The issue of choosing between the two welding methods
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If the nominal diameter of the equipment is too small, leaving no conditions for cleaning the interior or carrying out welding, then for Class AB welds, TIG welding is used as a backing process or temporary shims are placed to ensure full penetration. Which welding method is generally preferred in such cases? What are the advantages and disadvantages of these two welding methods? Which welding method is more popular among workshop workers?
Either one is fine; as for which welding method is more popular among workshop workers, one can only ask the workers themselves. It’s likely that different workers will give different answers
Our drawing designs prefer the use of shims, as we find it easier to achieve thorough welding in this way. When TIG welding is used for root pass welding, it can be difficult to make thorough repairs if corrections are needed, which is quite troublesome.
I think TIG welding for the root pass is a simple and feasible method; my previous employer generally used this welding technique.
With shims, or single-sided welding for double-sided formation (this method requires a high level of skill from the welder); different methods may be used by each manufacturer
TIG welding offers relatively high welding quality, and it is easier to control the shape of the back side as well as the overall welding quality. In production, TIG welding is often used for the root pass of welds, or with the use of backing rings. However, TIG welding has a lower production efficiency and its cost is much higher than that of shielded metal arc welding. Additionally, TIG welding requires stricter standards regarding the preparation of the joint surfaces; the amount of bevel and misalignment significantly affects the welding quality. Therefore, many companies use TIG welding only when welding pipe joints – they use it for the root pass on larger pipes, while using it directly for smaller pipes. For the circumferential joints of rolled cylinders, TIG welding is generally not employed, mainly because it is difficult to control the degree of beveling and misalignment; in such cases, backing rings are used, unless there are special requirements.
We generally use TIG welding for the root pass and manual welding for the finish pass, as some equipment does not allow the presence of backing plates or struts, and removing them is also a problem. TIG welding is still easier to operate!
TIG welding makes it easier to ensure quality, and our company primarily uses TIG welding for the root pass.
For small diameters, TIG welding is used for sealing the bottom, and that usually works fine
You can try using flux-cored TIG welding wire; there is no need to supply argon on the back side, which results in better shaping of that area.