Technical requirements for safety in metal scaffolding – Proprietary scaffold systems

5.3  Proprietary scaffold systems

5.3.1  A proprietary scaffold system comprises a complete set of prefabricated components of unique design, capable of erection without any other components. It will be necessary for the manufacturer of the system to provide a complete set of instructions, compatible with this Code and sufficient  to  ensure  the  safe  erection  and  use  of  the  scaffold.  Plane frame scaffolds and modular scaffolds are the most commonly used proprietary scaffold systems in Hong Kong. When using a proprietary type scaffold system, the scaffold system should be designed by professional engineer     making   reference   to   the   manufacturer ’s  instructions and in accordance with recognized engineering principles or other national/international      standards   or   provisions.   Reference   should also be made to Section 5.4 of this Code. An independent checking professional engineer should be arranged to cross-check the design and the erected scaffold when the case is warranted. As a general guidance, the following safety procedures should be taken into account:

(a)  The scaffold should be erected in accordance with professional engineer’s  design  in  which  reference  should  also  be  made  to the          manufacturer’s   recommendations   or   national/international standards or provisions. However, the professional engineer should avoid using two or more standards in one single design.

(b)     Regarding  the  strength  of  steel  elements  and  frame  scaffold, sampling tests, loading tests and mechanical tests (for example, yield stress, tensile strength, compressive strength, elongation, bend and buckling tests), reference should be made to the procedures laid down in relevant standards of the International Organization for Standardization or equivalent procedures.

(c)     Design  involving  structural  steel  should  be  in  accordance  with the Code of Practice for the Structural Use of Steel issued by the Buildings Department or other equivalent national/international standards or provisions.

(d)    The height limit of each proprietary scaffold system should be checked.

When the number of stages of scaffold increases, the strength of the

scaffold would be reduced.

(e)     Rusting  of  scaffold  members  would  reduce  the  strength  of  the scaffold.  Therefore,  attention  should  be  paid  to  the  severity  of rusting of scaffold members. When deciding the strength reduction factor, reference should be made to relevant national/ international standards or provisions.

(f)     The scaffold should be levelled until proper fit can easily be made.

Frames or braces should not be forced to fit.

(g)     Each frame or panel should be effectively braced to restrain from lateral               movement.   All   brace   connections   should   be   made secure in accordance with the manufacturer ’s recommended procedures.

(h)    A mixed structure of different proprietary systems should not be used.

(i)      When there is any deviation from the standard scaffold, or when sheeting or fan is added, or when other changes are made which will vary the structural loading or arrangement of the scaffold, professional engineer should be consulted well beforehand.

(j)      The tying and its attachment to appropriate points on the scaffold should be arranged in accordance with the design.

(k)  Suitability of the support should be checked against those requirements mentioned in Section 5.1.2.