Why are the groove shapes for the circumferential and longitudinal welds of the cylinder different?
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Why are the groove shapes for the circumferential and longitudinal welds of the cylinder different? What is the difference between X-type and U-type? Why is a U-shaped groove used on the outside of the circumferential weld and a V-shaped groove on the inside?
It is related to the assembly sequence. When welding the head to the cylinder with the final weld, submerged arc welding can be used on the outside, while manual welding is generally required on the inside.
For the butt welds of thick plates, a U-shaped groove is preferred when conditions permit, including single-sided U-shaped, U+V-shaped, and double U-shaped grooves. These grooves are used to minimize the amount of welding work while still ensuring quality; however, they require mechanical processing. For the container shown in this diagram, its longitudinal welds may be restricted by the cylinder rolling process, so flame cutting is considered.
Depending on the welding process, for longitudinal welds, manual welding can be used for the root pass on both the inner and outer sides, while automatic welding can be used for the cover pass; thus, the conditions are the same on both sides. For circumferential welds, automatic welding cannot be used on the inner side, so manual welding is employed there, while automatic welding is used on the outer side; as a result, the weld grooves for these two types of welds are different