Rank: Forum user
|
Hi all,
I am currently working on a construction site and we have had an Italian contractor install some fixed access ladders which go up to a platform. I used them for the first time yesterday to carry out an inspection and I noticed that they don’t appear to be very secure, by that I mean they seem to flex when people use them. I carried out an inspection of them and I noticed that these have been installed using M6 bolts and I am sure I have read somewhere that these should be M12. Does anyone know if this is correct or if I have just been dreaming it.
I have tried searching for the guidance but I can only find the BS standards which will cost £215 to download and they may not contain the answer.
Thanks in advance
|
|
|
|
Rank: Forum user
|
I don't know about what standards apply - the size and spacing of the bolts , the strength class of the bolt (different bolts of the same size have different strengths depending on the steel) the design of the ladder and fixings (including the way that the bolt is fixed into the supporting structure) and the type of loads you will be imposing all need to be taken into account. Bolts are often designed to tolerate tensile stress not shear stress with the fixing bracket doing the work of resisting shear. But applying H&S common sense says: - If there is excessive play/flex then something isn't right. But that sounds like the ladder itself is also insufficiently rigid.
- You use M10 to hang false ceilings - why would you use something less for a vertical ladder?
They ought to be able to show you calculations - ask for them. If they can't then you could get an engineer to do the calcs for you - get hold of the box that the bolts came in so you know exactly what bolts they have used, if the box doesnt give enough information about the strength of the bolt then the manufacturer will. So worth a phone call to the manufacturer - lots of them will have technical departments who will advise on suitability of their products for particular applications.
There are lots of online calculators
https://www.engineersedge.com/thread_strength/thread_bolt_stress_area_iso.htm But to be honest in a safety critical application like this I'd ask an engineer to do the calcs.
|
|
|
|
Rank: Super forum user
|
Is the ladder linked to fixed machiney, or is it fitted to a building for access to parts of the building?
|
|
|
|
Rank: Forum user
|
These ladders are fixed to a platform that houses two large silo's
We have asked for the calculations from the PC however as the project is coming to an end they are not forth coming with the information.
I have snagged this and other structural steelwork and I am battling with them, as they are saying that this is acceptable in Italy, but I am saying they are not in italy and must conform to UK standards.
|
|
|
|
Rank: Super forum user
|
I do not think you can say M6 are inadequate, as already mentioned the design should have stipulated what bolts to use. If you go down the British Standard route you will find that one standard will refer to another. As important as the bolt is the material being fixed into and position of any hole to an edge or other weakness. If CDM applied you could ask the Principal Designer to intervene and say it is required for the health & safety file. However I did find this “The distance between the fixing brackets is a maximum of 2.0m between the fixing centres. It is important that the fixing bracket can withstand a vertical load of 3KN and each fixing withstand a 0.5KN pull-out load” but cannot verify the source.
|
|
|
|
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.