Schedule Terminology

An introduction to pipes and the schedule terminology

For all pipe sizes the outside diameter (O.D.) remains relatively constant. The variations in wall thickness affects only the inside diameter (I.D.).

Welded and Seamless Wrought Steel Pipe

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:

• Light Wall
• Schedule 10 (Sch/10, S/10)
• Schedule 20 (Sch/20, S/20)
• Schedule 30 (Sch/30, S/30)
• Schedule 40 (Sch/40, S/40)
• Standard Weight (ST, Std)
• Schedule 60 (Sch/60, S/60)
• Extra Strong (Extra Heavy, EH, XH, XS)
• Schedule 80 (Sch/80, S/80)
• Schedule 100 (Sch/100, S/100)
• Schedule 120 (Sch/120, S/120)
• Schedule 140 (Sch/140, S/140)
• Schedule 160 (Sch/160, S/160)
• Double Extra Strong (Double extra heavy, XXH, XXS)

Note that many of the schedules are identical in certain sizes.

Stainless Steel Pipe

For stainless steel pipes thru 12-inch, schedule numbers from Schedule 5S to schedule 80S are used as published in ANSI/ASME 36.19M Stainless Steel Pipe.

• Schedule 5S (Sch/5S, S/5S)
• Schedule 10S (Sch/10S, S/10S)
• Schedule 40S (Sch/40S, S/40S)
• Schedule 80S (Sch/80S, S/80S)

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