Stud bolts, nuts and fasteners for flanged joints
Stud bolts and heavy hex nuts: B7 / 2H, B7M, B8M, L7, plain, galvanized and PTFE coated.
Overview
Flange bolting carries the entire load of the joint. We supply stud bolts and heavy hex nuts in the grades and coatings specified by Pakistani refineries, gas plants and fertilizer complexes, sized to ASME B16.5 / B16.47 flange tables so the correct length and quantity ships with each flange or valve.
ASTM A193 B7 studs with A194 2H nuts cover general hydrocarbon and steam service; B7M and 2HM, hardness controlled, meet NACE MR0175 for sour gas. A320 L7 and A194 Grade 4 or 7 are supplied for low-temperature service, and A193 B8 and B8M Class 1 and 2 with A194 8 and 8M nuts for stainless and corrosive duty.
Coatings include plain black, hot-dip galvanized, zinc plated and PTFE fluoropolymer (Xylan / Takecoat) for offshore and coastal plants where bolts must be removed after years in service. Washers, machine bolts, hex bolts and anchor bolts are available with the same certification.
Typical applications
- Flanged joints in refineries, gas plants and pipelines
- Sour-service bolting (B7M / 2HM)
- Low-temperature LPG and cryogenic flanges (L7)
- Stainless and duplex piping (B8M)
- Coastal and offshore plants (PTFE coated)
- Turnaround and gasket-and-bolt kits
Specifications
| Stud bolts | ASTM A193 B7 · B7M · B16 · B8 / B8M Cl. 1 & 2 · A320 L7 · L7M · B8 · A453 Gr. 660 |
|---|---|
| Nuts | ASTM A194 2H · 2HM · 4 · 7 · 7M · 8 · 8M · heavy hex to ASME B18.2.2 |
| Sizes | ½" – 4" diameter UNC / 8UN; M12 – M100 metric |
| Thread | ASME B1.1 UNC Class 2A/2B · 8UN above 1" · ISO metric |
| Coatings | Plain · hot-dip galvanized · zinc plated · PTFE (Xylan 1070 / 1424) · cadmium alternatives |
| Standards | ASME B18.2.1 · ASME B16.5 bolting tables · NACE MR0175 (B7M / L7M) |
| Testing | Tensile · hardness · impact (L7) · 3.1 certification · PMI for stainless |
| Also available | Hex bolts · machine bolts · washers · anchor bolts · tie rods |
Sizes, classes and materials listed are typical of our stock and supply programme. Other combinations are quoted against your specification.
Documentation supplied
- EN 10204 3.1 material test certificate, traceable to heat number (3.2 on request)
- Mill test certificate and dimensional report
- Certificate of origin and manufacturer's certificate of conformity
- NACE MR0175, fire-safe and third-party inspection documents where the order requires them
Frequently asked questions
B7 or B7M?
B7M is the same alloy as B7 but tempered to a maximum hardness of 22 HRC, which makes it resistant to sulphide stress cracking. Specify B7M with 2HM nuts for sour (H2S) service per NACE MR0175.
How do I work out stud bolt length?
Stud length depends on flange size, class, facing and gasket type. Send us the flange details and we supply studs to the ASME B16.5 bolting tables, or confirm against your bolt chart.
Why PTFE-coated bolts?
The fluoropolymer coating prevents corrosion and galling, keeps the tightening torque consistent and allows bolts to be removed without cutting after long service in humid or marine environments.
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Sizes, classes & brands →Request a quotation for stud bolts & fasteners
Send size, class, material, quantity and required documents on WhatsApp or through the form. We confirm availability, pricing and lead time within one working day.