1. What is ASTM A671 CJE115 Class 11 Steel Pipe?
Answer:
ASTM A671 CJE115 Class 11 is a cryogenic-grade electric-fusion-welded (EFW) carbon steel pipe designed for low-temperature service (operating temperature ≤ -55°F/-48°C). The "Class 11" designation indicates a minimum yield strength of 11 ksi (76 MPa), balancing strength and ductility for sub-zero applications.
2. Key Material Properties?
Answer:
Mechanical:
Yield Strength: ≥11 ksi (76 MPa)
Tensile Strength: 65–85 ksi (448–586 MPa)
Impact Test: Mandatory Charpy V-notch at -55°F/-48°C
Chemical:
Carbon (C): ≤0.22% (low carbon for cryogenic toughness)
Manganese (Mn): 0.70–1.40% (optimized for low-T performance)
P/S: ≤0.020% (strict impurity control)
3. Typical Applications?
Answer:
LNG (liquefied natural gas) transfer pipelines
Cryogenic storage vessels
Low-temperature chemical processing
Spacecraft liquid oxygen systems
4. How Does It Compare to Class 10 and Class 15?
Answer:
| Class | Yield Strength | Service Temperature |
|---|---|---|
| Class 10 | 10 ksi (69 MPa) | ≥ -50°F (-46°C) |
| Class 11 | 11 ksi (76 MPa) | ≥ -55°F (-48°C) |
| Class 15 | 15 ksi (103 MPa) | ≥ -20°F (-29°C) |
5. Fabrication & Certification?
Answer:
Welding:
Preheat: 225°F min. + PWHT (1150–1250°F)
Filler Metal: AWS A5.28 ER90S-G
Testing:
Hydrostatic: 1.75x design pressure
100% radiography (RT) + impact testing
Certification: ASTM A671 + ASME B31.3
