“2-inch stainless steel pipe” does not give a complete dimension. A buyer must state the nominal pipe size (NPS) and the wall designation, then check the actual outside diameter and wall thickness against the specified dimensional standard. Schedule 10S and 40S are different wall designations, not different stainless steel grades.
What the S schedule means
ASME B36.19 standardizes dimensions for welded and seamless wrought stainless steel pipe. It distinguishes pipe NPS from tube outside-diameter notation and uses the “S” suffix for its schedule designations. Its published description also warns that some B36.19 S-schedule walls differ from similarly named dimensions in ASME B36.10. Do not remove the S suffix from a drawing or assume interchangeability. See ASME’s B36.19 scope and dimensional explanation.
Check dimensions before ordering
| Item | State on the enquiry | Why it matters |
|---|---|---|
| Material specification | For example, ASTM A312 and its edition | Defines the pipe material and manufacturing requirements |
| Dimensions | ASME B36.19 edition, NPS and Schedule 10S or 40S | Identifies the intended outside diameter and nominal wall |
| Grade | For example, TP304L or TP316L, if specified by design | Does not follow from schedule alone |
| Project details | Length, end preparation, quantity, inspection and documents | Controls fit-up and acceptance |
A schedule is a dimensional designation; it is not by itself a pressure rating. Pressure suitability depends on the applicable design code, temperature, material, joint details and other design inputs. Obtain engineering approval rather than using a schedule label as a pressure guarantee.
Related pipe options
Review ASTM A312 stainless steel pipe for the product specification and industrial pipe range for related standards. For a price and dimensional check, send your NPS, S schedule, grade and drawing.
FAQ
Is 40S always suitable where 10S is specified?
No. A thicker wall can change bore, weight, welding and connection fit. Any substitution must be checked against the full design and drawing.
Is nominal pipe size the measured outside diameter?
Not for most common NPS sizes. Use the dimensional table for the specified standard and edition.