Welding process is a container welding technical requirements and operating rules, including: the welding method, welding groove, kinds and diameter of electrode, welding parameters, welding sequence, welding layer number, before welding and after welding process, welding environment requirements as well as the measures to prevent deformation, the deformation and so on. The welding process must be qualified by the process qualification, and the process requirements must be strictly carried out during the welding operation.
According to the welding conditions and welding parameters of the pressure vessel and the large parts, the deformation size and shape of the welding will be analyzed in advance, and the control measures are formulated in a targeted way:
(1) for large pressure vessels of multiple welding channels, such as spherical vessels, welding shall be carried out after the assembly is assembled into a whole, and the welding shall be carried out in a symmetrical manner and shall comply with the prescribed welding sequence.
(2) for large parts of multiple welding channels, such as the combined head of the melon flap and the transition section of the shell composed of flaps, in addition to carrying out the above requirements, there should also be a mouth type fixed fixture at the welding site.
(3) the pressure vessel with long and multi-section welding shall be appropriately released to the size of welding shrinkage when the cylinder is cut, so as to avoid the phenomenon of shortening of the shell after welding.
(4) for welding of pressure vessels, especially for complex pressure vessels with complex structure, reasonable assembly sequence and welding anti-deformation measures shall be taken to ensure that they are not deformed in manufacturing.
(5) the anti deformation measures: on the basis of practical experience or, on the welding parts in advance to the welding deformation in the opposite direction to the pre deformation after welding has just offset, particular way is: the longitudinal seam pressure vessels of shell joint two end arc pressure, in the direction of the welding deformation instead to set aside against deformation; The combined flaps and transition sections are considered to offset the deformation of the welding deformation.