How to Choosing Hex Bolts

How to Choosing Hex Bolts

Whether it’s finish, thread or size, the specification of hex bolt will depend on your needs.

Design of Hex Bolts

Stainless steel
Stainless steel hex bolts aren’t just strong and resistant because of their finish. The entire body of the bolt is made from stainless steel. Stainless steel is corrosion resistant so can be used in high-saline locations where other fasteners would rust too quickly. They are also a common choice because they don’t need coating.

A2 and A4 fixings indicate the levels of chromium in the stainless are both extremely corrosion resistant. For any M&E and BES engineers working in a marine environment, the best s/s fixing would be A4. For industry ‘near’ a marine environment, A2 is usually suitable.

We’ve written an entire article to help you decide if stainless steel fixings are right for you.

BZP
BZP Hex Bolts are the most common finish with fixings. It stands for bright zinc plated. An advantage of BZP finish is that it’s aesthetically pleasing and makes sure all fixings are uniform.

However, the BZP layer is thin which makes the steel resistant to moisture but won’t prevent rusting or oxidising in an external or outdoor environment.

Galvanised
The Galv Hex Bolt finish with hot-dip galvanisation creates an element resistant finish. This fixing finish is cost-effective and low maintenance once installed. If you intend to cut galvanised hex bolts, remember that the zinc finish will disappear and leave unprotected metal.

Thread
Fully threaded
Fully Threaded Hexagon Bolts, otherwise known as a ‘hex sets’, are designed for use in heavy-duty fastening applications. As the name states, these fasteners are threaded all the way up to the head of the bolt. This makes them great for installation into pre-threaded holes.

If your build is focused mainly on grip strength and less interested in alignment and shear strength, a fully threaded bolt is the best fastening solution. After application, a full thread bolt spreads pressure along its entire length, with the largest holding pressure placed on the head.

Plain/Partial Threaded
Plain hex bolts feature an unthreaded shank beneath the hex bolt head. This style of hex bolt is best for resistance and alignment. For a project that requires a lot of force to hold an object in place, a partially threaded bolt delivers the strength needed. The non-threaded segment, sometimes called grip length, has zero weak spots to prevent strain.

The entire fastening is more resistant to vibration and shear forces when the unthreaded portion is inserted into a correctly sized hole.

Size of Hex Bolts

As with most bolts, hex bolts comes in M size times length size. For heavier applications, larger diameters are needed. WINDO stock hex bolts up to M48 and 270mm in respective sizes throughout products in our range.