1. What is A671 CC65 Class62 steel pipe?
Answer:
A671 CC65 Class62 is an electric-fusion-welded (EFW) carbon steel pipe conforming to ASTM A671, designed for ultra-low-temperature and high-pressure service.
"CC65": Denotes a minimum yield strength of 65 ksi (448 MPa).
"Class62": Specifies double normalizing and tempering (N+T) post-welding, ensuring exceptional toughness and microstructural stability for extreme cryogenic conditions.
2. Key applications of A671 CC65 Class62 pipes?
Answer:
These pipes are critical in:
LNG terminals and transport systems (service temperatures down to -150°F/-101°C).
Offshore oil & gas platforms (high-pressure subsea pipelines).
Nuclear/power plant auxiliary systems requiring fracture-resistant welds.
3. Mechanical properties of A671 CC65 Class62?
Answer:
Yield Strength: ≥65 ksi (448 MPa).
Tensile Strength: 75–95 ksi (517–655 MPa).
Impact Toughness: Charpy V-notch tested at -150°F/-101°C (typical minimum requirement).
Hardness: ≤200 HB (strict control to prevent cold cracking).
4. How does Class62 differ from other A671 CC65 classes (e.g., Class61)?
Answer:
Heat Treatment: Class62 undergoes double normalizing + tempering, refining grain structure more rigorously than Class61 (single austenitizing + tempering).
Performance: Superior low-temperature ductility and resistance to brittle fracture.
Cost: Highest among A671 classes due to complex thermal cycles.
5. Compliance and certification requirements?
Answer:
Standards: ASTM A671 (latest 2025 revision), ASME B31.3/B31.8 (piping codes).
Testing:
100% radiography (RT) or ultrasonic testing (UT) of welds.
Extended Charpy testing at multiple temperatures.
Hydrostatic testing at 1.5x design pressure.
