The issue of selecting material for container support pads
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Dear experts, regarding the selection of materials for the backing plates of container supports in pressure equipment as specified in NB/T4712-2007 – for example, in the case of support-type Type B supports – if the equipment is made of S31603, can the backing plate be made of S30408? Where can I find explanations or guidelines regarding material selection? Thank you!
First, a correction: it should be JB/T4712-2007 regarding gaskets. It is best for them to be made of the same material as the main body, in order to avoid issues such as ferrite contamination caused by different materials, differences in thermal expansion, and problems that arise from welding dissimilar steels, like galvanic corrosion. Therefore, the standard recommends that it be “general,” the same as the container body. Will line 304 work? What is not prohibited by law can be done, but designers must have basic judgment and implement appropriate measures to ensure quality.
Sure. The calculation shows no issues; S30408 can be used. S30408 and S31603 have excellent weldability.
It is possible, yes. The question is, with such large tanks already made, is this backing plate still needed? Why not choose 304?
This is determined based on each company’s material management practices. The cylinder material is in bulk form; it’s basically supplied in double fixed lengths, with little excess material ； If it is an ear-type support, there is no major problem; but if the diameter is large and it is a saddle-type support, it may be difficult to find the appropriate material. Standard grades like 304 are still in stock; for 316 of the same thickness, it’s not certain that enough will be available. So generally, manufacturing plants face such dilemmas
Agree with what was said on the 2nd floor. Reasons, haha...
To be practical, using S30408 for this gasket is definitely fine; its chemical composition simply has a higher carbon content, which gives it better strength, so it’s suitable for use as a gasket.
S30408 can be used; pay attention to the selection of welding materials
During design, specific problems should be analyzed on a case-by-case basis...