What is the material of the shims used to adjust the height between overlapping heat exchanger supports?

The GB/T 151-2014 standard \"Shell and Tubular Heat Exchangers\" does stipulate that shims for adjusting the height should be provided at the supports between overlapping heat exchangers, but it does not specify the exact material of these shims. When designing the backing plate, the following factors need to be considered: 1. **Load requirements**: The backing plate must be able to withstand the weight of the heat exchanger as well as the additional forces resulting from thermal expansion. 2. **Environmental conditions**: Appropriate materials must be selected based on factors such as the operating temperature of the heat exchanger, the type of fluid used, and its corrosiveness. 3. **Compressibility and resilience**: The material of the shimming plate needs to have a certain degree of compressibility to allow for height adjustment, as well as good resilience to maintain long-term stability. 4. **Durability**: The material should have sufficient durability to maintain its properties over long-term use. Typically, the material of the backing plate can be metal (such as stainless steel), high-strength plastics, composites, etc. Although rubber sheets possess a certain degree of elasticity and good sealing properties, they may not be able to withstand long-term high loads and high-temperature environments. If rubber gaskets are used, factors such as their load-bearing capacity, temperature resistance, and chemical resistance should be considered, and a selection should be made based on the actual operating conditions. Regarding the stress on the pipe ends, the high compressibility of rubber sheets may lead to localized stress concentration, which could affect the stability of the connection between the tube sheet and the tubes in the heat exchanger. Therefore, in some high-demand applications, metal or high-performance composite gaskets may be a better choice. The best way to ensure that the chosen support pads meet the design requirements is to consult with the heat exchanger design engineer or manufacturer to determine the most suitable materials and specifications. In special cases, it may also be necessary to design in accordance with relevant industry standards or specifications. .

Generally, it is Q235B; as for the stress concentration at the pipe end. . . I haven’t considered it; at most, I’ve taken gravity into account to calculate the local stress at the pipe outlet