Hex Bolts & Heavy Hex Nuts
Giriraj Impex is a manufacturer, stockist, supplier and exporter of hex bolts, heavy hex bolts, hex nuts and heavy hex nuts – to ASME B18.2.1 and B18.2.2 for imperial sizes and ISO 4014, ISO 4017, ISO 4032 and DIN 931, 933 and 934 for metric sizes – in ASTM A193 / A194 alloy and stainless grades, A307 carbon steel, duplex and nickel alloys. We manufacture hex bolts and nuts plain, black, zinc plated, galvanised or PTFE coated, with mill test certificates.
Hex bolts and nuts are used to bolt flanges, valves, pumps, equipment and structures in process plants, power stations, oil and gas facilities and general engineering.
Types
- Hex bolts – standard hexagon head, partly or fully threaded, for equipment and general fastening.
- Heavy hex bolts – larger head across flats for higher bearing area, used with flanges and structures.
- Hex nuts – standard nuts for general use.
- Heavy hex nuts – thicker and wider than standard nuts; the standard nut for A193 studs on flanged joints.
- Hex head cap screws – fully threaded, with closer tolerances.
For flanged joints, stud bolts with two heavy hex nuts are more common than bolts.
Specifications
| Item | Details |
|---|---|
| Imperial dimensions | ASME B18.2.1 (bolts), ASME B18.2.2 (nuts); UNC, UNF and 8UN threads to ASME B1.1 |
| Metric dimensions | ISO 4014 / DIN 931 (part threaded), ISO 4017 / DIN 933 (fully threaded), ISO 4032 / DIN 934 (nuts); ISO metric threads |
| Material standards | ASTM A193, A194, A320, A307, A453; F593 / F594 (stainless); F467 / F468 (non-ferrous); ISO 898-1 / 898-2 property classes |
| Sizes | Imperial and metric diameters and lengths to order |
| Finish | Plain, black oxide, zinc plated, hot-dip galvanised, PTFE coated |
| Documents | Mill test certificate (MTC); third-party inspection on request |
Grades and matching nuts
| Bolt grade | Nut grade | Use |
|---|---|---|
| A193 B7 | A194 2H | General high-pressure and elevated-temperature bolting |
| A193 B7M | A194 2HM | Sour service |
| A193 B16 | A194 4 or 7 | High-temperature bolting |
| A320 L7 | A194 4 or 7 | Low-temperature service |
| A193 B8 / B8M | A194 8 / 8M | Stainless steel, corrosion resistance |
| A307 Gr A / B | A563 | General and low-pressure use |
| ISO 8.8 / 10.9 | ISO class 8 / 10 | Structural and machinery bolting |
The nut grade must match the bolt grade so the nut can carry the full bolt load without thread stripping.
Materials
- Carbon steel fasteners – A307, B7 with 2H nuts.
- Alloy steel fasteners – B7, B16, L7.
- Stainless steel fasteners – B8, B8M, A2 and A4.
- Duplex and super duplex fasteners, Inconel fasteners and Hastelloy fasteners.
All fastener materials are on the fasteners page.
How we manufacture hex bolts and nuts
Hex bolts are hot forged or cold headed from bar of certified heat, then heat treated to the grade's requirements, and threaded by rolling or cutting. Heavy hex nuts are hot forged or machined from hexagonal bar and heat treated to the grade's hardness range. Each lot is hardness tested and, as the standard requires, tensile and proof-load tested. Bolts and nuts are marked with the grade symbol and manufacturer's identification.
Imperial or metric?
Imperial bolts and nuts to ASME B18.2.1 and B18.2.2 are used with ASME B16.5 flanges and on projects designed to American standards. Metric bolts and nuts to ISO and DIN are used with EN 1092-1 flanges, machinery and structures designed to European or Indian standards. The two systems are not interchangeable, so the thread and size must be stated clearly on every order. Bolt hole sizes for flanges are in the flange dimensions chart.
Coatings and corrosion
For outdoor and marine use, carbon and alloy steel bolts are hot-dip galvanised or PTFE coated; galvanised nuts are tapped oversize to fit the coated bolt. Stainless steel bolts need no coating. When stainless bolts are used with carbon steel parts, insulating washers help prevent galvanic corrosion.
Ordering hex bolts and nuts
Please give the bolt and nut grades, diameter and thread, length and thread length, head type (hex or heavy hex), finish, quantity and any testing or inspection requirement.
Frequently Asked Questions
A heavy hex nut is thicker and wider across flats than a standard hex nut, giving more bearing area and thread engagement.
ASME B18.2.1 and B18.2.2 for imperial sizes; ISO 4014, 4017, 4032 and DIN 931, 933, 934 for metric sizes.
An ASTM A194 Grade 2H heavy hex nut.
DIN 931 bolts are partly threaded; DIN 933 bolts are fully threaded.
No. The threads and sizes differ, so the system must be stated on every order.
Yes. Bolts and nuts can be supplied zinc plated, hot-dip galvanised or PTFE coated.
Request a Quote for Hex Bolts & Heavy Hex Nuts
Tell us the product, grade, size, standard, quantity and delivery location, and our sales team will reply with a quotation.
Inconel® are trademarks of Special Metals Corporation; Hastelloy® of Haynes International.