Sealing Washers

When securing screws or bolts outside, it's important to protect the fasteners from water as well as vibratory forces. Sealing washers are designed to form a protective barrier against water whilst simultaneously ensuring the risk of loosening under vibratory forces is kept to a minimum. Here at Cromwell, we have a wide range of sealing washers from our trusted exclusive brand Qualfast® and national brands such as Monument.

What are sealing washers?

Also known as bonded sealing washers or Dowty washers, sealing washers are comprised of an outer metal ring and an inner ring usually manufactured from a softer material such as an elastomer. The two washers are bonded together and form a tight, waterproof seal, with the metal part of the washer absorbing any pressure from the head of the screw and the elastomer inner washer protecting the thread of the screw from the ingress of water.

When are sealing washers used?

Sealing washers are generally used in applications where bolts or screws are likely to be subject to adverse weather conditions such as rain or snow. They can also be used in applications where a fragile material is concerned, as the elastomer inner of the washer helps to provide cushioning under the head of the screw or bolt.

Considerations when choosing a sealing washer

Hole diameter - The size of your screw or bolt will ultimately determine what size sealing washer you will need. It's always best to check this measurement before purchasing to avoid having a sealing washer that doesn't perform effectively.

Material - The outer diameter of a sealing washer is generally made from a sturdy metal such as copper or mild steel for strength, whilst the inner washer is usually manufactured from an elastomer to provide cushioning and a water tight seal around the screw or bolt.

Sealing washer jargon buster

We want to make it easy for you to shop our range of sealing washers, so we have outlined some key terminology that will help you understand the range and applications a little better.

What does a self-centering sealing washer do?

As it sounds, a sealing washer that is referred to as a self-centering sealing washer has the ability to centre itself around the screw or bolt, which in turn reduces the likelihood of seal offset, where the sealing washer may not perform to the best of its abilities.


How do sealing washers work?

The inner elastomer section of the sealing washer provides a water-resistant seal around the bolt or screw, whilst the outer metal of the washer is designed to absorb vibratory forces and motions to keep the screw or bolt held firmly in place.