1. What is ASTM A671 CH115 Class 42?
Answer: A carbon steel pipe manufactured via electric-fusion welding (EFW) for low-temperature/high-pressure service.
CH115: Specifies chemical composition (e.g., controlled Mn, Si, S/P ratios for cryogenic toughness).
Class 42: Indicates a hydrostatic test pressure of 42,000 psi (higher than Class 41).
2. Key Applications?
Answer:
LNG terminals (operating at -46°C/-50°F).
Deep-sea pipelines (high external pressure resistance).
Nuclear/power plants (coolant systems under stress).
3. How does Class 42 differ from Class 22 or 41?
Answer:
Pressure rating: Class 42 > Class 41 (41,000 psi) > Class 22 (22,000 psi).
Material toughness: CH115 chemistry ensures better impact resistance at low temps than standard grades.
4. Critical Mechanical Properties?
Answer:
Tensile strength: ≥70 ksi (485 MPa).
Yield strength: ≥40 ksi (275 MPa).
Charpy V-notch test: Mandatory at -50°F/-45°C (ensures no brittle fracture).
5. Quality & Compliance Checks?
Answer:
Testing: 100% radiography (RT) + hydrostatic test per Class 42.
Certification: Mill Test Reports (MTRs) for traceability.
Installation: Follow ASME B31.3 for process piping.
