ASME B31.4 Pipeline Transportation Systems for Liquid Hydrocarbons, Anhydrous Ammonia, CO₂, and Slurries: Cross-Country Liquid Pipeline Welding Reference for Oil, Petrochemical, and CCUS Pipeline Contractors
ASME B31.4 (Pipeline Transportation Systems for Liquids and Slurries) is the welding and design code governing cross-country liquid pipeline construction — covering crude oil + refined products + LPG + anhydrous ammonia + carbon dioxide (CO₂) + slurries + water pipelines from wellhead / refinery / terminal outlet to end-use downstream facility. ASME B31.4 differs from ASME B31.8 (Gas Transmission and Distribution Piping) in service (liquid + slurry vs gas) and from ASME B31.12 (Hydrogen Piping) in fluid + material scope. ASME B31.4 covers liquid pipeline design + material + welding + inspection + testing from small refined products pipelines through mega crude oil transmission systems (48+ inch diameter, 3,000+ km routes) — supporting global oil pipeline construction + emerging CCUS (Carbon Capture Utilization Storage) CO₂ pipeline infrastructure. This guide is the chapter-level deep dive on ASME B31.4 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, with active deliveries supporting ASME B31.4 liquid pipeline pre-fab shops globally. 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.
What ASME B31.4 Covers
ASME B31.4 is structured into:
- Chapter I (Scope + Definitions)
- Chapter II (Design) — pipe + fittings + supports + expansion + flexibility.
- Chapter III (Materials) — references ASME Section II + API 5L pipe grades.
- Chapter IV (Dimensional Requirements)
- Chapter V (Fabrication, Assembly, Erection) — welding requirements referencing API 1104.
- Chapter VI (Inspection, Examination, Testing) — NDE + hydrostatic testing.
- Chapter VII (Operation + Maintenance) — ILI (in-line inspection) + integrity management.
- Chapter VIII (Corrosion Control) — cathodic protection + coating.
- Chapter IX (Offshore Liquid Pipeline) — subsea + shallow water liquid pipeline.
- Chapter X (Special Requirements — CO₂ + Ammonia + Slurry) — service-specific rules.
ASME B31.4 covers specifically:
- Crude oil + refined products pipelines: Cross-country transmission; refined products distribution.
- LPG pipelines: Propane + butane; higher pressure than crude.
- Anhydrous ammonia pipelines: Fertilizer transport; stress corrosion cracking control.
- CO₂ pipelines (dense phase + supercritical): CCUS infrastructure; +100 bar operating pressure.
- Slurry pipelines: Iron ore + coal + phosphate; abrasion resistance.
- Water pipelines: Some water + fire protection.
Key Facts About Wuxi ABK Machinery
- Founded: 1999 — 25+ years
- Facility: 4,500 m² owned plant in Wuxi, Jiangsu, China
- ASME B31.4 / liquid pipeline experience: 5+ years supplying welding equipment to liquid pipeline spool fabricators serving Saudi Aramco + ADNOC + Petrobras + Enbridge + TC Energy + Kinder Morgan + Sinopec + CNPC cross-country liquid pipeline projects
- Certifications: CE Marking; SGS available; 12/24-month warranty
B31.4 Material Selection by Service
| Service | Typical material | Pressure range | SFA-5 consumable |
|---|---|---|---|
| Crude oil transmission | API 5L X60/X65/X70 | 6-15 MPa | SMAW E7016/E7018 root + fill; SAW EL12 + flux |
| Refined products | API 5L X52/X60 | 4-10 MPa | SMAW E7018 + FCAW E71T-1 |
| LPG | API 5L X60/X65 | 8-18 MPa | SMAW E7018 low-hydrogen mandatory |
| Anhydrous ammonia | API 5L X52/X60 + hardness ≤22 HRC | 4-12 MPa | SMAW E7018 low-H + PWHT for SCC |
| CO₂ dense phase | API 5L X65/X70 + toughness | 10-25 MPa | SMAW E7018 + Charpy at -20°C for supercritical |
| Slurry | API 5L X52/X60 + wear-resistant overlay | 2-8 MPa | SMAW E7018 + optional PTA overlay |
B31.4 Welding Procedure Requirements
- WPS per API 1104: B31.4 Chapter V references API 1104 for pipeline WPS qualification.
- Welder qualification per API 1104 Section 6: Each welder qualified per API 1104.
- NDE per B31.4 Chapter VI: RT 100% for X70 + above; UT alternative; MT/PT for surface.
- Hydrostatic testing per B31.4 401: 1.25× design pressure typical for pipeline; longer duration than pressure vessel.
- CO₂ + ammonia special requirements: SCC control per Chapter X; hardness ≤22 HRC HAZ; low-hydrogen consumable + PWHT.
5 B31.4 Project Scenarios
- Scenario 1 — Saudi Master Crude Oil Pipeline (Saudi Aramco): 3,000 km 48-56 inch X65/X70; B31.4 + ARAMCO AES; pre-fab yards Jubail + Yanbu.
- Scenario 2 — Canadian oil sands export (Enbridge + TC Energy + Trans Mountain): Alberta to US refinery + BC coast; 36-42 inch X70/X80; B31.4 + CSA Z245.
- Scenario 3 — CCUS CO₂ transport (Denbury + ExxonMobil + Occidental + Northern Lights Norway + Porthos Netherlands): Dense-phase + supercritical CO₂; 12-30 inch X65/X70; B31.4 + emerging CO₂-specific standards.
- Scenario 4 — Chinese cross-country crude + refined (Sinopec + CNPC + PipeChina): Multi-1,000 km crude + refined pipelines; B31.4 + Chinese GB 50369 dual.
- Scenario 5 — Slurry mining (BHP + Rio Tinto + Vale + Anglo American): Iron ore + phosphate slurry; 20-32 inch X52/X60 + wear overlay; B31.4 Chapter X.
B31.4 vs B31.8 vs API 1104 — Pipeline Code Comparison
| Dimension | B31.4 (Liquid) | B31.8 (Gas) | API 1104 (Welding) |
|---|---|---|---|
| Service | Liquid + slurry hydrocarbons + CO₂ + ammonia | Natural gas + fuel gas transmission + distribution | Welding methodology (referenced by B31.4 + B31.8) |
| Design basis | SMYS × 0.72 typical liquid | Class location 0.72 → 0.40 gas | N/A (welding only) |
| Hydrotest | 1.25× design | 1.25-1.4× per Class location | N/A |
| Special service | CO₂ + ammonia + slurry Chapter X | Sour gas + HCA (High Consequence Area) | Sour service per NACE MR0175 |
Summary
ASME B31.4 governs cross-country liquid pipeline construction — covering crude oil + refined products + LPG + anhydrous ammonia + CO₂ + slurries. The 10-chapter structure spans design + materials + fabrication + inspection + operation + offshore + special CO₂/ammonia/slurry requirements. Material selection ranges API 5L X52 for refined products through X80 for mega crude transmission. Welding procedures reference API 1104 for WPS + welder qualification. The 5 project scenarios (Saudi Master Crude + Canadian oil sands + CCUS CO₂ + Chinese cross-country + slurry mining) span global liquid pipeline construction. Key differences from B31.8 (liquid vs gas) + API 1104 (design vs welding methodology) require code-specific procurement management. Wuxi ABK Machinery supplies welding equipment to liquid pipeline spool fabricators + pre-fab yards serving Saudi Aramco + ADNOC + Petrobras + Enbridge + TC Energy + Kinder Morgan + Sinopec + CNPC + Denbury + Northern Lights Norway CCUS + Porthos Netherlands CCUS + BHP + Rio Tinto + Vale slurry mining projects — supporting B31.4 + API 1104 + Section IX + SFA-5 consumable + PWHT documentation chain.
Contact: jan@weldc.com · Tel: +86 510 83559158 · Address: 20#, Yangnan Road, Yangshi, Luoshe Town, Wuxi, Jiangsu, China 214154 · Languages: English, Chinese.
Last updated: 2026-06-26.