Some precautions for welding titanium pipes and titanium alloy pipes

To obtain high-quality welded titanium pipe castings, the following points should be noted during the welding process:

(1) The surface of the welded castings must be cleaned and dried thoroughly. The castings should not be touched directly with hands before being placed in the welding box.
(2) During the welding of titanium pipes, it is essential to prevent the tungsten electrode from short-circuiting with the welded piece, which could cause the tungsten electrode to break and result in tungsten inclusions at the weld points.
(3) When the area and depth of the welding zone are large, it is necessary to perform multiple layers of distant-layer welding. The previous layer of weld should be completely cooled before proceeding to the next layer of welding. It is strictly prohibited to weld all at once to prevent the casting from deforming.
(4) At the end of the welding process, the current should be gradually reduced and the molten zone should be narrowed. Therefore, it is recommended to use pulsed current to prevent sudden arc extinction, which could lead to cracks.
(5) After the welding is completed, the casting should be allowed to cool in the box for a period of time before being removed. This is to prevent cracking or deformation of the weld area due to rapid cooling. The cooling time depends on the wall thickness of the casting and is usually 15-30mm.
(6) After the titanium pipe castings are welded, they should be annealed or subjected to hot isostatic pressing. They should not be left for too long, usually no more than 5 days. (7) The number of weldings should not exceed the regulations specified in the relevant technical documents.
The welding environment for titanium pipe manufacturers should not have flowing air. Other aspects are the same as in the welding in the welding box. However, special attention should be paid to:
(1) The welding area should not be too large. The flow rate of nitrogen should be larger during the welding process and there should be no interruption of the gas supply. (2) After the welding is completed, nitrogen should be continuously supplied for protection until the area cools down.
(3) For some special castings, such as complex thin-walled castings, to prevent oxidation on the backside of the welding area, argon gas can be blown onto the backside until the casting cools down.
(4) The welders are required to have high technical proficiency.