BIS Certification for Hexagon Nuts (Grade C)

This certification applies specifically to the general-purpose hexagon nut in Product Grade C, across the common size range of roughly M5 to M64. It is the matching nut for the Grade C hexagon bolt and screw family - and it is a separate notified product with its own place in the standard, which means if you manufacture hexagon nuts for the Indian market, you need this licence in its own right, not as an add-on to a bolt licence.

A nut is easy to dismiss as the simple half of a joint, but it does real work: it has to engage the mating thread cleanly, hold the clamping load, and - crucially - be strength-matched to the bolt so the assembly does not fail by thread stripping when it is tightened. "Grade C" describes the tolerance class - the coarser, general-purpose class for standard fastening - while the nut's own strength is expressed by its property class. The governing Indian Standard for this product is IS 1363 (Part 3):2018, which is technically aligned with the international standard ISO 4034 for general-grade hexagon nuts.

Knowing exactly where your product sits within the standard saves time and money at the testing stage. The practical scope for this product:

The Grade C hexagon nut is a high-volume, everyday fastener paired with general-purpose bolts and screws across almost every fabrication and engineering setting:

Because a nut's job is to hold clamping load through its thread, testing puts particular weight on proof load. A BIS-recognised laboratory checks samples, and BIS continues periodic surveillance testing for as long as the licence stays active:

The order carves out four specific exemptions. You may fall outside the requirement if you are: manufacturing purely for export; supplying nuts that are imported only as a part or component of a larger finished good or sub-assembly; a domestic maker importing to build products that are then exported; or a Udyam-registered micro unit whose plant & machinery investment (at original cost) does not exceed twenty-five lakh rupees and whose turnover did not exceed two crore rupees in the previous financial year, certified by a Chartered Accountant. These are narrow - crossing any threshold or selling one batch into the Indian market brings you back into scope.

BIS expects documentation in three broad groups. Getting the format right is the single biggest cause of delay for first-time applicants, which is exactly the part we take off your plate:

• Administrative: company registration, factory licence, trademark proof, and - for foreign makers - the Authorized Indian Representative appointment.
• Technical: product drawings and specification, raw-material details, machinery list, in-house test equipment list, and the recognised-lab test report.
• Quality control: the quality manual, competent QC personnel details, and the process and quality-control flow for the product.

The route depends on where your factory is. Indian manufacturers follow the domestic Scheme-I process - sample testing, documentation and a factory assessment before the licence is granted - set out step by step on our BIS Certification for Indian Manufacturers page. Manufacturers based outside India go through FMCS with an Authorized Indian Representative and typically an overseas factory audit, covered on our FMCS guide.

Once the licence is granted, BIS issues a unique licence number (the CM/L number). The ISI Mark together with that CM/L number must be applied to the product and its packaging in the manner the standard prescribes. For nuts, the property class is also expected to be marked so the nut can be correctly matched with a compatible bolt on site - a mark without a valid licence behind it is treated as non-compliance.

The Bureau of Indian Standards is the certifying and enforcing authority for this product, and non-compliance is dealt with under the BIS Act, 2016:

• Seizure of stock from the factory, warehouse or distribution chain.
• Customs detention of imported consignments that arrive without a valid licence and marking.
• Fines and imprisonment as provided under the BIS Act, 2016, for manufacturing, importing or selling without certification.
• Loss of tenders and contracts, since government, infrastructure and serious private buyers require the ISI Mark as a precondition.

Fasteners are a deceptively broad category - 19 notified products, overlapping standards, easy-to-miss exemptions and a demanding factory assessment. We work across the entire order as fastener specialists, not a general firm dabbling, and prepare every document to exact BIS format so your file keeps moving - for manufacturers in India and around the world.