Orifice plate standards

Dear sires

I have some questions in this regard:

1 - what is reference standards for size calculation and noise calculation respectively according to API.

2 - what is material for plate and flange if a high H2s/HCL high temperature application with oil fluid

3 - what is suggestion for plate type?

4 - Is it standard not to consider drain or vent hole?

5 - Is there any standard obligation on minimum plate thickness and diameter ratio(beta)?

thanks in advance
Masoud