Shear Nuts

Shear Nuts and Shear Bolts are permafix one way security fasteners which once installed cannot be removed with conventional spanners.

What are Shear Nuts?

Shear nuts are a form of versatile, one way security fastening that doesn’t require any special tooling. They consist of a threaded conical section with a non-threaded hexagonal section that’s used to tighten them. Once tightened using a standard spanner or socket drive, additional pressure will exceed the shear-torque of the nut and shear off the hexagonal section, leaving only the tightened, smooth, secure conical section in place.

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Shear Nuts are available manufactured from A2 Stainless Steel, or from steel with a BZP (Bright Zinc Plate) or weather resistant Galvanised finish.

Many sizes available from stock - other sizes can be manufactured to special order.

Shear Nut Sizes - normally available from stock:

Shear Nut Dimensions & Technical Information:

Shear Nut - Installation Guide

As noted, shear nuts are easilty installed using standard tooling (e.g. spanner, socket set, etc.). When the nut or bolt is fully tightened, the hexagonal drive head is designed to shear off as additional torque is applied, leaving the shear bolt or the threaded conical lower collar of the shear nut in position on the standard bolt or stud thread, thus making these products permanent fixings.

Uses and Applications

Saddle Bolts are often used with Galvanised Shear Nuts, i.e. for protecting Palisade Fencing installations: