Welded Threaded Pipe Fittings

Welded Threaded Pipe Fittings Common problems and solutions

Welding defects

Pores:The main reasons are impurities such as oil stains,rust,and moisture on the surface of the welded part,moisture in the welding material,impure protective gas,or insufficient flow rate.The solution is to thoroughly clean the surface of the workpiece before welding,dry the welding material to ensure the quality and flow rate of the protective gas.

Cracks:Hot cracks are usually caused by the limited solidification shrinkage of the metal during the welding process,resulting in significant tensile stress,and the presence of low melting point eutectics in the weld metal;Cold cracking is related to factors such as the hardening tendency of the steel,welding stress,and hydrogen content.The solution includes selecting appropriate welding materials and process parameters,controlling welding heat input,conducting pre weld preheating and post weld heat treatment,etc.

Lack of penetration and fusion:The reasons may be due to low welding current,fast welding speed,small groove angle,large blunt edge,and small gap.The solution is to adjust the welding parameters to ensure the quality of groove processing and ensure that the base metal and weld metal are fully fused during the welding process.

Welding deformation:mainly due to uneven thermal effects on the weld seam and its surrounding areas during the welding process,resulting in thermal expansion and contraction,leading to the generation of welding stress.The solution includes arranging the welding sequence reasonably,using rigid fixation method,anti deformation method,etc.to control deformation,and correcting after welding.

Sealing and installation precautions

Sealing material selection:Suitable sealing materials can be selected according to different working conditions and media,such as polytetrafluoroethylene(PTFE)sealing tape,sealant,rubber gasket,etc.The sealing material should have good corrosion resistance,elasticity,and sealing performance.

Thread protection:During the welding process,attention should be paid to protecting the threaded part of the pipe fittings.Thread protection sleeves can be used for protection to prevent welding spatter from damaging the threads and affecting the subsequent connection and sealing performance.

Installation torque control:When installing Welded Threaded Pipe Fittings,tighten them according to the specified torque value to avoid excessive torque causing thread damage,and insufficient torque may lead to poor sealing.