Is it allowed to weld on until the specified thickness is achieved when the equipment wall thickness is insufficient?
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During equipment manufacturing, if the local thickness of the head or cylinder is less than the designed minimum thickness, surfacing welding is used to restore it to the minimum thickness in order to avoid discarding the component. Is this method allowed?
Except that in the construction process, temporary lugs can be repaired by welding if their thickness becomes less than the designed thickness after removal, no repairs are allowed in any other cases
For pressure vessels, a contractor with the necessary construction capabilities is required to prepare a plan for inspection and repair; this plan must then be reviewed by a qualified design institute. After that, notification procedures for the repair must be carried out, and the repair itself should take place only after these procedures are completed. A hydrostatic test is also necessary after the repair
This cannot be called surfacing; surfacing mainly refers to corrosion-resistant or wear-resistant surfacing, and the surfacing layer is generally not taken into account in the strength calculations of the container. What you’re referring to is patch welding. In the case of mechanical damage, or when the weld marks left by tools and fixtures exceed the requirements specified in clause 6.2.1 of GB150.4, it is entirely possible to carry out repairs using patch welding.
It can be carried out in accordance with clause 6.2 of GB150.4, but attention should be paid to the requirements for non-destructive testing and heat treatment after welding repairs