Pipe Wall Thickness

what thickness? Nominal or minimum required?

Nominal thickness : from piping material, class and diameter.

minimum required thickness (inch):

(Design Pressure x OD)/(2 x (Maximum allowable stress+ (0.4x Design Pressure)).

for the example depend on the data.

Do your own homework

Do a theoretical slice down a diameter and carry out a force balance calculation on the slice plane at maximum pressure. Repeat by carrying out a theoretical slice across the pipe. Whichever is the larger thickness figure is the minimum the pipe can be to contain the pressure.

However, pipes come in scheduled tables of performance and availability and there is little need to approach this problem from first principles. Usually it is a case of looking up the answer in a table.