Stainless Pipe Schedules

Standard

ASME B36.19M

Schedules

5S, 10S, 40S and 80S

40S and 80S published to

NPS 24

5S and 10S published to

NPS 30

The S means stainless, not thinner

The most common belief about the S-schedules — that they are a thin-wall series with no carbon steel equivalent — is wrong. In most sizes an S-schedule carries exactly the same wall as the B36.10M schedule of the same number. What the S actually designates is the standard the pipe is made to: ASME B36.19M, the stainless steel pipe standard, with its own material scope, its own tolerances and a shorter size range.

Where the two standards actually disagree

Computed from the two tables rather than asserted — these are the only wall thickness disagreements between the S-schedules and their B36.10M counterparts:

Where a schedule “matches”, it matches only across the sizes B36.19M publishes — which is a far shorter list than B36.10M's.

The size range is the bigger difference

B36.19 publishes 40S and 80S through NPS 24, except NPS 22, and 5S and 10S through NPS 30. B36.10 runs to NPS 36 and beyond in the numbered schedules. Above NPS 12 every 40S wall is 0.375 in and every 80S wall is 0.500 in, which are the standard weight and extra strong walls, and B36.19 itself notes that they do not conform to B36.10. A drawing calling for “NPS 16, 40S” is therefore asking for a 0.375 in wall, not for the 0.500 in wall of NPS 16 Schedule 40. If the heavier wall is what is wanted, the drawing has to say Schedule 40.

Stainless S-schedule dimensions

Dimensions are given in inches, with the millimetre equivalent beneath in grey.

Each schedule in full

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