1. What is ASTM A671 CJB115 Class 22 Steel Pipe?
Answer:
ASTM A671 CJB115 Class 22 is an electric-fusion-welded (EFW) carbon steel pipe designed for high-pressure and elevated-temperature industrial applications (operating above -20°F/-29°C). The "Class 22" designation indicates a minimum yield strength of 22 ksi (152 MPa), positioning it between standard and specialized high-pressure systems in the CJB115 series.
2. Key Material Properties?
Answer:
Mechanical:
Yield Strength: ≥22 ksi (152 MPa).
Tensile Strength: 80–100 ksi (552–690 MPa).
Impact Test: Optional (required if specified for low-temperature use).
Chemical Composition:
Carbon (C): ≤0.35%, Manganese (Mn): ≤1.35%, P/S: ≤0.035%.
3. Typical Applications?
Answer:
High-pressure steam lines in power plants.
Process piping for oil refineries and chemical plants.
Industrial boilers and heat exchangers with moderate thermal stress.
4. How Does It Compare to Class 21 and Class 25?
Answer:
| Class | Yield Strength | Key Use Case |
|---|---|---|
| Class 21 | 21 ksi (145 MPa) | High-pressure systems |
| Class 22 | 22 ksi (152 MPa) | Enhanced high-pressure/thermal |
| Class 25 | 25 ksi (172 MPa) | Specialized high-pressure |
5. Fabrication & Quality Control?
Answer:
Welding: Preheat (300–400°F) required for thickness >1" (25.4 mm).
Testing: Hydrostatic (1.5x design pressure) + optional NDE (UT/RT).
Forming: Hot bending recommended for severe deformations.
Inspection: Full compliance with ASTM A671-26 standards.
