ASTM A320 Alloy Steel Fasteners are alloy-steel and stainless-steel bolting components specified for low-temperature and special-service applications, particularly pressure vessels, valves, flanges, and fittings. Common alloy-steel grades include L7, L7M, and L43. These fasteners are typically heat treated to provide the required strength and toughness for demanding industrial service.
ASTM A320 Alloy Steel Fasteners are high-strength bolting components specifically manufactured for low-temperature and high-pressure service conditions. These fasteners are commonly used in pressure vessels, pipelines, petrochemical plants, refineries, power generation systems, and other applications where mechanical strength and toughness at sub-zero temperatures are essential.
We manufacture and supply ASTM A320 Fasteners in different grades, sizes, thread configurations, and finishes to meet application-specific requirements. Popular grades include ASTM A320 Grade L7 Fasteners, ASTM A320 Grade L7M Fasteners, and ASTM A320 Grade L43 Bolts. These grades are selected according to temperature, strength, hardness, and sour-service requirements.
Our A320 Alloy Steel Stud Bolts and other low-temperature fasteners can be supplied according to applicable ASTM, ASME, and dimensional standards, with inspection and testing documentation available as required.
What Are ASTM A320 Alloy Steel Fasteners?
ASTM A320 is a specification covering alloy-steel and stainless-steel bolting materials intended primarily for pressure vessels, valves, flanges, and fittings used at low temperatures and in other special-purpose applications.
Unlike conventional high-temperature bolting specifications, A320 Low Temperature Fasteners are designed to maintain suitable toughness and mechanical performance under low-temperature service conditions. The specification includes several material grades, with L7, L7M, and L43 being commonly specified alloy-steel grades.
ASTM A320 Low Temp Alloy Bolts are available in forms such as:
- Stud bolts
- Full-thread studs
- Heavy hex bolts
- Hex bolts
- Machine bolts
- U-bolts
- Anchor bolts
- Custom alloy steel fasteners
The final dimensions and configuration can be manufactured according to applicable ASME/ANSI dimensional standards and customer drawings.
Table of Contents
- ➤ What Are ASTM A320 Alloy Steel Fasteners?
- ➤ ASTM A320 Alloy Steel Fastener Grades
- ➤ ASTM A320 Alloy Steel Fasteners Specifications Chart
- ➤ ASTM A320 Chemical Composition
- ➤ ASTM A320 Mechanical Properties
- ➤ ASTM A320 Fasteners Manufacturing Process
- ➤ ASTM A320 Fastener Dimensions and Standards
- ➤ ASTM A320 Fastener Weight Chart
- ➤ ASTM A320 L7 vs L7M vs L43
- ➤ ASTM A320 Equivalent Grades
- ➤ Applications of ASTM A320 Alloy Steel Fasteners
- ➤ Why Select Our ASTM A320 Alloy Steel Fasteners?
- ➤ ASTM A320 Grade L7 Stud Bolts Supplier in India
- ➤ Ordering ASTM A320 Alloy Steel Fasteners
ASTM A320 Alloy Steel Fastener Grades
The selection of an A320 fastener grade depends on the required strength, service temperature, hardness, and environmental conditions.
➤ ASTM A320 Grade L7 Fasteners
ASTM A320 Grade L7 Fasteners are chromium-molybdenum alloy-steel fasteners generally manufactured from a 4140/4142-type alloy steel. They are quenched and tempered to achieve the required strength and toughness.
ASTM A320 Grade L7 Stud Bolts are widely used for flange connections, pressure equipment, pipelines, valves, and process equipment exposed to low-temperature conditions.
➤ ASTM A320 Grade L7M Fasteners
ASTM A320 Grade L7M Fasteners are low-hardness alloy-steel bolting materials intended for applications where hardness control is important. They are frequently specified for sour-service environments when the complete application and material requirements call for this grade.
NACE MR0175 ASTM A320 Grade L7M Fasteners may be selected for oil and gas applications involving hydrogen sulfide-containing environments, subject to the applicable NACE/ISO requirements, hardness limits, heat treatment, and service conditions.
➤ ASTM A320 Grade L43 Bolts
ASTM A320 Grade L43 Bolts are alloy-steel fasteners developed for applications requiring high strength and suitable performance at low temperatures. They are commonly considered for heavy-duty bolting applications in pressure equipment and industrial systems.
Grade selection should always be based on the applicable engineering specification rather than simply choosing a grade based on tensile strength.
ASTM A320 Alloy Steel Fasteners Specifications Chart
| Specification | ASTM A320 / A320M |
|---|---|
| Product Name | ASTM A320 Alloy Steel Fasteners |
| Standard | ASTM A320 / A320M |
| ASME Equivalent | SA-320 |
| Fastener Type | Bolts, screws, studs, stud bolts, and other specified bolting |
| Material Grades | L7, L7M, L43 and other specified A320 grades |
| Material Type | Alloy Steel / Stainless Steel depending on grade |
| L7 Material | Chromium-Molybdenum Alloy Steel |
| L7M Material | Low-Hardness Chromium-Molybdenum Alloy Steel |
| L43 Material | Nickel-Chromium-Molybdenum Alloy Steel |
| Manufacturing Process | Cold/Hot Forged, Machined, Threaded |
| Heat Treatment | Quenched and Tempered for applicable alloy-steel grades |
| Minimum Tempering Temperature – L7 | 1100°F (593°C) |
| Minimum Tempering Temperature – L7M | 1150°F (620°C) |
| Minimum Tempering Temperature – L43 | 1100°F (593°C) |
| Tensile Strength – L7 | 125 ksi (860 MPa) min. |
| Yield Strength – L7 | 105 ksi (725 MPa) min. |
| Tensile Strength – L7M | 100 ksi (690 MPa) min. |
| Yield Strength – L7M | 80 ksi (550 MPa) min. |
| Tensile Strength – L43 | 125 ksi (860 MPa) min. |
| Yield Strength – L43 | 105 ksi (725 MPa) min. |
| Elongation – L7 | 16% min. |
| Elongation – L7M | 18% min. |
| Elongation – L43 | 16% min. |
| Reduction of Area | 50% min. |
| Maximum Hardness – L7 | 321 HBW / 35 HRC |
| Maximum Hardness – L7M | 235 HBW / 99 HRB |
| Maximum Hardness – L43 | 321 HBW / 35 HRC |
| Thread Type | UNC, UNF, 8UN and Metric as specified |
| Thread Standard | ASME B1.1 / ASME B1.13M as applicable |
| Dimensional Standard | ASME B18.2.1, ASME B18.31.2 or customer specification |
| Size Range | As specified by grade, product type and customer requirement |
| Surface Finish | Plain, Black Oxide, Zinc Plated, Hot-Dip Galvanized or as specified |
| Testing | Tensile, Yield, Hardness, Chemical Analysis, Dimensional Inspection and Impact Testing where specified |
| Inspection Documents | MTC, Inspection Certificate, PMI and Third-Party Inspection as required |
| Application | Low-Temperature, Pressure Vessel, Valve, Flange and Fitting Applications |
| Industry | Oil & Gas, Petrochemical, LNG, Chemical, Power and Process Industries |
ASTM A320 Chemical Composition
| Element | Grade L7 | Grade L7M | Grade L43 |
|---|---|---|---|
| Carbon | 0.37–0.49% | 0.37–0.49% | 0.30–0.50% |
| Manganese | 0.65–1.00% | 0.65–1.00% | 0.40–0.90% |
| Phosphorus, max. | 0.035% | 0.035% | 0.035% |
| Sulfur, max. | 0.040% | 0.040% | 0.040% |
| Silicon | 0.15–0.35% | 0.15–0.35% | 0.15–0.35% |
| Chromium | 0.75–1.20% | 0.75–1.20% | 0.80–1.10% |
| Molybdenum | 0.15–0.25% | 0.15–0.25% | 0.15–0.25% |
ASTM A320 Mechanical Properties
| Property | ASTM A320 L7 | ASTM A320 L7M | ASTM A320 L43 |
|---|---|---|---|
| Tensile Strength, min. | 860 MPa | 860 MPa | 860 MPa |
| Yield Strength, min. | 725 MPa | 655 MPa | 725 MPa |
| Hardness | Grade-specific | Controlled lower hardness | Grade-specific |
| Material | Cr-Mo Alloy Steel | Cr-Mo Alloy Steel | Alloy Steel |
ASTM A320 Fasteners Manufacturing Process
ASTM A320 Fastener Dimensions and Standards
| Product | Common Dimensional Standard |
|---|---|
| Hex Head Bolts | ASME B18.2.1 |
| Heavy Hex Bolts | ASME B18.2.1 |
| Heavy Hex Nuts | ASME B18.2.2 |
| Stud Bolts | ASME B18.31.2 / customer specification |
| Threaded Rods | ASTM/ASME/customer specification |
| Custom Fasteners | Customer drawing |
ASTM A320 Fastener Weight Chart
| Nominal Size | Approx. Weight Range* |
|---|---|
| 1/2 inch | 0.03–0.06 kg/pc |
| 5/8 inch | 0.05–0.10 kg/pc |
| 3/4 inch | 0.08–0.16 kg/pc |
| 7/8 inch | 0.12–0.22 kg/pc |
| 1 inch | 0.16–0.30 kg/pc |
| 1-1/4 inch | 0.28–0.55 kg/pc |
| 1-1/2 inch | 0.42–0.80 kg/pc |
| 2 inch | 0.75–1.45 kg/pc |
ASTM A320 L7 vs L7M vs L43
| Feature | L7 | L7M | L43 |
|---|---|---|---|
| Material Type | Cr-Mo Alloy Steel | Cr-Mo Alloy Steel | Alloy Steel |
| Primary Use | Low-temperature/high-strength bolting | Low-hardness/sour-service applications | Low-temperature/high-strength applications |
| Heat Treatment | Quenched & tempered | Controlled heat treatment | Quenched & tempered |
| Hardness Control | Standard grade requirement | More restrictive hardness control | Grade-specific |
| Typical Applications | Flanges, valves, pressure equipment | Oil & gas sour-service applications | Heavy-duty low-temperature bolting |
ASTM A320 Equivalent Grades
| ASTM A320 Grade | Common Material Reference | Typical Alloy Type |
|---|---|---|
| L7 | AISI 4140/4142-type steel | Chromium-Molybdenum |
| L7M | L7-type low-hardness alloy steel | Chromium-Molybdenum |
| L43 | Grade-specific alloy steel | Alloy Steel |
Applications of ASTM A320 Alloy Steel Fasteners
ASTM A320 Low Temperature Fasteners are used in industries where bolted joints must maintain reliable mechanical performance under demanding service conditions.
Typical applications include:
- Oil and gas pipelines
- Refineries
- Petrochemical plants
- LNG and cryogenic facilities
- Pressure vessels
- Heat exchangers
- Valves and flanges
- Power generation plants
- Chemical processing equipment
- Offshore platforms
- Gas processing systems
- Process piping
- Storage and pressure equipment
Their combination of strength, toughness, and controlled material properties makes them suitable for critical bolting connections.
Why Select Our ASTM A320 Alloy Steel Fasteners?
We supply ASTM A320 Alloy Steel Fasteners for domestic and international industrial requirements with attention to material traceability, dimensional accuracy, and specification compliance.
Our supply capabilities include:
- ASTM A320 L7, L7M and L43 grades
- Stud bolts and heavy hex bolts
- Custom sizes and configurations
- UNC, UNF and special threads
- Plain, black oxide, zinc-coated and other specified finishes
- Material Test Certificates
- PMI and hardness testing when required
- Third-party inspection support
- Export-quality packaging
- Bulk orders for industrial projects
As an ASTM A320 Alloy Steel Fasteners Manufacturer, we can support both standard and project-specific requirements. We also supply ASTM A320 Grade L7 Stud Bolts for customers requiring dependable low-temperature alloy-steel bolting.
ASTM A320 Grade L7 Stud Bolts Supplier in India
As an experienced ASTM A320 Grade L7 Stud Bolts Supplier in India, we supply alloy-steel stud bolts to industrial buyers, distributors, EPC contractors, maintenance companies, and engineering projects.
Our supply range can be customized according to diameter, length, thread type, grade, coating, testing requirements, and packaging instructions.
For international requirements, we also support ASTM A320 Grade L7 Stud Bolts Exporter in India to Middle East markets, supplying material suitable for oil & gas, petrochemical, construction, power, and process-industry applications.
Ordering ASTM A320 Alloy Steel Fasteners
When ordering ASTM A320 Fasteners, provide the grade, fastener type, diameter, length, thread specification, quantity, finish, testing requirements, and applicable dimensional standard.
For sour-service applications, specify the required NACE/ISO requirements and hardness restrictions. For low-temperature applications, the minimum design temperature and impact-testing requirements should also be clearly stated where applicable.
We can supply ASTM A320 Alloy Steel Fasteners with documentation and inspection requirements tailored to industrial and project applications.
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