What are people’s views on using MIG welding for pressure components in pressure vessels?
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At present, the welding methods for pressure vessels and pipelines in China still mainly rely on SAW and shielded metal arc welding; for critical welds, a process is used that involves tungsten inert gas arc welding for the root pass, followed by shielded metal arc welding for the fill and cap passes； The CO2 gas shielded welding method is not yet widely used in the welding of pressure vessels and pipelines. With the improvement of welding materials and welding skills, how should we view these issues?
Based on our unit’s usage experience, the welding quality is indeed not good; even though it is used for welding structural components, the quality remains poor. But I’ve also heard that some people make simple pressure vessels using GMAW.
MIG welding is seemingly used rarely for the main pressure-bearing components of pressure vessels, but it is widely employed for the primary welds in custom-made, atmospheric-pressure vessels, and many factories are using it nowadays.
What I saw were mostly those used for MIG welding. Then weld the faces using SMAW or SAW. I’m not sure if it’s correct.
CO2 gas shielded welding may affect the carbon content of the weld; caution is required when welding pressure vessels, and it is not recommended.
I have not yet encountered any cases where GMAW is permitted on the welds of pressure components; even for non-pressure components, such permission is very rare.
Our company uses gas shielded welding, and the wire used is flux-cored wire
As long as there is a qualified welding procedure qualification, it can be used.
The process evaluation conducted in our unit was successful... yet it should still be used with caution, due to the instability of the welding materials
The fillet welds between the skirt and the cover plate of pressure vessels can be used confidently, offering high efficiency.
MIG welding is primarily used for welding structural components and non-compressive elements; it is not recommended for welding components that are under significant compressive stress, and caution should be exercised in such cases.