Defects of Welded Steel Pipe

Welded steel pipe common defect identification Bite edge Bite edge is along the weld centerline in a groove weld edge and the tube body transition zone. Bite edge is matching the condition of welding speed, current, voltage and so on is not appropriate. Lap welded steel plate edge dislocation and docking, weld the uneven phenomenon, become a tube or pipe seam lap weld seam dislocation. Flash welding process, molten metal flowing on the parent metal outside of the weld is not melt metal formed by tumor. Burnt during the welding process, the melting metal temperature too high since the groove outflow, the formation of weld defects. Weld bead deviating from the weld centerline, produce the phenomenon of weld deviation. Porosity during welding, the bubbles during solidification of the molten pool has not escaped the residue formed in weld hole. Porosity can be divided into dense hole, worm porosity and needle hole, etc. Welding slag, the bubbles during solidification of the molten pool has not escaped the residue formed in weld hole. Porosity can be divided into dense hole, worm porosity and needle hole, etc. When lack of fusion welding joint of root incomplete fusion phenomenon, and in the case of weld depth does not meet the design requirements. Hot cracking in submerged arc welding, can produce hot cracks in weld, especially in arc starting and arc arc crater where likely to occur because of the large temperature difference between hot crack. Hot cracking in the weld stress is very big, or weld metal within the most easily when I was a high Si content. Welding on resistant High frequency electric resistance welding (HFW) welding method of welding defects. Is characterized by the impact tensile samples or sample weld macro ports of metallic grey areas. Usually think, resistant had no significant effect on weld strength level, but larger influence on weld seam toughness and plasticity.

Trench etching Trench etching is a kind of special ERW steel pipe weld corrosion phenomena. Service such as seawater and industrial water medium resistance welded pipe in the weld zone of selective local corrosion phenomenon called groove corrosion, starting from the surface is continuous or discontinuous trench, it can lead to welded pipe corrosion perforation in a year to several years. Pit roll pitting or roll surface between the tube billet and hard tool make the pipe surface produces dips creasing.