1. What is ASTM A671 CC70 Class 10?
Answer:
ASTM A671 CC70 Class 10 refers to electric-fusion-welded carbon steel pipes designed for low-temperature and moderate-pressure service (typically rated for -50°F/-45°C and below).
Grade CC70: Higher carbon-manganese content than CC65 (C ≤0.35%, Mn up to 1.20%) for improved strength.
Class 10: Indicates a minimum yield strength of 10 ksi (69 MPa) and specific wall thickness/pressure ratings.
Standard: ASTM A671, primarily for atmospheric/low-temperature pressure vessels.
Key Distinction: Lower yield strength than CC65 grades (e.g., Class 70/71), but cost-effective for less demanding低温applications.
2. Typical Applications of Class 10 Pipes?
Answer:
Used in industries requiring moderate低温resistance:
Refrigeration Systems: Ammonia or Freon pipelines.
Oil & Gas: Secondary low-pressure cryogenic lines (non-critical).
Chemical Plants: Mild corrosive fluid transport at reduced temperatures.
3. Material Properties & Testing Requirements?
Answer:
Mechanical Properties:
Yield Strength: ≥10 ksi (69 MPa).
Tensile Strength: 60–85 ksi (414–586 MPa).
Impact Testing: Optional for Class 10 (project-specific; Charpy V-notch at -50°F/-45°C if required).
NDT: Spot radiography (RT) or visual inspection (VT), unless specified otherwise.
4. How Does Class 10 Compare to CC65 Grades?
Answer:
| Parameter | CC70 Class 10 | CC65 Class 70/71 |
|---|---|---|
| Temperature Range | -50°F/-45°C | -65°F/-54°C |
| Yield Strength | 10 ksi (69 MPa) | 70+ ksi (483+ MPa) |
| Cost | Lower | Higher |
| Note: Class 10 is not suitable for severe cryogenic or high-pressure applications. |
5. Fabrication & Welding Guidelines?
Answer:
Welding:
Preheat 150–250°F (66–121°C) if thickness exceeds 1 inch (25 mm).
Electrodes: AWS E6010/E7018 for general welding.
Post-Weld Treatment: PWHT optional unless specified (e.g., for thick sections).
Corrosion Protection: Paint or epoxy coatings for mild environments.
