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Half-Sphere Head Round Tube Plugs

Half-sphere head round tube plugs give hollow round furniture legs a bold, fully rounded decorative finish. The hemisphere extends above the tube edge as a smooth, symmetrical dome, creating the most pronounced decorative profile in the range. Same PE construction and flexible ribbed body as the flat head range. Same press-fit installation. Hemisphere decorative tube plugs for furniture where maximum visual impact on exposed tube ends is the goal. 5 sizes: Ø 16, 20, 22, 25, and 30 mm. Wall thickness 1 to 1.5 mm (Ø 16 also available in 1.5 to 2 mm). Black, grey, and white. Sold in multiples of 4.

$0.70$1.00

4 = 1 chair · 8 = 2 chairs · 24 = 6 chairs

Item Number Not Available Product Type Features ,

Not sure what size? See the size chart ↓

📦 Sold in packs of 4 — quantity adjustable at checkout

Overview

Half-Sphere Head Round Tube Plugs

Flat heads are invisible. Domed heads are subtle. The half-sphere is deliberate. Half-sphere head round tube plugs give hollow round furniture legs a bold, fully rounded decorative finish that turns an exposed tube end into an unmistakable design feature. The hemisphere extends above the tube edge as a smooth, symmetrical dome, creating the most pronounced decorative profile in the range. On chair backs, armrest ends, exposed frame tops, and display fixtures, the half-sphere communicates that every detail was considered.

Same PE construction and flexible ribbed body as the flat head range. Same press-fit installation. The only difference is the head: a full hemisphere instead of a flat disc. Half-sphere head round tube plugs are hemisphere decorative tube plugs for furniture where maximum visual impact on exposed tube ends is the goal. 5 sizes from Ø 16 mm to Ø 30 mm. Wall thickness 1 to 1.5 mm (Ø 16 also available in 1.5 to 2 mm). Black, grey, and white. Sold in multiples of 4.

Available Sizes: 5 Half-Sphere Head Round Tube Plugs

Half-sphere head round tube plugs are available in 5 diameters, the broadest size range of any decorative head style. Each size matches a common furniture tubing specification. The right half-sphere head round tube plug matches your tube’s outside diameter (OD) and wall thickness.

Ø 16 mm

Wall: 1 to 1.5 mm (black, white) and 1.5 to 2 mm (black). The smallest half-sphere for lightweight chair backs, side chair frames, and narrow display fixture tubing. Three SKUs at this diameter.

Ø 20 mm

Wall: 1 to 1.5 mm. Black and white. Standard lightweight tubing for residential chair backs and accent furniture frames.

Ø 22 mm

Wall: 1 to 1.5 mm. Black. A common diameter for commercial chair backs and office seating frames. Half-sphere head round tube plugs in this size cover one of the most frequent commercial specifications.

Ø 25 mm

Wall: 1 to 1.5 mm. Black, grey, and white. The widest color range of any half-sphere size. Standard furniture tubing for commercial seating, restaurant chairs, and display fixtures.

Ø 30 mm

Wall: 1 to 1.5 mm. Black. The largest half-sphere for heavy-duty tubing on commercial frames, table structures, and industrial fixture ends.

For other diameters with a flat finish, flat head round tube plugs come in 26 sizes from Ø 10 to Ø 80 mm. For a subtler rounded profile, domed head round tube plugs are available in Ø 16 and 26 mm. For a geometric taper, conical head round tube plugs come in Ø 30 mm. For custom sizes or colors, contact Business Solutions.

How to Measure Your Tube for Half-Sphere Head Round Tube Plugs

Same two-measurement process as all tube plugs: outside diameter (OD) and wall thickness. Half-sphere head round tube plugs are available in Ø 16, 20, 22, 25, and 30 mm, all with 1 to 1.5 mm wall thickness (Ø 16 also available in 1.5 to 2 mm). If your tube does not match these specifications, check the other head styles for a compatible size.

Step 1. Measure the OD

Use calipers or a ruler across the widest point of the tube opening. Outside edge to outside edge. Match to one of the 5 available diameters for half-sphere head round tube plugs.

Step 2. Measure the wall thickness

Use calipers at the tube end, or calculate: (OD minus ID) / 2. Most sizes require 1 to 1.5 mm wall. Ø 16 mm is also available in 1.5 to 2 mm for thicker-walled tubing.

Step 3. Confirm both match

Both OD and wall thickness must fall within the listed range. A half-sphere head round tube plug sized for Ø 25 mm / 1 to 1.5 mm wall will not grip properly in a Ø 25 mm tube with 2.5 mm walls.

Non-floor-contact application: since half-sphere head round tube plugs are designed for visible, non-floor-contact tube ends, measure the tube that faces outward (chair back uprights, exposed frame tops, armrest ends, display fixture tubing) rather than the floor-contact legs. Floor-contact legs are better served by flat head plugs or pad slot plugs.

How to Install Half-Sphere Head Round Tube Plugs

Same press-fit installation as all our tube plugs. The half-sphere head does not change the process. At 1 to 1.5 mm wall thickness, most sizes press in by hand. A rubber mallet provides extra seating force on snug fits. Half-sphere head round tube plugs install in seconds per tube end.

What you need
  • The correct half-sphere head round tube plug matched to your OD and wall thickness
  • A rubber mallet (optional, for snug 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.
  2. Align the half-sphere head round tube plug with the tube opening. The hemisphere 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 hemisphere base sits flush with the tube edge.
  4. If needed, tap the hemisphere gently with a rubber mallet. Tap the base ring around the hemisphere, not the dome itself. Do not strike hard enough to deform the spherical profile.
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. Half-sphere head round tube plugs can often be reinstalled if the hemisphere and ribs are undamaged.

What Half-Sphere Head Round Tube Plugs Solve

Every benefit of a standard tube plug, plus the boldest decorative profile in the range. The National Wood Flooring Association (NWFA) recommends protective measures on all furniture legs, and half-sphere head round tube plugs contribute by sealing the tube end even on non-floor-contact applications.

Maximum decorative impact

The primary reason to choose half-sphere over any other head style. The full hemisphere protrudes above the tube edge as a smooth, symmetrical ball shape that catches light and draws the eye. On retail fixtures, restaurant seating, hospitality furniture, showroom displays, and exhibition frames, visible tube ends finished with half-sphere head round tube plugs communicate premium attention to detail. These are the decorative round tube plugs with a hemisphere profile bold enough for the most design-conscious environments. Available in black, grey, and white to match or contrast with the frame finish. The decorative round tube plugs hemisphere profile that design-forward environments demand.

Tube sealing and moisture protection

Same sealed end as flat head plugs. The hemisphere does not affect the seal. Moisture, debris, and insects are kept out of the tube interior. On steel tubing, this prevents the internal corrosion that weakens the structure from the inside out. Half-sphere head round tube plugs protect the tube interior regardless of orientation. Unlike leaving furniture hardware unprotected, sealed ends extend the life of the frame.

Noise dampening

Same resonance reduction as flat head plugs. The PE body fills the tube opening and absorbs the vibration that hollow, open tubes amplify. In environments with many metal-framed chairs, every sealed tube end reduces the cumulative metallic noise. Half-sphere head round tube plugs provide the same acoustic benefit as flat head plugs with the most impactful visual upgrade in the range.

Not recommended for floor contact

The hemisphere concentrates floor contact at a single point. This causes instability, rocking, and floor marking under furniture weight. For floor-contact legs, use flat head round tube plugs that spread load evenly. For floor contact with dedicated scratch protection, use pad slot round tube plugs with a PA6 pad insert. Half-sphere tube end plugs are designed for the visible tube ends that do not touch the floor.

Materials and Construction

Same PE (polyethylene) body and flexible ribbed grip as every tube plug in the range. The only difference is the head profile. Half-sphere head round tube plugs are molded from a single piece of PE with no joints, seams, or separate components. Half-sphere tube plugs for furniture that combine a bold decorative head with an engineered friction-fit body.

Half-Sphere PE Head Decorative finish

The hemisphere extends above the tube edge as a smooth, symmetrical half-ball. The protrusion is proportional to the tube diameter: smaller on the Ø 16 mm plug, larger on the Ø 30 mm plug. The surface is seamless with no mold lines visible on the dome. Half-sphere head round tube plugs use the same PE compound that resists UV, chemicals, moisture, and impact across all our plug products.

  • Full hemisphere profile: the most pronounced decorative head in the range
  • Protrusion proportional to tube diameter
  • Smooth, seamless molded surface
  • Black (RAL 9005), grey (RAL 7040), white (RAL 9003): availability varies by diameter
  • UV resistant, moisture resistant, impact resistant
Flexible Internal Ribs Grip mechanism

Identical rib structure to the flat head range. The ribs compress during insertion and expand against the inner tube wall for a secure friction fit. At the 1 to 1.5 mm wall thickness specified for most sizes, the ribs engage firmly. No adhesive, no screws, no tools beyond an optional rubber mallet. Half-sphere head round tube plugs rely entirely on mechanical grip.

  • Multiple ribs for distributed grip along the tube interior
  • Each rib compresses independently to adapt to wall thickness variations
  • Friction fit holds under vibration, movement, and sustained load
  • No adhesive required

Half-Sphere Head Round Tube Plugs vs. Other Head Styles

All head styles share the same PE body and ribbed grip. The choice comes down to appearance, floor contact needs, and how much decorative impact you want on the exposed tube end. Here is how half-sphere head round tube plugs compare to every other option.

vs. Flat Head (Standard)

Flat head round tube plugs sit flush with the tube end. No protrusion, no visual accent. Half-sphere head round tube plugs add the maximum protrusion and the boldest decorative effect. Choose flat for floor-contact legs and utilitarian applications. Choose half-sphere for the most visible, most design-critical tube ends on the furniture.

vs. Domed Head

Domed head round tube plugs have a gentler, lower curve that rises modestly above the tube edge. The half-sphere is a full hemisphere that protrudes significantly more. If you want subtle, choose domed. If you want bold, choose half-sphere. Domed comes in Ø 16 and 26 mm. Half-sphere head round tube plugs come in 5 sizes from Ø 16 to 30 mm, giving you more options.

vs. Conical Head

Conical head round tube plugs taper to a sharp geometric peak. Angular, modern, architectural. Half-sphere head round tube plugs are organic, smooth, symmetrical. The hemisphere and the cone are both bold statements, but in completely different visual languages. Conical is Ø 30 mm only. Half-sphere covers 5 sizes.

vs. Anti-Slip TPE

Anti-slip TPE round tube plugs have a rubber head that grips the floor. Functional, not decorative. Half-sphere head round tube plugs are the most decorative, not functional on floors. On the same piece of furniture, you might use anti-slip on the floor-contact legs and half-sphere on the visible back uprights or armrest ends.

vs. Pad Slot

Pad slot round tube plugs have a recessed channel that accepts a PA6 pad for hard-floor scratch protection. Flat profile, functional design. Half-sphere head round tube plugs offer maximum decorative impact with no floor-contact function. For the same piece of furniture, pad slot plugs handle the floor-contact legs while half-sphere heads finish the visible, non-floor-contact ends.

Where Half-Sphere Head Round Tube Plugs Work Best

Half-sphere head round tube plugs are designed for tube ends that are visible to the user but do not contact the floor. The hemisphere is a bold decorative choice for environments where visual detail signals quality.

Ideal applications
  • Chair back uprights on restaurant, hospitality, and commercial seating (Ø 16 to 25 mm covers most back tube profiles)
  • Armrest tube ends on lounge chairs, waiting room seating, and office furniture
  • Exposed frame tops on retail display fixtures, showroom furniture, and exhibition stands
  • Visible tube ends on garden structures, greenhouse frames, and architectural elements
  • Trade show and exhibition display frames where first impressions matter
  • Gym and fitness equipment where tube ends face the user during exercise
  • Any Ø 16 to 30 mm hollow round tube end that is visible and does not contact the floor
Not ideal for
  • Floor-contact legs: the hemisphere concentrates weight at a single point. Use flat head plugs
  • Stackable furniture: the hemisphere protrusion prevents flush nesting. Use flat head plugs
  • Tube diameters outside Ø 16 to 30 mm: check flat head (26 sizes, Ø 10 to 80 mm) for alternatives
  • Wall thickness outside 1 to 1.5 mm (or 1.5 to 2 mm for Ø 16 only): the ribs will not grip properly

All Round Tube Plug Head Styles

Every variant uses the same internal ribbed PE body. The head determines appearance, floor contact capability, and specialized function.

Flat Head (Standard)

Flush finish. 26 sizes, Ø 10 to 80 mm. Best for floor contact and general use.

Conical Head

Tapered peak. Ø 30 mm. Geometric decorative accent.

Domed Head

Rounded dome. Ø 16 and 26 mm. Subtle decorative finish.

Half-Sphere Head ← You are here.

Full hemisphere. 5 sizes, Ø 16 to 30 mm. Bold decorative effect. Black, grey, white.

Anti-Slip TPE

Rubber grip. Prevents sliding on hard floors.

Pad Slot

Recessed PA6 pad for hard-floor scratch protection.

Angled

For splayed or tilted legs. Base sits flat at an angle.

Where People Use Half-Sphere Head Round Tube Plugs

Anywhere Ø 16 to 30 mm hollow round tubing has a visible, non-floor-contact end that calls for a bold, decorative finish. Half-sphere head round tube plugs add the most impactful finishing detail in the range to commercial and residential furniture, fixtures, and structures.

Furniture and seating

Restaurant and hospitality seating where chair backs face guests and first impressions matter. Office and conference room chairs with exposed metal back uprights. Residential dining chairs with tubular metal frames. Half-sphere head round tube plugs pair well with flat head plugs on the same chair: half-sphere on the visible back, flat on the floor-contact legs. For floor-contact legs that also need scratch protection, pair with round self-adhesive furniture glides.

Fixtures, displays, and structures

Retail display racks, showroom fixtures, exhibition frames, trade show structures, garden features, and architectural elements. The bold hemisphere communicates premium quality on any visible tube end. Available in bulk for manufacturing runs and commercial fit-outs. For commercial pricing, visit Business Solutions.

Maintenance and Inspection

Half-sphere head round tube plugs require almost no maintenance. The PE material does not degrade under normal indoor or outdoor conditions. The hemisphere surface can be wiped clean with a damp cloth. The smooth dome sheds dust and fingerprints more easily than textured surfaces. Check periodically that the plug remains seated flush with the tube edge. The hemisphere is the most exposed point on any decorative plug: inspect for damage from impact, stacking contact, or rough handling.

On commercial furniture that gets moved, stacked, or handled frequently, inspect every 3 to 6 months. On static fixtures and display structures, an annual visual check is enough. Half-sphere head round tube plugs are sold in multiples of 4, so keeping spares on hand for commercial environments is practical. If a hemisphere is chipped or deformed, replace the plug. The PE surface does not stain, discolor, or absorb cleaning products.

Related Products

Flat head for floor-contact legs

Round Tube Plugs (Flat Head): flush finish, 26 sizes from Ø 10 to Ø 80 mm. The right choice for floor-contact legs on the same furniture that uses half-sphere head round tube plugs on the visible ends.

Threaded insert for leveling

Round Threaded Inserts: press-fit plug with threaded metal nut for adjustable leveling feet.

Specifications

Specification Details
Product Type
Tube Plug – Inner with Half Sphere Head
Shape
Round Tube
Materials
PE (Polyethylene) or PA (Polyamide)
Fit Style
Friction-fit ribbed compression
Floor Compatibility
All hard and soft floors
Furniture Compatibility
Barstools, chairs, tables, desks, carts, shelving units
Leg Compatibility
Metal and plastic round tubing
Sizes Available
Ø16 mm, Ø20 mm, Ø22 mm, Ø25 mm, Ø30 mm (for 1–2 mm wall thickness)
Color Options
Black, White, Grey
Installation Type
Press-fit (hand or rubber mallet)
Key Benefits
Rounded finish, vibration reduction, waterproof, durable
Indoor/Outdoor Use
Indoor | Covered Outdoor | Uncovered Outdoor
Recyclable
Yes

Size Chart

Outer Tube Diameter (Ø) Tube Wall Thickness (T) Insert Depth (H) Head Height (H1)
16 mm (0.63")
1 – 1.5 mm (0.04" – 0.06")
14 mm (0.55")
8 mm (0.31")
16 mm (0.63")
1.5 – 2 mm (0.06" – 0.08")
14 mm (0.55")
8 mm (0.31")
20 mm (0.79")
1 – 1.5 mm (0.04" – 0.06")
14 mm (0.55")
10 mm (0.39")
22 mm (0.87")
1 – 1.5 mm (0.04" – 0.06")
14 mm (0.55")
11 mm (0.43")
25 mm (0.98")
1 – 1.5 mm (0.04" – 0.06")
14 mm (0.55")
12.5 mm (0.49")
30 mm (1.18")
1 – 1.5 mm (0.04" – 0.06")
14 mm (0.55")
16 mm (0.63")

Frequently Asked Questions

How does the half-sphere compare visually to domed and conical heads?

The half-sphere is the most dramatic of the three decorative profiles. It extends as a full hemisphere above the tube edge, creating a bold, ball-like endpoint. Domed head plugs have a gentler, lower curve. Conical head plugs taper to a sharp geometric peak. If you want subtle, choose domed. If you want angular, choose conical. If you want maximum decorative impact, choose half-sphere.

Why does the half-sphere head come in more sizes and colors than the other decorative heads?

The half-sphere is the most popular decorative profile because its symmetrical hemisphere works on the widest range of furniture styles. Five diameters (Ø 16 to 30 mm) and three colors (black, grey, white) cover virtually every common chair back, armrest, and fixture tube end. Not all size and color combinations are available. Ø 25 mm has the full three-color range. Other sizes are limited to one or two colors.

Are half-sphere plugs suitable for floor-contact legs?

No. The hemisphere concentrates floor contact at a single point instead of distributing weight across a flat surface. This causes instability and floor marking. For floor-contact legs, use flat head round tube plugs. For floor contact with scratch protection, use pad slot round tube plugs. Round tube plugs half-sphere head are designed exclusively for visible, non-floor-contact tube ends.

Will the half-sphere protrusion interfere with furniture stacking?

Yes, in most cases. The full hemisphere protrudes significantly above the tube edge. If furniture stacks by nesting tube ends, the half-sphere will prevent flush stacking. For stackable furniture, flat head plugs are the right choice. Use half-sphere on non-stacking furniture where the decorative profile is visible and valued.

Can I mix half-sphere heads on visible ends with flat heads on floor-contact legs?

Yes. This is the most common application. Use round tube plugs half-sphere head on chair back uprights, armrest ends, or exposed frame tops where the bold decorative profile is visible. Use flat head plugs on the floor-contact legs where load distribution matters. All head styles use the same PE body and ribbed grip.

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