How can the stainless steel composite pipe be welded?
Because the stainless steel thermal conductivity is small, and the welding temperature when the residence time is not too long, so the welding composite layer, should choose a small amount of heat input welding method. At the same time, the welding sequence of composite pipe for the first welding composite layer, after welding base, so the composite layer is the welding quality of the welding process most importantly, it should consider adopting a welding method of high quality, is a composite pipe composite layer is the most ideal welding method.
The backing layer adopts melt-through bead welding process, the welding position is generally fixed, difficult to weld, welding layer is composite pipe to meet the highest quality requirements of the process, the technical level of the welder must have a strong and high sense of responsibility. Must be on the inside of the pipe before welding, argon weld filling 99.99% time tester oxygen content from the source of deep groove gap gas extraction measurement of internal oxygen tube, when the oxygen content is less than 50ppm at the start of the bottom in order to ensure the welding quality by tungsten arc welding by self to symmetry, before welding sealing; welding welding layer was burnished.
Because between the composite layer and the base layer is not easy to be welded together, so in the group before the first sealing. Welding should be welding method, using small amount of heat input so for sealing, we still used manual TIG welding. For the transition layer, the deposited metal composition is very complex. In order to make the alloy concentration gradient is not too large, we should choose the welding method with a larger heat input, then we use the electrode arc welding. As the base material is carbon steel, is a common material, welding process is very mature, so for the welding of the base welding arc welding, so as to improve the welding efficiency.
By hydrogen arc welding, stainless steel clad pure edge is 1. 5--2.0mm and welding torch nozzle porcelain tube diameter is 10mm, wire diameter of 2-3mm, the welding current is 80-100A, the argon gas flow is 8-12/min, the welding current is positive, after welding to conduct a comprehensive inspection, the existence of slag, crack, air hole welding incomplete fusion such defects are not allowed, or X - ray examination, can be carried out under the main welding sequence.
