LNG storage tanks generally undergo their first periodic inspection within three years of commissioning. Subsequent inspection cycles are determined by the inspection agency based on the safety condition rating of the pressure vessel, following these requirements:
(1) For safety condition ratings of Level 1 or Level 2, inspections are typically conducted every six years;
(2) For safety condition level 3, inspections are generally conducted every 3 to 6 years;
(3) For safety condition level 4, the tank is monitored during use. The inspection cycle is determined by the inspection agency, with cumulative monitored usage not exceeding 3 years. During the monitored usage period, the operating entity must implement effective monitoring measures;
(4) For safety condition level 5, defects must be addressed before the tank can continue operation.