The welding requirements of titanium pressure vessels are as follows.
(1) The grooved surface of the welded joint must be processed by mechanical method.
(2) Welding materials must be subject to hydrogen removal and strict cleaning treatment.
(3) Operators responsible for welding joint assembly must wear clean gloves, do not touch the groove and its adjacent areas on both sides, it is strictly prohibited to knock the surface and groove of a titanium plate with iron.
(4) Welding shall be carried out immediately after the assembly and cleaning of weldments.
(5) The purity of argon and helium for welding shall not be lower than 99.99%, the dew point shall not be higher than minus 50 ℃.
(6) Before titanium welding, the groove and the range of 25mm on both sides shall be strictly mechanically cleaned and degreased. Measures shall be taken to prevent groove pollution during welding.
(7) Effective measures shall be taken to avoid mutual dissolution of steel and titanium during welding. When required by the drawing, an iron pollution test shall be conducted.
(8) During the welding process, the surface color of the welding layer must be checked after each welding. The surface color of the weld and heat-affected zone is silver-white or golden yellow. All unqualified surface colors shall be removed and then re-welded. The surface color inspection shall refer to the provisions of relevant standards.
(9) Inert gas double-sided shielded arc welding or plasma welding must be used. The welded strength between the pipe and the expanded plate should be used.
(10) The weld surface after welding shall be free of undercut, air hole, crater, crack, and other defects.
