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Course 804 - Safe Scaffold Erection and Inspection

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Inspecting Fabricated Frame Supported Scaffolds

supported scaffold
Supported scaffold examples
(Click to enlarge)

Introduction

Supported scaffolds consist of one or more platforms supported by outrigger beams, brackets, poles, legs, uprights, posts, frames, or similar rigid support. Because frame scaffolds are the most common type of supported scaffold, this course uses the Fabricated Frame Scaffold to describe requirements that are common to all supported scaffolds. Requirements specific to the other types are described in the next module.

Self-Supporting Scaffolds

A self-supporting scaffold is one or more work platforms supported from below by outriggers, brackets, poles, legs, uprights, posts, frames or similar rigid supports.

fab frame

Inspecting Fabricated Frame Scaffolds

Fabricated frame scaffolds are the most common type of scaffold because they are versatile, economical, and easy to use. They are frequently used in one or two tiers by residential contractors, painters, etc., but their modular frames can also be stacked several stories high for use on large-scale construction jobs.

Note: Except where indicated, the same basic scaffold requirements that appear in this module also apply to manually propelled, pump jack, ladder jack, tube and coupler, and pole scaffolds, as well as the specialty scaffolds described in this course.

fab frame

Base Section

It is impossible for a stable structure to be built upon a foundation that does not start out square and level. OSHA has standards that apply specifically to the steps that must be taken to assure a stable scaffold base.

Foundations

foundation
Poor foundation: Scaffold end frames, which have no base plate, are erected on top of scrap wood and unstable cement blocks.
(Click to enlarge)

It is absolutely essential to understand that scaffolds are never as safe as the foundations they are built on.

  1. In order to assure stability, make sure supported scaffold foundations are set on:
    1. base plates
    2. mud sills
    3. other adequate firm foundations
  1. Ensure footings are capable of supporting the loaded scaffold without settling or displacement.
  2. Make sure unstable objects are not used to support scaffolds or platform units.
  3. Check that front-end loaders and similar pieces of equipment are not used as support scaffold platforms, unless they have been specifically designed by the manufacturer for such use.
  4. Ensure forklifts are not used to support scaffold platforms, unless:
    1. The entire platform is attached to the fork.
    2. The forklift is not moved horizontally while the platform is occupied.
unstable
Scaffold is not level because it was erected without base plates on an uneven surface.
(Click to enlarge)

Note: One way to ensure a stable foundation when a sill is used is to secure it to the baseplate.

Scaffold Plumb

Supported scaffold poles, frames, uprights, etc. must be plumb and braced to prevent swaying and displacement. In general, a level is the easiest way to achieve the desired right angles.

Inspecting the Support Structure

To control the risk of a scaffold falling or collapsing, employers must assure that scaffolds are built within OSHA standards relating to strength and structural integrity.

Note: Except where indicated, these requirements also apply to manually propelled, pump jack, ladder jack, tube and coupler, and pole scaffolds, as well as the specialty scaffolds described in their applicable sections.

Capacity

capacity
When scaffold frames are interconnected, failure of one frame can cause the whole system to collapse.

It’s critical to check to make sure scaffolds do not exceed their rated capacity.

  1. Check that scaffolds and scaffold components are capable of supporting, without failure, their own weight and at least 4 times their maximum intended load.
  2. Ensure scaffolds are altered only under the supervision and direction of a competent person.

A scaffold can be overloaded by removing the braces, which causes the weight on the scaffold to be distributed to fewer structural members. Even if they are "in the way," braces should not be removed while work is being performed on a scaffold!

Real-Life Example

Scaffold Collapses and Worker Injured

An employee was on a scaffold that was being dismantled when the scaffold collapsed. He fell, sustaining a concussion for which he was hospitalized. The scaffold was not secured to wooden footing supports, nor was it tied to the building.

Bracing

capacity

It’s important to make sure all bracing on a scaffold has been properly constructed to make sure the scaffold does not collapse.

  1. Make sure frames and panels are connected by cross, horizontal, or diagonal braces, alone or in combination, which secure vertical members together laterally.
  2. Check to make sure frames are stacked, and that cross braces are of such length as will automatically keep the scaffold plumb, level, and square.
  3. Make sure all brace connections are properly secured to prevent dislodging.

Note: A level should be used during assembly to make sure new structural components remain in line.

Pinning

capacity

Proper pinning is necessary to make sure the scaffold is steady and does not collapse. Separation of frames can occur in high winds (uplift), or when workers climb endframes, overload the platform, or strike the scaffold with tools, materials, etc.

  1. Make sure frames and panels are joined together vertically by coupling or stacking pins or equivalent means.
  2. Ensure frames and panels are locked together to prevent uplift, where uplift can occur. Uplift is the separation of a frame from the frame below it.

Components

components
How can the components of this jury-rigged scaffold possess sufficient structural integrity?

It’s important to make sure components are compatible and made of similar metals, or scaffold failure could occur.

  1. Make sure scaffold components manufactured by different manufacturers are not intermixed, unless they fit together without being forced and the scaffold's structural integrity is maintained.
  2. Ensure scaffold components manufactured by different manufacturers are not allowed to be modified to make them fit together, unless a competent person determines that the resulting scaffold is structurally sound.
  3. Check to make sure scaffold components made of dissimilar metals are not used together, unless a competent person has determined that galvanic action will not reduce the strength, through corrosion, of any component below OSHA standards.

Inspecting for Adequate Access

Workers are most vulnerable to fall hazards when climbing on or off a scaffold. Therefore, employers are required to provide safe scaffold access.

Erectors and dismantlers face additional access problems due to the incomplete condition of the scaffolding. Requirements to prevent falls that apply only to these workers are addressed separately below.

The competent person is responsible for determining the safety and feasibility of installing and using safe means of access, based on site conditions and the type of scaffold involved.

  1. Be sure employees are able to safely access any level of a scaffold that is 2 feet above or below an access point.
  2. Make sure employees do not use cross-braces as a means of access.
supported scaffold

Real-Life Example

Improper Access Leads to Serious Injuries

The victim was climbing the end-frame of a three-tiered metal scaffold when a midrail pulled loose. He fell approximately 12 feet to a concrete dock. He suffered multiple fractures to the head, left and right foot, and left wrist, and torn ligaments in the knees.

Ladders

ladder

The most frequent fall-from-elevation accident is a fall off ladders. They must be in good worker order or taken out of service.

  1. Make sure portable, hook-on, and attachable ladders are positioned so as not to tip the scaffold.
  2. Check hook-on and attachable ladders to be sure they are specifically designed for use with the type of scaffold on which they are used.
  3. Make sure hook-on and attachable ladder rungs:
    1. are positioned so that their bottom rung is not more than 24 inches above the scaffold supporting level
    2. have uniform spacing between rungs of a maximum 16¾ inches
    3. have minimum rung length of 11½ inches
    4. have rest platforms provided at a maximum of 35-foot vertical intervals
  1. Ensure stairway-type ladders:
    1. are positioned so that their bottom step is not more than 24 inches above the scaffold supporting level
    2. have rest platforms at maximum vertical intervals of 12 feet
    3. have a minimum step width of 16 inches, except for mobile scaffold stairway-type ladders, which must have a minimum step width of 11½ inches
    4. have slip-resistant treads on all steps and landings
  1. Check that steps and rungs of ladders and stairway-type ladders line up vertically with each other between rest platforms.
ladder

Integral (Built-in Access)

  1. Make sure integral (built-in) scaffold access frames:
    1. are specifically designed and constructed for use as ladder rungs
    2. are not used as work platforms when rungs are less than 11½ inches in length, unless each affected employee uses appropriate fall protection
    3. have rungs which are uniformly spaced and a length of at least 8 inches, with a maximum space between rungs of 16¾ inches
    4. have rest platforms provided at a maximum of 35 foot vertical intervals
  1. Stair towers have many specific design requirements. Make sure stair towers have:
  2. stairs
    1. a stair rail consisting of a toprail and a midrail on each side of the stairway
    2. a toprail of each stair rail system capable of serving as a handrail, unless a separate handrail is provided
    3. sufficient handhold on handrails, and toprails serving as handrails, for employees grasping them to avoid falling
    4. stair rails and handrails surfaced to prevent punctures or lacerations to employees, and to prevent snagging of clothing
    5. stair rails and handrails constructed so that they do not constitute a projection hazard
    6. a space of at least 3 inches between handrails, or stair rails used as handrails, and other objects
    7. a distance of no less than 28 inches and no more than 37 inches from the upper surface of the stair rail to the forward edge of the tread, in line with the face of the riser
    8. a landing platform at least 18 inches wide by 18 inches long at each level
    9. a scaffold stairway width of at least 18 inches between stair rails
    10. slip-resistant surfaces on treads and landings
    11. stairways installed between 40 degrees and 60 degrees from the horizontal
    12. guardrails meeting OSHA requirements on the open sides and ends of each landing
    13. uniform riser height, within ¼-inch, for each flight of stairs
    14. greater variations in riser height are allowed for the top and bottom steps of the entire system (not for each flight of stairs)
    15. uniform tread depth, within ¼-inch, for each flight of stairs
fab scaffold

Ramps and Walkways

  1. Ensure ramps and walkways 6 feet or more above lower levels have guardrails that comply with 1926 Subpart M - Fall Protection.
  2. Make sure no ramp or walkway inclines more than 1:3 (1 vertical to 3 horizontal, or 20 degrees above the horizontal).
  3. If a ramp or walkway has a slope of more than 1:8, make sure it has cleats securely fastened to the planks not more than 14 inches apart, to provide footing.
direct access

Direct Access

Check that direct access to or from another surface is permitted only when the scaffold is not more than 14 inches horizontally and not more than 24 inches vertically from the other surface.

Erectors and Dismantlers

  1. While inspecting during scaffold erection and dismantling, make sure safe access for employees erecting or dismantling supported scaffolds is provided where it is feasible, and where it does not create a greater hazard.
  2. Ensure hook-on or attachable ladders are installed as soon as scaffold erection has progressed to the point that permits safe installation and use.
  3. When erecting and dismantling tubular, welded-frame scaffolds, and end frames are used as climbing devices for access, make sure:
    1. Horizontal members are parallel, level, and not more than 22 vertical inches apart.
    2. Horizontal members are erected in a manner that creates a usable ladder and provides good hand hold and foot space.
  1. Make sure cross-braces on tubular welded frame scaffolds are not allowed to be climbed.

Inspecting for Fall Protection

The number one scaffold hazard is worker falls. Fall protection consists of either personal fall-arrest systems or guardrail systems, and must be provided on any scaffold 10 feet or more above a lower level. Specific requirements are described below.

Note: Except where indicated, these requirements also apply to manually propelled, pump jack, ladder jack, tube and coupler, and pole scaffolds, as well as the specialty scaffolds.

  1. Make sure each employee on a scaffold more than 10 feet above a lower level is protected from falling to that lower level.
  2. Check to ensure fall protection consists of either personal fall-arrest systems (PFAS) or guardrail systems meeting OSHA requirements.
  3. Ensure that employees performing overhand bricklaying operations from a supported scaffold are protected from falling from all open sides and ends of the scaffold, except at the side next to the wall being laid.
platform

Fall-Arrest Systems

Personal fall-arrest systems used on scaffolds should be attached by lanyard to a vertical lifeline, horizontal lifeline, or scaffold structural member.

  1. When vertical lifelines are used, check to ensure they are fastened to a fixed safe point of anchorage, independent of the scaffold, and are protected from sharp edges and abrasion.
  2. Check to ensure safe points of anchorage, such as structural members of buildings, are being used.
  3. Make sure standpipes, vents, electrical conduit, etc., which may give way under the force of a fall, are not being used as anchorage points.
  4. Make sure two or more vertical lifelines are not attached to each other, or to the same point of anchorage.
  5. When horizontal lifelines are used, make sure they are being secured to two or more structural members of the scaffold.

Guardrail Systems

components
This scaffold has no guardrails and is not fully planked. If you work on a supported scaffold more than 10 feet above a lower level, you must be protected from falling.

Guardrail systems must be installed along all open sides and ends of platforms, and must be in place before the scaffold is released for use by employees other than erection/dismantling crews.

Make sure walkways located within a scaffold have guardrail systems installed within 9½ inches of, and along at least one side of the walkway.

  1. Verify each toprail or equivalent member of a guardrail system is able to withstand a force of at least 200 pounds applied in any downward or horizontal direction, at any point along its top edge.
  2. Measure to ensure the top edge height of toprails on supported scaffolds are between 36 inches and 45 inches. When conditions warrant, the height of the top edge may exceed the 45-inch height, provided the guardrail system meets all other criteria. (The minimum top edge height on scaffolds manufactured or placed in service after January 1, 2000 is 38 inches).
  3. Verify that midrails, screens, mesh, intermediate vertical members, solid panels, etc., are able to withstand a force of at least 150 pounds applied in any downward or horizontal direction, at any point along the midrail or other member.
  4. When midrails are used, check to ensure they are installed at a height approximately midway between the top edge of the guardrail system and the platform surface.
  5. When screens and mesh are used, check to ensure they extend from the top edge of the guardrail system to the scaffold platform, and along the entire opening between the supports.
  6. When intermediate members (such as balusters or additional rails) are used, check to ensure they are no more than 19 inches apart.
  7. Ensure guardrails are surfaced to prevent punctures or lacerations to employees and to prevent snagging of clothing, which may cause employees to lose their balance.
  8. Make sure the ends of rails do not extend beyond their terminal posts, unless they do not constitute a projection hazard to employees.
  9. If crossbracing is used In lieu of guardrails, the crossbracing may serve as a toprail or midrail, providing the crossing point is:
    1. between 20 and 30 inches above the work platform for a midrail
    2. between 38 and 48 inches above the work platform for a toprail

Real-Life Example

Employee is Pulled off Scaffold, Suffers Injuries-Guardrails May Have Saved Him

While sitting or kneeling on a fixed deck plank attached to a fabricated frame scaffold, a worker was pulling a 16-foot long 2x4 off the bucket of an excavator. There were no guardrails at the working level. When the other end of the 2x4 slipped off the bucket, the employee did not let go of his end, and was pulled off the deck. He fell 16 feet to the ground, sustaining facial fractures and other injuries.

Inspecting the Platform

Except when used only as a walkway, the platform is the work area of the scaffold. Therefore, an inspection of a scaffold platform requires safety checks of both the platform structure and how the platform is used by the workers.

Planking

  1. Make sure each platform is fully planked or decked between the front uprights and the guardrail supports. Note: Platforms used solely as walkways, or during erection or dismantling, require only the planking that the employer establishes is necessary to provide safe working conditions.
  2. Make sure no gaps greater than 1 inch are permitted between adjacent planks or deck units, or between the platform and the uprights.
  3. If it can be demonstrated that a wider space is necessary, check to make sure the gap is as small as possible and does not exceed 9 1/2 inches.
  4. Ensure planking is free of cracks and splits and within deflection limits (see below)
  5. Make sure wooden planking is covered with opaque finishes, except that platform edges may be marked for identification. Note: Platforms may be coated periodically with wood preservatives, fire retardants, and slip-resistant finishes, provided they do not obscure the top or bottom wood surfaces.
  6. Ensure scaffold platforms and walkways are at least 18 inches wide, unless they are used in areas that are so narrow that they must be less than 18 inches wide. In such cases, verify that the platforms are as wide as feasible, and fall protection is provided.
  7. Make sure that anything that could cause a slip, trip or fall (i.e. tools, scrap material, chemicals, snow, ice, etc.) has not been allowed to accumulate on the platform. Note: For the same reason, cleats or other means of connecting planks should be on the underside.
  8. Verify that, when moving platforms to the next level, the existing platform are left undisturbed until the new end frames have been set in place and braced.
components
This scaffold is overloaded and planks are strained.
gaps
The platform gaps are too wide. The spaces between platforms cannot exceed one inch.
components
Each end of platform, unless cleated or otherwise restrained by hooks, must extend over support by at least six inches.

Deflection

To assure that scaffold planking remains within its safe load-bearing capacity, it may not be allowed to deflect more than 1/60th of its span between supports.

Workers should be aware of deflection because it can indicate when a platform is overloaded, and a competent person should not allow employees to occupy a platform that exceeds the 1/60th ratio.

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 are the most common type of scaffold because they are versatile, economical, and easy to use?

2. Ensure forklifts are not used to support scaffold platforms unless the entire platform is attached to the fork, and the forklift is not moved horizontally _____.

3. What can happen if component parts made of dissimilar metals are used together on a scaffold?

4. While inspecting, you notice a worker's lanyard attached to a building's electrical conduit. What should you tell the worker?

5. During your inspection, you notice workers improperly moving platforms to the next level. What do you tell the workers?


Have a great day!

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