Welding method of LNG (Liquefied Natural Gas) low-temperature storage tank 9-percnet Ni steel butt weld pass

The invention provides a welding method of an LNG (Liquefied Natural Gas) low-temperature storage tank 9-percnet Ni steel butt weld pass. The welding method of the LNG low-temperature storage tank 9-percnet Ni steel butt weld pass is characterized by comprising the following steps of S100, designing a narrow-gap butt-joint groove with truncated edges, wherein the butt-joint groove is in a U shape, the clearance between the truncated edges of the butt-joint groove is 0mm, the thickness of each truncated edge of the butt-joint groove is ranged from 1.5 to 2.0mm, the angle of each truncated edge of the butt-joint groove is ranged from 3 to 5, and the chamfering of the bottom part of each truncated edge of the butt-joint groove is ranged from 3 to 5mm; and S200, adopting a narrow-gap hot wire TIG (Tungsten Inert Gas Welding) process for sequentially carrying out single-layer backing welding, bottom reinforcemnet welding, filling welding and cosmetic welding. 本发明提供种LNG低温储罐9％Ni钢对接焊道的焊接方法，其特征在于，包括如下步骤：S100、设计带钝边的窄间隙