Under what circumstances can a pressure test be carried out? How to do it?

When the pattern specifies the use of air pressure. How to check the tolerance specifications

1. The container’s volume is too large, and it cannot withstand the weight of water. 2. The structure is complex, and hydrostatic testing is insufficient to fully verify the pressure testing requirements for all components. 3. Due to the design of the structure, water is not suitable (for example, residual test liquid in the container is not allowed). 4. Other insurmountable difficulties, such as those who face difficulties in supplying water to large containers. Safety measures should be in place for pressure testing. This safety measure must be approved by the technical director of the testing unit, and supervised by the unit’s safety department. The gas used in the experiment should be dry, clean air, nitrogen, or other inert gases. For carbon steel and low-alloy steel vessels, the temperature of the medium during pressure testing must not be lower than 15℃ ； The pressure testing temperature for other containers shall be as specified in the drawings. During the test, the pressure should be increased gradually until it reaches 10% of the specified test pressure; this pressure level should be maintained for 5 to 10 minutes. After that, a preliminary leak check should be conducted on all welds and joints. If any leaks are detected, they must be repaired before the test is repeated. After the initial leak check is successful, the pressure is gradually increased to 50% of the specified test pressure; if no abnormalities are detected, the pressure is then raised in steps of 10% of the specified test pressure at each stage until the target pressure is reached. After holding the pressure for 30 minutes, reduce it to 87% of the specified test pressure and maintain it for a sufficient length of time before conducting a leak check. In the event of a leak, repair it and then retest in accordance with the above regulations. It is considered qualified if there is no air leakage and no visible abnormal deformation. Continuous pressure application shall not be used to maintain the test pressure constant. It is strictly prohibited to tighten bolts under pressure during the pressure test.