1. What is ASTM A671 CH115 Class 43?
Answer: A carbon steel pipe manufactured via electric-fusion welding (EFW), designed for ultra-high-pressure and cryogenic service (-50°F/-45°C).
CH115: Specifies enhanced Mn/Si content and controlled impurities (S/P ≤0.025%) for low-temperature toughness.
Class 43: Hydrostatic test pressure of 43,000 psi, the highest in ASTM A671 Class series.
2. Typical Applications?
Answer:
Subsea oil/gas pipelines (deepwater high-pressure environments).
LNG storage/transport (cryogenic tanks, loading arms).
Nuclear power systems (primary coolant loops under extreme conditions).
3. Key Differences from Class 42 or Lower?
Answer:
Pressure capacity: Class 43 (43,000 psi) > Class 42 (42,000 psi) > Class 22 (22,000 psi).
Material rigor: Stricter impact testing (-50°F Charpy V-notch) and 100% radiographic inspection (RT).
4. Mechanical & Chemical Properties?
Answer:
Tensile strength: ≥70 ksi (485 MPa).
Yield strength: ≥40 ksi (275 MPa).
Chemistry: C≤0.30%, Mn≤1.35%, Si≥0.10% (optimized for weldability and toughness).
5. Quality Assurance & Standards?
Answer:
Testing: Hydrostatic + RT + ultrasonic testing (UT, if specified).
Certification: MTRs (Mill Test Reports) with traceable heat numbers.
Compliance: ASTM A671 (material) + ASME B31.3 (installation).
