how to calculate natural gas pipe size?

Answer 1

There is no simple method for determining the size of a natural gas pipeline. There are several formlas, nomographs and the corresponding computer programs. However , as for any fluid you need to first know: what is the mass flow rate, the pressure, viscosity, and density at the entrance, the desired pressure at the end, the length of pipe , the number of fittings, the piping material.

Answer 2

you ned to know the demand (usage at worst case) to size the pipe