ASME B36.10M Pipe Dimensions — Schedule, OD & Wall Thickness Calculator
ASME B36.10M — Welded and Seamless Wrought Steel Pipe
ASME B36.10M — Welded and Seamless Wrought Steel Pipe — is the dimensional standard that defines the outside diameter (OD) and wall thickness for every standard schedule of carbon and alloy steel pipe from DN 6 (NPS ⅛") to DN 3 600 (NPS 144"). It is the first reference an engineer reaches for when specifying a pipe run: the OD is fixed across all schedules for a given nominal bore, and only the wall thickness t changes — from the lightest Schedule 5 through Standard (STD), Extra Strong (XS), Double Extra Strong (XXS) and the numeric schedules 10 through 160. All downstream calculations — section properties, hoop stress, pressure rating, flow area and pipe mass — are derived from the OD and t values tabulated in this standard.
ASME B36.10M is published by the American Society of Mechanical Engineers and is cited by every major piping code — ASME B31.3 (process piping), B31.4 (liquid pipelines), B31.8 (gas transmission) and others — as the dimensional basis for pressure design. Companion standard ASME B36.19M covers the same schedule system for austenitic stainless steel pipe. MechanixCalc carries the full B36.10M dimension tables in the DN / Piping Standards calculator, which returns OD, ID, wall thickness, flow area, moment of inertia, section modulus, radius of gyration and pipe mass for any nominal size and schedule, together with a Barlow allowable-pressure screen and a Darcy-Weisbach pressure-drop calculation.
Calculators that implement ASME B36.10M
What ASME B36.10M covers
- Outside diameter (OD) — fixed per nominal size (DN / NPS), tabulated from DN 6 (OD 10.2 mm) to DN 3 600 (OD 3 657.6 mm); OD does not change with schedule
- Wall thickness (t) — schedule designations: 5S, 10S, 10, 20, STD (standard), 40, 60, XS/80 (extra strong), 100, 120, 160 and XXS (double extra strong), per NPS and DN
- Inside diameter, flow area and pipe mass per unit length — derived quantities computed from OD and t; mass uses the tabulated unit weight for steel
- Material scope — carbon and alloy steel pipe manufactured by butt-welding, electric resistance welding (ERW) or seamless process; stainless steel is covered by the companion ASME B36.19M
- Companion standards — B36.10M provides dimensions for ASME B16 flanges, ASME B16.9 fittings, and is the dimensional reference for ASME B31.1 / B31.3 / B31.4 / B31.8 pressure design
- Tolerances — mill tolerance on wall thickness is −12.5 % of the nominal value (relevant to ASME B31 pressure-design deductions); OD tolerances are specified by product form (seamless vs. welded)
Governing formulas
I = π / 64 · (OD⁴ − ID⁴)where I = second moment of area (cm⁴ when OD and ID are in cm); OD = outside diameter (fixed per schedule per B36.10M); ID = inside diameter = OD − 2t; t = nominal wall thickness (from B36.10M schedule table)
m = π · t · (OD − t) · ρwhere m = mass per metre (kg/m); t = nominal wall thickness (m); OD = outside diameter (m); ρ = material density — 7 850 kg/m³ for carbon/alloy steel (B36.10M scope), 8 000 kg/m³ for stainless steel (B36.19M scope)
P_allow = 2 · SMYS · t · F / ODwhere P_allow = allowable operating pressure (MPa, using consistent SI units); SMYS = specified minimum yield strength of the pipe material (MPa); t = nominal wall thickness from B36.10M (mm, same unit as OD); F = design factor per applicable B31 code (e.g. 0.72 for B31.3 normal service); OD = outside diameter from B36.10M (mm). Note: this is a screening equation — the final code design must deduct the 12.5 % mill tolerance on t and apply weld efficiency and temperature de-rating per the applicable B31 code.
Frequently asked questions
What is ASME B36.10M used for?
ASME B36.10M specifies the outside diameter and wall thickness for every standard schedule of carbon and alloy steel pipe. It is the dimensional reference for every ASME B31 piping code (B31.1 power piping, B31.3 process piping, B31.4 liquid pipelines, B31.8 gas transmission): when a code equation asks for t (wall thickness) or OD, the numbers come from B36.10M. It is also the basis for selecting ASME B16 flanges and B16.9 fittings to match a given pipe size.
What is the difference between ASME B36.10M and ASME B36.19M?
B36.10M covers carbon and alloy steel pipe — the most common material for process, utility and transmission piping — in schedules 5 through XXS. B36.19M covers austenitic stainless steel pipe in the S-series schedules (5S, 10S, 40S, 80S). For a given DN / NPS the outside diameter is identical in both standards; the wall thicknesses differ slightly for some sizes. The MechanixCalc DN tool carries both.
Does the schedule number equal the allowable pressure?
No. The schedule number (10, 40, 80, 160 etc.) is purely a wall-thickness designator defined in B36.10M — it is not a pressure rating. Allowable pressure depends on material grade (SMYS), design temperature, weld efficiency and the applicable B31 code. The Barlow formula (P = 2·SMYS·t·F/OD) is the standard screening equation; the MechanixCalc DN tool applies it with the ASME B31 design factor.
What is the 12.5 % mill tolerance and why does it matter?
ASME B36.10M allows the manufacturer to deliver pipe with wall thickness up to 12.5 % under the nominal value. When the applicable B31 code (e.g. B31.3 §304.1.1) performs the pressure wall-thickness calculation, it therefore uses t_min = 0.875 × t_nominal to find the minimum required t, which is then rounded up to the next available schedule. If you screen with the Barlow formula, you should reduce t by 12.5 % to account for this tolerance.
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