1. What is A671 CC65 Class60 steel pipe?
Answer:
A671 CC65 Class60 is an electric-fusion-welded (EFW) carbon steel pipe conforming to ASTM A671, designed for low-temperature and high-pressure service.
"CC65": Denotes a minimum yield strength of 65 ksi (448 MPa).
"Class60": Indicates post-weld heat treatment (PWHT) with tempering for enhanced toughness and stress relief, suitable for critical applications.
2. Where are A671 CC65 Class60 pipes typically used?
Answer:
Common applications include:
Cryogenic systems (e.g., LNG storage, -50°F/-45°C environments).
Power generation (high-pressure steam lines, boiler components).
Oil & gas pipelines requiring weld integrity and low-temperature ductility.
3. What are the key mechanical properties?
Answer:
Yield Strength: ≥65 ksi (448 MPa).
Tensile Strength: 75–95 ksi (517–655 MPa).
Impact Toughness: Charpy V-notch tested at -50°F/-45°C (typical requirement).
Hardness: ≤225 HB (Brinell) to prevent cracking.
4. How does Class60 differ from other A671 CC65 classes (e.g., Class52, Class53)?
Answer:
Heat Treatment: Class60 undergoes tempering after welding, balancing strength and ductility, whereas:
Class52 is normalized.
Class53 is quenched and tempered (Q&T).
Performance: Class60 prioritizes stress relief and weld stability over extreme strength (unlike Class53).
Cost: Moderate, between Class51 (stress-relieved) and Class53 (Q&T).
5. What standards and tests apply to A671 CC65 Class60?
Answer:
Primary Standard: ASTM A671 (EFW pipes for low-temperature service).
Testing:
Hydrostatic testing (per ASTM A671).
Charpy impact tests (ASTM A370).
Hardness and nondestructive examination (NDE).
