In the process of welding titanium pipelines, the following operating points should be strictly implemented:
(1) Before welding, argon gas should be turned on for some time before replacement. The open flame detection method can be used to check the weld joints, and after confirming that the gas in the pipeline is argon as a whole, perform welding.
(2) The extension length of the tungsten electrode should be short, so as not to hinder the view of the molten pool; the flow of argon should be moderate, too much flow is not easy to form a stable airflow layer, but will form turbulent flow in the protection zone, making it harmful The gas is immersed in the molten pool. In addition, too much airflow will accelerate the cooling rate of the molten pool, and cracks are prone to appear on the surface of the weld. The argon flow should not be too large, otherwise, it will affect the efficiency of the front protection.
(3) During the welding process, not only must there be argon protection in the welding torch, but also an argon protection drag cover must be added behind the welding torch, and the titanium pipeline should be filled with argon for protection. During welding, the distance between the drag hood and the nozzle should always be kept in the range of 20~25mm. At the end of welding, the protection of the drag hood cannot be finished immediately. You must wait for the temperature of the welding seam to drop below 200 ℃ to stop the air supply.
(4) During the welding process, the temperature between layers must be strictly controlled. After each layer is welded, the temperature should be lowered to room temperature before continuing the welding of the lower layer.
(5) When welding, the arc starting and ending points must be in the groove, and the arc starting and ending on the base metal cannot be started and ended. When feeding the wire, it is not possible to move the welding wire one by one and withdraw quickly. The welding wire should be filled into the molten pool at a slow speed and evenly, otherwise, it will cause gas turbulence and affect the protective effect.
(6) The welding construction site must be kept dry and clean. The ambient temperature during welding should be controlled above 10°C, and there should be no excessive wind in the welding area.
(7) Short arc welding, rapid welding, straight welding torches, and filler wire should be used for welding titanium pipelines. Welding torches and wires are not allowed. Even if the surface is to oscillate, it can only oscillate slightly and slowly.
(8) The head of the welding wire must not leave the protection range during welding, otherwise, the end of the welding wire will be oxidized. If the end of the welding wire is found to have been oxidized, the oxidized part must be cleaned up before it can be used.
