When selecting supports, does the thickness of the backing plate need to be the same as that of the cylinder or head?
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Normally, the thickness of the shimming plate is chosen in accordance with the standards for supports, and this approach also works in SW6 calculations. Recently, I came across in some books that the thickness of the shimming plate can be set to be the same as that of the cylinder or the head. Could the teacher help clarify this?
They don’t have to be consistent; for dozens of thick cylinder heads, the thickness of the gaskets can vary greatly. But it’s best to calculate the weld.
Like the housing, the backing plate is probably also intended for ease of material preparation
The main function of the shims is to reduce the local stress at that location. If the equipment itself is not very thick, it is necessary for the shims to have a uniform thickness, which facilitates material preparation and procurement. If it’s too thick, there’s no need to make it of exactly the same thickness; as long as the calculations show it meets the requirements, that’s sufficient. The standard thickness values have already been calculated for you, so you can simply use those values – this ensures full safety. If it doesn’t match the specifications in the engineering standards, as long as the calculations confirm it meets the requirements, there’s no problem at all. These requirements that the shims and the head or cylinder wall have the same thickness are essentially stipulated by engineering codes.
So, I have a question: if the material for the cylinder or head is Q345R, can Q245R be used for the gasket plates?
There’s no problem under normal circumstances.
The reason why cylinders are made of different materials is that they come into contact with the medium being handled. The material used is determined by taking into account the properties of that medium, the suitability of the material sheets, the procurement timeline, and the overall cost of the equipment. Gaskets, on the other hand, serve merely as load-bearing components; as long as their mechanical properties and welding characteristics are compatible with those of the main material, there is no problem with using them. Of course, this is only possible if the client agrees – some clients are quite unreasonable and refuse to consent