1. What is ASTM A671 CC60 Class 31?
Definition: Ultra-high-performance EFW pipe for extreme-pressure and cryogenic service, designed for critical energy and industrial infrastructure.
Key Specs:
Yield Strength: 60 ksi (414 MPa) at -20°F (-29°C).
Pressure Rating: 18,000 psi (1,241 bar) (Class 31).
Material: Carbon steel with enhanced fracture toughness (Charpy V-notch ≥25 ft-lb at -50°F/-45°C).
2. Where is it Used?
Oil & Gas:
Subsea umbilicals in >4,000m depths.
HP/HT (High-Pressure/High-Temperature) wells.
Industrial:
Supercritical fluid systems (CO₂, H₂O).
Nuclear fusion reactor coolant loops (non-radioactive zones).
3. Material & Testing Requirements
| Property | Requirement | Test Standard (ASTM) |
|---|---|---|
| Hydrostatic Test | 1.5x design pressure (27,000 psi) | A671 Section 12 |
| Charpy Impact | ≥25 ft-lb (34 J) at -50°F (-45°C) | A673 (Group 4) |
| NDT | Phased-array UT + DR radiography | E2704 / E1032 |
4. Manufacturing & Certification
Process:
Laser-hybrid welding with AI-powered defect mapping.
Quench & temper + PWHT (mandatory for all thicknesses).
Certification:
ASME B31.3 Class 2 + API 5L PSL3.
NACE MR0175 Level IV (sour service).
5. Operational Limits & Standards
Temperature: -50°F to 800°F (-45°C to 427°C).
Max Pressure: ≤18,000 psi (1,241 bar).
Compliance:
ISO 3183:2027 (Ultra-HP pipelines).
ASME BPVC Section III (Nuclear applications).
