Stud Bolts Manufacturer & Supplier: Double End Studs, B7, B8 and Full Thread Studs

A flange joint is only as reliable as the stud bolts holding it, and every gasketed connection has a specification behind it — material, thread length, hardness, coating and certificate. Yuanpai manufactures double end studs, full thread studs and flange bolting sets from ASTM A193, A320 and ISO 3506 materials, with the documentation that project QA/QC and third-party inspectors expect.

Yuanpai — Stud Bolts Quick Reference:

- Products: double end studs (B16.5 pattern), full thread studs, tap-end studs, flange bolting sets with heavy hex nuts

- Materials: ASTM A193 B7, B7M, B16, B8, B8M; A320 L7, L7M; ASTM A194 2H, 2HM, 8, 8M; ISO 3506 A2/A4

- Sizes: M12 – M100 (1/2" – 4"), lengths per flange class and project BOM

- Applications: ASME B16.5 / B16.47 flanges, API 6A and 17D connections, heat exchangers, pipelines, pressure vessels

- Finishes: plain, phosphate and oil, hot-dip galvanized, PTFE-coated, per specification

- Certification: EN 10204 3.1 material certificate, hardness and tensile reports, dimensional report

Based on our supply records to global EPC contractors, stud bolt acceptance usually hinges on three practical details: correct configuration selection, strict grade matching, and complete certification.

Double End Stud vs Full Thread Stud: Which to Specify

Two stud configurations dominate industrial bolting:

• Stud bolts (ASME B16.5 pattern) — typically fully threaded or with equal-length threads at both ends, designed for ASME B16.5 and B16.47 gasketed flange bolting.
• Double end / tap-end studs (API 6A / heat exchanger pattern) — threaded at both ends with a plain center section; the shorter tap-end engages the blind tapped hole, the longer end takes the nut. Common for API 6A wellhead connections and TEMA heat exchangers.

The flange standard or the project BOM defines the length, thread length and point configuration. For blind tapped holes the stud must have the correct tap-end length; getting this wrong shows up at site as proud threads or stripped engagement.

Stud Bolt Material Grades We Manufacture

For sour service and offshore applications, the material, hardness and coating must be selected together — see our Custom Fastener Engineering Guide for the selection process.

Grade Matching: Stud Bolts and Heavy Hex Nuts

Stud bolts are supplied with matching heavy hex nuts, and the grade match is part of the joint design:

The nut grade must meet or exceed the stud hardness requirement. Mixed grades in one joint — a B7 stud with a low-strength nut, for example — fail both the standard and the inspector's checklist. For broader project requirements, our Fastener Selection Guide covers how to match bolting materials to specific global project specifications.

Finish and Coating Selection

The finish is specified together with the material, not as an afterthought:

• Plain — carbon steel studs, phosphate and oil typical; used indoors or where coating is not required
• Hot-dip galvanized — for atmospheric corrosion resistance; over-tap control required on nuts
• PTFE / Xylan — for galling control on stainless studs and consistent tightening behavior
• Zinc flake — thin, hydrogen-embrittlement-safe coatings for hardened bolting

For sour and offshore service, the coating choice interacts with the hardness limit — confirm both with the project specification. For projects requiring alternative materials or complex geometries, explore our Stainless Steel Fasteners and Hex Bolts, Nuts & Washers ranges.

Certification and Inspection

Project QA/QC commonly requires:

• EN 10204 3.1 certificate — material certificate with chemical and mechanical properties, issued by the mill and validated by our QA
• Hardness and tensile reports — per heat or per lot, per project scope
• Dimensional report — thread fit, length and point configuration verified against the BOM
• Third-party inspection — witness testing and documentation review where the project requires

We prepare the certificate package per lot, with heat number traceability from raw bar to finished stud. Yuanpai supplies stud bolts to global EPC projects and international distributors, ensuring that every certificate package meets the QA/QC requirements of worldwide oil & gas, petrochemical and power generation industries.

FAQ

Q: What is the difference between a stud bolt and a threaded rod?

A: A stud bolt is a precision fastener made to a bolting standard (ASME B16.5 pattern, ASTM A193 material) with defined thread length and points, supplied with matching nuts. A threaded rod is a general-purpose continuous thread product without the bolting-grade material and certification requirements.

Q: What stud bolts are used for ASME B16.5 flanges?

A: ASTM A193 B7 studs with ASTM A194 2H heavy hex nuts are the standard choice for carbon steel service; B8M studs with A194 8M nuts are used in corrosive service. The flange class determines the size and length.

Q: Do you supply the nuts with the studs?

A: Yes. Studs are supplied with matching heavy hex nuts and washers as a bolting set, with the grade match documented on the packing list and certificate.

Q: What certificates are included?

A: EN 10204 3.1 material certificates, hardness and tensile reports, and dimensional inspection reports per lot. Third-party inspection with witness is available where the project requires.

Get your stud bolt quote within one working day — simply reply with:

• Grade & standard (e.g. B7 ASTM A193 with 2H nuts)
• Size & length (e.g. 1-1/8" x 6-1/2", B16.5 pattern)
• Quantity & certificate scope (e.g. 8,000 sets with 3.1 certificates)

Download the flange bolting specification checklist — grade, nut match, finish, length and certificate requirements.

Request sample kits — evaluate thread fit, material finish and certificate documentation before ordering.

Direct WhatsApp engineering support: [+1 XXX XXX XXXX] — send the flange BOM or project inquiry directly to our engineering team.

Related guides: Hex Bolts, Nuts & Washers · Stainless Steel Fasteners · Custom Fastener Manufacturer · Fastener Selection Guide