OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 23 Scaffolds and Temporary Work Platforms

Section 343 Requirements for swingstage scaffold

A light duty scaffold is intended for workers only. Materials other than tools should not be stored on this type of scaffold. Such a scaffold is designed to support the equivalent of an evenly distributed load of no more than 122 kilograms/square metre (25 pounds/square foot).

Figure 23.21 shows the proper parallel positioning of suspension ropes. This positioning eliminates the creation of lateral forces on those structures supporting the ropes. Lateral forces could cause thrustouts and thrustout blocking to suddenly shift, damage parapets, and cause the swingstage to become unstable. Figure 23.22 shows suspension ropes that have been positioned improperly.

Figure 23.22 Improper suspension rope positioning

A parapet or cornice hook is a device that functions as a portable or temporary anchor for a suspension line. A parapet clamp functions as a portable or temporary anchor for a suspension line, lifeline or tieback line (Figure 23.23 shows both devices in use). As such, each hook or clamp should be designed with a minimum breaking strength of 22.2 kilonewtons (5000 pounds-force). If a parapet clamp is used to anchor a lifeline i.e. life safety rope (vertical lifeline), it must have a minimum breaking strength of 16 kilonewtons (3600 pounds-force ) or two times the maximum arresting force per worker attached as required by subsection 152.1(2).

The tieback of a thrustout, parapet hook or parapet clamp can only function as an effective anchor if it is positioned on a part of the building or structure that is structurally sound and able to support the loads that the tieback will apply. These tiebacks should, as much as possible, be rigged at right angles to the building face from which the scaffold is suspended. Selection of proper tieback points is extremely important.

Figure 23.23 Parapet clamp and parapet or cornice hook

 

A “constant pressure control” is one that requires a deliberate, sustained application of force by a human body part for the machine to operate. Removal of this force immediately stops the machine from operating. A control equipped with a locking mechanism that keeps the control active without contact by a human body part is unacceptable.

“Positive drive”, in relation to a swingstage scaffold power unit, means that the  up but permits it to descend freely.