1. What is ASTM A671 CC65 Class 40 Pipe?
Definition: An electric-fusion-welded (EFW) carbon steel pipe for low-temperature and high-pressure service, meeting ASTM A671 standards.
Grade: CC65 (carbon steel: ≤0.30% C, ≤1.00% Mn).
Class: 40 (higher pressure rating than Class 33, designed for cryogenic/critical applications).
2. Key Material Properties
Tensile Strength: ≥65 ksi (448 MPa).
Impact Testing: Required at -50°F (-45°C) or lower (validates extreme cold toughness).
Welding: 100% radiography (RT) or ultrasonic testing (UT) mandated.
3. Typical Applications
Oil & Gas: LNG transport, cryogenic pipelines.
Energy: High-pressure steam systems in cold climates.
Industrial: Arctic infrastructure, pressure vessels.
4. How Does Class 40 Differ from Lower Classes (e.g., 30-33)?
| Parameter | Class 40 | Class 30-33 |
|---|---|---|
| Design Pressure | Highest (~400 psi) | Lower (~300-330 psi) |
| NDT Requirements | 100% RT/UT + PMI (strictest) | Partial RT/UT for lower classes |
| Impact Test Temp | -50°F or below | -20°F to -50°F |
5. Testing & Certification
Hydrostatic Test: 1.5x design pressure for ≥10 sec.
Certification: MTRs with chemistry, mechanical tests, and NDT reports.
Optional: Charpy V-notch, hardness, PMI.
