Ultimate guide to tube inserts

Read time: 12 minutes | Updated on: 10 June 2024

Product Resources

Tube inserts are more than just a finishing touch for furniture or equipment legs. These versatile components can protect your floors, add stability, and even hide imperfections. But with so many varieties available, choosing the right tubing inserts can feel overwhelming. We’ve designed this guide to help you, covering:

What are tube inserts?

Tube inserts are small components designed with ribs or straight walls that fit snugly inside the open ends of tubes, pipes, or posts. They come in a variety of shapes, from round tube inserts and square tube inserts to more unusual shapes like ovals or rectangles. Tubing inserts are a versatile and inexpensive way to add function and finish to furniture, while protecting floors from scuffs.

View our range of tube inserts

When to use them: applications

They can serve several functions:

1. Finish off tubes, posts, boxes or pipes

Plastic inserts are commonly used to enhance the appearance of applications. They’re popular for furniture, such as feet for office and school chairs, desks and workstations. They’re also put to use on light-duty machinery. You’ll find them in consumer products, too, such as tripods. As feet, plastic inserts grip the floor while protecting floors from damage.

2. Protect assemblies against ingress and sharp edges

Some threaded tube inserts are designed to protect assemblies from a tube’s sharp edges while still providing an aesthetic appearance. Tube inserts are also ideal for preventing dirt and moisture ingress to protect your application and prolong its life. Depending on the material, tube inserts can be used outside to cap off posts to prevent oxidation and reduce maintenance costs.

What are glides?

Glides are used on the bottom of furniture legs to protect the floor from damage. They’re sometimes called glide inserts. Some have adhesive backs that stick onto furniture legs, while others are nailed on or screwed in.

Glides fit into a tube to reduce friction and dampen noise. When a tube insert is used on the bottom of furniture feet – or as feet themselves – you’ll usually find a glide is part of the tube insert’s design.

To help you understand feet, our experts put together this guide:A guide to levelling feet.

View our range of glides

Types of tube inserts

Tube inserts and tube insert glides are available with different features. Some are ideal for attaching levelling feet or castors to.

You can learn more in our Guide to levelling feet and Rubber Castors vs Polyurethane Castors.

Round Glides

Load bearing glides designed to use as a protection plug or as a glide
Protects and finishes tube ends in moderate to heavy-duty applications
Stepped lid for easy insertion and secure fit
PE, ABS, Nylon, Butyrate, LDPE, HDPE

Round Inserts & Glides

Finishes round tubing for a stylish look
Prevents damage to floors
Ribbed shank, which provides easy insertion
Accommodates multiple tube gauges
ABS and PP, chrome plated

Rectangular Chrome-Capped Tube Inserts

Chrome-plated cap provides a neat and attractive, high-gloss finish
Protects floors
Includes ribbed options for easy insertion and snug fit
ABS and PE

Rectangular Tube Inserts

Available in both ribbed and straight wall designs
Designed to fit into the end of a rectangular tube or pipe
Provides a smooth, durable base for furniture, appliances and more
Protects floors from scratches, scuffs and other damage caused by heavy or sharp objects
PE, LDPE, ABS in black or white
Also available with internal threads to accommodate adjustable levelling feet with a ribbed design to accommodate multiple tube gauges

Square Tube Insert Glides

Available in both ribbed and straight wall designs
Designed to fit into the end of a square tube or pipe.
Provide a smooth, durable base for furniture, appliances and more
Protects floors from scratches, scuffs and other damage caused by heavy or sharp objects
ABS, Butyrate, LDPE, HDPE in black, clear or white

Threaded Square Tube Inserts

Protects assemblies from the tube’s sharp edges
Internal threads can accommodate levelling feet, tilt glides or castors
Ideal for adjustable levelling mounts and fee
Ribbed to accommodate multiple gauges
HDPE with zinc-plated steel threaded insert

Also available:

Robust square heavy-duty threaded inserts made of glass-filled black nylon with brass threaded insert – can be used indoors and outdoors – and for machinery use
Nylon threaded tubing Inserts suitable for use with adjustable feet and tilt glides
All-metal, threaded square tube Inserts made from zinc-plated steel – metal ribs lock on to the inside of a square tube for a secure assembly

Round Inserts & Glides

Ribbed shank design that provides added positive-gripping power
Fits into the end of a round tube or pipe
Provides a smooth, durable base for furniture, appliances and more
Protects floors from scratches, scuffs and other damage
LDPE, nylon, and PE

Square Angled Tube Insert Glides

Ideal for applications with fixed leg angles
Choice of insert glides that fit 5°, 15°, or 25° angles
Perfect for stacking chairs, children's play equipment, and step ladders
LDPE

Threaded Inserts & Glides

Internal threads accommodate adjustable levelling feet
Ribbed design fits multiple tube gauges
Ideal for use in furniture, automotive and construction
Helps ensure safety and longevity of mounted structures or equipment
HDPE

Threaded Round Tube Inserts

Internal thread accommodates adjustable levelling feet, tilt glides and castors

Available in:

All-metal inserts made from steel with zinc-plated finish – metal ribs lock onto the inside of round tubes
HDPE with zinc-plated steel threaded insert – rib accommodates multiple gauges
Heavy duty inserts made from glass-filled nylon with brass threaded insert, suitable food indoor and outdoor use – ideal for machinery use
Threaded round tube inserts in nylon or HDPE

Materials

Tube inserts and glides are manufactured in both plastics and metal. Popular metal tube inserts include steel and aluminium. Steel and aluminium are good choices for heavy-duty applications, when structural integrity is paramount. Both aluminium and steel tube inserts do an excellent job of resisting compression. Also available are plastic tube varieties with metal thread inserts, such as brass, or plastic inserts.

Plastics offer more variety. You can formulate any plastic to bring out the characteristics you want. For instance, nylon on its own does not stand up well to UV rays in the long term, but additives can strengthen this ability. Plastic box sections, or tube inserts, are easily available. To decide which plastic tube inserts are best for you, start with comparing materials:

Plastics	ABS	Nylon	GF nylon	PVC	LDPE	HDPE
Electrical insulation	Good	Good	Good	Excellent	Good –Excellent	Good –Excellent
Acids & alkalis resistance	Poor—Good	Poor—Good	Poor—Good	Good	Very good	Very good
Aromatic hydrocarbons resistance	Poor	Excellent	Good	Poor	Poor	Poor
Dimensional stability	Excellent	Poor	Good	Good (with annealing)	Good	Poor – fair
Tensile strength	Excellent	Good	Excellent	Excellent	Fair – good	Very good
Impact resistance	Good	Good	Excellent	Excellent	Good	Excellent
Heat resistance	Good (with additives)	Good (excellent with additives)	Very good	Good (with additives)	Fair	Good

Measuring for the correct tube-insert size

To get the perfect fit, follow these steps for measuring, whether for oval or round tube inserts, or rectangular or square tube inserts.

Step 1 - OD

Find the outside diameter of the tube (OD) by measuring the distance between the outer lips, or end to end, as shown below.

Step 2 - ID

Find the inside diameter (ID) of the tube by measuring the distance between the inner lips, as shown here.

Step 3 - Wall thickness

Wall thickness is also known as the tube gauge. You can either use a tube-thickness calliper to measure the wall thickness as shown below or use the formula: OD-ID ÷ 2.

Step 4 - Matching the tube to the tube insert

When using a tube-thickness calliper to measure wall thickness, you’ll get a round figure. Popular gauges range from 10 to 20. Using the formula gives you your wall thickness in inches or millimetres.

Using our square angled tube inserts as an example, you can see how to read what size tube insert you need. In the table below, you’re given both the tube gauge and the wall thickness, in case you used the formula.

The lower the gauge number, the thicker the tube’s wall thickness. Generally, the rule of thumb for gauge and wall thickness works out like this, but there will always be slight variances:

Gauge	inches	millimetres
10	.134	3.4
11	.120	3.04
12	.109	2.76
13	.095	2.41
14	.083	2.1
16	.065	1.65
18	.049	1.24
20	0.35	0.89

Using outside diameter and tube gauge to choose your tube insert

As an example, let’s look at our square domed inserts, shown here. Online, these are grouped by the size of the tube you need the insert for, with the gauge. By size, we mean the tube’s outside diameter. If you only know the outside diameter of your tube, find the size in the left hand column, as in the example below. The righthand column tells you the gauge that’s compatible with your tube.

How to install tube inserts

Tube inserts come in various types, but installation methods typically fall into two categories: press-in and threaded inserts.

Press-in Inserts

First, prepare the tube by cutting to the desired length with a clean, straight edge.

Align and insert: Place the insert squarely into the tube opening.
Tap it in gently: Using a mallet or hammer, carefully tap the insert until it's flush with the tube end. To protect the insert, use a scrap piece of wood or cloth between the hammer and insert as you tap.

Threaded Inserts

Threaded inserts provide a stronger hold. You’ll need a hole saw or drill bit per the manufacturer’s size recommendation.

Drill the hole: Create a hole in the centre of the tube end.
Clean the hole: Debur the hole (remove any sharp edges) to ensure a smooth insertion of the threaded insert.
Screw it in securely: Apply a small amount of threadlocker (optional for additional hold) to the threads of the insert. Then, screw it into the prepared hole until it's flush with the tube end.

General tips for success

Match the insert size: Double-check that your insert's diameter aligns with your tube's diameter for a proper fit.
Right tool for the job: Use the appropriate size drill bit or hole saw to create a snug fit for the threaded insert.
Start light, increase gradually: When tapping in press-in inserts, begin with light taps and gradually increase force as needed to avoid damaging the insert.

Download free CADs and try before you buy

Free CADs are available for most solutions, which you can download. You can also request free samples to make sure you’ve chosen exactly what you need. If you’re not quite sure which tube insert will work best for your application, our experts are always happy to advise you.

Whatever your requirements, you can depend on fast despatch. Request your free samples or download free CADs now.

Questions?

Email us at sales@essentracomponents.co.uk or speak to one of our experts for further information on the ideal solution for your application 0345 528 0474.