Questions regarding the material of the saddle (support) pad
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This post was last edited by cxd11888 on 2021-12-18 08:20. The material of the container support pad is generally required to be the same as that of the container – what are the reasons for this? For example: if the cylinder (head) is made of stainless steel, and the gaskets should also be made of stainless steel, then can gaskets made of composite material (carbon steel base with a stainless steel coating) be used?
Considerations regarding strength and interfacial corrosion.
It’s mainly a problem related to the material’s effects during welding; otherwise, a transition gasket should be used
If strength and interfacial corrosion are considered, it would also be possible to use composite plates for the support pads (with a coating made of the same material as the cylinder body), right? !
In the case of welding dissimilar steels, taking the ear-type support as an example: the gasket is made of the same material as the cylinder, and welding the stiffener plate to the gasket also constitutes welding of dissimilar steels! (Unless the gusset plates are also made of the same material as the cylinder body)
I look forward to getting answers from senior colleagues or qualified editors!
Although the gasket plate and the rib plate/web are made of different types of steel, the gasket plate is not a component that bears load directly; this is better than having the cylinder/head, which is subject to more severe stress, bear the load directly, and it can be considered a form of substitution.
I think it makes sense to understand it that way. The rib plates are made of carbon steel, while the gaskets are made of stainless steel; this way, iron ions will not contaminate the pressure-bearing components. It’s exactly what you meant – using one to take the place of another!
Taking stainless steel containers as an example: 1, avoid welding different types of steel together; 2, prevent intergranular corrosion with the shell material – if the saddle corrodes, it can be replaced without having to modify the shell material; 3, they are used for support purposes, and carbon steel has higher strength; 4, the design itself follows economic principles, as carbon steel is cheaper and easier to work with
I have two questions regarding your reply, taking stainless steel containers as an example: 1. To avoid welding of different steel types – there is also the issue of welding different steel types in the case of gusset plates (carbon steel) and gaskets (stainless steel)； 2. Will intergranular corrosion occur if the gasket plate is welded to the container using carbon steel?
The gusset plate is not a primary compression member, and the welds between the stiffener plates and the gusset plate are not compression member welds. Intergranular corrosion is likely to occur in the presence of water, acid, and other electrolytes without any protective coating. I think the two questions you raised are a bit unnecessary