Description
Impact-tested low-temperature alloy steel
ASTM A320 L7 Low Temperature Threaded Rod
Quenched-and-tempered threaded bar for flanges, valves, pressure vessels and equipment designed for low-temperature service.
Product overview
ASTM A320 Grade L7 threaded rod is alloy-steel bolting material for low-temperature service. The specification combines mechanical-property requirements with Charpy impact-energy requirements and a defined test temperature.
The purchaser must state the exact ASTM A320/A320M edition and any lower project impact-test temperature or supplementary requirement. Finished rod diameter, thread geometry, heat treatment, impact test sampling and mating nuts should be reviewed as one procurement package.
ASTM A320 L7 threaded rod specifications
| Bolting standard | ASTM A320/A320M, ordered edition |
|---|---|
| Grade / material | Grade L7 quenched-and-tempered alloy steel |
| Low-temperature test | Charpy impact energy and test temperature to the ordered specification |
| Thread systems | ASME B1.1 UNC, UNF or 8UN; ASME B1.13M / ISO metric when ordered |
| Size range | 1/4–4 in and M6–M100 typical; grade limits and project testing apply |
| Compatible nuts | Impact-tested nut grade to ASTM A320 requirements or project specification |
| Finish options | Plain, black, zinc or qualified fluoropolymer coating |
| Documentation | EN 10204 3.1, impact results, mechanical properties and dimensions |
Final dimensions, tolerances, heat treatment, coating, testing and acceptance criteria follow the confirmed purchase order and the applicable standard edition. Availability depends on diameter, length, thread form and production quantity.
Why specify this material?
L7 is selected when a low-temperature equipment or piping code requires ferritic alloy-steel bolting with documented notch toughness. It is commonly considered for cold climates, refrigeration, LPG/LNG support systems and low-temperature pressure equipment.
Engineering note
The minimum design metal temperature is not automatically equal to the standard Charpy test temperature. The responsible engineer must set the required test temperature, energy, specimen orientation and any exemptions.
Typical applications
Quality, inspection and documentation
L7 inspection should demonstrate grade chemistry, heat treatment, tensile properties, hardness and Charpy results at the ordered test temperature. Nuts used with low-temperature bolting also require the impact-test basis defined by the order.
- EN 10204 3.1 material test certificate
- Heat-number and batch traceability
- Chemical composition and mechanical properties
- Dimensional inspection and thread gauging
- PMI for stainless and nickel alloys when ordered
- Coating thickness or surface inspection when applicable
- Third-party inspection and additional testing by agreement
- Export marking and seaworthy packing
Information required for quotation
- Material grade, governing material/bolting standard and required edition
- Diameter, thread series, pitch and thread class or tolerance
- Overall length, cut-end requirements and quantity
- Heat treatment, surface finish or coating system
- Matching nuts and washers, including anti-galling requirements
- Inspection plan, MTC, PMI, NDE and third-party witness requirements
- Delivery destination, packaging and required schedule
Frequently asked questions
What does ASTM A320 Grade L7 cover?
It covers quenched-and-tempered alloy-steel bolting for low-temperature pressure vessels, valves, flanges, fittings and related service.
Does every L7 order use the same impact-test temperature?
No. The standard contains grade requirements, but a project may require a lower temperature or additional impact criteria. State the exact requirement on the purchase order.
What nuts are supplied with L7 threaded rod?
An impact-tested nut grade compatible with the rod, coating and service is required. The exact ASTM A194 or ASTM A320 nut provision must follow the project specification.
Can L7 be substituted for B7?
Not automatically. Although their base alloy may be similar, ASTM A320 L7 includes low-temperature impact requirements that ASTM A193 B7 does not address in the same way.
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Request a technical quotation
Send your bill of materials, drawing or project specification. SASA FLANGE will review the grade, thread, dimensions, documentation and delivery requirements before quotation.
