Fasteners – Manufacturer, Stockist, Supplier & Exporter
Giriraj Impex is a manufacturer, stockist, supplier and exporter of industrial fasteners – stud bolts, hex bolts, heavy hex nuts and washers – in alloy steel, carbon steel, stainless steel, duplex and super duplex steel, nickel alloys and titanium. Our fasteners are supplied to ASTM A193, A194 and A320 for pressure and temperature service, and to ASME, ISO and DIN dimensional standards.
In a flanged joint the bolting holds the gasket under load at the design pressure and temperature, so the bolt and nut grades must suit the flange material, the service temperature and the corrosion conditions. We supply studs, nuts and washers together as matched sets for each flange size and class.
Bolting grades for pressure service
| Standard | Grades | Typical use |
|---|---|---|
| ASTM A193 (bolts and studs) | B7, B7M, B16; B8 and B8M (Class 1 and 2) | High-temperature and high-pressure service; B7M for sour service with controlled hardness; B8/B8M stainless for corrosion resistance |
| ASTM A194 (nuts) | 2H, 2HM, 4, 7, 8, 8M | Heavy hex nuts paired with A193 and A320 studs, e.g. B7 with 2H |
| ASTM A320 (low temperature) | L7, L7M, L43, B8, B8M | Bolting for low-temperature service with impact testing |
| ASTM A453 | Grade 660 | High-temperature bolting |
| ISO 898-1 / IS 1367 | Property classes 8.8, 10.9 and 12.9 | Structural and general engineering bolts |
Fasteners by material
- Alloy steel fasteners – A193 B7, B7M and B16 studs with A194 2H and 2HM nuts, the standard bolting for carbon steel flanges.
- Carbon steel fasteners – hex bolts and nuts for structural and general use.
- Stainless steel fasteners – A193 B8 (304) and B8M (316) studs with A194 8 and 8M nuts.
- Duplex and super duplex fasteners – for seawater and offshore service.
- Inconel, Incoloy, Monel and Hastelloy fasteners – for severe corrosion and high temperature.
- Titanium fasteners – light weight and high corrosion resistance.
Product types and dimensional standards
| Product | Dimensional standards |
|---|---|
| Stud bolts (fully threaded, double-ended) | ASME B18.31.2; lengths for flanges as given in ASME B16.5 |
| Hex bolts and heavy hex bolts | ASME B18.2.1; ISO 4014, ISO 4017; DIN 931, DIN 933 |
| Hex and heavy hex nuts | ASME B18.2.2; ISO 4032; DIN 934 |
| Washers | ASME B18.21.1, B18.22.1; DIN 125, DIN 127 |
| Threads | UNC and 8UN (ASME B1.1); metric coarse and fine (ISO 261) |
Bolts, studs and special fasteners are also made to drawings. Please give the diameter, thread, length, grade and quantity, or the flange size and class so we can work out the stud size and length.
For flange bolting, ASME B16.5 calls for coarse (UNC) threads up to 1 inch diameter and the 8-thread (8UN) series for 1 inch and larger. The stud lengths in the B16.5 tables are measured without the chamfered points, so studs are ordered by the effective length plus the end condition. Heavy hex nuts to ASME B18.2.2 are used on pressure flanges because their larger across-flats size spreads the load and suits torque tools.
Coatings and finishes
Fasteners can be supplied plain, black oxide, zinc plated, hot-dip galvanised or with PTFE (fluoropolymer) coating, as ordered. Coatings are chosen for the environment – for example PTFE-coated B7 studs for offshore and coastal plants – and should be stated in the enquiry together with any coating thickness or colour requirement.
Manufacturing and inspection
Fasteners are made from bar of the specified grade by hot forging or cold heading, thread rolling or cutting, and heat treatment as the specification requires – for example quenching and tempering for B7. Each lot is checked for dimensions and threads, and the head or end of each stud or bolt carries the grade marking required by the standard. Fasteners are supplied with mill test certificates (MTC); third-party inspection is available on request, and B7M/2HM bolting can be supplied to NACE MR0175 / ISO 15156 on request.
Matching bolting to the flange
The bolting grade is chosen with the flange material and the service temperature in mind:
- Carbon steel flanges (ASTM A105) in normal service – A193 B7 studs with A194 2H nuts.
- Low-temperature carbon steel flanges (ASTM A350 LF2) – A320 L7 studs with A194 Grade 7 nuts, impact tested.
- Sour service – A193 B7M studs with A194 2HM nuts, to NACE MR0175 / ISO 15156 on request.
- Stainless steel flanges – B8 or B8M studs with Grade 8 or 8M nuts; Class 2 (strain hardened) is chosen when higher strength is needed.
- Duplex, super duplex and nickel alloy flanges – bolting in the same or a compatible alloy, or coated B7 where the specification allows.
Ordering fasteners
Please give the product type, diameter and thread, length, grade of stud or bolt and nut, number of nuts per stud, coating and quantity – or simply the flange standard, size, class and number of flanges, and we will work out the bolting.
Applications
Our fasteners are used to bolt flanges, valves and equipment in refineries, petrochemical and chemical plants, offshore and onshore oil and gas, power stations, fertiliser plants, water treatment and structural steelwork. Fasteners are machined from round bars in the same grades we supply. See all product forms on the products page.
On a typical process project the bolting list runs to thousands of studs across many flange sizes and classes, so we work from the flange schedule to supply complete, correctly sized sets.
Each set is packed and labelled by size and grade so the site team can match bolting to flanges quickly.
Why Giriraj Impex
- Wide range of materials, grades, sizes and international specifications, supplied since 2008
- Mill test certificates (MTC) supplied with material; third-party inspection on request
- Inspection and quality verification before dispatch
- ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018 certified
- Competitive pricing and timely delivery
- Supply across India and for export, from our Mumbai headquarters
Frequently Asked Questions
B7 is a quenched and tempered chromium-molybdenum alloy steel grade in ASTM A193, used for studs and bolts in high-pressure and high-temperature service. It is normally paired with ASTM A194 Grade 2H heavy hex nuts.
B7M is the same alloy steel with a lower maximum hardness, produced and tested to suit sour service where hydrogen sulphide is present. It is normally used with A194 2HM nuts.
ASTM A320 covers alloy and stainless steel bolting for low-temperature service. Grades L7 and L43 are common, and the standard requires impact testing at the specified temperature.
B8M stainless steel (316) studs are normally used with ASTM A194 Grade 8M heavy hex nuts, so that the stud and nut have matching corrosion resistance.
Yes. Stud bolts and nuts can be supplied with PTFE (fluoropolymer) coating, zinc plating or hot-dip galvanising as ordered. Please state the coating and colour in your enquiry.
Yes. Give us the flange size, pressure class and standard, and we will supply the matching number of stud bolts, nuts and washers of the correct diameter and length.
Request a Quote for Fasteners – Manufacturer, Stockist, Supplier & Exporter
Tell us the product, grade, size, standard, quantity and delivery location, and our sales team will reply with a quotation.
Inconel®, Incoloy® and Monel® are trademarks of Special Metals Corporation; Hastelloy® of Haynes International.