The air tightness test is mainly to check whether there is leakage in the connecting parts of the container. The pressure vessel with extreme toxicity level, high hazard or no trace leakage in design must stop the air tightness test.
The pressure vessel shall stop the air tightness test according to the following request:
(1) The air tightness test should be stopped after the hydraulic test is qualified. For the pressure vessel designed for pressure experiment, the air tightness experiment can be stopped at the same time as the air pressure experiment. The experimental pressure should be the pressure of the air pressure experiment.
(2) Pressure vessels made of carbon steel and low alloy steel shall have gas temperatures not less than 5 C. Pressure vessels made of other materials shall follow the design rules.
(3) The gases used in the air tightness test shall be dry, clean air, nitrogen or other inert gases.
(4) When the air tightness test is stopped, the safety accessories shall be fully equipped.
(5) The pressure should rise slowly during the experiment, hold for 10 minutes after reaching the regular experimental pressure, then drop to the design pressure, and stop inspecting all welds and joints with soap water, so as to be qualified without leakage. If leakage occurs, the hydraulic test and air tightness test shall be stopped again after repair.
The air tightness experiment is different from the air pressure experiment. First of all, they have different purposes. The air tightness test is to test the tightness of pressure vessel, and the air pressure test is to test the pressure strength of pressure vessel. Secondly, the experimental pressure is different, the experimental pressure of air tightness is the design pressure of the vessel, and the experimental pressure of air pressure is 1.15 times of the design pressure.