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Recently, with the completion of the hydrostatic testing of Tank No. 7 at the first-phase expansion project of China National Offshore Oil Corporation’s Yancheng \"Green Energy Port\", China’s largest LNG storage facility, all 6 tanks in this project – which boast the largest single-tank capacity in the world – have now undergone hydrostatic testing, 71 days ahead of the planned schedule. The hydrostatic test is one of the key tests for evaluating the performance of LNG storage tanks; it is also an important procedure for checking whether the welds of the inner tank are sound and whether the load-bearing capacity of the tank foundation meets the design requirements. The water filling height for the hydraulic testing of the 270,000 cubic meter LNG tank is 25.85 meters, with nearly 180,000 cubic meters of water required to fill each tank. To ensure the safe and efficient conduct of the hydrostatic test, the project team for the first-phase expansion made advance arrangements and meticulous plans. Two centrifugal pumps were installed at the water intake point to serve as backups for each other, while 18-inch carbon steel pipes were used for the main water supply lines; three branch lines were installed in parallel to enable simultaneous water supply to the three storage tanks. The water supply pipeline is laid along the ground, passes through the booster pump in front of the tank and up to the tank via the pipe supports outside it; water is then injected into the tank through the material access holes on the top of the tank, in order to reduce the impact on the tank’s bottom plate. During the hydrostatic testing of the storage tanks, to prevent damage to equipment, pipelines, valves, etc. caused by low temperatures, the project team took proactive measures to address this issue, such as installing electric heating strips and wrapping insulation material. At the same time, dedicated personnel are assigned to be on duty around the clock, and the frequency of inspections is increased to promptly eliminate various potential hazards, ensuring that the hydraulic testing of the storage tanks proceeds smoothly. During the water injection, drainage, and standing observation periods, once the liquid level reached 1/4, 1/2, 3/4, and the test level, the project team measured the settlement amount by assessing the elevation changes at the 46 settlement monitoring points installed on both the inner and outer tanks of the storage tank. Special attention was paid to checking the tightness of the bottom plate of the inner tank along its perimeter as well as the walls of the inner tank. After filling each storage tank with water, they inspected the tanks and found no leaks. They also re-measured various settlement points and calculated the differential settlements, with all values meeting the design requirements.