Storage tank welding issues
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Dear colleagues, the welding sequence for storage tanks is as follows: 1. Welds on the middle gusset plates; 2. The 300 mm section near the edge of the butt welds on the bottom edge plates; 3. The fillet welds connecting the bottom plate to the tank wall plates (to be welded after the longitudinal welds on the bottom ring wall plates are completed); 4. The remaining butt welds on the edge plates; 5. The contraction joints between the edge plates and the middle gusset plates. First, how should we understand the phrase “the 300 MM section near the edge of the butt welds on the bottom edge plates”? Second, why are the fillet welds in step 3 welded after the longitudinal welds on the bottom ring wall plates? It would be helpful if a diagram could be provided to illustrate the positional relationship between the edge plates and the tank wall in cross-section. Thank you all!
The determination of the welding sequence for the tank bottom plate and its first ring wall plate takes into account primarily the issue of welding shrinkage deformation. ““The 300 mm portion near the edge of the butt weld of the bottom edge plate” refers to the 300 mm section extending from the outer edge of the edge plate toward the center of the tank bottom. II. When welding the longitudinal welds of the first ring of wall plates on the tank, it is necessary to ensure that they can contract freely; if the fillet welds are welded first, this will restrict the free contraction of the wall plates, resulting in high local stresses.
Generally, it is a bottom plate, with welding in the horizontal direction first—followed by welding in the vertical direction； Then the welding of the side walls to the bottom plate.