Code of Practice for Safe Use and Operation of Suspended Working ...

5.3.4 Where bolts are used for anchoring rails to the roof, they should have aminimum diameter of 16 mm. These bolts may, for additional security, belocked beneath some of the reinforcement of the roof slab. Whereappropriate all nuts securing fixings should be kept in place by lockingdevice. Nuts should be tightened to, but not beyond, the torquerecommended by the manufacturer.5.3.5 Any metal components used to interconnect between the trolley rails,ancillary equipment and the roof should be of steel suitably protectedagainst corrosion, including electrolytic reaction.5.3.6 The deflections of the rail under load should not exceed 1/250 of thespan between the rail supports. The rails should be capable of safelywithstanding the forces resulting from the maximum total suspended load,the weights of the various parts of the roof rig, the self-weight of the rails,any counterweights or beams attached thereto, the longitudinal surgesresulting from traversing the roof rig and from the wind effects.5.3.7 Roof fixing5.3.7.1 When roof fixings of a permanent suspended working platform are reliedon to ensure stability, the factor of safety against overturning should beat least 3. The roof and fixings should then be designed according to thedesign stresses appropriate to the materials. The design and constructionof the roof fixing should be approved by a professional engineer.5.3.7.2 When roof fixings of a temporary suspended working platform are reliedupon as the sole means of achieving stability, they should be capable ofproviding a factor of safety of at least 3 against uplift. Where a roof isinsufficiently strong to provide this factor of safety, counterweights shouldbe added to provide an overall factor of safety against overturning of atleast 3. The roof fixing should be approved by a professional engineer.20