What is the pressure rating of schedule 40 black steel pipe?

Answer 1

Pipe ratings are the operating pressures that a pipe can be constantly operated at.

There are a few classes of Plumbing pressures. Schedule 40 black iron is 150 psi class, meaning that the "operating pressures" are 150 psi.

The 300 psi class is the class for most schedule 80 black iron (no seam [welded]).

Each class has it's own fittings at the same ratings. The fittings wont be listed as a schedule just a class or a psi rating.

Other ratings can exceed 3000 psi for hydraulic actuated machinery applications. Again, these classes have there own set of 3000 class fittings which are usually forged instead of cast.

The ratings include a safety factor of 2 and an extra surge allowance of 100 psi for very short term operation. The rating only goes to the yield strength of the pipe not the failure strength, know the difference. So the burst pressures someone else gave as the pressure rating (2700 +psi) is wrong unless the person asking this question was trying to make a "pipe bomb."