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Products > Studs & Nuts > Stud Bolts
Stud Bolts
Our Thread Studs Bolts are manufactured to ASTM A193 and A320 specifications to ensure reliable performance in high-pressure, high-temperature, and cryogenic service environments. Available in Grades B7, B7M, B8, B8M, B16, B8C2, B8M C2, L7, and L7M, these studs provide exceptional strength and durability for critical bolting applications across industrial sectors.
Each stud is precision-machined and heat-treated to meet the mechanical and chemical requirements of its grade. From carbon and alloy steels (B7, B16, L7) to austenitic stainless steels (B8, B8M, B8C2), we offer materials suited for demanding environments such as refineries, power plants, and process facilities.
Available with a variety of finishes including plain, zinc-plated, hot-dip galvanized, or PTFE-coated, all studs are fully traceable with MTRs upon request.
Features:
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Conforms to ASTM A193 / A320 and ASME B18.31.2 standards
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Available in sizes from ¼” to 4” diameter and custom lengths
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Heat-treated and hardness tested for superior mechanical properties
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Threaded full-length for secure and adjustable bolting connections
Applications:
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Flange connections and valve assemblies
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Pressure vessels and heat exchangers
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Oil & gas, petrochemical, and power generation industries
Stud Bolt Overview
All-thread stud bolts are fully threaded fasteners with chamfered ends and no head, designed for high-strength bolting applications. They are typically used with two heavy hex nuts to create secure connections in pressure-rated systems.
These studs are known for their superior tensile strength compared to standard threaded bolts and are widely used in flange connections, as well as anchoring, automotive, and electrical applications.
Industries relying on stud bolts include oil and gas, chemical processing, power generation, manufacturing, pipeline construction, and municipal infrastructure. A wide range of materials and grades are available to meet various temperature, pressure, and corrosion-resistance requirements.
Grades and Identification
Stud bolts are classified by ASTM grades according to their mechanical strength, chemical composition, and service temperature. Each stud is stamped with a grade mark and manufacturer’s identification—usually on one or both ends. Certain grades, such as ASTM F1554, may also use color-coded markings for easy visual identification.
ASTM A193 vs. ASTM A320
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ASTM A193 defines alloy and stainless steel bolting materials for high-temperature and high-pressure service.
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ASTM A320 covers similar materials but for low-temperature service.
Materials tested to ASTM A320 undergo additional impact testing to verify performance in cryogenic or sub-zero conditions, ensuring reliability in demanding environments such as LNG, power, and petrochemical applications.
Common Stud Bolt Grades
ASTM A193 Grade B7
Manufactured from chromium-molybdenum steel, quenched and tempered for strength and durability.
B7 studs are the most commonly used grade for flange bolting and other general-purpose, high-pressure applications. Each stud 3/8" and larger is stamped with “B7” and the manufacturer’s mark.
ASTM A193 Grade B16
Produced from chromium-molybdenum-vanadium steel, this grade offers superior high-temperature performance compared to B7.
Typical applications include boilers, turbines, and pressure systems in the power generation and petrochemical industries.
ASTM A320 Grade L7
Made from AISI 4140/4142 alloy steel, quenched and tempered.
This grade provides the same strength as B7 but is qualified for low-temperature service, meeting a Charpy impact value of 20 ft-lb at -150°F. Commonly used for valves, flanges, and pressure vessels operating in cryogenic environments.
ASTM A193 Grade B8 (304 Stainless Steel)
Manufactured from AISI 304 stainless steel for high-temperature and corrosive environments.
Used extensively in pressure vessels, valves, and fittings requiring strength and corrosion resistance.
ASTM A193 Grade B8 Class 2 (304 Stainless, Strain Hardened)
Strain hardened for increased tensile strength and marked B8SH.
Used in high-temperature and high-pressure stainless steel bolting applications where added strength is required.
ASTM A320 Grade B8 (304 Stainless Steel)
Similar to A193 Grade B8, but tested and certified for low-temperature performance, making it ideal for cryogenic or sub-zero process systems.
ASTM A193 Grade B8M (316 Stainless Steel)
Produced from AISI 316 stainless steel for enhanced corrosion resistance, especially in chloride-rich or marine environments.
Used in flange bolting, pressure vessels, and chemical process equipment.
ASTM A193 Grade B8M Class 2 (316 Stainless, Strain Hardened)
Strain hardened to achieve higher tensile strength while maintaining excellent corrosion resistance.
Ideal for high-pressure, high-temperature, and chemical process service where both strength and corrosion protection are critical.
ASTM A320 Grade B8M (316 Stainless Steel)
Designed for low-temperature service and built to resist corrosion in aggressive environments. Common in cryogenic and marine applications where performance under stress is vital.
ASTM A193 Grade B8 Class 2B
A less common variant, often specified in LNG applications, offering higher tensile strength and a wider range of diameters than standard Class 2.
Although it has no A320 equivalent, these studs can perform reliably to -325°F when certified accordingly.
Common Stud Bolt Finishes
Surface coatings enhance corrosion protection, torque control, and ease of disassembly. A.R. Thomson Group supplies stud bolts with a variety of protective finishes depending on environmental and application requirements.
Plain or Black Oxide Finish
Uncoated or lightly oiled studs offering minimal corrosion resistance. Suitable for indoor or controlled environments.
Galvanized Finish
Provides sacrificial zinc protection against corrosion.
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Hot-Dip Galvanized: Immersed in molten zinc for a thick, durable coating.
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Mechanically Galvanized: Zinc powder applied through tumbling; produces a smoother finish but less protection than hot-dip.
Zinc or Cadmium Plated
Electroplated for a uniform, thin coating that improves corrosion resistance and torque consistency. Ideal for mildly corrosive environments.
PTFE (Teflon®) Coated
PTFE-coated studs provide exceptional chemical resistance, consistent torque values, and ease of removal after long-term service.
Common in chemical processing, marine, and water treatment applications where corrosion resistance and clean disassembly are critical.
Dependable Bolting Solutions
At A.R. Thomson Group, we supply a complete range of ASTM A193 and A320 all-thread studs and matching heavy hex nuts to meet the needs of industrial, energy, and process markets across North America.
All products are available with material test reports (MTRs) and can be custom cut, coated, or packaged to meet project specifications.
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