SO01 Shear Nuts (Security Breakaway Nuts)
Two-part breakaway security nuts: the hex drive section shears off at a built-in groove once installation torque peaks, leaving a plain tapered cone with nothing to grip — a permanent, one-way tamper-resistant fixing. Steel zinc-plated, A2/A4 stainless or galvanised.
Last updated: 2026-11
Specifications
A shear nut — also sold as a breakaway, snap-off or permacone nut — is the classic one-way permanent security fixing. It starts life as a hex nut with a conical lower section separated by a reduced groove: you tighten it with an ordinary spanner or socket, and when torque passes the groove's limit the hex shears away, leaving the tamper-resistant cone seated on the bolt. There is then nothing left to turn, which is why shear nuts are the standard choice for perimeter fencing, public-area equipment in schools and hospitals, and automotive fixtures — anywhere a permanent fixing must survive unsupervised public access. The collected stock table covers metric M4 to M24 plus an imperial series (10-24 to 5/8-11), in zinc-plated steel, A2 and A4 stainless steel, and galvanised mild steel. The trade-offs are inherent to the principle: the installed joint cannot be retightened or removed without destruction, and installed torque is bounded by the shear groove.
| Designation | SO01 — shear nut (breakaway / snap-off / permacone), hex drive shears at installation |
|---|---|
| Metric size range (tabulated) | M4 – M24 |
| Imperial sizes listed | 10-24, 1/4-20, 5/16-18, 3/8-16, 1/2-13, 5/8-11 |
| Width across flats AF, sample clean cells (mm) | Zinc-plated steel: M6 14.0 · M8 16.0 · M10 19.0 · M12 22.0 · M16 24.0 · M20 32.0 · M24 36.0; galvanised: M8 17.0 · M10 19.0 · M12 22.0 · M16 24.0 · M20 32.0 · M24 36.0; A2 stainless: M4 7.0 · M14 22.0 |
| Security principle | Hex drive breaks off at a groove at full torque, leaving a grip-less tapered cone — permanent one-way fixing |
| Installation | Standard spanner or socket; suitable for high torque applications per the collected page; vibration resistant |
| Materials / finishes | Steel zinc-plated (BZP); A2 and A4 stainless steel; galvanised mild steel |
Materials
- Steel, zinc plated (BZP)
- Stainless steel A2
- Stainless steel A4
- Galvanised mild steel
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (SO01 Shear Nuts (Security Breakaway Nuts)) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
What happens if a shear-nutted joint needs service later?
Plan for destruction or redesign. Once the hex has sheared, the cone cannot be turned by any standard tool — that is the security — so legitimate maintenance means splitting the nut (nut splitter or careful grinding) and replacing it, or moving the fixings to a removable security nut for the rework. This is why shear nuts suit joints expected to stay closed for their service life; anything with scheduled access should start on a removable pattern such as the KM01.
Why do the tabulated sizes and AF values have gaps?
The collected stock table lists sizes per material and finish, and not every material is offered in every size — for example the stainless rows cover a different spread than the zinc-plated rows. We render the clean single-value cells as samples and leave the table's ambiguous or incomplete cells unrendered rather than guess; state your thread size, material and finish on the RFQ and we confirm exact availability at quotation.
What is the MOQ and lead time for this nut type?
The minimum order quantity is 10,000 pieces. Stock items ship in 3–7 days; non-stock items are confirmed at quotation. Common diameters in this nut type are widely stocked; confirm the exact schedule against quantity and size mix at quotation.
What should an RFQ for this nut type state?
State the standard designation (for example DIN 985 or DIN 6923), nominal thread size and pitch (metric coarse unless fine pitch is required), material and strength pairing with the mating bolt, finish (plain, zinc, or hot-dip galvanized where compatible), required certificates such as a mill test report per EN 10204 3.1, and quantity per size — plus destination country.
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support