Square Nut

A square nut is a threaded fastener with four flat sides. It is used where a hex nut is hard to turn or where a square head bolt is used.

A square nut threads onto a bolt or stud to clamp parts together. Its square form gives more flats for a spanner and resists turning in a square recess or channel. It takes a bolt of the same thread and class, and often a washer under it.

This kind of nut is usually made of steel. It can be plain or coated. The material affects strength and corrosion resistance.

This is a general guide to checking this kind of part. It says nothing about any supplier's parts.

Ask for a certificate of conformance if you need proof of grade or dimensions. On receipt, check the thread with a gauge. Look for cracks or damaged corners.