High Tensile Nut Manufacturer — HSFG, Heavy Hex and Nuts to Drawing
S.R. Forgings manufactures high tensile nuts at Focal Point, Ludhiana, and has done since 2009. The range covers hex and heavy hex nuts in property classes 8, 10 and 12, IS 6623 high strength structural nuts for HSFG assemblies, ASTM A194 Grade 2H and 2HM nuts for stud bolt service, square nuts, one-piece forged dome nuts, and nuts made to customer drawing where no standard size fits.
A nut is not an accessory to the bolt — it is half the joint. A property class 10.9 bolt tightened into a class 8 nut will strip the nut before the bolt reaches its preload, which is why the standards pair grades the way they do. We supply matched assemblies rather than loose parts wherever the application is structural, so bolt, nut and washer arrive tested together and certified together.
Nuts are forged, not machined from bar. Heat treatment and proof load testing are carried out to the governing standard, and NABL-approved test reports are issued where the specification calls for them.
Nut standards we manufacture to
| Standard | What it covers | Grades | Matching bolt |
|---|---|---|---|
| IS 6623 | High strength structural nuts for friction grip connections | 8S, 10S | IS 3757 HSFG bolts, with IS 6649 washers |
| IS 1363 / IS 1364 | Hex nuts, product grades A, B and C | Class 4, 5, 8 | General engineering bolts |
| ASTM A563 | Carbon and alloy steel nuts for structural bolting | Grade C, DH | ASTM F3125 A325 and A490 |
| ASTM A194 | Nuts for high pressure and high temperature service | 2H, 2HM | ASTM A193 B7 and B7M stud bolts |
| EN 14399-3 / -4 | Preloaded structural bolting assemblies, system HR and HV | Class 8, 10 | EN 14399 HSFG bolts |
| DIN 934 / ISO 4032 | Standard metric hex nuts | Class 8, 10, 12 | Property class 8.8, 10.9, 12.9 bolts |
What to tell us when you enquire
- Size and thread — nominal diameter and pitch, coarse or fine.
- Property class or grade, or the bolt the nut has to go with. Either is enough; we will match it.
- Standard — IS, ASTM, EN, DIN, or to your drawing.
- Finish — plain, zinc plated, hot dip galvanised or zinc flake. Galvanised nuts are tapped oversize and supplied lubricated.
- Quantity, and whether nuts alone or complete bolt, nut and washer assemblies.
- Certification — mill certificate, proof load test, or NABL laboratory report.
A drawing or a photograph of the nut you are replacing is usually faster than a description. Send it and we will identify it.
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Hex & Heavy Hex Nuts
Hex and heavy hex nuts in property classes 8, 10 and 12, to IS 1364, ISO 4032, DIN 934 and DIN 6915, or to customer drawing. Heavy hex nuts carry a larger across-flats and greater thickness than a standard hex nut of the same thread, which is what allows them to develop the full preload of a high tensile bolt without stripping.
Finish: plain, zinc plated, hot dip galvanised or zinc flake
HSFG Nuts
High strength structural nuts for friction grip connections, supplied against the bolt they are to be used with.
Standards: IS 6623 (class 8S, 10S), ASTM A563, ASTM A194, EN 14399-3 and -4
Material: carbon and alloy steel, heat treated and proof load tested
Supply: loose, or as matched bolt, nut and washer assemblies
Finish: plain, zinc plated or hot dip galvanised with lubricated thread
Square Nuts
Square nuts for channel fixings, timber connections, track and railway fittings and general engineering, where a flat face has to bear against the work or the nut has to be held against rotation in a slot. Manufactured to standard sizes or to customer drawing, in mild steel and high tensile grades.
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Dome Nuts
A dome nut closes off the end of a bolt, protecting the exposed thread and removing a sharp projecting end. Dome nuts are made either as a two-piece nut with a pressed cap fitted on, or as a single solid piece. S.R. Forgings manufactures the one-piece forged type, so there is no cap to work loose or come away in service.
Size: M16 to M36, and to customer drawing
Finish: zinc plated, hot dip galvanised, black or as required