Research On Pressure Sealing Technology Of LNG Pipeline At Low Temperature

China’s oil imports reached 70% in 2018.Among them,LNG(liquefied natural gas)imports increased by 47.5% year-on-year,accounting for 60% of the total imports of natural gas.19 LNG receiving stations had been built along the coast.Because of the flammable,explosive and low temperature characteristics of LNG,the leakage of LNG will cause fire,explosion,cold injury,suffocation and other hazards.Therefore,in order to prevent more casualties and property losses after LNG pipeline leakage,effective measures should be taken to plug it.This paper will purse research on it.Firstly,according to the properties of LNG,the sealing technology of pressure injection is chosen as the method to plug the leakage of LNG pipeline.The operation method of the sealing technology of pressure injection was established,and the required machine tools were analyzed.The sealing agent and the raw materials for fixture used under low temperature were determined.Secondly,according to the national standard GB-150,the fixture of the sealing technology of pressure injection is designed,and the pre-tightening force applied by fixture in pressure seal operation is researched by using finite element software ANSYS.The optimum pre-tightening force values of high and low pressure pipelines are obtained.Then,ANSYS is used to analyze and evaluate the strength and sealability of the designed fixture structure.By adjusting the size of key parts,the strength and sealability of the fixture can reach a reasonable state.Finally,FLACS software is used to simulate the pipeline leakage of LNG receiving station,and the dangerous range under different leakage rate and wind speed is calculated.According to the calculation results,the requirements of operation safety protection are put forward according to the potential hazards in the operation process.