Production process of SSAW pipes

Posted by zora li on December 1st, 2022

Submerged arc welding is an important welding method. Its inherent advantages such as stable welding quality, high welding productivity, no arc, and less smoke and dust make it an important steel structure in the production of pressure vessels, pipe sections, box girders, and columns. In recent years, although many new welding methods with high efficiency and high quality have appeared one after another, the application field of submerged arc welding has not been affected at all. Judging from the weight share of deposited metal by various welding methods, submerged arc welding accounts for about 10%, which has not changed much over the years.

Therefore, in the production process of SSAW pipes, the following three process defects often appear.

1) Defects in the processing of heating elements. In the heat treatment process, appropriate and effective heat treatment heating equipment and heating media must be selected. If the heating temperature exceeds the process requirements, the surface of the part will be affected by the oxidizing heating medium, which will easily cause product defects. In addition, during the heating process, there will be problems such as too coarse grains or even melting grain boundaries. Parts will seriously affect the appearance and inner quality of the steel pipe.

2) The surface hardening defect is the overall heat treatment of the part, and the required hardness and requirements can be obtained inside and outside the part. Surface hardening is used only for surface hardening of parts, the core remains in its pre-treatment structural state. Therefore, attention should be paid to factors such as surface quenching temperature, heating time, and depth of hardened layer, which will greatly affect the characteristics of the spiral steel pipe and reduce its service life.

3) Defects of chemical heat treatment of different-diameter spiral tubes. Spiral tube chemical heat treatment is a heat treatment process in which metal or non-metal atoms on the surface of the part are infiltrated to obtain the required surface properties (such as high wear resistance), which endows the part with dual functions and but if the process formula and process parameters are changed improperly, it will lead to deformation and cracking of the part , the structure and hardness are unqualified. Therefore, full attention should be paid to the chemical heat treatment of parts, otherwise the meaning of chemical heat treatment of parts will disappear completely.