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Anchorage
The safe use of a suspended scaffold begins with secure anchorage. The weight of the scaffold and its occupants must be supported by both the structure to which it is attached and by each of the scaffold components that make up the anchorage system. Note: Except where indicated, these requirements also apply to multi-level, single-point adjustable, multi-point adjustable, interior hung, needle-beam, catenary, and float (ship) scaffolds.
Tiebacks
  • Tiebacks must be secured to a structurally sound anchorage on the building or structure, which may include structural members, but not vents, electrical conduit, or standpipes and other piping systems. [1926.451(d)(3)(ix)]

  • Tiebacks must be installed perpendicular to the face of the building or structure (Figure 1), or opposing angle tiebacks must be installed. Single tiebacks installed at an angle are prohibited. [1926.451(d)(3)(x)]

  • Tiebacks must be equivalent in strength to the suspension ropes and hoisting rope. [1926.451(d)(3)(vii) and 1926.451(d)(5)(iv)]
Figure 1. An example of a parapet hook tieback that is perpendicular to the face of the building.

Figure 1.
An example of a parapet hook tieback that is perpendicular to the face of the building.




Counterweights
  • Suspended scaffold outrigger beams must be stabilized by:

    • Counterweights, or

    • Bolts or other direct connections to the floor or deck. [1926.451(d)(3)]
  • Counterweights used to balance adjustable suspension scaffolds must be capable of resisting:

    • At least 4 times the tipping moment imposed by the scaffold when it is operating at the rated load of the hoist, or

    • A minimum of 1½ times the tipping moment imposed by the scaffold when it is operating at the stall load of the hoist, whichever is greater. [1926.451(a)(2)]
  • Only items specifically designed as counterweights may be used to counterweight scaffold systems. [1926.451(d)(3)(iii)]

  • Masonry units, rolls of roofing felt, and other similar construction materials shall not be used as counterweights. [1926.451(d)(3)(iii)]

  • Counterweights must not be made of flowable materials such as sand, gravel, and similar materials that can be easily dislocated. [1926.451(d)(3)(ii)]

  • Counterweights must be secured by mechanical means to the outrigger beams (Figures 2 & 3) to prevent accidental displacement. [1926.451(d)(3)(iv)]

  • Counterweights must not be removed from an outrigger beam until the scaffold is disassembled. [1926.451(d)(3)(v)]
Figure 2. These counterweights are supposed to be secured to the outrigger system by a steel plate clamped with bolts...

Figure 2.
These counterweights are supposed to be secured to the outrigger system by a steel plate clamped with bolts...


Figure 3. ...but they have been pulled away by the weight on this yellow fall protection rope. Since fall protection must be independent of the scaffold, the counterweight violation was caused by this fall protection violation. If the counterweights had succeeded in working completely loose, what would have secured the lifelines when the scaffold came down?

Figure 3
....but they have been pulled away by the weight on this yellow fall protection rope. Because fall protection must be independent of the scaffold, the counterweight violation was caused by this fall protection violation. If the counterweights had come completely loose, what would have secured the lifelines when the scaffold came down?




Direct Connections
  • Suspended scaffold outrigger beams must be stabilized by:

    • Bolts or other direct connections to the floor or deck, or

    • Counterweights. [1926.451(d)(3)]
  • Direct connections to roofs and floors must be capable of resisting:

    • at least 4 times the tipping moment imposed by the scaffold when it is operating at the rated load of the hoist, or

    • a minimum of 1½ times the tipping moment imposed by the scaffold when it is operating at the stall load of the hoist, whichever is greater. [1926.451(a)(2)]
 
 
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