ASTM A320 L7 Fasteners: Bolts, Studs & Nuts for Low-Temperature Service
Jade Special Metals is a leading Manufacturer, Supplier, and Exporter of superior A320 L7 Fasteners. These fasteners include a complete range of ASTM A320 L7 Bolts, studs, nuts, and other threaded items. These fasteners are made from quenched and tempered AISI 4140/4142 alloy steel which is specified under ASTM A320 Grade L7 for strength, toughness, and reliability in low temperature service including cryogenic service.
The A320 specification covers alloy steel bolting for pressure vessels, valves, flanges, and fittings. Grade L7 is the most common grade in the A320 specification, because it has high strength and toughness down to -150°F (-101°C). We encourage you to use Jade Special Metals for fasteners that meet the stringent requirements of your particular industry and project.
Quick Section Links
- What Are ASTM A320 L7 Fasteners?
- Types of ASTM A320 L7 Fasteners
- ASTM A320 L7 Bolts Specifications
- ASTM A320 L7 Bolts Chemical Composition
- ASTM A320 L7 Bolts Mechanical Properties
- ASTM A320 L7 Bolts Equivalent Grade
- Heat Treatment for ASME SA320 Grade L7 Fasteners
- Dimensions of ASTM A320 Gr L7 Bolts
- ASTM A320 Gr L7 Nuts Size Chart
- ASTM A320 L7 Bolts Inventory
- Available Stock of ASTM A320 L7 Bolts
- Applications of ASTM A320 L7 Bolts
What Are ASTM A320 L7 Fasteners?
ASTM A320 L7 Fasteners are high-strength bolting components, designed for high performance at low temperatures. ASTM A320 is a standard specification that covers alloy steel fasteners specified as ASTM A320 L7 Bolts, studs, stud bolts, screws, or threaded rods, and manufactured from material such as quenched and tempered AISI 4140/4142 alloy steel.
The primary purpose of A320 L7 Bolts and other L7 fasteners is to bolt or join critical components such as flanges, valves, and pressure vessels that are used at sub-zero temperatures, where the standard carbon steels become brittle and fail when used in this service. The “L7” signifies a material that has met certain heat treatment requirements (which typically consist of quenching and tempering), plus a mandatory impact test to ensure adequate toughness for use at very low operational temperatures to minimize the risk of brittle fracture.
There are various industries that use these fasteners; for example, oil and gas processing (especially at liquefied natural gas or LNG facilities), petrochemical facilities, refrigeration and cryogenic applications. Jade Special Metals manufactures and supplies a complete range of A320 L7 Fasteners in a wide variety of sizes, threads, and types including hex bolts, heavy hex bolts, stud bolts, and socket products–all produced to meet the rigorous requirements of ASTM A320 Grade L7 for safety and reliability.
Both ASTM A320 Grade L7 and L7M fasteners are made from similar alloy steels for low-temperature use, but they have key differences. A320 L7 Bolts are stronger and harder, designed for general cold applications. In contrast, A320 L7M Bolts have slightly lower strength and a stricter, lower maximum hardness. This makes L7M fasteners more resistant to cracking in “sour service” environments (those with hydrogen sulfide, H₂S), a critical feature for safety in certain oil and gas applications. So, while L7 is for general low-temp strength, L7M is specifically for low-temp and sour service conditions.
Types of ASTM A320 L7 Fasteners
ASTM A320 L7 Hex Cap Screws
ASTM A320 L7 Double End Studs
ASTM A320 L7 Heavy Hex Bolts
ASTM A320 L7 CSK Screws
ASTM A320 L7 Stud Bolts
ASTM A320 L7 Hex Bolts
ASTM A320 L7 Anchor Bolts
ASTM A320 L7 Threaded Rods
ASTM A320 L7 Eye Bolts
ASTM A320 L7 U-Bolts
ASTM A320 L7 Socket Head
ASTM A320 L7 Bolts Specifications
Jade Special Metals supplies A320 L7 Fasteners conforming to rigorous international standards and precise customer requirements.
|
Specification Attribute |
Details for ASTM A320 Grade L7 Fasteners |
|
Primary Standard |
ASTM A320 / A320M; ASME SA320 / SA320M |
|
Grade Designation |
ASTM A320 : Grade L7, L7M, B8, B8M |
|
Base Material |
Alloy Steel (typically AISI 4140, 4142, or equivalent quenched and tempered alloy steel) |
|
Common Fastener Types |
Bolts (Hex, Heavy Hex, Socket Head Cap, T-Head, Eye, U-Bolts, J-Bolts, Foundation, Structural), Stud Bolts (Full Thread, Double End), Threaded Rods, Screws, Nuts. |
|
Head Types (for Bolts) |
Hex, Square, Round, Hex Flange, Flat, T-Head, Triangular, etc. |
|
Manufacturing Process |
Cold Heading, Hot Forging, Wire Drawing, Machining, Heat Treatment, Threading, Surface Finishing. |
|
Heat Treatment |
Quenched and Tempered. Minimum tempering temperature is typically 593°C (1100°F). |
|
Size Range (Typical) |
Diameters: 1/4″ to 4″ (M6 to M100). <br>Lengths: Various, from 1/2″ (12mm) up to very long (e.g., 236″ / 6000mm for studs/rods), as per standards or custom. |
|
Threads |
UNC, UNF, 8UN (for diameters >1″), Metric Coarse, Metric Fine (as per ASME B1.1, B1.13M, ISO, DIN, etc.), or custom. |
|
Compatible Nuts (Common) |
ASTM A194 Grade 4 or Grade 7 (for L7 bolts/studs). |
|
Dimensional Standards (Examples) |
ASME B18.2.1 (Bolts/Screws), ASME B18.2.2 (Nuts), ASME B18.3 (Socket Products), ASME B18.31.2 (Stud Bolts). |
|
Impact Testing Requirement |
Mandatory Charpy V-notch impact testing at specified low temperatures (e.g., -101°C / -150°F) to verify toughness. |
|
Testing & Certification |
Chemical Analysis, Mechanical Tests (Tensile, Yield, Elongation, Hardness, Impact), Dimensional Checks. Mill Test Certificate (MTC) to EN 10204 3.1 provided. |
ASTM A320 L7 Bolts Chemical Composition
| Element | L7 (AISI 4140) | L43 (AISI 4340) | B8 (AISI 304) | B8M (AISI 316) |
| Carbon | 0.37 – 0.49% | 0.38 – 0.43% | 0.08% max | 0.08% max |
| Manganese | 0.65 – 1.10% | 0.75 – 1.00% | 2.00% max | 2.00% max |
| Phosphorus, max | 0.035% | 0.035% | 0.045% | 0.045% |
| Sulfur, max | 0.040% | 0.040% | 0.030% | 0.030% |
| Silicon | 0.15 – 0.35% | 0.15 – 0.35% | 1.00% max | 1.00% max |
| Chromium | 0.75 – 1.20% | 0.70 – 0.90% | 18.0 – 20.0% | 16.0 – 18.0% |
| Nickel | 1.65 – 2.00% | 8.0 – 11.0% | 10.0 – 14.0% | |
| Molybdenum | 0.15 – 0.25% | 0.02 – 0.30% |
|
2.00 – 3.00% |
ASTM A320 L7 Bolts Mechanical Properties
| Grade | Size | Tensile ksi, min | Yield, ksi, min | Elong, %, min | RA % min | Charpy Impact 20-ft-lbf @ temp |
| L7 | Up to 2-1/2 | 125 | 105 | 16 | 50 | -150° F |
| L43 | Up to 4 | 125 | 105 | 16 | 50 | -150° F |
| B8 Class 1 | All | 75 | 30 | 30 | 50 | N/A |
| B8 Class 2 | Up to 3/4 | 125 | 100 | 12 | 35 | N/A |
| 7/8 – 1 | 115 | 80 | 15 | 35 | N/A | |
| 1-1/8 – 1-1/4 | 105 | 65 | 20 | 35 | N/A | |
| 1-3/8 – 1-1/2 | 100 | 50 | 28 | 45 | N/A | |
| B8M Class 1 | All | 75 | 30 | 30 | 50 | N/A |
| B8M Class 2 | Up to 3/4 | 110 | 95 | 15 | 45 | N/A |
| 7/8 – 1 | 100 | 80 | 20 | 45 | N/A | |
| 1-1/8 – 1-1/4 | 95 | 65 | 25 | 45 | N/A | |
| 1-3/8 – 1-1/2 | 90 | 50 | 30 | 45 | N/A |
“Contact Jade Special Metals today with your requirement for ASTM A320 L7 Bolts. We assure you of the best quote.
ASTM A320 L7 Bolts Equivalent Grade
| L7 | AISI 4140/4142 Quenched and tempered |
| L7M | AISI 4145 Quenched and tempered |
| L43 | AISI 4340 Quenched and tempered |
| B8 Class 1 | AISI 304, carbide solution treated |
| B8 Class 2 | AISI 304, carbide solution treated, strain hardened |
| B8M Class 1 | AISI 316, carbide solution treated |
| B8M Class 2 | AISI 316, carbide solution treated, strain hardened |
Heat Treatment for ASME SA320 Grade L7 Fasteners
ASME SA320 Grade L7 fasteners achieve their optimal low-temperature properties through a controlled heat treatment process:
|
Heat Treatment Stage |
Process Details |
Minimum Tempering Temperature |
|
Quenching |
Material is heated to a suitable austenitizing temperature and then rapidly cooled in an appropriate liquid medium. |
N/A |
|
Tempering |
After quenching, the material is reheated, held for an adequate time based on section size, and then cooled. |
593°C (1100°F) |
Dimensions of ASTM A320 Gr L7 Bolts
| Nominal Size (D) | Across the Flats (F) | Head Thickness (H) | Body Diameter (D) | Across Corners (C) | ||||
| Max | Min | Max | Min | Max | Min | Max | Min | |
| M10 | 17.00 | 15.73 | 6.63 | 6.17 | 10.00 | 9.78 | 18.48 | 17.77 |
| M12 | 19.00 | 17.73 | 7.76 | 7.24 | 12.00 | 11.73 | 20.78 | 20.03 |
| M14 | 22.00 | 20.67 | 9.09 | 8.51 | 14.00 | 13.73 | 24.25 | 23.35 |
| M16 | 24.00 | 23.67 | 10.32 | 9.68 | 16.00 | 15.73 | 27.71 | 26.75 |
| M20 | 30.00 | 29.16 | 12.88 | 12.12 | 20.00 | 19.67 | 34.64 | 32.95 |
| M24 | 36.00 | 35.00 | 15.44 | 14.56 | 24.00 | 23.67 | 41.57 | 39.55 |
| M30 | 46.00 | 45.00 | 19.48 | 17.92 | 30.00 | 29.67 | 53.12 | 50.85 |
| M36 | 55.00 | 53.80 | 23.38 | 21.63 | 36.00 | 35.61 | 63.51 | 60.79 |
| M42 | 65.00 | 62.90 | 26.97 | 25.03 | 42.00 | 41.38 | 75.06 | 71.71 |
| M48 | 75.00 | 72.60 | 31.07 | 28.93 | 48.00 | 47.38 | 86.60 | 82.76 |
| M56 | 85.00 | 82.20 | 36.20 | 33.80 | 56.00 | 55.26 | 98.15 | 93.71 |
| M64 | 95.00 | 91.80 | 41.32 | 38.68 | 64.00 | 63.26 | 109.70 | 104.65 |
| M72 | 105.00 | 101.40 | 46.45 | 43.55 | 72.00 | 71.26 | 121.24 | 115.60 |
| M80 | 115.00 | 111.00 | 51.58 | 48.42 | 80.00 | 79.26 | 132.72 | 126.54 |
| M90 | 130.00 | 125.50 | 57.74 | 54.26 | 90.00 | 89.13 | 150.11 | 143.07 |
| M100 | 145.00 | 140.00 | 63.90 | 60.10 | 100.00 | 99.13 | 167.43 | 159.60 |
ASTM A320 Gr L7 Nuts Size Chart
|
Diameter (mm) |
Nut Size (mm) |
Height (mm) |
Jam Nut (mm) |
Hex Nut (mm) |
Nylock Nut (mm) |
|
5 |
2.5 |
1.6 |
2 |
– |
– |
|
6 |
3 |
1.8 |
2.4 |
4 |
– |
|
7 |
4 |
2.2 |
3.2 |
5 |
– |
|
8 |
5 |
2.7 |
4 |
5 |
– |
|
10 |
6 |
3.2 |
5 |
6 |
– |
|
11 |
7 |
3.5 |
5.5 |
– |
– |
|
12 |
8 |
4 |
6.5 |
8 |
– |
|
13 |
8 |
4 |
6.5 |
8 |
– |
|
17 |
10 |
5 |
8 |
10 |
– |
|
19 |
12 |
6 |
10 |
12 |
– |
|
22 |
14 |
7 |
11 |
14 |
– |
|
24 |
16 |
8 |
13 |
16 |
– |
|
27 |
18 |
9 |
15 |
18.5 |
– |
|
30 |
20 |
10 |
16 |
20 |
– |
ASTM A320 L7 Bolts Inventory
ASTM A320 L7 Bolts
ASTM A320 L7 Stud Bolts
ASTM A320 L7 Hex Bolts
Available Stock of ASTM A320 L7 Bolts
- ASME SA 320 L7 Hex Domed Cap Nuts
- ASME SA 320 L7 SS J-Bolts
- ASTM A320 L7 Locking Bolts
- ASTM A320 L7 Foundation Bolts
- ASME SA 320 L7 Castle Bolts
- ASTM A320 L7 Carriage Bolt
- ASTM A320 L7 SS Hex Head Bolt
- ASTM A320 L7 Self locking Bolts
- ASTM A320 L7 SS Step Bolt
- ASME SA 320 L7 Eye Bolt
- ASTM A320 L7 SS Elevator Bolt
- ASTM A320 L7 Stud Bolts
- Stainless Steel L7 Shoulder Bolt
- ASTM A320 L7 Lag Bolt
- ASTM A320 L7 Hex Bolt
- ASTM A320 L7 Serrated Flange Bolts
- ASTM A320 L7 Counter sunk Bolt
- ASTM A320 L7 U Bolt
- ASTM A320 L7 Hex Head Bolts
- Stainless Steel L7 Stud Bolts
- ASTM A320 L7 Structural Bolts
- ASTM A320 L7 T-Head Bolts
- ASME SA 320 L7 Round Head Bolts
- ASME SA 320 L7 Anchor Bolts
- ASTM A320 L7 Stove Bolt
- Stainless Steel L7 Mushroom Head Square Neck Bolts
- ASME SA 320 L7 Nylon Insert Bolts
Applications of ASTM A320 L7 Bolts
The superb low-temperature toughness and high strength of ASTM A320 L7 bolts make them useful for:
Oil & Gas Processing: LNG (Liquefied Natural Gas) facilities, cryogenic processing units, pipelines and connecting equipment in cold environments or refrigerated hydrocarbons.
Petrochemical & Chemical Plants: Reactors, vessels, and piping systems containing low-temperature chemicals or are in cold environments.
Refrigeration & Cryogenic Systems: Components for industrial refrigeration units, cold storage facilities, and cryogenic equipment.
Valves & Flanges for Low-Temperature Service: Ensuring leak-tight and reliable connections in sub-zero conditions.
Pressure Vessels: For the construction and operations of pressure vessels designed to safely operate at low temperatures.
Why Choose Jade Special Metals for Your ASTM A320 L7 Fasteners?
Jade Special Metals is the Manufacturer, Supplier, Exporter of A320 L7 Fasteners:
- Specialized Low-Temperature Expertise: Knowledge of ASTM A320 Grade L7 specifications and detailed knowledge of the critical in-service requirement for heat treatment and impact testing.
- High-Quality Materials: When manufacturing our ASTM A320 L7 Bolts and other fasteners, we use only certified alloy steels (AISI 4140/4142 direct couple, others on an exception).
- Compliant with ASTM A320: All fasteners are manufactured and tested under direct accordance with ASTM A320/A320M and ASME SA320/SA320M specifications.
- Variety of Product Types: We offer all types of fasteners, including hex bolts, heavy hex bolts, stud bolts, threaded rods, nuts, and washers.
- Competitive Pricing: We offer an excellent Price for high-quality A320 L7 Fasteners without compromising on material integrity or manufacturing precision.
- Export Worldwide: Efficient logistics and proven experience in exporting our fastener products to clients worldwide.
- Custom & Technical Support: We can provide fasteners of custom sizes, and technical support on your low-temperature application needs.
Related Products
ASTM A320 L7 Fasteners are a crucial part of our portfolio of high-strength bolting solutions, specifically engineered for reliable performance in demanding low-temperature and cryogenic environments. Explore our full range of related products to complete your project requirements for various service conditions:
Jade Special Metals provides a comprehensive selection of industrial fasteners. Contact us to discuss your specific project needs and ensure you have the optimal bolting solution for any service condition.
Get a Competitive Price & Quote for Your ASTM A320 L7 Fasteners
Jade Special Metals is a leading manufacturer and direct supplier, offers highly competitive pricing on ASTM A320 L7 Fasteners by managing production in-house and eliminating unnecessary markups. The final cost is customized based on factors like dimensions, order volume, and any protective coatings such as PTFE or Hot-Dip Galvanizing.
We provide custom quotes to ensure accurate and fair pricing. Contact our expert sales team today with your requirements—product type, size, and quantity—and receive a fast, no-obligation quote. We are committed to delivering certified ASTM A320 L7 Fasteners on time and at the best value.
FAQ’s About ASTM A320 L7 Bolts
What is A320 L7 bolt material?
ASTM A320 Grade L7 is a specification for high-strength alloy steel bolts, studs, and other fasteners designed specifically for low-temperature service. They are typically made from quenched and tempered AISI 4140 or 4142 alloy steel to ensure they remain tough and don’t become brittle in cold environments.
What is ASTM A320 L7 equivalent to?
ASTM A320 Grade L7 is an alloy steel (typically based on AISI 4140/4142). It is not equivalent to stainless steel grades like ASTM B638 Grade 660 (Alloy A286 / UNS S66286), which are entirely different materials for high-temperature and corrosion-resistant applications. The closest equivalent for L7 is usually its ASME designation, SA320 Grade L7.
What is the difference between L7 and L7M A320?
Both L7 and L7M are for low-temperature service, but:
- L7 bolts are stronger and have a higher maximum hardness. They are for general low-temperature use.
- L7M bolts have slightly lower strength and a stricter, lower maximum hardness. Every L7M fastener (and its compatible A194 Grade 7M nut) must be hardness tested. This makes L7M suitable for “sour service” (environments with H₂S) where cracking resistance is critical.
What is the yield strength of A320 L7M bolts?
ASTM A320 Grade L7M bolts typically have a minimum yield strength of 80 ksi (550 MPa) and a minimum tensile strength of 100 ksi (690 MPa) for diameters up to 2-1/2 inches. They also have good ductility, generally with a minimum elongation of 18%.
