Round Tube Plugs

Two measurements determine the correct plug: the tube's outside diameter (OD) and the wall thickness. Getting either one wrong means the plug will not fit. Too large and it will not enter the tube. Too small and it will not grip. Round tube plugs are sized to match the OD of the tubing, not the inside diameter.

Step 1. Measure the outside diameter (OD)

Use calipers or a ruler across the widest point of the tube opening. Measure outside edge to outside edge, not the inside. This is the OD that determines which round tube plug you need.

Step 2. Measure the wall thickness

Use calipers to measure the thickness of the tube wall at the open end. Or measure the OD and the inside diameter (ID), then calculate: wall thickness = (OD minus ID) / 2. The flexible ribs must match your wall thickness range for a proper grip.

Step 3. Match both measurements

Find the round tube plug that matches your OD and includes your wall thickness in its range. Both must match. A plug sized for Ø 25 mm / 1.5 to 2 mm wall will not grip properly in a Ø 25 mm tube with 3 mm walls.

Common mistake: measuring the inside diameter instead of the outside diameter. Round tube plugs press inside the tube, but they are sized by the OD because that number is printed on most tubing specifications and is easier to measure accurately. If you only have the ID, add twice the wall thickness to get the OD.

No tools required for most sizes. The flexible PE body compresses as it enters the tube, then the internal ribs expand against the inner tube wall to create a friction fit. Larger sizes or thick-walled tubes may benefit from a gentle tap with a rubber mallet. Installation takes seconds per leg.

What you need

• The correct round tube plug matched to your OD and wall thickness
• A rubber mallet (optional, for larger sizes or tight fits)
• Clean, dry tube ends free of burrs or sharp edges

Installation steps

1. Inspect the tube end. Remove any burrs, sharp edges, or debris from the inside of the tube opening. A clean, smooth edge ensures the ribs seat properly.
2. Align the round tube plug with the tube opening. The flat head faces outward. The ribbed body faces into the tube.
3. Press the plug into the tube by hand. The flexible ribs compress as the plug enters, then expand against the inner wall. Push until the head sits flush with the tube end.
4. For tight fits or larger diameters, tap the plug head gently with a rubber mallet until flush. Do not strike hard enough to deform the head.

Removal: pry gently from one edge with a flat-head screwdriver or push from the opposite end of the tube if accessible. The PE body flexes without breaking. Plugs can often be reinstalled if undamaged.

Open tube ends create multiple problems that a single plug addresses in one installation. Every unsealed hollow leg is a source of noise, floor damage, moisture entry, and visual clutter. The National Wood Flooring Association (NWFA) recommends protective measures on all furniture legs. Round tube plugs are the first step for any hollow metal leg on smooth, hard floors or carpet. Not recommended for rough hard floors like textured tile or stamped concrete, where the PE material wears quickly.

Floor protection

Bare metal tube edges are sharp, thin contact points that concentrate the furniture's full weight on a narrow ring. Every movement drags that sharp edge across the floor. Round tube plugs replace the sharp metal edge with a smooth, flat PE head that distributes load and eliminates scratching on hardwood, tile, laminate, vinyl, and concrete. For dedicated hard-floor protection beyond basic PE contact, apply a round self-adhesive furniture pad to the plug head, or choose the pad slot variant with a PA6 pad channel built in (pad sold separately).

Noise and vibration control

Hollow tubes amplify vibration and resonate with every bump, drag, and contact. The result is rattling, buzzing, and metallic noise that multiplies across a room full of metal furniture. Round tube plugs seal the tube end and dampen the resonance. The PE body absorbs contact vibration instead of transmitting it through the hollow cavity. In restaurants, classrooms, and conference rooms where dozens of metal chairs move simultaneously, the difference is immediate and significant.

Moisture and debris sealing

Open tubes collect moisture during floor cleaning, condensation in humid environments, and debris from daily use. Trapped moisture causes internal corrosion on steel tubing that weakens the structure from the inside out. Round tube plugs seal the opening and prevent moisture, dirt, and insects from entering the tube interior. In coastal, tropical, or high-humidity environments, this protection is especially important for steel-framed furniture.

Finished appearance

An open tube end looks unfinished. On retail fixtures, display furniture, restaurant seating, and any customer-facing application, exposed tube ends signal incomplete manufacturing. Round tube plugs give every leg a clean, professional endpoint. Available in black, gray, and white to match the frame finish or contrast for a design accent.

✓ Common applications for these plugs

• Metal dining chairs, kitchen chairs, and bar stools with hollow round legs
• Office seating and conference room chairs
• Restaurant, hotel, and hospitality seating
• Retail display fixtures and shelving units
• Industrial racking, workbenches, and equipment frames
• Outdoor and patio furniture with hollow round tubing
• Gym and fitness equipment frames
• Garden structures, greenhouse frames, and trade show displays
• Any hollow round tube from Ø 10 mm to Ø 80 mm

✗ Not the right product for

• Solid wood legs: use round nail-on furniture glides or self-adhesive pads
• Tubes that need leveling feet: use round threaded inserts
• Splayed or tilted legs: use angled round tube plugs
• Legs that need anti-slip grip: use anti-slip TPE round tube plugs
• Legs that need dedicated hard-floor protection: use pad slot round tube plugs
• Square tubing: use square tube plugs
• Rectangular tubing: use rectangular tube plugs
• Oval tubing: use oval tube plugs
• Ellipse tubing: use ellipse tube plugs

All round tube plugs use the same internal ribbed PE body. The difference is the head profile, which determines appearance, floor contact, and specialized function.

Flat Head (Standard) ← You are here.

Flush, low-profile finish. The most common choice for general-purpose furniture and fixtures. Flat PE surface contacts the floor.

Conical Head

Tapered head for a contoured, slightly raised appearance on visible tube ends.

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Domed Head

Rounded dome for decorative applications and non-floor-contact ends.

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Half-Sphere Head

Full hemisphere for maximum decorative effect on exposed frame ends.

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Anti-Slip (TPE)

Rubber TPE head that grips smooth floors. Prevents sliding on hardwood, tile, and vinyl.

View anti-slip TPE →

Pad Slot

Recessed channel accepts a PA6 pad (sold separately) for hard-floor scratch protection.

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Angled

Angled head for splayed or tilted legs. Base sits flat on the floor at an angle.

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