Why is wall thickness of pipe measured as schedule?

Question

Why "Schedule" word is used for wall thickness of pipes when it is measured in mm and inches. Where from the work "schedule" arrive in measuring thickness of pipe. And what is the significant of nos 10,20,40,80,etc ...

Answer 1

Standard sizes for steel pipe are established in American Standards B36.10 and B36.19 of the American Standards Association (ASA).. These standards set up a number of "schedules" which specify wall thickness for given standard diameters. ASA B36.10 refers to wrought-steel and wrought-iron pipe and includes schedules 10, 20, 30, 60, 80, 100, 120, and 160. ASA B36.19 refers to stainless steel pipe and includes schedules 5S, 10S, 40S, and 80S.

The lower the schedule number the thinner the wall, for example for a 8" pipe, schedule 20 is a .250" wall, schedule 60 is .406", schedule 140 is .812" ...

Answer 2

To distinguish different weights of pipe, it is common to use the Schedule terminology from ANSI/ASME B36.10 Welded and Seamless Wrought Steel Pipe:

This will answer your questions on how schedule works.

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