STAINLESS STEEL SHEAR NUTS

Shear Nuts — A shear nut looks like a simple domed cap from the outside, but underneath is a standard hex nut base joined to that cap by a deliberately weak neck: tightened with an ordinary socket or spanner like any hex fixing, it behaves normally right up until installation torque reaches a pre-set design point, at which the hex head shears cleanly away, leaving nothing behind but a smooth cone or collar with no flats, slot, or recess for any tool to grip. That's what sets this apart from every other product in the security range — hexalobular, hex-socket, and 2Hole fasteners rely on a restricted drive shape and matching tooling to stop unauthorised removal, while a shear nut needs no special bit or key to fit at all; its tamper resistance comes entirely from the shear-off action itself, which is also why removal afterwards is effectively destructive, generally requiring cutting, grinding, or specialist extraction. That combination of ordinary installation and permanent, drill-or-grind-only removal makes shear nuts a common choice for number plate fixings, street and road furniture, signage, CCTV housings, and access covers and utility fittings where a genuinely permanent fixing is wanted and the added cost or complexity of pin-drive security tooling isn't justified. The critical selection point is matching shear torque to the application: because the shear torque is fixed for each nut size and grade, the correct nut has to be paired with the bolt or stud diameter and the tightening specification the joint actually needs, rather than assuming any nut of the right thread size will do — too low a shear torque risks premature failure before the joint is properly clamped, while too high a torque risks over-stressing the bolt or the material being fixed before the cap shears. Grade should be chosen on both structural and environmental grounds here, since shear torque and corrosion resistance are linked: A4 is generally the safer specification outdoors or in exposed locations, where consistent, predictable shear behaviour over years of service matters as much as resisting the corrosion that could otherwise weaken the neck prematurely. There's no dedicated ISO or DIN standard for the shear mechanism itself, though the underlying nut blank generally follows conventional hex nut proportions before the shear-away head is added.

FAQs
Is a torque wrench needed to fit a shear nut correctly?
Not necessarily — the shearing action itself is the built-in torque limiter, so a standard socket or spanner, hand or power, can be used without a calibrated torque wrench, since the nut is designed to fail predictably at its set point regardless of how much further torque is applied.

Is the shear torque adjustable, or fixed by the manufacturer?
Fixed. It's set for each specific size and grade combination during manufacture, which is why the nut must be matched to the bolt or stud and the application rather than treated as a universal fit.

Does the sheared-off cap need removing, or does the remaining collar stay in place?
It stays in place — the cone or collar remaining after shearing is the finished, tamper-resistant appearance, not a remnant to be removed.