Corrosion allowance should be considered on both sides of the split diaphragm

Let me share my opinion. Actually, this is also an issue I’ve encountered; later, during training, the instructor asked about it and I also looked it up in relevant materials. There are generally two types of responses: one is to ignore the corrosion margin and simply choose the minimum nominal thickness without any calculations. This approach holds that the main consideration in designing partition plates is stiffness, and regarding strength, they are generally safe enough； The other method is to perform calculations based on the pressure difference on both sides of the partition, taking into account corrosion on both sides while ensuring compliance with the minimum nominal thickness requirements. Personally, I think the first explanation seems a bit forced; perhaps it’s just that I haven’t understood it thoroughly enough. As for the second explanation, it is more in line with the standard requirements, but determining the appropriate value for the pressure difference is a challenge. I’ve read in some sources that for two-pass systems, the pressure drop at the inlet and outlet can be used directly as the pressure difference; however, this approach is not appropriate for multi-pass systems. Therefore, the sources recommend using the average pressure drop between adjacent passes as the pressure difference in multi-pass systems. Since I haven’t worked on such processes, I’m not sure whether this averaging method results in a conservative value or if the resulting figure is on the low side. On the surface, it seems like a reasonable approach, but of course, it’s up to the process engineers to make the judgment. At the same time, the partition is prone to bending or even tearing at the weld joints due to the impact of the incoming fluid. While welding quality issues cannot be ruled out, sometimes the impact is so severe that there are indeed problems with the stiffness of the partition. In such cases, two measures can be taken: either thickening the partition, or adding reinforcing plates beneath it; or both measures can be employed simultaneously. Of course, some people suggest using impact guards, but I am not very optimistic about this approach, as impact guards are generally not very thick, their welding quality is not better than that of the partition itself, and they are more likely to fail. This is my opinion; I welcome everyone’s feedback