- Define common types of scaffolds and terms associated with their use.
- Identify hazards associated with scaffolds.
- Recognize who may build and design scaffolds.
- Recognize required safe practices for working on or near scaffolds.
- Identify fall protection requirements specific to work on scaffolds.
- Identify requirements for operating and working in aerial lifts.
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Labor Statistics, OSHA
Scaffolds are widely used throughout the industrial world for construction and maintenance, typically, to give employees access to heights ranging from a few feet to over several hundred feet.
OSHA defines a scaffold as “any temporary elevated platform and its supporting structure used for supporting employees or materials.”
Let’s run through some basics on scaffolding safety…
No matter how safe or sturdy a scaffold may look, it can only support the weight capacity specified by the manufacturer. Workers must recognize terms associated with capacity limits when working with scaffolds. OSHA requires each scaffold and scaffolding component to be capable of supporting, without failure, its own weight and at least four times the maximum intended load.
The “rated load” is the manufacturer's specified maximum load to be lifted by a hoist or to be applied to a scaffold or scaffold component.
The “maximum intended load” is the total load of all persons, equipment, tools, materials, transmitted loads, and other loads reasonably anticipated to be applied to a scaffold or scaffold component at any one time.
If a scaffold is overloaded, it will eventually collapse. OSHA requires each scaffold and scaffold component to be capable of supporting, without failure, its own weight and at least four times the maximum intended load, otherwise known as its safety factor. When calculating the amount of weight to be placed on a scaffold, do not use the safety factor capacity. Ask your supervisor if you have questions about the capacity limits of any scaffold you use.
To protect workers:
- Scaffolds are rated by the manufacturer to withstand a specific load.
- The rating is determined by the frame and cross-bracing design of the scaffold and its plank requirements.
- Is limited to a specific load expressed as pounds per square foot - load ratings are usually referred to as light, medium or heavy duty with a corresponding capacity of 25, 50 and 75 pounds respectively;
- Never exceed the maximum intended load nor the planking load at any time;
- Use only scaffold grade lumber for wooden planking;
- Never use standard construction lumber.
“Point-loading” can cause severe sagging of the planks and result in a collapse. To avoid point-loading or the placement of too much weight in one location of the scaffold, distribute a load evenly across the deck of a scaffold.
A deflection of 1/60th of the length of the plank is allowed when loaded. For instance, a 12 foot plank is allowed to bend or deflect no more than 2 inches when loaded.
When possible, distribute loads over the frame members for greater stability. Where side brackets or cantilevered structures are used for material, make sure the design capacity of the scaffold is not exceeded, resulting in the load pulling the scaffold over. Make sure the structure you are working on can safely withstand the load placed upon it before using it.
- Fatalities sustained by workers erecting scaffolds
- Overhead power lines in the vicinity
- Long scaffold poles reaching power lines
- Improperly Constructed or Erected Scaffolds
If the first section of scaffolding is not properly set, as the scaffold grows in height it will be increasingly out of balance and unstable.
To maintain balance and stability:
- Erect all self-supporting scaffolding plumb and square and on a firm solid foundation.
- Use the mud sill, base plate, and screw jack to establish stable level contact with the ground.
- Ensure the ground surface is dry and compact so the scaffold will not sink under its weight.
- Do not place concrete blocks under the legs for leveling purposes.
- Nail the base plate to the mud sill to prevent “kick-out” if the scaffold should shift.
- Never advance the screw jack more than half its total length.
- Do not inter mix scaffold components with different load ratings or different scaffold manufacturers.
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