Compliance & standards
What is BS EN 39?
BS EN 39 is the European standard for loose steel tubes used in tube and coupler scaffolds. Tube to this standard has an outside diameter of 48.3mm and a wall thickness of either 3.2mm or 4.0mm.
Scaffold tube is not generic steel pipe. The standard specifies what the tube has to be, which is what allows a compliance sheet or a design to assume a known strength from a member it has never seen.
This is the practical reason tube from an unknown source is a problem. A structure designed on the assumption of standard tube, built from something else, is not the structure that was assessed. The standard also sets requirements for marking, so tube can be identified long after it was delivered.
The corresponding standard for the fittings that join the tube together is BS EN 74.
What goes wrong on site
- Mixing tube of unknown specification into a structure designed on a standard assumption.
- Assuming visually similar tube is equivalent tube.