) , the valve is in full Open state, close the upper seal, fill the body cavity with test medium, and gradually pressurize to the specified test pressure, then check the upper seal performance  Shell test Close the valve inlet and outlet, press the packing gland to maintain the test pressure, and the opening and closing member is partially open. Fill the body cavity with the test medium and gradually pressurize it to the test pressure (the check valve should be pressurized from the inlet end ) , then inspect the housing ( including the stuffing box and the valve body and bonnet joint )  Seal test The main valve type pressurization method is as specified in Table 5 . However, for valves that specify the direction of flow of the medium, pressurize in the specified direction of flow ( except for check valves ) . During the test, the pressure should be gradually increased to the specified test pressure, and then the sealing performance of the seal pair should be checked.   Fourth, the evaluation indicators Shell test During the shell test, there shall be no visible leakage at the joint between the pressure-bearing wall and the valve body and the bonnet, and there shall be no structural damage to the casing ( including the stuffing box and the joint between the valve body and the bonnet ) . If there is no special regulation, the packing is allowed to leak under the test pressure of the shell, but when the test pressure drops to the sealing test pressure, there should be no visible leakage.  Upper seal test No visible leakage for the duration of the test  Seal test The maximum allowable leakage of the seal test is specified in Table 6 . The amount of leakage in Table 6 applies only to emissions to the atmosphere. Class A is suitable for non-metallic elastomeric sealing valves, and Class B , C , and D are suitable for metal sealing valves. Among them: Class B is suitable for more critical valves, Class D is suitable for general valves. The maximum allowable leakage ( grade ) of each type of valve shall be in accordance with the relevant product standards. If the relevant standards are not specified, the non-metallic elastic sealing valve shall be in accordance with Class A requirements, and the metal sealing valve shall be in accordance with Class D requirements. If the user requirements are in Class B or Class C , it shall be specified in the order contract.