Welding with backing plate
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Among butt welds, there are structures with backing plates for welding. Under what circumstances should we use backing plate welding structures? What are the advantages of welding with backing plate? Does welding with a backing plate count as penetration welding?
This post was last edited by ylb913 on 2017-5-7 07:00. I have seen the edge plates at the bottom of large tanks with backing plates underneath when they are butted together. This must be welded through, and everything inside is lap welded (one plate presses against another plate). Judging from this phenomenon, the backing plate underneath is mainly to prevent welding sparks from directly contacting the base surface of the tank.
Pressure vessel manufacturing generally requires single-sided welding butt welds that require full penetration. Backing plates can be used. The advantage is that welding with backing plates is easy to pass, but the weld coefficient is small and the plates may need to be thicker. Nowadays, generally argon arc welding and gas shielded welding can be used for single-sided welding and double-sided forming without the need for backing plates, and the weld coefficient has also been improved. Board thickness can be reduced.
I agree with what you said, like it.
Thanks for the answer, what will be the effect if sparks directly contact the surface of the tank foundation? The foundation is usually concrete or sand
Thanks for the answer, does welding with a backing plate count as a penetration structure?
To pass the filming, it must be completely melted.
I have some objections to ylb913 Bamboo’s explanation :). The edge plate is welded to the backing plate because it forms a T-shaped joint with the bottom tank wall plate. Coordinated deformation makes the stress complex. Butt welding or backing plate welding to ensure full penetration should be used. At this time, the backing plate must not be removed after welding. Since the middle bottom plate is far away from the joint and has basic support, it can be basically considered to be stress-free, so lap welding is sufficient.