The bottom layer of stainless steel precision tube shall be welded. In the past, manual tungsten electrode argon arc welding and solid cored wire welding shall be adopted. Ar shall be filled in the tube to prevent oxidation at the root of the weld and ensure the internal quality of the weld.However, it is difficult to fill Ar in the tube in the field construction, and the amount of Ar is large in the welding of equipment, tank head and long pipeline. Especially, the operation at high altitude is not conducive to the construction, and the auxiliary labor is too much, which is not economical.In order to solve these problems and ensure the quality of welding seams, flux-cored tungsten argon arc welding (TIG) is adopted in the bottom layer of the welding and gas shielded metal arc welding (MAG) is adopted in the filling and cover.

Base welding, welding gun Angle, welding wire Angle and carbon steel welding is basically the same.

Stainless steel precision tube

In the welding process, the welding gun should swing in a circular arc. The purpose is to accelerate the separation of molten iron and slag, so as to facilitate the observation of the molten pool.At the same time, the heat input on both sides of the base metal groove can be increased to prevent unilateral non-fusion.When filling the welding wire, the welding wire should be sent to the root of the melting pool and gently pressed down to ensure that the root is fully melted and formed in the root.

The frequency of wire in and out is faster than that of solid cored wire.The distance of the wire should be removed so that the end of the wire is within the argon protection zone to avoid oxidation of the end.

When the arc is closed, the arc pit should be filled.If arc pit cracks, shrinkage holes and other defects are found, they should be cleaned before welding, so as to ensure the quality of welding.When welding the cover surface, pay attention to whether the nozzle and conductive nozzle are clean before welding, whether the gas flow rate is appropriate, clean the bottom surface and control the temperature between layers.

Due to gas shielded welding for filling and cover layer, the length of wire extension has a great influence on the stability of the welding process. The longer the wire extension length is, the greater the resistance value of the wire will be. As a result, the welding process is unstable, the metal spillage is serious, the welding seam is not good, and the welding pool is not well protected.If the welding wire is stretched out too short, the welding current will increase, the distance between the nozzle and the workpiece will be shortened, the welding sight will be unclear, and the welding pass will be formed badly. At the same time, the nozzle will be overheated, resulting in spatters sticking or blocking the nozzle, thereby affecting the gas flow.