Hi

I have some question about the stress checking between static analysis and dynamic analysis.
According to load case combination of dynamic analysis, it shown the S1 (represent load case from static analysis) and D1 (represent dynamic case).
If I need to find stress in case of water hammer. I have to combine the W+P1 and D1 isn't it?

The above combination is for Steel pipe. But for Plastic pipe (FRP) by refer from UKOOA, what is the recommended combination.?

Thanks.