1. What is ASTM A671 CD80 Class 12 Steel Pipe?
Answer:
ASTM A671 CD80 Class 12 is an electric-fusion-welded (EFW) carbon steel pipe designed for low-temperature service (down to -80°F/-62°C). Key specifications:
CD80: Material grade requiring Charpy V-notch impact testing at -80°F to ensure cryogenic toughness.
Class 12: Minimum yield strength of 12 ksi (83 MPa), suitable for low-pressure cryogenic applications (e.g., liquid nitrogen pipelines, industrial cold storage systems).
2. What are the manufacturing and certification requirements?
Answer:
Welding: EFW process with filler metal, 100% radiography (RT) or ultrasonic testing (UT) for weld integrity.
Heat Treatment: Stress-relieved or normalized to enhance low-temperature ductility.
Certification: Mill test reports (MTRs) include:
Chemical composition (e.g., C ≤ 0.30%, Mn ≤ 1.30%).
Mechanical properties (yield strength ≥ 12 ksi, tensile strength 48–68 ksi).
Impact test results at -80°F.
3. How does Class 12 compare to other ASTM A671 classes?
Answer:
| Parameter | CD80 Class 12 | CD80 Class 20 | CD80 Class 60 |
|---|---|---|---|
| Yield Strength | 12 ksi (83 MPa) | 20 ksi (138 MPa) | 60 ksi (414 MPa) |
| Application | Low-pressure cryogenic | Moderate-pressure | High-pressure cryogenic |
| Cost | Low-to-mid range | Mid-range | Premium |
4. What are standard dimensions and tolerances?
Answer:
Diameter: 16"–120" OD (standard for industrial use).
Wall Thickness: Tolerance ±10% nominal thickness (per ASTM A671).
Length: Typically 40ft (12.2m), customizable up to 60ft.
5. How to ensure corrosion protection and longevity?
Answer:
External:
Epoxy or polyethylene coating for indoor/mild environments.
Cathodic protection for buried installations.
Internal:
FBE lining for chemical resistance (e.g., ammonia-based refrigeration).
Maintenance: Annual inspections for coating integrity.
