Where does the "Schedule 10, 40, 80 4

[waitaki]

Where does the "Schedule 10, 40, 80 etc" description for pipe grade come from? Does Schedule 40 relate to 40 feet psi or other measurement?

 

[IFRs]

The pipe schedule refers to the wall thickness. Of course, wall thickness relates to weight, strength and pressure capability. Pipe has constant outside diameter so as the schedule increaases, the inside diameter decreases.

 

[Leoroncetti]

The schedule comes from the ANSI.B.36.10.
SCH number = (1000 * P) / S
where P is the internal pressure in service in psig and S is the allowable stress of the material in psi.
The numbers are 10,20,30,40,60,80,100,120,140 and 160.