Tube Clamp Fitting Sizes and Types – the Selection Guide
Tube clamp fitting sizes and types: the selection guide
A tube clamp fitting is defined by two pieces of information: the type number says what shape the component has, the size code says which tube diameter it fits. Once you have understood the system, you can find any part in seconds.
The size code
What always matters is the outside diameter of your tube – not the inside diameter, not the wall thickness. If in doubt, measure across the tube with a vernier caliper.
| Code | Imperial | Tube outside diameter | Typical use |
|---|---|---|---|
| T21 | 1/2" | 21.3 mm | Infill bars, light barriers, displays |
| A27 | 3/4" | 26.9 mm | Infills, indoor handrails, shelving |
| B34 | 1" | 33.7 mm | Handrails, light railings, furniture |
| C42 | 1 1/4" | 42.4 mm | The standard in railing construction |
| D48 | 1 1/2" | 48.3 mm | Posts, large spans, industry |
| E60 | 2" | 60.3 mm | Heavy structures, impact protection |
The inside diameter of the fittings is deliberately made slightly larger than the nominal dimension. This means that internationally varying tube dimensions are also accommodated reliably – an A27 fitting takes tube up to about 28 mm.
Type number and size code make up the part number
The part number is put together very simply:
- Short tee (101) for Ø 42.4 mm (C42) → 101C42
- Elbow 90° (125) for Ø 33.7 mm (B34) → 125B34
- Oval base flange (132) for Ø 48.3 mm (D48) → 132D48
For reducing fittings both sizes appear in the number: 101D48/C42 is a tee that joins a Ø 48.3 tube to a Ø 42.4 tube.
The most important types at a glance
| No. | Component | What for |
|---|---|---|
| 101 | Short tee | 90° branch, intermediate post under a continuous handrail |
| 104 | Long tee | Branch with the tube passing through |
| 116 | Through corner fitting | Corner where one tube continues |
| 119 | Through cross | Four tubes at one joint |
| 125 | Elbow 90° | Take the end of a handrail downwards |
| 128 | Three-way corner fitting 90° | Railing corner with post |
| 131 | Round wall flange | Anchor a tube end in the wall |
| 132 | Oval base flange | Set a post on concrete or timber |
| 133 | Plastic plug | Close off a tube end |
| 134 | Ground socket | Set a post in concrete |
| 143 | Handrail bracket | Carry a handrail along the wall |
| 170/171 | Mesh panel clip | Clamp steel mesh to the tube |
| 179 | Collar | Stop or support on the tube |
Fixed or adjustable angles?
As long as you are building right angles, the standard components will do. As soon as a staircase, a ramp or a sloping roof comes into play, you need parts with variable angles:
- 0–11 degrees – for shallow slopes: base flange 152, elbow 154, tees 153 and 155, cross 156
- 15–70 degrees – variable elbows 123 and 124
- 30–60 degrees – tees 127 and 129 for common stair pitches
- freely adjustable – angle swivel 148, swivel fittings 167, 168 and 173
Measure the pitch angle before you order. On a staircase, lay a spirit level across two step nosings and measure the angle to the horizontal.
How much load does a tube clamp fitting take?
You will find this with every item under “Technical data”: the permissible bending moment in kNm and the permissible slip resistance in kN. Both values come from the type test by TÜV Rheinland and already include a safety factor of 2.0.
An example: depending on size, the tee 101 withstands a bending moment of between 0.3 kNm (T21) and 2.3 kNm (E60). For a normal terrace railing with a post spacing of 1.3 m you are on the safe side with C42 or D48. For larger spans, public areas or commercial use, a structural engineer should check the design.
Which size for which project?
| Project | Recommendation |
|---|---|
| Balcony or terrace railing | Ø 42.4 mm (C42), post spacing 1.0–1.5 m |
| Indoor stair railing | Ø 33.7 mm (B34) or Ø 42.4 mm (C42) |
| Industrial railing, fall protection | Ø 48.3 mm (D48) for posts |
| Fence with mesh infill | Ø 33.7–42.4 mm plus mesh panel clips 170/171 |
| Shelving, furniture, shop fitting | Ø 26.9 mm (A27) or Ø 33.7 mm (B34) |
| Impact protection, bollards | Ø 60.3 mm (E60) |
Still unsure?
Give us a call. We will go through your design and put the parts list together with you – it rarely takes longer than ten minutes and saves ordering the wrong items.
Next: building a handrail – the guide · TÜV testing and material