Heat treatment of equipment subjected to H2S stress corrosion
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Dear colleagues: There is a device used for high-sulfur natural gas, and stainless steel composite panels are planned to be used. The pressure is not high, and the base layer meets the requirements of relevant specifications and standards; thus, post-weld heat treatment is not necessary. Question: Since H2S does not cause stress corrosion in stainless steel, is it unnecessary to perform post-weld stress-relief heat treatment for this equipment after welding?
I think heat treatment is not necessary. Clause 8.2.5 of GB/T150.4 specifies that welded joints of austenitic stainless steel may not require heat treatment. According to HG/T20581, when austenitic stainless steels are used in environments prone to intergranular corrosion, they should undergo re-solution treatment or stabilization treatment. H2S corrosion belongs to intergranular corrosion. For the above reasons, heat treatment is not necessary. Let’s all talk about it.
Heat treatment is recommended. Standards stipulate that equipment subject to stress corrosion requires heat treatment, and such treatment focuses primarily on the base material. The heat treatment temperature for composite panels is difficult to control, but it is not impossible to carry out heat treatment on them
Using stainless steel composite panels eliminates the need for heat treatment.
SH/T3193-2017 \"Guidelines for the Design of Wet Hydrogen Sulfide-Exposed Equipment in the Petrochemical Industry\" also does not specify whether post-weld heat treatment is required for equipment made of composite panels.
What are the conditions for stress corrosion? The media do not come into contact with the base layer, so how can stress corrosion occur? Of course, heat treatment can be applied to address coating leakage… However, if the thickness of the base layer is low, the risks associated with heat treatment increase
What material is stainless steel? Is heat treatment required for welding procedure qualification? Taking into account factors such as material thickness and H2S stress corrosion, if heat treatment is necessary, it is recommended to carry out the treatment separately for the base layer and the cladding layer, or consult the designer.
It is difficult to control the heat treatment temperature of composite panels
If the medium does not cause stress corrosion in the composite layer, heat treatment is not recommended. Thermal treatment of composite materials is difficult. It is recommended to perform 100% ultrasonic testing on the cylinder welds and the pipe connection welds. Then cancel the heat treatment