Liquefied natural gas storage tanks shall undergo their first periodic inspection within three years of being placed into service. Subsequent inspection intervals shall be determined by the authorized inspection body based on the safety condition grade of the pressure vessel, in accordance with the following provisions:
- (1) For vessels with a safety condition grade of 1 or 2, inspections are generally conducted once every six years.
- (2) For vessels with a safety condition grade of 3, inspections are generally required every 3 to 6 years.
- (3) For vessels with a safety condition grade of 4, continued operation is permitted only under monitored conditions. The inspection interval shall be determined by the inspection authority, and the cumulative period of monitored operation shall not exceed three years. During this period, the operating entity must implement effective monitoring measures.
- (4) For vessels with a safety condition grade of 5, defects must be rectified before further use. If such defects remain unaddressed, the vessel shall not be operated.