1. What is ASTM A671 CJF115 Class 61?
A high-performance electric-fusion-welded pipe for extreme cryogenic and ultra-high-pressure service (down to -75°F/-60°C).
CJF115: Carbon steel with 2.25% nickel for superior low-temperature toughness.
Class 61: Hydrostatic test pressure of 61,000 psi (421 MPa)-the highest grade in the ASTM A671 standard.
2. Key Applications?
Designed for the most demanding environments:
Ultra-high-pressure LNG export terminals
Deep-sea cryogenic pipelines (subsea manifolds, risers)
Nuclear or aerospace cryogenic systems
High-pressure hydrogen infrastructure
Arctic drilling platforms with extreme pressure requirements
3. Manufacturing & Testing Requirements?
Double-welded seams with 100% RT/UT (radiographic + ultrasonic testing).
Charpy V-notch testing at -75°F/-60°C (minimum 30 ft-lb avg. energy).
Quenched & tempered heat treatment for optimal strength-toughness balance.
Strict hardness control (≤190 HBW) with mandatory PWHT (Post-Weld Heat Treatment).
4. Mechanical Properties?
Tensile strength: ≥80 ksi (550 MPa)
Yield strength: ≥50 ksi (345 MPa)
Elongation: ≥18% (ensures ductility under extreme loads).
Impact toughness: Certified for -60°C with enhanced energy absorption.
5. How does Class 61 surpass Class 60?
Higher pressure capacity (61k vs. 60k psi).
Tougher impact requirements (30 ft-lb vs. 25 ft-lb).
Stricter weld integrity checks (additional UT beyond RT).
Reduced maximum hardness (190 HBW vs. 200 HBW) for crack resistance.
