What Is ASME B36.10?

ASME B36.10M is the dimensional standard for welded and seamless wrought steel pipe. It defines the outside diameter (OD), wall thickness, and weight per unit length for carbon steel, alloy steel, and ferritic stainless steel pipe designated by NPS and schedule number. Every pipe specification for ferrous materials, including ASTM A106, ASTM A53, API 5L, and ASTM A335, references ASME B36.10 for its dimensions.

The standard covers pipe from NPS 1/8 (DN 6) through NPS 80 (DN 2000).

Property	ASME B36.10M
Scope	Carbon steel, alloy steel, ferritic SS pipe
Size range	NPS 1/8 to NPS 80
Schedule range	SCH 5 to XXS
OD basis	Fixed per NPS (does not change with schedule)
Companion standard	ASME B36.19M (austenitic stainless steel)
Units	Dual: SI (mm) and US Customary (inches)

Key Dimensional Excerpts

NPS	DN	OD (mm)	SCH 40 WT (mm)	SCH 80 WT (mm)	SCH 160 WT (mm)
1/2	15	21.3	2.77	3.73	4.78
1	25	33.4	3.38	4.55	6.35
2	50	60.3	3.91	5.54	8.74
4	100	114.3	6.02	8.56	13.49
6	150	168.3	7.11	10.97	18.26
8	200	219.1	8.18	12.70	20.62
10	250	273.1	9.27	15.09	25.40
12	300	323.9	10.31	17.48	33.32
16	400	406.4	12.70	21.44	36.53
24	600	610.0	17.48	30.96	59.54

Schedule System in ASME B36.10

ASME B36.10 defines the following schedule numbers: 5, 10, 20, 30, 40, 60, 80, 100, 120, 140, 160, plus the legacy designations STD (Standard), XS (Extra Strong), and XXS (Double Extra Strong).

Legacy Name	Equivalent	Notes
STD	SCH 40 (NPS 1/8 to NPS 10)	Above NPS 10, STD = 9.53 mm (fixed)
XS	SCH 80 (NPS 1/8 to NPS 8)	Above NPS 8, XS = 12.70 mm (fixed)
XXS	No schedule equivalent	Fixed wall: varies by NPS

Pro Tip

STD and SCH 40 are identical only for NPS 1/8 through NPS 10. Above NPS 10, the wall thicknesses diverge. For NPS 12, SCH 40 = 10.31 mm but STD = 9.53 mm. Specifying “STD” when you mean “SCH 40” on a purchase order for NPS 12+ pipe will result in thinner pipe than intended. Always use the schedule number, not the legacy name, for sizes above NPS 10.

ASME B36.10 vs B36.19

Feature	ASME B36.10M	ASME B36.19M
Material	Carbon steel, alloy steel	Austenitic stainless steel
Schedules	5 to XXS	5S, 10S, 40S, 80S
OD	Same (shared OD table)	Same (shared OD table)
Wall thickness	Defined for all schedules	Only “S” schedules defined
SCH 40 vs 40S	Different WT for some sizes	Different WT for some sizes

The OD is identical between the two standards for the same NPS. A stainless NPS 6 pipe per B36.19 has the same 168.3 mm OD as a carbon steel NPS 6 pipe per B36.10. The difference is in the wall thickness values associated with each schedule designation. Complete dimensional tables for both standards are available in the ASME B36.10/B36.19 pipe size charts.

Read the full guide to pipe types