Tube insert & end cap sizes

Your guide to choosing tube inserts and end caps – Part 2

Choosing tube inserts and end caps – Part 2

Measuring up

Tube inserts are extremely useful and versatile.

  • They can be used to finish off a pipe or tube to prevent scratching or damage.
  • They can be used as feet for furniture with tubular legs.
  • They can be used to stop the internal section from moisture and dirt getting inside, which can help keep your equipment cleaner and in better condition for longer.
  • You can even use an insert to give improved capabilities to your item. For example, by adding a threaded tube you can then attach adjustable feet.

Whether you’re looking for threaded inserts for adjustable feet, parallel tube nut inserts, or height adjusters, or something else, you’ll find everything you need on our online store

On the rare occasion that you can’t find an insert to fit the bill, you could always speak to us about our Custom Mouldings Service.

What is a tube insert?

A threaded insert is an insert that fits within a tube to cap the end, however, it also houses a threaded hole for the attachment on a further fitting such as castors or adjustable legs.

Three benefits of using a tube insert

  • Tube inserts are really easy to fit. They can be fitted at the time of manufacture, or retrospectively and literally take 30 seconds.
  • They are extremely cost-effective with tube inserts starting at just pennies per unit.
  • There are many different styles, sizes, colours and shapes to choose from to give your unit the versatility and usability and even the added design feature that you’re looking for.

How to measure for an internal tube insert

Whether you choose to fit an internal tube insert threaded insert, on an external end cap, the measurements you need will be the same. There are three types of measurements you may need for choosing your internal or external tube or wire fitting.

Outside diameter

The outside diameter of a tube is sometimes referred to as the external fitting of a tube. This is the measurement from the mid-point on one outside side, crossing through the very centre of the space to the mid-point on the opposite outside wall. For ovals and rectangles, you’ll need two outside diameter measurements – one from width to width and one from length to length, each time crossing through the central point.

The easiest way to do this is by using a vernier, but if you don’t have a vernier, a simple ruler should work well enough.

Internal diameter

This is from the internal wall on one side of the tube to the mid-point on the opposite internal wall of the tube.

Wall thickness

This can usually be found on a manufacturer’s website. However, once you have the outside diameter and internal diameter of your fitting, it’s easy to work out the wall thickness with the following equation:

External diameter- internal diameter / 2 = wall thickness

Taking your measurements in centimetres will remove the need for you to convert from imperial to metric later down the line, saving you time.

Type of fitting

If you want your fitting to sit over the top of the end of your pipe, pole, or leg, then you’ll want an external ferrule fitting.

A ferrule is a rim around the top of the cap which fits over the end of the pole. This works for legs and poles that aren’t hollow too. Alternatively, if you want your fitting to sit within the pole, a threaded tube insert will provide grip to keep the insert in place.

For more about what type of fitting to choose, see our Guide to Choosing Tube Inserts and End Caps Part 1.

If you need any help or advice on finding the right internal or external tube fitting, you can reach us on 0844 7766800 or chat with our friendly advisors online. We’ll help you find the right tube fitting for your application.