Low-temperature applications make bolting difficult. A stud that is strong at room temperature can lose toughness as the metal gets colder. A brittle fastener on a flange or valve is a real risk.
L7 All Thread Studs are used on these joints. The alloy steel is tested to check its toughness at low temperatures. The full-length threads let nuts sit wherever the joint needs them. That flexibility also makes installation and later maintenance easier for crews working in tight spaces.
In practice, L7 All Thread Studs made to ASTM A320 Grade L7 turn up in refrigeration systems, low-temperature process piping, valves, heat exchangers, pressure vessels, and other low-temperature equipment in oil and gas, petrochemical, and industrial gas plants.
L7 All Thread Studs Overview
L7 All Thread Studs are fully threaded and heat-treated alloy-steel studs. They are used for bolted joints. These studs require continuous threading and meet specified low-temperature performance. Unlike a conventional stud bolt with an unthreaded shank, an all-thread stud lets you position nuts along the stud. This makes it suitable for varied joint thicknesses, different engagement lengths, and maintenance work where access is limited.
For cold-service applications, ASTM A320 Grade L7 Stud Bolts offer a dependable bolting solution designed to meet demanding operating requirements.
At Clarion, we verify material certification, impact-test requirements, thread dimensions, coating selection, and applicable code compliance against approved drawings and project specifications.
Key Features of L7 All Thread Studs
Full-length threading
Continuous external threads allow flexible nut positioning. These studs adapt to different engagement lengths.
Low-temperature toughness
Manufactured to applicable ASTM A320 Grade L7 requirements, including Charpy impact testing at -150°F (-101°C) for standard L7 within its applicable size range.
High strength
Quenched-and-tempered alloy steel with minimum tensile strength of 125 ksi and minimum yield strength of 105 ksi for sizes up to 2½ in. diameter.
Reliable clamping
Helps maintain bolt preload and gasket compression when correctly installed.
Custom sizing
Available in specified diameters, lengths, thread series, and finishes.
Documented quality
Material test reports and heat-number traceability available when specified on the purchase order.
L7 All Thread Studs in a single length can sometimes cover multiple joint thicknesses, helping reduce part variety in storeroom inventory.
Standards and Compatibility
| Standard / Compatibility | Application |
|---|---|
| ASTM A320 Grade L7 | Material, mechanical, and impact-test requirements for alloy-steel bolting intended for low-temperature service |
| ASTM A194 Grade 7 | Heavy hex nuts commonly paired with L7 studs, subject to project specification |
| ASME B1.1 | Unified inch screw-thread dimensions and tolerances |
| ASME B1.13M | Metric screw-thread requirements, where applicable |
| ASME B16.5 | Flange and flanged-fitting requirements within its scope |
| ASME B31.3 | Process piping design, materials, fabrication, examination, and testing requirements within its scope |
| Custom drawings | Project-specific diameters, lengths, thread series, coatings, and testing requirements |
Coating Options for L7 All Thread Studs
The coating must work well at the lowest design temperature, without affecting thread fit or tightening.
| Coating Option | Best Suited For |
|---|---|
| Black Oxide | Mild corrosion resistance, oil retention, and a uniform black appearance with minimal dimensional change |
| Black Phosphate | Oil retention, lubrication, and controlled surface finish |
| Xylan Coating | Chemical resistance, reduced friction, and controlled tightening |
| Zinc Plating | General corrosion protection in atmospheric and moderate environments |
| Cadmium Plating | Corrosion protection with lubricity, where permitted by project and environmental requirements |
| Project-Specific Finish | Qualified coatings for environmental, chemical, or customer-specific requirements |
Applications
L7 All Thread Studs are used wherever bolted joints must remain tough in cold service. Common applications include:
Refrigeration Systems
Used on flanged connections in industrial refrigeration, where repeated cooling cycles and low operating temperatures are routine.
Low-Temperature Process Piping
Secures flanged joints in piping systems that carry cold process fluids, in line with ASME B16.5 and B31.3 requirements.
Industrial Gas Plants
Suited for bolted joints in plants that handle liquefied and chilled industrial gases, where equipment operates at sustained low temperatures.
Valves and Valve Bonnets
Hold valve bodies and bonnets together in cold-service lines, helping maintain preload and gasket compression.
Heat Exchangers
Fastens channel covers, shell flanges, and removable heads on exchangers that operate at low temperatures or see wide temperature swings.
Pressure Vessels
Used on flanged nozzles and closures of vessels that work in low-temperature service.
Petrochemical and Gas Processing Facilities
Applied in cold-service equipment for oil and gas and petrochemical plants, including chilled and low-temperature process units.
Cold-Climate and Outdoor Installations
Used on piping and equipment exposed to very low ambient temperatures, where brittle fracture is a concern.
Why Choose Clarion as Your L7 Stud Bolts Supplier
Clarion Industrial is a Houston-based manufacturer with more than 25 years of experience producing studs and precision-engineered components. As an L7 Stud Bolts Supplier, Clarion manufactures L7 All Thread Studs to your drawings and specifications, with inspection, testing, and documentation available as required.
Request a Quote for L7 All Thread Studs
L7 All Thread Studs from Clarion are made to your specifications. Send us your requirements, and please include:
- Your drawing or sketch
- Diameter and overall length
- Thread type and size
- Material grade: ASTM A320 Grade L7
- Coating requirement
- Lowest design metal and temperature condition
- Quantity and delivery timeline
- Required material test reports, traceability, and inspection documentation
Don't have the full drawing yet?
Send your requirements. Our team helps you find the right fit!
Get Your L7 All Thread Studs QuoteFrequently Asked Questions
What is the minimum temperature for L7 All Thread Studs?
L7 is impact tested at -150°F (-101°C). Always confirm the minimum design metal temperature against your project specification.
What material are L7 All Thread Studs made of?
They are made from chromium-molybdenum alloy steel, such as AISI 4140 or 4142, heat-treated by quenching and tempering.
What is the tensile strength of L7 All Thread Studs?
For sizes up to 2½ in., the minimum tensile strength is 125 ksi and the minimum yield strength is 105 ksi.
What nuts should be used with L7 All Thread Studs?
ASTM A194 Grade 7 heavy hex nuts are most common. Nuts must also meet the project's low-temperature requirements.
How do I order custom L7 All Thread Studs?
Send your drawing, diameter, length, thread series, coating, minimum design temperature, quantity, and delivery timeline to Clarion.