Tube Insert Sizing & Ordering Guide
Tube Insert Sizing & Ordering Guide
Selecting the correct tube insert requires two simple measurements in millimetres: the outside dimensions (OD) of the metal leg and the wall thickness. Follow our step-by-step guide below to ensure a flush, secure fit every time.
The Golden Rule: Measure in Millimetres (mm)
Always measure in millimetres (mm) for accurate fitting. Tube inserts are ordered by the OUTSIDE DIAMETER / EXTERNAL DIMENSION of the tube (e.g. a 25mm outside tube takes a 25mm insert). The internal flexible ribs automatically compress to grip the inside wall securely.
Measure Outside Dimensions (OD) in mm
Using a metric ruler, tape measure, or digital calliper, measure straight across the outer edges of the tube opening in millimetres:
- Round Tubes: Measure across the widest point of the outer circle.
- Square Tubes: Measure the width of one outer face.
- Rectangular Tubes: Measure both outer width and length in mm (e.g. 50mm x 25mm).
Check the Wall Thickness & Size Chart
Check the thickness of the metal tube wall. Wall thickness ranges vary depending on the diameter of the insert (for example, a 25mm round insert typically fits 1.0mm–3.0mm walls).
Always check the specific size chart on each product page to confirm that your measured wall thickness falls within that size's recommended range.
Example Sizing & Wall Thickness Reference (mm)
| Tube Outer Measurement (OD) | Compatible Wall Thickness Range | Typical Inside Opening (ID) | Size to Order |
|---|---|---|---|
| 25mm Round | 1.0mm – 3.0mm | 19.0mm – 23.0mm | 25mm Round Insert |
| 25mm x 25mm Square | 1.0mm – 3.0mm | 19.0mm – 23.0mm | 25x25mm Square Insert |
| 50mm x 25mm Rectangular | 0.8mm – 3.0mm | 44.0–48.4mm x 19.0–23.4mm | 50x25mm Rectangular Insert |
Simple Fitting Tips
Use a Soft Mallet
Avoid using a metal hammer directly on plastic inserts. Use a rubber mallet or place a scrap piece of wood over the insert before tapping it down.
Clear Rough Edges
Ensure the inside of the tube is clear of burrs or metal shavings so the flexible plastic fins can slide down cleanly.
Firm Friction Hold
The horizontal ribbed fins lock the insert tightly inside the metal leg without needing any glue or adhesives.
Very Tight Fit?
If the insert feels slightly too tight to push in by hand, placing the plastic bung in warm water for a minute softens the ribs for an easier fit.
Need Help Checking Your Size?
Send a photo of your furniture leg next to a millimetre ruler to our technical team. We also supply free sizing sample packs for schools, facilities managers, and commercial trade accounts.
Email: sales@keayvitalparts.co.uk | Phone: 020 3038 5708
Let customers speak for us
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1st class product and service from a 1st class company.
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