Square Nut, Metric — GB/T 39 / ISO 4034 (Series 076) are used primarily for the clamped counter-face of a bolted joint. This page summarizes where they fit, the industries that rely on them, and the practical points to get right when you specify them — to GB/T 39 / ISO 4034. Stocked across roughly M3 to M24, they cover general to heavy-duty work.
Typical Applications for Square Nut, Metric — GB/T 39 / ISO 4034 (Series 076)
The most common settings where these are specified:
- Maintenance & repair (MRO): a stocked size for servicing existing plant where the original fastener spec must be matched.
- Fabrication & metalwork: bench and on-site assembly of steel frames, enclosures and weldments.
- Bolted joints: the clamping counter-face on studs and bolts across every assembly type.
- Vibration-prone equipment: where a locking or flanged style resists loosening.
- Frames & weldments: captive or welded options for repeatable assembly.
How to Specify Square Nut, Metric — GB/T 39 / ISO 4034 (Series 076) for Your Application
- Size: Match the nominal size to the mating thread or hole. This product spans M3–M24; check the full table below for the exact dimensions of each size.
- Locking & grade: Match the strength grade to the bolt, and choose a locking style (nyloc, all-metal, serrated flange) if the joint sees vibration.
- Environment: For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
- Standard: This product is supplied to GB/T 39 / ISO 4034. Quoting the standard on your order guarantees interchangeable dimensions between suppliers.
Where Square Nut, Metric — GB/T 39 / ISO 4034 (Series 076) Are Not the Right Choice
Not on their own — they need a matching bolt or stud — and a plain nut is not a substitute for a locking type under heavy vibration.