Cap Nut

A cap nut is a nut with a closed dome on top. It covers the end of a thread and gives a neat, snag-free finish.

A cap nut covers the end of a thread and gives a neat, rounded finish that protects the thread and the user from sharp edges. It takes a bolt or stud of the same thread and is tightened with a spanner or socket. The nut suits furniture, railings, guards and visible fixings where a domed head is wanted.

Hot-dip galvanising gives a thick zinc coating for outdoor use. Plain finish has no coating and suits dry indoor work. PTFE coating gives low friction and helps resist chemicals and sticking.

This kind of nut is often made in steel, stainless steel 304 or 316, or brass. Stainless steel 316 suits wet or salty sites, and brass suits decorative and electrical work. Steel gives general strength at lower cost.

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 and a material certificate for the bar or wire. On receipt, check the thread, the dome depth and the across-flats size against your order. Check the finish for bare patches or uneven coating.