1. What is ASTM A671 CJH115 Class 12?
A specification for electric-fusion-welded steel pipe designed for low-temperature service (down to -50°F/-46°C).
CJH115: Carbon steel with 3.5% nickel for superior cryogenic toughness.
Class 12: Hydrostatic test pressure of 12,000 psi (83 MPa).
Key upgrade: 9% higher pressure rating vs. Class 11 (12k vs. 11k psi).
2. Where is it typically applied?
Ideal for:
LNG terminal secondary piping
Cryogenic pump headers
Industrial refrigeration systems
Chemical transport in cold climates
3. What are the manufacturing standards?
Double-welded seams with 100% radiographic inspection.
Charpy V-notch testing at -50°F/-46°C (min. 20 ft-lb impact energy).
Normalized heat treatment for uniform grain structure.
Hardness control: ≤200 HBW to prevent weld cracking.
4. Mechanical properties?
Tensile strength: ≥65 ksi (448 MPa)
Yield strength: ≥40 ksi (276 MPa)
Elongation: ≥22% (ensures ductility under thermal stress).
Impact toughness: Verified at -46°C per ASTM A370.
5. How does it compare to similar grades?
| Feature | CJH115 Class 12 | CJF115 Class 12 |
|---|---|---|
| Nickel | 3.5% | 2.25% |
| Temp | -46°C | -60°C |
| Cost | Higher | Lower |
| Use Case | Moderate cryogenics | Extreme cryogenics |
