Which Pipe Schedule Do You Need?
Schedule 40 pipes may be the most popular kind of pipes on the market, but they’re far from the only kind you can buy. Since the thickness of a pipe has a direct effect on the pipe’s strength and by extension its use, there are pipes that are built with thicker walls than those found in a schedule 40 pipe and consequently have different schedule numbers.
Pipes are available in varying thickness for the same NPS number (meaning they have the same outer diameter) and instead of noting down the minute differences in thickness in mm or inches, the pipes are just classified according to their schedule numbers. So, continuing the above example, a pipe of NPS size ¾ has a thickness of 0.154” if it is a schedule 80 pipe, while a schedule 40 pipe has a thickness of 0.113” in the same NPS number.
As you can see from the above example, a pipe with a larger schedule number has thicker walls, but the increase in the thickness is not proportionate to the change in the schedule number. Otherwise, the thickness of a schedule 80 pipe would be double that of a schedule 40 pipe.
This does, however, let us quickly compare a schedule 40 pipe to other schedule numbers; any pipe with a lower schedule number is going to have thinner walls than the schedule 40, while pipes with higher schedule numbers are going to have thicker walls. Overall, the schedules available for pipes in the market are 5, 10, 20, 30, 40, 80, 120 and 160, but the most commonly used ones are the 40 and 80 schedules.