Spanner, Bihexagonal Ring

Quick Answer: A bihexagonal ring spanner is a spanner whose closed ring end has a 12-point, or double hexagon, opening that fits over a hexagon nut or bolt head. The ring spanner encloses the fastener completely, so it grips more securely than an open-ended spanner.

Twelve Points on a Six-Sided Nut

A bihexagonal opening is two hexagons overlaid at 30 degrees to each other. A six-sided nut can therefore enter the ring in twelve positions instead of six, and the spanner can be refitted after a turn of only 30 degrees. That matters in tight corners, such as behind a machine frame or under a bench, where the handle has little room to swing.

Because the ring bears on all six flats, the load is spread and the nut is much less likely to round off than with an open-ended spanner, which touches only two flats. Many spanners of this type also have the ring set at an angle to the shank, so the knuckles clear the surface. Most are double-ended with two different sizes; the sizes, size system and ring offset of this spanner can be confirmed with LabEquip.

The drawback is access: the ring has to go over the nut from the end, so it cannot be used on a nut in the middle of a pipe or rod. There an open-ended spanner is needed, and for fast repeated turning a socket on a ratchet handle is quicker.

Specifications

Applications

• Tightening and loosening nuts and bolts on machine frames, stands and fixtures
• Breaking loose tight or rusted nuts before spinning them off with an open spanner
• Automobile and mechanical maintenance practicals in vocational courses
• Assembling steel furniture, racks and apparatus frames

Care & Handling

• Use the exact size; a loose fit rounds the corners even with a 12-point ring.
• Position yourself to draw the handle towards you, so a sudden slip carries the hand away from sharp edges.
• Never add a length of tube for leverage or hammer on the shank; only striking spanners are made for blows.
• Keep the ring clean and free of grease so it grips the nut.

Why Choose LabEquip

Mechanical, automobile and TVET workshops, and technicians who maintain steel frames and stands, rely on closed-ring spanners for nuts that need firm tightening. LabEquip supplies this spanner as part of its general lab products; give the sizes you need on the contact page.

Frequently Asked Questions

What does bihexagonal mean?

It means the ring has a 12-point opening formed by two hexagons offset by 30 degrees. It fits a six-sided nut in twelve positions, so the spanner can be refitted after a small swing.

Is a 12-point ring weaker than a 6-point ring?

A 6-point ring grips a little further from the corners and is preferred for very tight or damaged nuts. For normal work a 12-point ring grips well and is easier to place in tight spaces.

Why use a ring spanner instead of an open-ended spanner?

The ring surrounds the nut and bears on all six flats, so it is less prone to slipping or damaging the nut’s corners, and it can take more force. An open-ended spanner is faster to put on and can reach nuts on pipes.

Can it turn square nuts?

A 12-point ring can fit a square nut of the matching size, since a square fits within the twelve points. The grip is less secure than on a hexagon, so use moderate force.

How do I find the correct size?

Spanner sizes are marked on the shank and refer to the distance across the flats of the nut. Use metric spanners on metric nuts and inch sizes on inch nuts; near-fits round the corners.

Why is the ring angled to the handle?

An offset or cranked ring lifts the handle above the surface around the nut, giving room for the knuckles and a better grip when the nut sits on a flat face.

Last Updated: September 2026