Welding issues in heat treatment equipment
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For pressure vessels that have undergone heat treatment, welding items such as insulation nails on the surface of the equipment – to what extent is this harmful to the vessel? Are there experts who have dealt with such issues? After the heat exchanger, which has undergone partial heat treatment, was installed on site, the construction party welded insulation nails to it in order to provide insulation. Is this a proper approach?
Welding is not permitted on the equipment body itself that has undergone heat treatment.
Welding after heat treatment will destroy the original heat-treated state. Doing this is a serious violation.
Attachments such as insulation nails that are welded to the main body must be welded in place before heat treatment. If such attachments are forgotten to be welded due to carelessness before heat treatment, local heat treatment can be carried out as a remedy.
It depends on the specific situation. For materials such as Q245\Q345, heat treatment is sufficient as long as the thickness meets the standard requirements; after heat treatment, actions like welding retaining nails have little impact. For heat treatment in low-temperature containers, high-strength steel, or applications where the toxicity of the medium is a concern, welding cannot be performed after heat treatment.
Agree with the opinion above. The key is to know why heat treatment was originally performed. Now, for those that require rework after heat treatment, it’s no longer necessary to undergo heat treatment again
I think it can’t be welded again after heat treatment; all the parts to be welded together need to be welded first before heat treatment
It still depends on the specific situation – we need to consider what material it is. However, as the designer, if you weld the attachments after heat treatment, we will definitely have you perform local heat treatment.
If it is only for insulation purposes, welding may not be necessary; ask the insulation company whether a bundled insulation solution can be used instead.
According to the specifications, welding is not allowed after heat treatment; if welding must be carried out, reheat treatment is required. In practical applications, heating strips are generally used for local heat treatment. However, some experts believe that using heating strips for such purposes is not advisable, as it can generate new stresses and reduce the service life of the equipment. Since no reports of relevant destructive tests were found, it is unclear who is actually close to the truth.
It is best to carry out local heat treatment.