ASTM A320 Grade L7 Bolt, is a standard specifically developed for pressure vessels, valves, flanges and fasteners for operation at low temperatures (cryogenic). Made from alloy steel, these bolts and studs maintain their mechanical strength in extremely cold environments down to -101°C (-150°F). The main feature that distinguishes L7 quality from others is the Charpy V-Notch impact test, which is compulsory during the production process; this test proves that the material does not become brittle at temperatures well below freezing and proves its impact absorption capacity (toughness). It is commonly used in LNG plants, refrigeration systems and pipelines in arctic climates. ASTM A320 L7 studs are generally used for full compliance and safety. ASTM A 194 Grade 7 used together with nuts.
| Feature | |
| Standard | ASME |
| Material | Alloy Steel |
| Type | Hex Head Bolt |
| Quality | ASTM A320 Grade L7 |
| Coating | Electrogalvanized (White/Yellow), Hot-Dip Galvanized (HDG), Nickel, Black Oxide, Geomet |
| Tooth Type | Metric (Coarse) – UNC / UNF (optional) |
| Measurement Range | M10 to M64, 1/2″-2 1/2″ |
| Production Method | Cold forging, hot forging, or machining |
| Thread Direction | Right-Hand Thread (standard) / Left-Hand Thread (upon request) |
- LNG (Liquefied Natural Gas) storage and filling facilities
- Cryogenic (extremely cold) gas lines and equipment
- Oil/gas pipelines in Nordic countries and cold climates
- Industrial refrigeration systems and compressors
- Underwater connections of offshore platforms
- ISO 9001:2015 Quality Management System
- ISO 14001:2015 Environmental Management System
- ISO 45001:2018 Occupational Health and Safety Management System
- EU Declaration of Conformity (PED) certificate (Compliance with the Pressure Equipment Directive)
- Our production processes, DIN, EN, ISO, and ASTM is fully compliant with the standards
- Upon request EN 10204 3.1 certificate is provided
Their chemical structure and tensile strength are very similar. However, B7 is designed for high temperatures, while L7 is designed for low temperatures.
The ASTM A320 standard recommends the use of ASTM A194 Grade 7 nuts in combination with L7 studs. Grade 7 nuts are also low temperature impact tested products and are critical to the integrity of the system.
Standard soft iron washers (DIN 125 etc.) are crushed under the high clamping force applied by the L7 and cause the connection to loosen. ASTM F436 washers made of hardened steel and suitable for cold weather conditions must be used with these products.
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