Can CO2 gas shielded welding be used on pressure vessels?
Thread Content
The workers in our company’s workshop prefer to use CO2 gas shielded welding for manufacturing pressure vessels, which has led to numerous welding quality issues. So, can pressure vessels be welded using CO2 gas shielded welding?
It can be used! Of course, it’s not as good as TIG welding!
Carbon steel is generally fine, but stainless steel is absolutely not suitable
It’s possible. There are several reasons for the frequent problems: 1. The welding process is not carried out in strict accordance with the required procedures, or the process needs to be adjusted; 2. There are issues with the gas shielded welding wires – the quality of these wires produced by many manufacturers is not very good at present!
If the quality of the gas shielded welding wire is not good, problems are likely to occur
The main welds of pressure vessels cannot be welded using CO2 gas shielded welding, unless there is a specific requirement or support from process evaluations, as the welding wires used for CO2 gas shielded welding in China are all acidic electrodes. However, CO2 gas shielded welding can be used on unpressured areas. Welding of important pressure vessels must also be prohibited, as neither the carbon content nor the hydrogen content will meet the requirements.
I’ve never seen pressure vessels welded using CO2 welding; TIG welding is the best choice! Safety first
If the tolerance specifications do not prohibit its use, then it can be used. However, the quality is not as easy to ensure with TIG welding; for safety reasons, it is better to use TIG welding.
Pressure vessels can be welded using CO2 gas shielding, and this method is primarily used for carbon steel structural components such as reinforcement rings and supports. Our company is currently developing CO2 gas shielded welding for welding stainless steel, but mainly for structural components. For the main stressed components, submerged arc automatic welding and manual welding are still used the most!
Many problems have arisen. What are they?
Welding components using CO2 gas shielding is indeed much more efficient than shielded metal arc welding, but it tends to produce defects such as pores and slag inclusions; it is generally not used for welded joints under stress, but mainly for welding joints that are not under stress.
What I have seen is that TIG welding is used for welding the bodies of supports such as saddles, but I have not seen TIG welding used for welding pressure-bearing components such as pressure vessels; it would be best to ask a welding expert to explain this.
The wire used in FCAW is not sealed, and the flux contained within it can become damp, which often leads to defects such as pores. Additionally, the alloy composition of the flux is not very uniform; therefore, its use is not recommended
CO2 gas shielded welding is convenient for welding; it is particularly useful for batch welding in a systematic manner, and it is cost-effective. It is mainly used on components that are not under pressure, as the welds are subjected to only minimal stress. For example, with reinforcing rings, it is sufficient if the welds are subjected to less stress. There are also gussets with low weld strength.
Civil liquefied petroleum gas cylinders are now welded using gas shielded welding. Carbon steel for simple pressure vessels is generally welded with gas shielded welding, though carbon dioxide is not necessarily used.
It can be used; the non-primary welds of stainless steel can also be utilized
It can be used, but it is not recommended. First, a welding procedure qualification must be carried out; only after it is successful can the process be used. Even if the qualification is successful, the welder cannot guarantee that no pores or slag inclusions will appear during welding. Compressed components are not recommended.
It can be used for welding non-compressed welds.