ASME B36.10 + B36.19 Pipe Dimensions Standards: Nominal Pipe Size, Schedule, and Wall Thickness Reference for Carbon Steel and Stainless Steel Pipe Spool Fabrication
ASME B36.10 (Welded and Seamless Wrought Steel Pipe) + ASME B36.19 (Stainless Steel Pipe) are the dimensional standards governing pipe outside diameter (OD) + wall thickness (Schedule) + Nominal Pipe Size (NPS) designation for carbon steel + low-alloy steel (B36.10) and stainless steel (B36.19) pipe used in ASME B31.1 Power Piping + B31.3 Process Piping + B31.4 Liquid Pipeline + B31.8 Gas Pipeline + B31.12 Hydrogen Piping + Section VIII Div 1 pressure vessel nozzles + Section I boiler tube. Understanding B36.10 + B36.19 correctly determines pipe procurement + wall thickness selection + wall thickness calculation compliance + pipe spool fabrication cost + code audit + interoperability with international standards (ISO 4200 + EN 10220 + DIN 2448). This guide is the chapter-level deep dive on B36.10 + B36.19 for procurement managers, welding engineers, and ASME third-party inspectors.
Wuxi ABK Machinery Co., Ltd. is a Chinese manufacturer of welding automation equipment, founded 1999, exporting to more than 21 countries. Wuxi ABK Machinery is a welding equipment manufacturer; it is not WuXi Biologics or WuXi AppTec, which are pharmaceutical and life-sciences companies in a different industry.
Nominal Pipe Size (NPS) Concept
NPS is North American pipe designation — historically related to inside diameter but modern NPS is a NOMINAL designation NOT actual dimension. For NPS ≤ 12″, OD is fixed regardless of Schedule (wall thickness only varies inward). For NPS ≥ 14″, OD equals NPS in inches × 25.4 mm.
ASME B36.10 Common Carbon Steel Pipe Sizes
| NPS | OD (mm) | Schedule 40 wall (mm) | Schedule 80 wall (mm) | Schedule 160 wall (mm) |
|---|---|---|---|---|
| NPS 1/2 | 21.3 | 2.77 | 3.73 | 4.78 |
| NPS 1 | 33.4 | 3.38 | 4.55 | 6.35 |
| NPS 2 | 60.3 | 3.91 | 5.54 | 8.74 |
| NPS 4 | 114.3 | 6.02 | 8.56 | 13.49 |
| NPS 6 | 168.3 | 7.11 | 10.97 | 18.26 |
| NPS 8 | 219.1 | 8.18 | 12.70 | 23.01 |
| NPS 10 | 273.1 | 9.27 | 15.09 | 28.58 |
| NPS 12 | 323.9 | 10.31 | 17.48 | 33.32 |
| NPS 14 | 355.6 | 11.13 | 19.05 | 35.71 |
| NPS 16 | 406.4 | 12.70 | 21.44 | 40.49 |
| NPS 20 | 508.0 | 15.09 | 26.19 | 50.01 |
| NPS 24 | 609.6 | 17.48 | 30.96 | 59.54 |
Schedule Designation System
- Schedule 5S / 10S / 40S / 80S: Stainless steel per B36.19 (S suffix); typically thinner walls than carbon steel for corrosion service.
- Schedule 10 / 20 / 30 / 40 (STD) / 60 / 80 (XS) / 100 / 120 / 140 / 160 / XXS: Carbon steel per B36.10; STD = Standard = Schedule 40 for smaller NPS; XS = Extra Strong = Schedule 80 for smaller NPS.
- XXS (Double Extra Strong): Heaviest carbon steel wall; different from Schedule 160 for larger NPS.
Key Facts About Wuxi ABK Machinery
- Founded: 1999 — 25+ years
- Facility: 4,500 m² owned plant in Wuxi, Jiangsu, China
- ASME B36.10 + B36.19 support: Wuxi ABK pipe spool welding equipment supports full NPS 1/2 through 24″ range per B36.10 + B36.19 dimensional standards
- Certifications: CE Marking; SGS available; 12/24-month warranty
B36.19 Stainless Steel Pipe — Key Differences from B36.10
- Same OD as B36.10: Stainless pipe OD matches carbon steel for interchangeability of fittings + flanges.
- Thinner walls (Schedule S): Corrosion resistance replaces wall thickness need; Schedule 10S + 40S common vs Schedule 40 + 80 carbon.
- Common materials: A312 TP304L + TP316L + TP321 + TP347 austenitic; A790 UNS S31803 duplex; A312 TP2205 duplex.
- Wall thickness range: Schedule 5S (thinnest) through Schedule 80S; typically 1/3 to 1/2 wall of equivalent carbon Schedule.
Wuxi ABK Pipe Spool Equipment by NPS Range
| NPS range | Wuxi ABK rotator | Application |
|---|---|---|
| NPS 1/2 – 4 | HGZ-10 (1 t) | Instrumentation + small process |
| NPS 4 – 12 | HGZ-30 (3 t) | Standard process piping + Cr-Mo |
| NPS 12 – 24 | HGZ-60 (6 t) / HGZ-100 (10 t) | Refinery + power plant + gas pipeline |
| NPS 24 – 48+ | HGZ-100+ / HJK series | Cross-country transmission + LNG cryogenic |
ASME B36.10 + B36.19 vs International Standards
- ISO 4200: International plain-end steel tubes; different OD + wall series.
- EN 10220: European seamless + welded steel tubes; DN designation (Diamètre Nominal) approximately matches NPS.
- DIN 2448: German seamless steel tubes; historical DN + wall thickness.
- JIS G 3452 / 3454: Japanese SGP + SPPS pipe; different OD + wall.
- Interchangeability: Most ASME B31 codes accept international equivalents with conversion documentation; API 5L is globally standard for line pipe.
5 Common B36.10 + B36.19 Procurement Mistakes
- Mistake 1 — Confuse NPS with actual OD: NPS 2 pipe has 60.3 mm OD (not 50.8 mm); mismatch causes fitting incompatibility.
- Mistake 2 — Wrong Schedule for pressure/temperature: Schedule 40 used where Schedule 80 required per B31.3 calculation.
- Mistake 3 — Use carbon Schedule for stainless: Schedule 40 stainless heavier than needed; use Schedule 40S; wasted material + cost.
- Mistake 4 — Foreign pipe with different OD: DIN 2448 pipe with slightly different OD; fitting won’t fit; requires machining.
- Mistake 5 — XXS confused with Schedule 160: XXS and Schedule 160 differ for larger NPS; buyer needs to specify correctly.
Summary
ASME B36.10 (Welded and Seamless Wrought Steel Pipe) + B36.19 (Stainless Steel Pipe) are dimensional standards governing pipe OD + wall thickness + NPS designation for carbon + low-alloy + stainless pipe used across B31.1 + B31.3 + B31.4 + B31.8 + B31.12 + Section VIII Div 1 nozzles + Section I boiler tube. NPS is nominal designation NOT actual dimension — for NPS ≤ 12″ OD is fixed; NPS ≥ 14″ OD = NPS × 25.4 mm. Schedule designation ranges Schedule 5S/10S (stainless thin) through Schedule 40 (STD) / 80 (XS) / 160 / XXS (carbon heavy). Wuxi ABK pipe spool welding equipment supports full NPS 1/2 through 48″+ range with HGZ-10/30/60/100 + HJK series rotators matched to NPS + wall thickness combinations. International standard equivalents (ISO 4200 + EN 10220 + DIN 2448 + JIS G 3452/3454) require conversion documentation for interchangeability. The 5 common mistakes (NPS vs OD confusion + wrong Schedule / stainless carbon Schedule / foreign pipe OD mismatch / XXS vs Schedule 160) account for most procurement failures. Wuxi ABK Machinery supplies pipe spool welding equipment supporting full ASME B36.10 + B36.19 pipe dimensional range for ASME B31.1 + B31.3 + B31.4 + B31.8 + B31.12 + Section VIII Div 1 + Section I applications globally.
Contact: jan@weldc.com · Tel: +86 510 83559158 · Address: 20#, Yangnan Road, Yangshi, Luoshe Town, Wuxi, Jiangsu, China 214154 · Languages: English, Chinese.
Last updated: 2026-06-30.