TÜV Type-Tested Tube Clamp Fittings – Material, Testing, Load Values
TÜV type-tested tube clamp fittings: what that actually means
“Tested quality” appears in many shops. With us you can read what was tested, by whom, by what procedure – and with what result. Our range of tube clamp fittings in malleable cast iron is type-tested by TÜV Rheinland, test report no. 17704961 001.
What was tested
The type test comprises two mechanical load tests and a document review. It is not a single sample that is tested but at least three samples per type of tube clamp fitting and per load case. The mean of the measured results gives the nominal value. This nominal value is divided by the safety factor – which gives the permissible value that you will find with every item under “Technical data”.
| Test | What happens | Result |
|---|---|---|
| Bending load | The fitting is bolted to a tube. A bending moment is applied through the tube in the least favourable direction – until permanent deformation of more than 10 degrees or fracture. | Permissible bending moment in kNm |
| Tensile/compressive load | The tube is pulled or pushed until it begins to slip inside the fitting. | Permissible slip resistance in kN |
| Alternating load | Fittings for railing construction are additionally subjected to 100 load cycles in both unfavourable directions – base and wall flanges at 0.5 kNm, other railing components at 0.25 kNm. | Proof of fatigue strength |
The safety factor of 2.0
All the values we state with the items have already been divided by 2.0. So if a tee 101C42 is listed with a permissible bending moment of 0.9 kNm, the measured failure value was 1.8 kNm. This reserve is not marketing but part of the test specification.
What else was tested and confirmed
- Minimum wall thickness: the tube clamp fittings in malleable cast iron have a wall thickness of at least 2.5 mm.
- Corrosion protection: resistance to atmospheric corrosion – tested and confirmed.
- Inclusions: the parts are free from casting defects and inclusions that could impair use.
- Corners, edges, burrs: free from sharp edges on which you could injure yourself while handling them.
- Screwed connections: effective, easy to check and secured against unintentional loosening. The tightening torque is specified by the manufacturer.
- Technical documentation: dimensioned construction drawings, material data, data sheets with strength values and evidence of corrosion protection – reviewed and in order.
The material behind it
The material is malleable cast iron to ASTM A197. Malleable cast iron differs from ordinary grey cast iron in having a tough microstructure: it does not fracture in a brittle way but deforms visibly under overload before it fails. For a component that holds a guardrail together, that is exactly the difference between a warning and sudden failure.
The surface is hot-dip galvanised to ASTM A153. Hot-dip galvanising creates a zinc layer metallurgically bonded to the base material, which holds even on edges and in threads – unlike a paint coating, which flakes off there first. In addition, our tube clamp fittings go through an electro-galvanising process. The result is an even, smooth surface over the robust hot-dip galvanising.
The screw: stainless steel, not galvanised
Every tube clamp fitting is supplied with a grub screw in stainless steel 304 (V2A). That is not a minor detail. Outdoors, a galvanised screw in a galvanised fitting becomes inseparably bonded to the thread after a few years – when you retighten or dismantle it, the head shears off. Stainless steel prevents this. Your structure stays maintainable and can be taken apart again.
The tightening torque is 40 Nm – for the 1/4" screw of sizes A27 and B34 just as for the 3/8" screw of sizes C42, D48 and E60.
Where the tube clamp fittings may be used
The test programme covers use in railing, shelving and storage construction and for installations of a similar kind. Typical applications are handrails, fall protection, fences, machine guarding, shelving systems, bicycle racks, enclosures and furniture structures.
Use in scaffolding is not permitted. Scaffolding is covered by its own standards and test procedures, which these components do not meet. We point this out with every item because the risk of confusion is real – a tube clamp fitting looks similar to a scaffold coupler but is something different.
Also note: part of our range is expressly not intended for railing construction because these components have not been subjected to alternating load testing – this includes the mesh panel clips 170 and 171, the collars with hook 182, the adjustable corner fittings 125H and the handrail brackets 143W. For these items the note appears in the product description.
What you have to do as the operator
The test covers the component, not your structure as a whole. Three points are your responsibility:
- Substrate and fixing. For base and wall flanges the permissible bending moments apply only if they are mounted on a level substrate. You must check the load-bearing capacity of anchors, threaded studs and building materials yourself.
- Observe the tightening torque. Too loose means the tube slips. Too tight means the screw can cut through the tube.
- Retighten regularly. Dynamic loading can loosen screwed connections. The inspection interval depends on your application and must be determined by the operator.
Requesting documents
Do you need the test report or the manual for your building file, your risk assessment or your client? Call us or write to info@fenau.eu – we will send you the documents.
Continue to the guide to building a handrail or go straight to the range: tube clamp fittings Ø 42.4 mm · Ø 48.3 mm