Scaffold-Based or Scaffold-Free Bioprinting: Competing or ...
Scaffold Construction
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Transcript of Scaffold Construction
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By: Georgia Tech Occupational
Safety and Health Program
Scaffolding: Your Key to
Stability
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29 CFR 1926 Subpart L
1926.450 Scope and Application
1926.451 General Requirements
1926.452 Additional Requirements
1926.453 Aerial Lifts
1926.454 Training RequirementsAppendices A thru E
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Most Frequently Cited Hazards
Scaffolds above 10 ft.-Fall Protection
Scaffold Access
Scaffold Working Levels-Decked
Aerial Lift-Harness/Lanyard
Training in use of scaffolds
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National Statistics
A significant percentage
of personnel in
construction (65) work
from scaffolds routinely
There are approximately
50 fatalities related to
scaffolds each year.
There are approximately
4500 employee injuries
each year as a result of
using scaffolds.
For the period 1980-1985
falls from scaffolds
accounted for 17% of the
fatalities for falls fromelevations.
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Georgia Statistics
The total number of fall related fatalities in
2000 was 25.
The number of fatalities involving scaffolds
were 6.
Falls from scaffolds represented twenty five
percent of the total fatalities in the state
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Hazards
Injured workers revealed that 72% of the
accidents were caused by:
Platform failure
Support failure
Slipping
Being struck by an object
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Requirements for Competent
Person A competent person is a person on the
project who has knowledge to identify and
the authority to correct site hazardsOSHA 10 or 30 hour training card could
support the fact you had training and areknowledgeable
The 10 or 30 hour OSHA training card alonedoes not necessarily mean you are a competent
person
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Requirements for Competent
Person Scaffolds have to be inspected daily by a
competent person
Scaffolds must be erected, moved,
dismantled or altered under the supervision
of a competent person
Work by qualified workers selected by thecompetent person
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Capacity 29 CFR 1926.451(a)
Each scaffold and scaffold component must
be capable of supporting four times the
intended weight.
Direct connections to the roof and
counterweights of suspended scaffolds must
resist four times the tipping moment or 1.5times tipping moment imposed by scaffold
operating at stall load
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Capacity 29 CFR 1926.451(a)
Suspension ropes including hardware must
support six times the maximum intended
load
The stall load of any scaffold hoist shall not
exceed three times its rated load.
Scaffolds must be designed by a qualifiedperson and loaded accordingly.
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Platform Construction 29 CFR
1926.451(b) All working levels of scaffolds are required
to be fully decked.
No gaps greater than one inch allowed
Each scaffold platform shall be at least 18
inches wide.
Ladder jack, roof bracket and pump jack can be12 inches wide.
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Platform Construction 29 CFR
1926.451(b) The front edge shall not be more than 14
inches from face (if in excess rails
required).
The end of each platform will extend over
the center line by six inches (unless
hooked).
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Platform Construction
Requirement for overhang based on length:
10 ft or less platformnot to exceed 12 inches
More than 10 ft not toexceed 18 inches
For extended
platforms overlap oversupports by 12 inches(unless secured)
Wood platforms shall
not be covered with
opaque finishes. Components
(different) shall not be
mixed unless they fit
(integrity maintained).
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Supported Scaffolds, 29 CFR
1926.451(c) Scaffolds with a width to height of more
than 4:1 need to be restrained
Guys, ties, and braces installed in
accordance to manufacturer
Ties, guys, wires must be used for eccentric
load
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Supported Scaffolds, 29 CFR
1926.451(c) Supported poles, legs, and posts need to
bear on base plates and mudsills or other
firm foundation. Footing must be rigid and sound.
No unstable objects for supports or
platform. Legs, posts, frames must be plumb andbraced to prevent swaying.
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Scaffold Access, 29 CFR
1926.451(e) When scaffold
platforms are 2 feetabove or below a pointof access ladders, stairtowers or personnelhoist must be used.
Cross braces can not be
climbed. Ladders set up so not
to tip scaffold.
Stairway type ladders
can be used in
1926.451(e)(3) Railing has to be
provided
Ramps 1926.451(e)(5)
Rails over 6 feet
No slope greater than
20 degrees
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Scaffold Access
Integral prefabricated
scaffold access
frames: Designed and
constructed as ladder
rungs
Rung length of 8inches
Uniform space
Direct Access shall only
be used when scaffold is
not more than 14
horizontal and 24 verticalaway.
Safe means of access shall
be provided during
erecting or dismantling asdetermined by competent
person.
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Scaffold Use 1926.451(f)
Scaffolds shall not beexcessively loaded
Inspection by competent
person before each shift Damaged scaffold
immediately repaired orreplaced.
Maintain adequatedistance from power lines(3 ft for less than 300 Vand 10 ft for greater than300)
Must not work on
slippery platforms,
debris or during highwinds.
Standing on objects to
increase height
prohibited.
Ladder may be used
on wide area scaffold.
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Scaffold Use
Scaffolds must be inspected before use each
shift by competent person.
All damaged components must be repairedor replaced immediately.
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Fall Protection, 29 CFR
1926.451(g) Required on all
scaffolds greater than10 feet.
Boatswains chair,floatscaffold or similarrequire fall arrest.
Suspension scaffoldrequires rails and fallarrest system(independent life line).
Rail system design:
Top rail installed between
38 and 45 inches
mid rail between top andworking surface
Finished components
must with stand:
A force 200 pounds for toprail
150 pounds for mid rail
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Fall Protection
Guardrails must be free ofsharp edges.
Ends of rails must be
constructed so it doesoverhang the terminal
posts
Steel or plastic bands arenot acceptable as railing
Cross brace may be usedas a mid rail if it meets theheight requirement (cross
between 20-30 inches)
Falling objectrequirements are:
Employees on scaffold(in
addition to hard hats) mustbe protected by toe boards,debris nets or canopy
Area below must beprotected by barricades,canopies, toe boards on
scaffolds over 10 feet
Toe boards- withstand 50pounds of force and be 3.5inches wide.
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Additional Scaffolds-
Supported, 29 CFR 1926.452 Tube and coupler:
The existing platform
shall not be moveduntil bearers are set
X bracing installation
Couplers have to made
of structural steel Scaffolding over 125
ft. have to be designed
by registered engineer
Fabricated Frame:
The existing platform
shall remain until theframes are set/braced
Frames and panels
shall be braced (joined
with stack pin
Scaffolding over 125
ft. have to be designed
by registered engineer
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Additional Scaffold-Supported
Horse scaffolds:
Limited to two tiers (10 ft.)
Horses arranged directly
over each other
Legs nailed down and tiers
braced
Crawling boards:
Extend from peak to eavesand secured to roof by ridge
hooks or equivalent
Pump jack scaffolds:
Bracket must have twopositive grips
Poles secured at the top andbottom
Work bench is not aplatform
Continuous length polesjoined at seam parallel to
bracket
Mending plates must beinstalled at 2X4 splices forstrength
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Additional Scaffolds-Supported
Ladder jack scaffolds:
Not to exceed 20 feet
Ladder meet requirement of
part X
No bridging of platform
Ladders must be provided
with device to prevent
slipping
Constructed to bear on side
rails and rungs or rungs (if
rungs at length of 10
inches)
Window jack scaffold:
Attached to window
opening and not used to
place planks betweenscaffolds
Step, trestle, and ladder
scaffolds:
Platform not placed higher
than second highest rung
and ladder secured
Ladders designed to part X
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Additional Requirements-
Suspended Swing Stages:
Platform limited to 36
Platform must be securely
fastened to hangars
Platforms shall be of the
ladder, plank, or beam type
Two point scaffolds shall
not be bridged together
unless bridged and hoist isappropriately sized
Multi level scaffolds:
Equipped with
independent support
lines (equal to number
of suspension points)
and not attached to the
same point as
suspension ropes
Supports for platform
attached to stirrup only
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Additional Requirements-
Mobile Requirements for mobile
scaffolds:
Adequately plumbed,
braced, level and squared
Must have means to lock
wheels/casters
Force to move scaffold no
higher than 5 feet above
support surface
Power system must be
designed for scaffold
Stabilized to prevent tip
Platform must not extendbase support without
outriggers Caster stems-pinned
Riding not allowed unless:
surface floor level and freeof debris and 2:1 BXH ratio
Outriggers on both sides
No one allowed onextended platform
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Additional Requirement-Stilts
Only to be used on large area scaffold
Surfaces must be flat and free of pits
No obstructions
Stilts have to be maintained
Guardrails must be raised by an amount
equal to stilts
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Requirements for Aerial Lifts
29 CFR 1926.453 Meet the design criteria of
ANSI
Aerial ladders must be
secured in lower travelingposition by a lockingdevice before it is moved.
Ext./Art. Platforms:
Boom must be adequatelystowed before move
Insulated portion must notbe altered
A body belt or harness and
lanyard must be used
Employees must stand on
floor of basket Never exceed load capacity
Lift truck shall not be
moved with men in basket
unless adequately designed
(upper controls-personnelcarriers)
Brakes set for outrigger use
(wheels chock)
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Aerial Lifts
Extensible and articulating platforms:
Lift controls must be tested each day
Authorized employees only
No belting off to adjacent structure
All pneumatic and hydraulic components
comply with ANSI A92.2-1969 and noncritical parts must have burst factor 2:1.
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Training-General
29 CFR 1926.454 Employees must receive training from
qualified person that includes:
Nature of electrical, fall, and falling itemsUse of scaffold/handling
Maximum intended load and load carryingcapabilities of scaffold
Methods for dealing with electrical hazardsand fall protection system
Requirements of sub L
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Training-Setup or Dismantling
Employees must be trained in:
Nature of scaffold hazards
Procedures for setup, dismantling or movingthe system
Design criteria, maximum intended load
carrying capacities and use of scaffoldRequirements of subpart L
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Training-Need for Retraining
When the employer has reason to believe an
employee lacks the skill or understanding needed
for safe work involving scaffolds, retraining shallbe performed until proficiency is regained.
Retraining is required:
When additional or new hazards exist.
Changes in the type of scaffold and fall protection exist. Where there are inadequacies in an employees work.
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Resources
www.osha.gov
29 CFR 1926.451
NAHB-OSHA Job Site Safety Handbook
Construction Industry Digest
Scaffolding Industry Association
www.scaffold.org
American National Standards Institute A92 (SIA): Scaffolds and other elevating devices