ASTM A320 Bolts: Reliable Performance in Low-Temperature Environments

ASTM A320 bolts are engineered for applications where low temperatures demand materials with high toughness and strength. These bolts are commonly used in oil and gas, power generation, and chemical processing, and maintain structural integrity in cold environments.

What is ASTM A320?

ASTM A320 is a specification that covers alloy steel and stainless steel bolting materials intended for low-temperature service. It includes various grades designed to perform reliably in environments where temperatures can drop significantly. The specification ensures that the bolts have the necessary mechanical properties and impact resistance for such conditions.

Key Properties of ASTM A320 Bolts

• Material: Alloy steel or stainless steel, depending on the grade.

• Tensile Strength:

• Grade L7: 125 ksi minimum.

• Grade B8 Class 1: 75 ksi minimum.

• Yield Strength:

• Grade L7: 105 ksi minimum.

• Grade B8 Class 1: 30 ksi minimum.

• Elongation:

• Grade L7: 16% minimum.

• Grade B8 Class 1: 30% minimum.

• Reduction of Area:

• Grade L7: 50% minimum.

• Grade B8 Class 1: 50% minimum.

• Impact Energy:

• Grade L7: 20 ft-lbf at -150°F.

• Grade B8 Class 1: Not required.

Grades and Classifications

ASTM A320 bolts are available in several grades, each tailored for specific applications:

• Grade L7

• Material: Alloy steel.

• Applications: Pressure vessels, valves, flanges, and fittings in low-temperature service.

• Notes: Requires impact testing at -150°F.

• Grade L43

• Material: Alloy steel with higher strength.

• Applications: Similar to L7 but suitable for larger diameters and higher strength requirements.

• Notes: Requires impact testing at -150°F.

• Grade B8 Class 1

• Material: AISI 304 stainless steel.

• Applications: Corrosion-resistant applications in low-temperature environments.

• Notes: Does not require impact testing.

• Grade B8M Class 1

• Material: AISI 316 stainless steel.

• Applications: Enhanced corrosion resistance, suitable for marine and chemical processing environments.

• Notes: Does not require impact testing.

Common Applications

• Oil and Gas Industry: Used in pipelines, refineries, and offshore platforms where low temperatures are prevalent.

• Power Generation: Applied in equipment exposed to cold environments, such as turbines and boilers.

• Chemical Processing: Suitable for reactors and storage tanks operating at low temperatures.

• Cryogenic Facilities: Employed in systems handling liquefied gases like LNG.

• Infrastructure Projects: Utilized in bridges and structures located in cold climates.

Benefits of Using ASTM A320 Bolts

• Low-Temperature Performance: Designed to maintain mechanical properties in cold environments.

• Versatility: Available in various grades to suit different applications and environmental conditions.

• Corrosion Resistance: Stainless steel grades offer enhanced resistance to corrosion.

• Compliance: Meets stringent industry standards for safety and reliability.

How to Select the Right ASTM A320 Grade

• Assess Environmental Conditions: Determine the lowest operating temperatures and select a grade with suitable impact resistance.

• Evaluate Corrosion Exposure: For environments with high corrosion potential, consider stainless steel grades like B8M.

• Determine Mechanical Requirements: Choose a grade that meets your application's tensile and yield strength requirements.

• Consult Industry Standards: Ensure the selected grade complies with relevant industry codes and standards.

ASTM A320 Compared to Other Standards

• ASTM A193: Covers similar materials but is intended for high-temperature service, whereas A320 is for low-temperature applications.

• ASTM A194: Specifies nuts compatible with A320 bolts, ensuring complete fastener assemblies for low-temperature service.

• ASTM A307: Covers low-carbon steel bolts for general applications, unsuitable for low-temperature environments.

Frequently Asked Questions

Q1: Can ASTM A320 bolts be galvanized?
Yes, specific grades of ASTM A320 bolts can be galvanized. However, it is essential to make certain that the galvanizing process does not adversely affect the mechanical properties required for low-temperature service.

Q2: Are impact tests mandatory for all ASTM A320 grades?
No, impact testing is required for specific grades like L7 and L43, which are intended for low-temperature applications. Stainless steel grades like B8 and B8M typically do not require impact testing.

Q3: What is the difference between Class 1 and Class 2 in stainless steel grades?
Class 1 bolts are carbide solution treated, while Class 2 bolts are carbide solution treated and strain hardened, resulting in higher strength.

Q4: Can ASTM A320 bolts be used in high-temperature applications?
No, ASTM A320 bolts are designed explicitly for low-temperature service. For high-temperature applications, ASTM A193 bolts are more appropriate.

Enhance Your Low-Temperature Applications with ASTM A320 Bolts

ASTM A320 bolts provide reliable performance in environments where low temperatures challenge structural integrity. Selecting the appropriate grade ensures your applications maintain safety and functionality under cold conditions. For expert guidance and a comprehensive selection of ASTM A320 bolts, contact California Fastener today.