1. What is ASTM A671 CF65 Class 70 Pipe?
Answer:
ASTM A671 CF65 Class 70 is an electric-fusion-welded (EFW) carbon steel pipe designed for low-temperature service (down to -65°F/-54°C).
Standard: ASTM A671 (for atmospheric/cryogenic pressure vessels).
Grade: CF65 indicates carbon steel with enhanced toughness at low temps.
Class 70: Minimum yield strength of 70 ksi (483 MPa).
Key Use: Cryogenic storage, LNG pipelines, and refrigeration systems.
2. Material Composition & Properties
Answer:
Chemistry: Low-carbon steel with controlled sulfur/phosphorus (e.g., max 0.025% S/P) for impact resistance.
Impact Testing: Charpy V-notch tested at -65°F to ensure ductility.
Welding: Longitudinal seam welded (SAW or similar), often with PWHT (Post-Weld Heat Treatment).
3. How Does It Compare to Similar Grades?
| Feature | A671 CF65 Class 70 | A672 (EFW Pipes) | A333 (Low-Temp Seamless) |
|---|---|---|---|
| Temp Range | Down to -65°F | -50°F to +800°F | Down to -150°F |
| Process | EFW | EFW | Seamless |
| Strength | 70 ksi yield | Varies by class | Grade-dependent |
4. Dimensions & Tolerances
Answer:
Sizes: Typically 16" to 120" OD (large-diameter pipelines).
Wall Thickness: Ranges from 0.3" to 2", depending on pressure requirements.
Tolerances: Complies with ASTM A671 Annex A (±1% OD, ±10% wall thickness).
5. Common Applications
Answer:
Primary Uses:
LNG terminals (cryogenic fluid transport).
Chemical plants (ethylene, ammonia pipelines).
Power generation (cold storage systems).
Advantage: Balances cost-effectiveness with low-temperature performance.
