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  Anchorage
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.

Accident Report

Workers Killed When Scaffolds Without Tiebacks Fall

Case Report from OSHA files

  • Two employees were working on a two-point suspension scaffold without safety belts, lifeline, or tiebacks. They attempted to move a hook to reposition it when the hook slipped off the parapet, causing one end of the scaffold to drop. The victim fell five stories to his death. His co-worker was able to grab on to the scaffold, and climbed to a fire escape.

  • A worker was on a two-point suspension scaffold that was suspended by cornice hooks at the top of a parapet wall (approximately 42 ft.). The cornice hooks were not tied back with a secondary tieback system. The left side of the parapet wall collapsed, causing the left cornice hook to fall and the left end of the scaffold to fall to the ground. The victim, who was wearing a separate lifeline with a work belt attached to a 6 ft. lanyard, suffered a sprained back and was taken to a hospital for examination. The scaffold had not been tied back according to the manufacturer's specifications. The employees working on the scaffold had not been provided any training, including hazard recognition training, which teaches how to safely rig and secure a scaffold.


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?

Accident Report

Inadequate Counterweights Cause Two Deaths

Case Report from OSHA files

  • A 53-year-old painting foreman and a 28-year-old painter were killed when their scaffold collapsed. They were working on a 48-foot-high tank from a two-point suspension scaffold supported by two steel outriggers. The scaffold manufacturer specified 600 pounds of counterweight for this scaffold and load, but the painters had rigged the scaffold using only 200 pounds of counterweight (100 pounds per outrigger). The outriggers were not tied off or otherwise secured. No personal fall protection equipment was being used by either worker. While the two men were working on the scaffold, their weight caused the outriggers to slip, and the scaffold, rigging, and victims fell to the ground.


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)]
Accident Report

Scaffold Attachments Fail; Two Die

Case Report from OSHA files

  • Two employees were sandblasting a 110-foot water tank while working on a two-point suspension scaffold 60-70 feet above the ground. The scaffold attachment point failed, releasing the scaffold cables, and the scaffold fell to the ground. The employees were not tied off independently, nor was the scaffold equipped with an independent attachment system.
 
 
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