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Course 804 - Safe Scaffold Erection and Inspection

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Inspecting Special Use Suspended Scaffolds

single point

Inspecting Single-Point Adjustable Scaffolds

A single-point adjustable scaffold consists of a platform suspended by one rope from an overhead support and equipped with means to permit the movement of the platform to desired work levels. The most common among these is the scaffold used by window washers to clean the outside of a building.

  1. Make sure the supporting rope between the scaffold and the suspension device is kept vertical, unless:
    1. The rigging has been designed by a qualified person.
    2. The scaffold is accessible to rescuers.
    3. The support rope is protected from rubbing during direction changes.
    4. The scaffold is positioned so swinging cannot bring it into contact with other surfaces.
  2. Make sure, when combining two single-point scaffolds to form a two-point suspension system, the resulting scaffold comply with 1926.452(p) requirements.
  3. Check that the maximum intended load for single-point adjustable suspension scaffolds is 250 pounds.

Inspecting Boatswain's Chairs

chair

A Boatswains’ Chair is a suspended seat designed to accommodate one worker in a sitting position. It is most commonly used by window washers to clean the outside of buildings. It may be also used to clean the inside of storage tanks, etc.

  1. Check to make sure boatswain's chair tackle consists of the following:
    1. correct-size ball bearings or bushed blocks containing safety hooks
    2. properly eye-spliced first-grade manila rope, or other rope of equivalent strength and durability
    3. chair
  2. Inspect seat slings to make sure they:
    1. pass through four corner holes in the seat
    2. bcross on the underside of the seat
    3. are rigged to prevent slippage which could cause the chair to be out-of-level
    4. are at least 5/8-inch diameter fiber, synthetic, or other first-grade manila rope of equivalent criteria (strength, slip resistance, durability, etc.)
    5. seat slings used for gas or arc welding are made of at least 3/8-inch wire rope
  3. Check to make sure non-cross-laminated wood chairs are reinforced on the underside with cleats to keep the board from splitting.
  4. Check wood seats for boatswain's chairs to make sure they are:
    1. no less than 1 inch thick (if made of non-laminated wood)
    2. 5/8-inch thick (if made of marine-quality plywood)
outrigger
Inspecting Catenary Scaffolds.
Click to enlarge

Inspecting Catenary Scaffolds

A catenary scaffold is a suspension scaffold consisting of a platform fastened to two essentially horizontal and parallel ropes, which are secured to structural members. Horizontal ropes are usually supported by intermediate vertical pickup ropes to reduce sag and anchorage load.

  1. Make sure catenary scaffolds do not have:
    1. more than one platform between consecutive vertical pickups
    2. more than two platforms altogether
  2. Ensure platforms supported by wire rope have hook-shaped stops on each of the platforms to prevent them from slipping off the wire ropes. Make sure these hooks are positioned so they prevent the platform from falling if one of the horizontal wire ropes breaks.
  3. Look to determine if wire ropes are not over-tightened to the point that a scaffold load will overstress them.
  4. Make sure wire ropes are continuous without splices between anchors.
  5. Ensure each employee is protected by a personal fall-arrest system (PFAS). Note: The use of body belts is prohibited.
  6. Check to see if the scaffolds maximum intended load of 500 pounds is not exceeded.
  7. Make sure that no more than two employees at a time are permitted on the scaffold.
  8. Ensure the maximum capacity of each come-along is 2,000 pounds.
  9. Make sure vertical pickups are spaced no more than 50 feet apart.
  10. Make sure ropes are equivalent in strength to at least ½ inch-diameter improved plow steel wire rope.

Inspecting Multiple-Point Adjustable Scaffolds

A multiple-point adjustable suspension scaffold is a suspension scaffold consisting of a platform(s) suspended by more than two ropes from overhead supports and equipped with means to permit the raising and lowering of the platform to desired work levels.

  • A stone setter’s multiple-point adjustable suspension scaffold is a two-point or multiple-point adjustable suspension scaffold designed and used for stone setting operations.
  • A mason’s adjustable suspension scaffold is a two-point or multiple-point adjustable suspension scaffold designed and used for masonry operations.

When inspecting multi-point adjustable scaffolds, check for each of the following:

multi-point
  1. Make sure multi-point adjustable scaffolds are suspended only from:
    1. metal outriggers
    2. brackets
    3. wire rope slings
    4. hooks
    5. means that meet equivalent criteria for strength, durability, etc.
  2. When two or more scaffolds are used they are not bridged together unless:
    1. their design allows them to be connected
    2. the bridge connections are articulated
    3. the hoists are properly sized
  3. If bridges are not used, make sure the passage between platforms is made only when they are at the same height and are abutting.

When inspecting a mason’s multi-point adjustable suspension scaffold, check each of the following:

  1. Make sure that for a maximum intended load of 50 pounds per square foot, each outrigger beam is at least a standard 7 inch, 15 foot, 15.3 pound steel I-beam.
  2. Make sure outrigger beams do not project more than 6 feet 6 inches beyond the bearing point.
  3. Make sure overhangs exceeding 6 feet 6 inches are composed of stronger outrigger beams or multiple beams.

Inspecting Multi-Level Suspended Scaffolds

multi-level

A multi-level suspended scaffold is a two-point or multiple-point adjustable suspension scaffold with a series of platforms at various levels supported by common stirrups.

  1. Make sure multi-level suspended scaffolds are equipped with additional independent support lines:
    1. equal in number to the number of points supported
    2. equal in strength to the suspension ropes
    3. rigged to support the scaffold if the suspension ropes fail
  2. Ensure support lines and suspension ropes are not anchored to the same points.
  3. Check to make sure supports for platforms are attached directly to support stirrups (not to other platforms).

Inspecting Float (Ship) Scaffolds

multi-level

A float (ship) scaffold is a suspension scaffold consisting of a braced platform resting upon two parallel bearers and hung from overhead supports by ropes of fixed length.

  1. Make sure platforms are supported by, and securely fastened to, a minimum of two bearers extending at least 6 inches beyond the platform on both sides.
  2. Ensure rope connections do not allow the platform to shift or slip.
  3. Check to make sure only two ropes are used with each float.
  4. Make sure ropes are arranged to provide four ends that are securely fastened to overhead supports, and that each rope:
    1. is hitched to one end of the bearer
    2. passes under the platform and is hitched again at the other end
    3. leaves enough rope for supporting ties
  5. Ensure each employee on a float (ship) scaffold is protected by a personal fall-arrest system.
  6. Check for the following for maximum intended loads of 750 pounds:
    1. Platforms are made of ¾-inch plywood.
    2. Bearers are made from 2 x 4-inch or 1 x 10-inch rough lumber, and free of knot and flaws.
    3. Ropes have a strength equivalent to at least 1 inch-diameter, first-grade manila rope.

Inspecting Interior Hung Scaffolds

wire rope

An interior hung scaffold is a suspension scaffold consisting of a platform suspended from the ceiling or roof structure by fixed length supports.

  1. Make sure interior hung scaffolds are suspended from roof structures (e.g., ceiling beams).
  2. Make sure roof structures are inspected for strength before scaffolds are erected.
  3. Ensure suspension ropes/cables are connected to overhead supports by shackles, clips, thimbles, or equivalent means.
  4. Check bearers to ensure they have dimensions of 2 x 10 inches, and are used on edge.
  5. Check or an intended maximum load of 25 to 50 lbs. per square foot, the maximum span is 10 feet.
  6. Check or an intended maximum load of 75 lbs. per square foot, the maximum span is 7 feet.

Inspecting Needle Beam Scaffolds

wire rope

This simple type of scaffold consists of a platform suspended from needle beams, usually attached on one end to a permanent structural member.

  1. Make sure scaffold support beams must be installed on edge.
  2. Ensure ropes or hangers are being used for supports. (Exception: One end of the scaffold may be supported by a permanent structural member.)
  3. Check that ropes are securely attached to needle beams.
  4. Make sure support connections are arranged to prevent the needle beam from rolling or becoming displaced.
  5. Check to make sure platform units are attached by bolts or equivalent means. Cleats and overhang are not considered adequate means of attachment.

For a maximum intended load of 25 pounds per square foot, check for the following:

  1. Ensure beams are at least 4 x 6 inches in cross section, with a maximum beam span of 10 feet, and the platform span is no more than 8 feet.
  2. Ensure ropes are attached to the needle beam by a scaffold hitch or eye splice, and that the loose end is tied by a bowline knot or a round turn and a half hitch.
  3. Make sure the rope strength is at least be equal to 1-inch diameter, first-grade manila rope.

Instructions

Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. Which of the following is the most common scaffold used by window washers to clean the outside of a building?

2. Check the wood seats for boatswain's chairs to make sure they are not less than _____ (if made of marine-quality plywood).

3. Which of the following scaffolds has a series of platforms at various levels supported by common stirrups?

4. When inspecting Interior Hung Scaffolds, verify that _____ have been inspected for strength before scaffolds are erected.

5. When inspecting Needle Beam Scaffolds, verify support connections are arranged to prevent the needle beam from _____.


Have a great day!

Important! You will receive an "error" message unless all questions are answered.