1. What is ASTM A671 CJB115 Class 20 steel pipe?
Answer:
ASTM A671 CJB115 Class 20 is an electric-fusion-welded (EFW) carbon steel pipe designed for high-pressure industrial applications (typically operating above -20°F/-29°C). The "Class 20" designation indicates a minimum yield strength of 20 ksi (138 MPa), making it suitable for demanding pressure systems in industrial settings.
2. Key specifications and material properties?
Answer:
Material Grade: CJB115 carbon steel (higher carbon content than CJA grades)
Yield Strength: ≥20 ksi (138 MPa)
Tensile Strength: 70-90 ksi (483-621 MPa)
Impact Test: Required only for specified low-temperature applications
Chemical Composition:
Carbon (C): ≤0.35%
Manganese (Mn): ≤1.35%
Phosphorus/Sulfur (P/S): ≤0.035%
3. Typical industrial applications?
Answer:
High-pressure fluid transport (steam, oil, gas)
Power plant piping systems
Industrial process lines with elevated pressure requirements
4. How does it compare to adjacent classes?
Answer:
| Class | Yield Strength | Typical Use Case |
|---|---|---|
| 15 | 15 ksi | Medium-high pressure |
| 20 | 20 ksi | High-pressure industrial |
| 25 | 25 ksi | Special high-pressure systems |
5. Fabrication and quality control requirements?
Answer:
Welding: Preheat (200-300°F) required for thickness >1" (25.4 mm)
Testing: Hydrostatic test at 1.5x design pressure + optional NDE
Forming: Hot bending recommended for severe deformations
Inspection: Full compliance with ASTM A671-26 standards
