Technical requirements for safety in metal scaffolding – Modular scaffolds

5.3.3  Modular scaffolds

(a)     Modular scaffolds are mainly made of tubes, angle steel, I-beams, channels, steel columns,  etc.  Most  systems  of  modular  scaffold are composed of standards with preformed connectors welded at intervals along their length to which ledgers are fixed with a proprietary clamping or wedging arrangement. (See Figure 9)

(b)    Each  scaffold  should  be  constructed  in  accordance  with  the design and drawings of professional engineer. If there is any need to deviate from the original design and drawings, the scaffold should be re-designed by professional engineer.

(c)    A  modular  scaffold  system  mainly  consists  of  the  following components:

(i)     Standards

They come in a variety of lengths and have preformed connectors  welded  at  fixed  distances  along  their  length. A spigot arrangement or socket is provided at one end of the standard for extension purposes.

(ii)    Ledgers

They are in varying lengths with connectors welded to each end. The connection is made when the wedge, cup or bolt is hammered or screwed tight.

(iii)   Transoms

They are generally made to support scaffold boards or stagings. The ends of the transoms are connected to the standards in the same way as the ledgers. Some systems might require intermediate transoms to support the boards or stagings.

(iv)   Bracings

Bracings in each direction are made to fit the different bay sizes. Some systems use standard tubes and fittings for bracings.

(v)    Scaffold boards

They are also called stagings and come in a variety of lengths, thicknesses and widths. Decking is seldom interchangeable as each system is designed to sit exactly on the narrow lip of the transom. Scaffold boards are often made from steel with a slip resistant surface and pre-drilled drainage holes. These systems allow for the attachment of proprietary toe-boards.

(vi)   Ties

Ties are generally formed in tube and fittings.

(vii)  Adjustable base plates

They are essential and care should be taken to establish their safe working loads and whether they are designed for heavy or light duty use.

(d)    These scaffolds all employ different patented locking devices (wedges, locking pins, etc.) and are designed to different specifications. It is therefore difficult and sometimes dangerous to interchange one system with another. As such, there should not be a mixing of two different systems in one scaffolding system.

(e)    It  is  vital  that  specific  instruction,  training  or  an  erection handbook be provided for the workmen erecting any modular scaffold. Users should pay strict attention to their loading capacities and methods of erection published in the manufacturer’s instructions. There is no common specification for modular scaffolds.