1. What does "CJH115 Class 20" signify?
CJH115: Charpy V-notch impact testing at -115°F (-81°C) (H=high-strength, J=longitudinal test).
Class 20: Hydrostatic test pressure of 20,000 psi (138 MPa), indicating higher pressure tolerance than Class 12.
2. Key differences from Class 12?
Higher pressure rating (20K vs. 12K psi).
Stricter toughness requirements for cryogenic applications.
Typically uses modified chemistry/heat treatment (e.g., microalloyed steels).
3. Typical applications?
LNG terminals, subzero pipelines, and offshore platforms in Arctic regions.
Critical for high-pressure cryogenic storage (e.g., ethylene transport).
4. Mechanical properties?
Tensile: ≥70 ksi (483 MPa)
Yield: ≥40 ksi (276 MPa)
Impact energy: ≥20 ft-lb (27 J) at -115°F
Elongation: ≥20% (2" gauge length).
5. Fabrication requirements?
100% radiography + PWHT (Post-Weld Heat Treatment).
Double-welded seams for integrity.
Traceability for alloy batches due to stringent low-T specs.
