ASTM A320 L7 L7M Low Temperature Stud Bolt

ASTM A320 L7 and L7M stud bolts are specially engineered alloy steel fasteners designed for low-temperature and cryogenic applications where excellent impact toughness and reliable mechanical performance are required. Manufactured through quenching and tempering processes, these stud bolts maintain high strength and resistance to brittle fracture in temperatures as low as -101°C (-150°F).

Key Advantages of ASTM A320 L7 L7M Low Temperature Stud Bolt

✔ Excellent low-temperature impact toughness

✔ Superior resistance to brittle fracture under cryogenic service

✔ Stable mechanical properties at sub-zero temperature

✔ Suitable for pressure-containing equipment in cold environments

✔ Good tensile strength and hardness consistency

✔ Reliable performance for pipeline and vessel flange joints

✔ Compatible with ASTM A194 Grade 7 nuts

Technical Specifications

Property	ASTM A320 L7	ASTM A320 L7M
Material	Alloy Steel	Alloy Steel
Standard	ASTM A320	ASTM A320
Thread Type	UNC / UNF / 8UN	UNC / UNF / 8UN
Diameter Range	1/2″ – 4″	1/2″ – 4″
Length Range	Up to 6000 mm	Up to 6000 mm
Surface Finish	Plain, Black Oxide, Zinc Plated, Xylan, PTFE, Hot Dip Galvanized	Plain, Black Oxide, Zinc Plated, Xylan, PTFE, Hot Dip Galvanized
Marking	ASTM A320 L7 / L7M + Heat Number	ASTM A320 L7M + Heat Number
Matching Nuts	ASTM A194 Grade 4, 7, 7M, 8M	ASTM A194 Grade 4, 7, 7M, 8M

Chemical Composition

Elements	ASTM A320 L7	ASTM A320 L7M
Carbon	0.36–0.47%	0.28–0.47%
Manganese	0.45–0.70%, max	0.45–0.70%, max
Phosphorus	≤0.04%	≤0.04%
Sulfur	≤0.04%	≤0.04%
Silicon	0.15–0.35%	0.15–0.35%
Chromium	0.80–1.15%	0.80–1.15%
Molybdenum	0.50–0.65%	0.50–0.65%
Vanadium	0.25–0.35%	0.25–0.35%
Aluminium	≤0.02%	≤0.02%

Mechanical Properties

Elements	ASTM A320 L7	ASTM A320 L7M
Tensile Strength	≥125 ksi (860 MPa)	100–125 ksi (690–860 MPa)
Yield Strength	≥105 ksi (725 MPa)	≥80 ksi (550 MPa)
Hardness	24–34 HRC	20–30 HRC
Impact Test	Required (Charpy V-notch)	Required (Charpy V-notch)
Min. Service Temperature	Down to -101°C	Down to -101°C

Applications

LNG & Cryogenic Facilities	Oil & Gas Industry	Industrial Equipment
LNG Storage Tanks	API 6A Wellhead Equipment	Pressure Vessels
LNG Loading Systems	Offshore Platforms	Heat Exchangers
Cryogenic Pipelines	Subsea Systems	Compressors
Gas Processing Plants	Refinery Piping Systems	Low Temperature Valves

Application

ASTM A320 L7 ✔ Non-sour low-temperature pressure boundary joints ✔ Cryogenic vessels, pipelines & valves ✔ LNG, petrochemical and power cold service systems. ASTM A320 L7M ✔ NACE sour low-temperature flange connections ✔ Anti-sulfide stress cracking oil & gas service ✔ Offshore and cryogenic sour pressure equipment

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