The chemical composition and mechanical properties of X65 and SA234 WP22 CL3 seamless steel pipes are briefly introduced

and their weldability is analyzed respectively

then the selection of welding materials and the formulation of welding parameters are determined. According to the welding technical requirements of X65 main pipe and SA234 WP22 CL3 three-way pipe fittings for compressors

the welding procedure qualification of X65 and SA234 WP22 CL3 seamless steel pipe with φ168.30×14.27 mm is carried out. The results show that all index of welded joints meet the design requirements by using tungsten argon arc welding wire ER50-G for backing welding and manual arc welding electrode E5015-G for filling and cosmetic wleding

the microstructure of welded joints is mainly ferrite and a small amount of pearlite. Site welding has also achieved good results

indicating that the welding parameters and heat treatment procedure are reasonable and feasible.