ASME B36.10 / B36.19 Steel Pipe Dimensions & Sizes Chart

　　ASME/ANSI B36.10 & B36.19 Steel Pipe Dimension 3 Characters:A completely description for steel pipe dimension includes outer diameter (OD), wall thickness (WT), pipe length (Normally 20 ft 6 meter, or 40 ft 12 meters).

　　Through these characters we could calculate the pipe weight, how much pressure pipe could bear, and the cost per foot or per meter.

　　Therefore, that’s why we always need to know a right pipe size.

　　Steel Pipe Dimensions Chart

　　ASME/ANSI B36.10 & B36.19 steel pipe dimensions chart. Covers NPS 1/8" to 48", wall thickness for schedules SCH 5S through XXS, in mm.

　　Reference: Pipe Dimension Standards & Terminology

　　Steel pipe dimensions are defined by outer diameter (OD) , wall thickness (WT) , and length. These parameters determine pipe weight, pressure capacity, and cost. The primary standards for steel pipe dimensions are ASME/ANSI B36.10M (carbon/alloy steel) and ASME/ANSI B36.19M (stainless steel).

　　ASME/ANSI B36.10 & B36.19 Standards

　　● ASME B36.10M / ANSI B36.10: Dimensions for carbon and alloy steel pipes (seamless or welded), for high or low temperature and pressure service.

　　● ASME B36.19M / ANSI B36.19: Dimensions for stainless steel pipes (seamless or welded), with additional schedules (e.g., 5S, 10S) for thinner walls.

　　Note on Pipe vs. Tube: The ASME B36.10 standard applies to pipe used for pipeline systems and fluid transmission (oil, gas, water). Unlike tube, where OD is fixed, pipe sizes are defined by NPS and schedule.

　　NPS (Nominal Pipe Size)

　　North American standard for pipe sizes, based on inches.

　　Key rule: For NPS 12" and below, the NPS number does not equal the actual OD (e.g., NPS 4" has an OD of 4.5" / 114.3mm). For NPS 14" and above, NPS equals the actual OD.

　　Pipe size is specified by NPS + Schedule (e.g., NPS 4" Sch 40).

　　DN (Nominal Diameter)

　　Metric equivalent of NPS (e.g., DN50 ≈ NPS 2"). DN is a nominal value for identification, not an exact measurement.

　　Schedule (SCH)

　　SCH indicates the wall thickness series. For the same NPS, a higher SCH number means a thicker wall and higher pressure resistance.

　　● Common schedules: SCH 5, 5S, 10, 10S, 20, 20S, 30, 40, 40S, 60, 80, 80S, 100, 120, 140, 160.

　　● "S" suffix: Used for stainless steel pipes (ASME B36.19). Example: SCH 40S.

　　● Schedule Formula: Sch. = P / [σ]t × 1000

　　(P = Design pressure in MPa;

　　[σ]t = Allowable stress at design temperature in MPa).

　　Weight Class (STD / XS / XXS)

　　Older wall thickness designations:

　　● STD (Standard): For NPS 10" and below, STD ≈ SCH 40.

　　● XS (Extra Strong): For NPS 8" and below, XS ≈ SCH 80.

　　● XXS (Double Extra Strong): Approximates SCH 160 for some sizes.

　　Refer to ASME B36.10 for exact correspondence.

　　How to describe steel pipe dimensions and size correctly?

　　For example:

　　a. Expressed as “pipe outside diameter × wall thickness”, such as Φ 88.9mm x 5.49mm (3 1/2” x 0.216” ).  114.3mm x 6.02mm (4 1/2” x 0.237”), length 6m (20ft) or 12m (40ft), Single Random Length (SRL 18-25ft), or Double Random Length (DRL 38-40ft).

　　b. Expressed as “NPS x Schedule”, NPS 3 inch x Sch 40, NPS 4 inch x Sch 40. Same size as above specification.

　　c. Expressed as “NPS x WGT Class”, NPS 3 inch x SCH STD, NPS 4 inch x SCH STD. Same size above.

　　d. There is another way, in North America and South America, usually use “Pipe Outer Diameter x lb/ft” to describe pipe size. As OD 3 1/2”,  16.8 lb/ft. lb/ft is pound per feet.

　　Frequently Asked Questions:

　　Q1: What is the difference between ASME B36.10 and B36.19?

　　A: ASME B36.10 covers carbon and alloy steel pipes, while ASME B36.19 covers stainless steel pipes. Both define dimensions and schedules, but B36.19 includes additional schedules (e.g., 5S, 10S) with thinner walls for stainless steel.

　　Q2: Is Schedule 40 the same as STD (Standard) for all pipe sizes?

　　A: No. For NPS 10" and below, SCH 40 and STD have the same wall thickness. For NPS 12" and above, STD has a thinner wall than SCH 40. Always refer to the ASME B36.10 table for exact values.

　　Q3: What does the "S" suffix in schedules like SCH 40S mean?

　　A: The "S" suffix indicates the schedule is from the stainless steel standard (ASME B36.19). For example, SCH 40S is the stainless steel equivalent to SCH 40 in carbon steel, though wall thicknesses may differ for larger sizes. For a detailed comparison of SCH 40 vs. SCH 40S pipes, including dimensions and applications, please refer to our dedicated guide.

　　Q4: Can I use this chart for welded steel pipes as well?

　　A: Yes. The dimensions and schedules defined in ASME B36.10 and B36.19 apply to both seamless and welded steel pipes.