1. What is ASTM A671 CJB115 Class 30 Steel Pipe?
Answer:
ASTM A671 CJB115 Class 30 is a high-strength electric-fusion-welded (EFW) carbon steel pipe designed for ultra-high-pressure industrial applications (operating above -20°F/-29°C). The "Class 30" designation indicates a minimum yield strength of 30 ksi (207 MPa), making it suitable for extreme pressure and structural load conditions.
2. Key Material Properties?
Answer:
Mechanical:
Yield Strength: ≥30 ksi (207 MPa)
Tensile Strength: 90–110 ksi (621–759 MPa)
Impact Test: Required for specified applications (e.g., cyclic loading)
Chemical Composition:
Carbon (C): ≤0.35%
Manganese (Mn): ≤1.40% (adjusted for strength)
Phosphorus/Sulfur (P/S): ≤0.035%
3. Typical Applications?
Answer:
Ultra-high-pressure hydraulic systems (e.g., oilfield equipment)
Power plant main steam lines (up to 1,000 psi+)
Heavy industrial structural supports (e.g., offshore platforms)
4. How Does It Compare to Class 25 and Class 35?
Answer:
| Class | Yield Strength | Key Difference |
|---|---|---|
| Class 25 | 25 ksi (172 MPa) | High-pressure systems |
| Class 30 | 30 ksi (207 MPa) | Ultra-high-pressure/structural |
| Class 35 | 35 ksi (241 MPa) | Specialized extreme-pressure |
5. Fabrication & Quality Control?
Answer:
Welding: Preheat (350–450°F) mandatory + PWHT (Post-Weld Heat Treatment)
Testing: Hydrostatic (2x design pressure) + mandatory UT/RT for critical welds
Forming: Hot bending only for severe deformations
Inspection: Full compliance with ASTM A671-26, including hardness testing
