Mandatory requirements for containers undergoing gas-liquid and pressure tests

Thread Content

For pressure vessels that cannot be filled with liquid due to structural or support reasons, or those for which the operating conditions do not permit the retention of test liquid, a pneumatic test can be used； The gas used in the experiment should be dry and clean air, nitrogen, or another inert gas. For pressure vessels that cannot be filled with liquid due to load-bearing constraints or other reasons, it is possible to first fill them partially with liquid based on their load-bearing capacity, and then add gas, in order to conduct a gas-liquid combined pressure test. The weld joints between the nozzle (flange) and the shell, as well as those of the jacketed pressure vessel, shall adopt a fully penetrated structure. Type A and Type B butt joints of the shell shall undergo 100% non-destructive testing (RT/UT/TOFD). The weld joints of pressure vessels require magnetic particle or penetrant testing on their surfaces. The basis for calculating the test pressure is that, when the container has a specified MAWP, this MAWP should be used in place of the design pressure for calculations. The test temperature (metal wall temperature) should be 30°C higher than the ductile-to-ductile transition temperature of the metal material of the wall. When calculating the test pressure, t should not be lower than the minimum allowable stress of the material governed by Rm and ReLt (the value on the left side of the black line). Its Class A and Class B welded joints shall undergo 100% non-destructive testing (RT/UT/TOFD). The test temperature should be 30°C higher than the plasticity transition temperature of the container material: for Q345R, Q370R, and 07MnMoVR, the test temperature should be ≥5℃ ； Other carbon steels and low-alloy steels: test temperature ≥ 15℃ ； Low-temperature container: Test temperature ≥ Impact test temperature + 20℃