@robyengIT
I have found some manual at PPI, and I also found some manual at PPFA(plastic pipe and fitting association). thanks for you prompting.
@mk3223
these plastic pipes are used in waste water treatment plant, used as chemical dosing pipes, above ground.
Thanks for your reply.
@littleinch
yes, I mean some HDPE/PVC/GRP pipes.
I know some material standard, such as ASTM standard, I want to find the general technical piping standard for HDPE/PVC/GRP pipes.
thanks your prompting.