Oil & Gas Fasteners Manufacturer & Supplier: Stud Bolts, Flange Bolts and NACE-Compliant Bolting

GL Fastener is an oil & gas fastener manufacturer and supplier in China, specializing in stud bolts, flange bolting and NACE-compliant solutions for upstream, midstream and downstream applications. We serve EPC contractors, valve and pump manufacturers, and oil and gas distributors across the Middle East, Europe, Southeast Asia and Australia, with documentation packages structured for regional QA/QC audits.

What Oil & Gas Buyers Look For in a Fastener Supplier

During oil and gas vendor qualification, buyers normally focus on three areas: heat traceability, hardness verification and document completeness. A stud bolt that fails a hardness check during a vendor audit delays the whole package, so the supplier's production control matters as much as the price per piece.

GL Fastener runs cold heading, machining, heat treatment and testing lines for bolting used in flanges, valves, wellheads and process piping. Every lot is traceable by heat number from incoming bar stock to finished stud, and the certificate set is prepared before shipment, not after the audit request.

Product Range: Stud Bolts, Flange Bolts and Bolting Assemblies

Thread details follow the project specification: 8UN thread series for studs above 1 inch, UNC / UNF for smaller sizes, and metric threads (M12–M64) where the drawing calls for them.

NACE MR0175 / ISO 15156 Compliance

Sour service bolting is the most audit-sensitive fastener category in oil and gas procurement. We supply NACE MR0175 / ISO 15156 compliant bolting with controlled hardness:

• B7M studs with max hardness 22 HRC (237 HBW), per ASTM A193 (hardness conversion per ASTM E140 where applicable)
• 2HM nuts with hardness matched to the stud
• L7M studs for low-temperature sour service
• Duplex and super duplex studs with hardness verified per heat and lot

Hardness is recorded on the test certificate with the heat number, so the auditor can trace the value back to the production lot. Where the project specification requires a lower hardness cap, the heat treatment is adjusted before testing.

High-Temperature and HP/HT Bolting

For high-temperature service, ASTM A193 B7 remains the workhorse grade for stud bolts in process piping. Where the design temperature or the project specification demands more, we supply:

• B16 / B8M Class 2 for elevated-temperature service in process plants
• Inconel 718 (UNS N07718) studs for HP/HT wells and critical sour environments, with properties verified per ASTM B637 and finished product per ASTM A1014/A1014M
• API 20E (alloy) and API 20F (CRA) bolting support, with grade and BSL (Bolting Specification Level) defined against the project specification

Documentation and QA/QC Support

GL Fastener's documentation package is structured for Aramco / ADNOC-style audits:

• EN 10204 3.1 inspection certificates (3.2 with third-party witnessing where specified)
• Mill certificates with heat numbers for raw material
• Hardness and mechanical test reports per lot
• Dimensional inspection reports (thread gauging, length, coating thickness)
• First-article inspection reports for non-standard studs and bolts
• Material specification cross-references (AMS, NACE, ISO 15156) where required

Our quality system documentation is compiled before dispatch, so EPC and valve manufacturers receive an audit-ready file with the shipment rather than a partial certificate set.

Surface Protection for Oil & Gas Bolting

• Zinc plating — standard finish for lower-strength structural items or carbon steel components; high-strength bolting (≥110 ksi tensile / >31 HRC) requires electroplating per ASTM F1941 / F1941M with mandatory hydrogen embrittlement relief baking (baking within 4 hours of plating)
• Hot-dip galvanizing per ISO 1461 / ASTM F2329 — for structural and outdoor applications
• Zinc-flake coating (Dacromet / GEOMET type) — for corrosion-critical and high-strength bolts
• PTFE / Xylan coatings — for galling prevention on stainless and nickel alloy threads
• Phosphate and black oxide — for assemblies with subsequent lubrication

Coating thickness is verified according to the project coating specification, with thread fit checked after coating where applicable.

Why MENA and EPC Buyers Choose GL Fastener

• Dedicated production lines focused exclusively on ASME/ASTM flange and stud bolting rather than generic commercial fasteners
• In-house metallurgical and hardness testing on 100% of heat-treated lots to satisfy NACE MR0175 / ISO 15156 audit criteria
• Documentation ready before dispatch — EN 10204 3.1 / 3.2 and inspection reports structured for audits
• Standards coverage — ASME, ASTM, API, NACE, ISO, EN, DIN and GB against the project specification
• Logistics — export through major China ports with inspection coordination for third-party witnessing

FAQ

Q: What is the difference between B7 and B7M stud bolts?

A: B7 is a chromium-molybdenum steel stud for elevated-temperature service; B7M is the hardness-controlled version (max 22 HRC / 237 HBW, conversion per ASTM E140 where applicable) used for NACE MR0175 / ISO 15156 sour service. B7M is usually supplied with 2HM nuts to match the hardness envelope.

Q: Which stud bolt standard do I need for ASME B16.5 flanges?

A: For ASME B16.5 flanges, stud bolts are typically ASTM A193 B7 (or B7M for sour service) with dimensions per ASME B18.31.2, using 8UN thread series above 1 inch and A194 2H / 2HM heavy hex nuts.

Q: Can you supply API 20E / API 20F certified bolting?

A: We supply bolting to API 20E (alloy) and API 20F (CRA) requirements across BSL-1, BSL-2 and BSL-3 levels, matching your project-defined Bolting Specification Level, material class and service environment. The certificate package includes material, hardness, and mechanical test documentation.

Q: What documentation do you provide for NACE MR0175 compliance?

A: EN 10204 3.1 inspection certificates with heat number traceability, hardness test reports per lot, mill certificates, and dimensional reports — structured for Aramco / ADNOC-style vendor audits.

Q: Do you supply duplex and Inconel stud bolts?

A: Yes. Duplex (S31803 / S32205 / S32750) studs per ASTM A1082 / A479, and Inconel 718 studs per ASTM B637 material / ASTM A1014 finished product, for sour and HP/HT service.

Q: What is your typical lead time for stud bolts?

A: Selected stock sizes of B7 / B7M studs and 2H / 2HM nuts may be available for rapid dispatch, subject to size, quantity and coating requirements; production lots of 5,000–50,000 pieces typically ship in 2–4 weeks depending on heat treatment and coating requirements.

Request a Quote for Your Bolting Package

Send the flange rating, pressure class, stud size, thread series and material grade — or the project specification. Our engineering team will confirm compliance (NACE, API, or project-specific), certificate scope, and delivery schedule within one working day.

📄 Download the bolting RFQ checklist — stud size, thread, material, coating, hardness and documentation requirements.

📦 Request sample studs and MTC examples — evaluate product quality and certificate format before ordering.

💬 WhatsApp engineering support — send the flange specification or drawing directly to our team.