Materials
Alloy Steels: A320 (L7, L7M, L43)
A320 L7
Material: Quenched and tempered alloy steel, similar in chemistry to A193 B7.
Mechanical Properties:
High tensile and yield strength.
Maintains toughness at low temperatures (down to –150°F / –101°C).
Manufacturing Considerations:
Commonly produced as bolts, studs, and nuts.
Requires proper heat treatment to balance strength and notch toughness.
Applications:
Pressure vessels, valves, flanges, and piping systems in cryogenic and subzero service.
Oil & gas, LNG, petrochemical, and power generation industries.
A320 L7M
Material: Same base alloy steel as L7, but with modified properties.
Mechanical Properties:
Lower hardness (capped at 235 HB) compared to L7.
Slightly lower strength, but improved ductility and notch toughness.
Designed to reduce the risk of hydrogen embrittlement and stress cracking.
Manufacturing Considerations:
Often specified when softer, more ductile fasteners are preferred.
Still requires precise heat treatment to meet low-temperature impact requirements.
Applications:
Pressure vessels and piping in wet H₂S service (sour service).
Used in oil & gas production, subsea, and refining environments where embrittlement risk is high.
A320 L43
Material: A chromium-molybdenum-vanadium steel (more advanced alloy than L7).
Mechanical Properties:
Higher strength than L7.
Excellent notch toughness at cryogenic temperatures (down to –150°F / –101°C).
Strong resistance to tempering embrittlement.
Manufacturing Considerations:
More difficult to machine and heat treat due to higher alloy content.
Used where strength + toughness must both be maximized.
Applications:
Critical bolting for cryogenic processing plants, LNG storage, aerospace ground support, and nuclear power.
Often chosen for mission-critical engineered fasteners in extreme cold.
Key Takeaways for Engineered Fasteners
L7 → Standard low-temperature high-strength fastener.
L7M → Softer version of L7, designed for sour service / hydrogen environments.
L43 → Premium alloy grade with higher strength and cryogenic toughness for critical applications.
Materials
BRASS
BRONZE
COPPER
PH STAINLESS STEEL
DOING WHATEVER IT TAKES
Putting Manufacturing Exellence Into Practice
The manufacturing processes, testing capabilities, and quality systems featured throughout WN Global support the production of critical components and engineered fastening solutions across demanding industries. Connect with our team to learn how our manufacturing capabilities can support your project requirements.
