| 摘要 |
PURPOSE: An air-tightness test method for a liquefied natural gas(LNG) cargo tank is provided to systematically implement an air-tightness inspection process by implementing a second insulated film test step, a fist insulated film test step and a liquid dome air-tightness test step. CONSTITUTION: In a second insulated film test step, a strength test(S10), a bearing test(S20), a defect repairing process(S30), a helium gas injecting process(S55), a mechanical stressing test(S40), a helium leakage checking process(S50), a repairing process for the leakage part(S65), a repaired part test(S60), a helium concentration measuring test(S75), a corrected part bearing test(S25), and a global test(S80) are performed. In a first insulated film test step, the mechanical stressing test, the bearing test, the helium gas injecting process, a secondary helium leakage checking process, the repairing process for the leakage part, the repaired part test, the helium concentration measuring test, the corrected part bearing test, the strength test, and the global test. A liquid dome air-tightness test step including a welding process for a helium injection hole is implemented.
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