Welding Technology Of Titanium Tube
1.When welding, small heat input welding should be selected within the qualified process parameters, and the temperature between layers should not be higher than 200 ℃ to prevent the crystal grains from growing up for a long time at high temperature.
2.The welding of seamless titanium pipes should be carried out under argon protection: the welding torch nozzle is used to protect the molten pool, the torch drag cover protects the hot weld and the outer surface of the near-joint area, and the pipe is filled with argon to protect the weld and The inner surface of the near seam area, specific measures: when welding a pipe with a larger diameter, the staff in the pipe wear a gas mask and hold a protective cover to protect the back of the weld pool; when welding a pipe with a smaller diameter or a fixed port, The inner surface is sealed with soluble paper at a distance of 150-300mm from the groove (whichever is greater according to the operability), and then a ball of soluble paper is inserted to prevent the air pressure in the tube from being damaged, and then filled with argon gas The air in the pipe is exhausted. Argon gas must be fully pre-filled before welding, and argon must be delayed after welding to fully cool the high temperature area and prevent surface oxidation.
3.The filler wire should always be kept under the protection of argon during the welding process. The welding wire shall not be exposed to the atmosphere immediately after the arc is extinguished, and should be taken out when the weld is out of protection. If the welding wire is contaminated, oxidized and discolored, the contaminated part should be removed.
4.Do not ignite arc or test arc on the surface of the weldment; ensure the quality of arc starting and closing during welding; fill up the arc crater when closing the arc, and stagger the interlayer joints of multi-layer welding.
5. Except for special requirements, each weld should be welded continuously at one time. If it is interrupted for some reason, it must be inspected when re-welding, and welding can be continued after confirming that there is no crack.
6.If tungsten is inadvertently encountered during welding operation, the welding operation should be stopped, the tungsten spot should be removed with a grinder, and the tungsten-grade end can be re-polished. The welding operation can be restarted after reaching the requirements. The requirements are the same as starting the welding operation.
7.If one of the following situations occurs in the welding environment of titanium pipes, the welding should be stopped when protective measures are not taken:
1) Wind speed ≥2m/s
2) Relative humidity is greater than 90%
3) It rains and snows;
4) The temperature is below 0°C.
8.The welding seam repair process is the same as the original welding process. The number of repairs for the same part should not be more than two. If a second repair is required, repair measures should be formulated. It shall be carried out after approval by the responsible welding engineer, and shall be indicated in the construction record.
