Leading Supplier, Stockist and Exporter of Fasteners, Nuts, Bolts & Washers
BB Infras is a recognised supplier, stockist and exporter of high-strength industrial fasteners for flange bolting, structural connections, pressure vessel assembly, and general engineering in oil & gas, petrochemical, power, and construction industries. We supply fully traceable fasteners with material certificates for all critical applications.
Our fastener range covers stud bolts, hex bolts, machine bolts, hex nuts, heavy hex nuts, flange nuts, flat washers, spring washers, lock washers and custom fastener assemblies. All fasteners are manufactured and tested to ASTM A193, A194, A307, A325, A490, and equivalent ISO / DIN standards.
Materials available include Alloy Steel (ASTM A193 B7, B16), Carbon Steel (A193 B7M, A307 Gr.B), Stainless Steel (A193 B8/B8M), Duplex (F51/F55), Nickel Alloys (Inconel 625, Hastelloy C276), and Titanium Grade 5 for extreme service conditions.
Fastener Types and Grades
| Type | Grade / Standard | Application |
|---|---|---|
| Stud Bolt (Full Thread) | ASTM A193 B7 / B8 / B8M | Flange bolting, pressure vessels |
| Hex Bolt / Machine Bolt | ASTM A307 / A325 / A490 | Structural, general engineering |
| Heavy Hex Nut | ASTM A194 2H / 8 / 8M | Flange bolting with A193 studs |
| Hex Nut (Standard) | ASTM A194 / ISO 4032 | General engineering |
| Flat Washer | ASME B18.22.1 / ISO 7089 | Load distribution under bolt heads |
| Spring Lock Washer | ISO 7090 / DIN 127 | Vibration-resistant connections |
| Flange Nut / Serrated Nut | ISO 4161 / DIN 6923 | Sheet metal, auto, structural |
Frequently Asked Questions
- Q: What is ASTM A193 B7?
- A: ASTM A193 B7 is a chromium-molybdenum alloy steel stud bolt grade for high-temperature and high-pressure bolting applications. It is the most widely used grade for flange bolting in refineries and petrochemical plants.
- Q: Which nut is used with A193 B7 studs?
- A: ASTM A194 Grade 2H heavy hex nuts are the standard pairing for A193 B7 stud bolts. For stainless studs (B8/B8M), use A194 Grade 8 or 8M nuts.
- Q: Do fasteners come with certification?
- A: Yes — all fasteners are supplied with EN 10204 3.1 MTC including chemistry, mechanical properties, hardness and dimensional inspection. NABL-accredited lab certificates available on request.
