ASTM A193 Grade B7 Stud Bolts
Stud bolts and threaded rod in ASTM A193 Grade B7 — medium carbon alloy steel, quenched and tempered, 125 ksi minimum tensile (115 ksi over 2-1/2" to 4", 100 ksi over 4"), C35 hardness, paired with A194 2H heavy hex nuts. The workhorse grade for flanged piping, refineries and oil & gas construction.
Last updated: 2026-11
Specifications
B7 is the default high-strength stud-bolt grade of the inch series: quenched-and-tempered medium carbon alloy steel per ASTM A193, threaded over its full length as continuous-thread studs to ASME B18.31.2 and clamped with heavy hex nuts on both ends. Flanged joints favour it because the full thread allows complete nut engagement at any grip length and the joint can be tensioned or torqued from either side. Thread convention follows flange practice — UNC coarse up to 1" diameter, 8 threads per inch above that. In corrosive service (offshore, splash zone) B7 depends on its protection system: hot-dip galvanizing or fluoropolymer coatings applied over the prepared base.
| Standard | ASTM A193 Grade B7 (material); continuous/double-end stud dimensions per ASME B18.31.2 |
|---|---|
| Material | Medium carbon alloy steel, quenched and tempered |
| Tensile strength, min | 125 ksi (1/4"–2-1/2"); 115 ksi (2-5/8"–4"); 100 ksi (4-1/8"–7") |
| Hardness | C35 |
| Thread convention | UNC coarse to 1" diameter; 8 threads per inch (8UN) above |
| Nut pairing | ASTM A194 Grade 2H heavy hex nuts — the default for refinery and pipeline service |
| Stocked sizes | Studs 1/2"–2-1/2" diameter, cut lengths to 15.25" per supplier weight charts |
| Corrosion protection | Hot-dip galvanizing or fluoropolymer (PTFE-family) coatings for offshore/splash-zone and severe service |
| Typical applications | Pipe flanges (ASME B16.5 joints), refinery and process plant bolting, construction, oil & gas |
Materials
- Medium carbon alloy steel, quenched and tempered
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (ASTM A193 Grade B7 Stud Bolts) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 1,000–10,000 pieces depending on size. Stock items run 3–7 days. High-strength and custom parts run 15–25 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
What should a B7 stud bolt RFQ line state?
The complete callout, not just the grade. A typical line reads: stud bolt to ASME B18.31.2, 1"-8UN × 140 mm, ASTM A193 B7, with 2 heavy hex nuts A194 2H, PTFE-coated — dimensional standard, thread series, length, material grade, matched nuts and coating. ASME B18.31.2 is a dimensional standard only; the strength comes from the ASTM material specification, so the two are always quoted together.
Can B7 stud bolts be used in corrosive or offshore environments?
Only with a designed protection system. B7 is a carbon alloy steel whose strength makes it the workhorse for flanged connections in less corrosive areas, but in offshore and splash-zone service bare B7 does not survive: suppliers protect it with hot-dip galvanizing for atmospheric exposure or fluoropolymer coatings (PTFE family, applied over a phosphate or zinc-plated base) for immersion and severe service. Where the specification calls for bare corrosion resistance, stainless grades such as A193 B8/B8M are the usual substitution — with their own strength trade-offs.
Related knowledge
- What Bolt Property Classes 8.8, 10.9 and 12.9 Encode — and When High Strength Stops Being the Right Choice
- Bolt Grade Selection: ISO 898-1 8.8/10.9/12.9 vs ASTM A307 and A325
- 8.8 vs 10.9 vs 12.9 Bolts: Strength, Hardness and Cost — What the Evidence Settles
- Calculating Bolt Preload and Clamp Force: Torque, Friction and Tightening Method
- How to Determine Tightening Torque and Choose a Tightening Method for a Bolted Joint
- Fastener Failure Modes: Which Fatigue, Creep and SCC Controls the Evidence Supports
- Hydrogen Embrittlement in High-Strength Bolts: Which Grades Need Controls, Which Coatings and Baking Schedules Are Acceptable, and What to Require Before the RFQ
- Threaded Rod and Stud Bolt Standards: Mapping DIN 975/976 and ASTM A193/A320 to Grades, Coatings and Certification
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support