Stainless Steel Pipe Sizes, Schedules and Weight Chart (ASME B36.19)

Stainless steel pipe is ordered by nominal pipe size (NPS) and schedule, and its dimensions come from ASME B36.19. This page gives the complete size chart from ASME B36.19-2022 — outside diameter, wall thickness and nominal weight for every NPS from ⅛ to 30 in Schedules 5S, 10S, 40S, 80S and 160S — and explains how to read it, how to calculate weight for stainless grades, and what to write in an enquiry.

1. How stainless steel pipe sizes work

• NPS and DN are names, not measurements. NPS is the inch designation and DN its metric equivalent (for example NPS 2 = DN 50).
• NPS 12 (DN 300) and smaller: the outside diameter is fixed for each size and is numerically larger than the nominal size — NPS 1 pipe has an OD of 1.315 in (33.40 mm), NPS 2 pipe 2.375 in (60.32 mm).
• NPS 14 (DN 350) and larger: the outside diameter equals the nominal size — NPS 14 is 14.00 in (355.6 mm).
• The schedule sets the wall thickness. For a given NPS the OD never changes; a higher schedule means a thicker wall and a smaller bore.

Tube is different: a tube’s size is its actual OD. If you are not sure whether you need pipe or tube, see pipe vs tube: the difference and how to specify each.

2. What Schedules 5S, 10S, 40S, 80S and 160S mean

• The “S” suffix marks a stainless steel schedule under ASME B36.19 and distinguishes it from carbon steel pipe schedules in ASME B36.10.
• Schedule 10S and 5S are light-wall schedules. Stainless steel’s corrosion resistance allows thin-wall piping systems, and fusion welding removed the need to thread them; Schedule 10S walls were set to the nearest Birmingham Wire Gauge, and Schedule 5S was added later for even lighter pipe.
• Schedule 40S and 80S are heavier walls, used where more pressure capacity or threaded ends are needed.
• Schedule 160S was added in the 2022 edition for NPS ⅛ to NPS 3 and NPS 4 to NPS 6.
• Threading: Schedules 5S and 10S walls do not permit threading in accordance with ASME B1.20.1. If the pipe will be threaded, specify a heavier schedule.
• 40S vs 40, 80S vs 80, 10S vs 10: for most sizes the S and non-S walls are the same, but they differ for NPS 14–22 in Schedule 10S, NPS 12 in Schedule 40S, and NPS 10 and 12 in Schedule 80S. Always state the S schedule for stainless pipe.

3. Stainless steel pipe size and schedule chart (ASME B36.19-2022)

Find your NPS, then read across the schedule row for OD, wall thickness and nominal weight. On a phone, scroll the table sideways.

Source: ASME B36.19-2022, Table 2-1. “–” means the standard lists no wall thickness for that schedule and size. Weights are the standard’s nominal plain-end values, which are calculated for carbon steel — see section 4 for stainless steel.

4. How to calculate stainless steel pipe weight

ASME B36.19 calculates nominal plain-end weight from the outside diameter D and wall thickness t:

• kg/m = 0.0246615 × (D − t) × t, with D and t in millimetres
• lb/ft = 10.69 × (D − t) × t, with D and t in inches

The tabulated weights are based on carbon steel. The standard notes that austenitic stainless steels such as 304/304L and 316/316L are about 2% heavier, and ferritic stainless steels about 5% lighter. For example, NPS 2 Schedule 40S (60.32 mm × 3.91 mm) is listed at 5.44 kg/m; for 304 or 316L pipe, allow roughly 5.55 kg/m when estimating freight or price per metre.

5. Tolerances

ASME B36.19 sets nominal dimensions only. Permissible variations in OD, wall thickness and length depend on how the pipe is made and are given in the product specification you order to — for stainless pipe usually ASTM A312. Quote the product specification together with the size and schedule.

6. What to write in your enquiry

• Product specification (for example ASTM A312) and grade (304/304L, 316/316L, 321…)
• Seamless or welded
• NPS (or DN) and schedule, for example “NPS 2 Sch 40S” — or OD × wall if your design uses a non-standard wall
• Length (random or fixed) and end finish: plain, bevelled or threaded (remember 5S and 10S cannot be threaded to ASME B1.20.1)
• Quantity per size, testing and documents (EN 10204 3.1 or 3.2) and delivery term

How TeCarve can help

TeCarve is the sole export arm of two stainless steel tube factories in Foshan and Wenzhou, China, supplying seamless and welded stainless steel pipe to ASTM A312. Send us your NPS, schedule, grade and quantity and we will confirm availability and quote within 24 hours. Every order ships with an EN 10204 3.1 mill test certificate; trial orders start from 100–300 kg, in-stock sizes ship in 7–10 days and custom production in 10–25 days. Contact sales@tecarve.com or use our contact page.

Frequently asked questions

What is the wall thickness of 2 inch Schedule 40S stainless steel pipe?

NPS 2 Schedule 40S has an OD of 2.375 in (60.32 mm) and a wall of 0.154 in (3.91 mm), with a nominal weight of 5.44 kg/m (3.66 lb/ft).

What is the difference between Schedule 40 and Schedule 40S?

Schedule 40S is the stainless steel schedule in ASME B36.19; Schedule 40 belongs to ASME B36.10. Their walls are the same for most sizes but differ at NPS 12, so stainless pipe should always be ordered with the S schedule.

Can Schedule 10S stainless pipe be threaded?

No. ASME B36.19 notes that Schedule 5S and 10S wall thicknesses do not permit threading in accordance with ASME B1.20.1. Use a heavier schedule, such as 40S or 80S, for threaded joints.

Why is 1 inch pipe not 1 inch in diameter?

For NPS 12 and smaller, the nominal size is a designation rather than a measurement. NPS 1 pipe has an outside diameter of 1.315 in (33.40 mm). From NPS 14 upward, the OD equals the nominal size.

Are the chart weights correct for 304 and 316 stainless steel?

They are nominal weights calculated for carbon steel. Austenitic grades such as 304 and 316 are about 2% heavier, so add roughly 2% to the listed value.

Related reading: Pipe vs tube · ASTM A312 stainless steel pipe guide · Stainless steel pipe price guide · Seamless vs welded pipe & tube