Scaffold General Requirements – 1926.451(d)Criteria for Suspended Scaffolds

All suspension scaffold support devices, such as outrigger beams, cornice hooks, parapet clamps, and similar devices, shall rest on surfaces capable of supporting at least 4 times the load imposed on them by the scaffold operating at the rated load of the hoist (or at least 1.5 times the load imposed on them by the scaffold at the stall capacity of the hoist, whichever is greater).

Suspension scaffold outrigger beams, when used, shall be made of structural metal or equivalent strength material, and shall be restrained to prevent movement.

The inboard ends of suspension scaffold outrigger beams shall be stabilized by bolts or other direct connections to the floor or roof deck, or they shall have their inboard ends stabilized by counterweights, except masons’ multi-point adjustable
suspension scaffold outrigger beams shall not be stabilized by counterweights.

Before the scaffold is used, direct connections shall be evaluated by a competent person who shall confirm, based on the evaluation, that the supporting surfaces are capable of supporting the loads to be imposed. In addition, masons’ multipoint adjustable suspension scaffold connections shall be designed by an engineer experienced in such scaffold design.

Counterweights shall be made of non-flowable material. Sand, gravel and similar materials that can be easily dislocated shall not be used as counterweights.

Only those items specifically designed as counterweights shall be used to counterweight scaffold systems. Construction materials such as, but not limited to, masonry units and rolls of roofing felt, shall not be used as counterweights.

Counterweights shall be secured by mechanical means to the outrigger beams to prevent accidental displacement.

Counterweights shall not be removed from an outrigger beam until the scaffold is disassembled.

Outrigger beams which are not stabilized by bolts or other direct connections to the floor or roof deck shall be secured by tiebacks.

Tiebacks shall be equivalent in strength to the suspension ropes.

Outrigger beams shall be placed perpendicular to its bearing support (usually the face of the building or structure). However, where the employer can demonstrate that it is not possible to place an outrigger beam perpendicular to the face of the building or structure because of obstructions that cannot be moved, the outrigger beam may be placed at some other angle, provided opposing angle tiebacks are used.

Tiebacks shall be secured to a structurally sound anchorage on the building or structure. Sound anchorages include structural members, but do not include standpipes, vents, other piping systems, or electrical conduit.

Tiebacks shall be installed perpendicular to the face of the building or structure, or opposing angle tiebacks shall be installed. Single tiebacks installed at an angle are prohibited.

Suspension scaffold outrigger beams shall be – Provided with stop bolts or shackles at both ends; and Securely fastened together with the flanges turned out when channel iron beams are used in place of I-beams, installed with all bearing supports perpendicular to the beam center line.

Set and maintained with the web in a vertical position; and When an outrigger beam is used, the shackle or clevis with which the rope is attached to the outrigger beam shall be placed directly over the center line of the stirrup.

Suspension scaffold support devices such as cornice hooks, roof hooks, roof irons, parapet clamps, or similar devices shall be

Made of steel, wrought iron, or materials of equivalent strength; Supported by bearing blocks; and Secured against movement by tiebacks installed at right angles to the face of the building or structure, or opposing angle tiebacks shall be installed and secured to a structurally sound point of anchorage on the building or structure.

Sound points of anchorage include structural members, but do not include standpipes, vents, other piping systems, or electrical conduit.

Tiebacks shall be equivalent in strength to the hoisting rope.

When winding drum hoists are used on a suspension scaffold, they shall contain not less than four wraps of the suspension rope at the lowest point of scaffold travel. When other types of hoists are used, the suspension ropes shall be long enough
to allow the scaffold to be lowered to the level below without the rope end passing through the hoist, or the rope end shall be configured or provided with means to prevent the end from passing through the hoist.

The use of repaired wire rope as suspension rope is prohibited!

Wire suspension ropes shall not be joined together except through the use of eye splice thimbles connected with shackles or coverplates and bolts.

The load end of wire suspension ropes shall be equipped with proper size thimbles and secured by eyesplicing or equivalent means.

Ropes shall be inspected for defects by a competent person prior to each workshift and after every occurrence which could affect a rope’s integrity. Ropes shall be replaced if any of the following conditions exist.

Any physical damage which impairs the function and strength of the rope.

Kinks that might impair the tracking or wrapping of rope around the drum(s) or sheave(s). Six randomly distributed broken wires in one rope lay or three broken wires in one strand in one rope lay.

Abrasion, corrosion, scrubbing, flattening or peening causing loss of more than one-third of the original diameter of the outside wires.

Heat damage caused by a torch or any damage caused by contact with electrical wires. Evidence that the secondary brake has been activated during an overspeed condition and has engaged the suspension rope.

Swaged attachments or spliced eyes on wire suspension ropes shall not be used unless they are made by the wire rope manufacturer or a qualified person.

When wire rope clips are used on Suspension Scaffolds:

• There shall be a minimum of 3 wire rope clips installed, with the clips a minimum of 6 rope diameters apart
  • Clips shall be installed according to the manufacturer’s recommendations
  • Clips shall be retightened to the manufacturer’s recommendations after the initial loading
  • Clips shall be inspected and retightened to the manufacturer’s recommendations at the start of each work shift thereafter
  • U-bolt clips shall not be used at the point of suspension for any scaffold hoist
  • When U-bolt clips are used, the U-bolt shall be placed over the dead end of the rope, and the saddle shall be placed over the live end of the rope
• Suspension scaffold power-operated hoists and manual hoists shall be tested by a qualified testing laboratory
• Gasoline-powered equipment and hoists shall not be used on suspension scaffolds
• Gears and brakes of power-operated hoists used on suspension scaffolds shall be enclosed
• In addition to the normal operating brake, suspension scaffold power-operated hoists and manually operated hoists shall have a braking device or locking pawl which engages automatically when a hoist makes either of the following uncontrolled movements: an instantaneous change in momentum or an accelerated overspeed
• Manually operated hoists shall require a positive crank force to descend
• Two-point and multi-point suspension scaffolds shall be tied or otherwise secured to prevent them from swaying, as determined to be necessary based on an evaluation by a competent person. Window cleaners’ anchors shall not be used for this purpose
• Devices whose sole function is to provide emergency escape and rescue shall not be used as working platforms. This provision does not preclude the use of systems which are designed to function both as suspension scaffolds and emergency systems

In Summary

• Employers must ensure that all employees are trained to recognize the hazards associated with the type of scaffold being used.
• All support devices must rest on surfaces capable of supporting at least four times the load imposed on them by the scaffold when operating at the rated load of the hoist, or at least one-and-a-half times the load imposed on them by the scaffold at the stall capacity of the hoist, whichever is greater.
• A competent person must evaluate all direct connections prior to use to confirm that the supporting surfaces are able to support the imposed load.
• All suspension scaffolds must be tied or otherwise secured to prevent them from swaying, as determined by a competent person.
• Guardrails, a personal fall-arrest system, or both must protect each employee more than 10 feet (3.1 m) above a lower level from falling.
• A competent person must inspect ropes for defects prior to each workshift and after every occurrence that could affect a rope’s integrity.
• When scaffold platforms are more than 24 inches (61 cm) above or below a point of access, ladders, ramps, walkways, or similar surfaces must be used.
• When using direct access, the surface must not be more than 24 inches (61 cm) above or 14 inches (36 cm) horizontally from the surface.
• When lanyards are connected to horizontal lifelines or structural members on single-point or two-point adjustable scaffolds, the scaffold must have additional independent support lines equal in number and strength to the suspension lines and have automatic locking devices.
• Emergency escape and rescue devices must not be used as working platforms, unless designed to function as suspension scaffolds and emergency systems.