Ihab Saad – Subpart L Scaffolds
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The proper construction of scaffold infrastructure is crucial, and training and training of employees is required. Work sites must be designed properly to ensure proper safety and performance, and safety measures such as preventative maintenance and worker safety measures are discussed. Safety measures include keeping work sites at least 10 feet away from power lines, not allowing work sites to be installed close to power lines, and providing proper equipment and mobile scaffolding for worker safety. Safety measures include hazards like suspended scaffold and proper safety and protection for workers.
AI: Summary ©
On the concrete, because the concrete is going to have a solid,
smooth level surface, so there's not going to be any bumps that can
destabilize a person, for example, standing or working on top of that
platform or scaffold.
The second part after the foundations or the legs, the
footings at the bottom are the structural members. They must be
plum and braced, verticality, horizontality, and then braced
with cross braces to provide strength for that scaffold.
The platform must be fully planked. So the platform is the
area on which people are going to be standing and working it must be
fully planked. This one, for example, is not fully planked. So
this is not proper.
It should be fully planked on the working levels. If we look at this
picture here, for example, how many working levels do we have? We
have one here, maybe one here, one here, and one here, and none of
them is fully planned, fully plant, which means across the
whole width of this member, we should have these planks. So these
are, this is not yet properly assembled,
one inch maximum gap between the planks. If you're going to place
them next to each other, there's going to be only one inch maximum
gap again to prevent the hazard of tripping or falling
or falling debris either, and it has to support four times the
maximum load that's per the specifications for a proper
scaffold. We can see here for this one, we have the outriggers that
increase the base width of the scaffold. To improve its strength,
we have also the casters, but in this case, the casters are going
to have some brakes on them to prevent this scaffold from moving
while some people are working on top of it. It also has the ladder
like access, so it's already built in so people can climb that to get
to the upper level of that scaffold, it has the cross
bracing, which, again, is going to offer additional strength. So with
the exception of the planking, the proper planking, this looks like a
good scaffold.
Here are the planks, but they are not properly overlapped. The
overlap should always be over on top of the joint, and the overlap
should be at least 12 inches at supports, unless restrained to
prevent movement. So the overlap is always going to be each end
over support. So this one should extend to this side here, and
there should be at least 12 inches over the support.
Remember what we talked about in ladders? If you have a wooden
ladder, you shouldn't paint it or apply dark varnish, for example,
to it, because that might conceal some of the defects and some of
the cracks. Same thing applies here to scaffolds. No paint on
wood platforms, because that might cover and hide some of the cracks.
Use only scaffold grade wood, and that's going to have a
certification or a a stamp on it, fully planked platforms on the
working levels. This is a working level here. It seems to be
properly planked, and so is this one
compatible components or pieces, so many by the same manufacturer
or generic, but they can work together
and erection on stable level ground,
so it doesn't show here at the bottom of the scaffold, but there
should be some clearing and some good housekeeping to make sure
that the footings or the foundations of the scaffold are on
solid ground and at the Same level to prevent differential settlement
and shaking.
Scaffold boards
are not required to be stamped scaffold grade. It's up to the
competent person to determine if boards used to meet scaffold grade
requirements. So the competent person is gone. These are the ones
used for clanking. Basically, the best practice is used graded and
stamped lumber. This one is going to have the step that shows what
capacity can it withstand before breaking or collapsing.
The scaffold boards must be in good condition, and if not, they
should be removed from service. Plywood is not acceptable. In lieu
of scaffold boards, they have to be solid wood and not plywood.
Now here we have,
what? How would you classify this? Would this be a platform scaffold?
It's definitely not a suspended scaffold. Here we have several
violations, by the way, no fault protection.
Change the ratio between the height and the width because you
you base it on the width of the base of the platform, or widen the
base add another scaffold section to stabilize so you want to make
it wider to give it better balance.
So here we can see ties that are going to tie the scaffold to the
facade of the building or the work area,
a designer is going to be required when the fabricated frame of
scaffolds is greater than 125 feet high. Can a scaffold be more than
125 feet high. Yes, in fact, there was a picture. Then you go back
very quickly to one of the slides here that showed something like
that. It
was towards the very beginning. Here, you kind of have scaffolds
for the whole facade of the building that can exceed 125 feet
high. So in this case, it has to be designed by a professional
engineer. It becomes a design project on its own. And that also
applies to things like in heavy construction. If you're gonna have
a bridge, for example, or something like that, then
definitely that's going to be done by a designer. It's not going to
be something for anyone to do.
The design must be done by a registered professional engineer.
If you remember, we have seen that when we were talking about
excavation. If the excavation is going to exceed 20 feet, then the
support is going to be designed by a professional engineer. Here's
another area where a professional engineer is going to design some
part of of our work that we need to perform.
The erector training requirements, you must train the employees who
erect or dismantle scaffolds or maintain them. Training must be
performed by a competent person. Training must includes the hazards
procedures for acting and the design criteria. What's the
maximum load capacity? When should it be inspected? How is it going
to be braced and so on and so forth.
You must train employees who work on scaffolds. Training must be
done by a qualified person, in this case, the competent person,
and it must include fall protection, falling object
protection, power line hazards, use of scaffold, handling
materials on scaffolds, especially if there's going to be some loose
material or some fluid that can cause imbalance to the whole
scaffold And the load capacities on the scaffolds,
you have to retrain whenever you change the work site, because each
site might have its own characteristics. Change in type of
scaffold or fault protection measures if you're going to use
PFAs versus handrails or guardrails observed in adequacies,
inadequacies in worker performance. If you notice that
some of the workers are not paying close attention to the safety
precautions on for working on scaffolds, then you must retrain
them.
How are we going to access these scaffolds? This one looks like a
good scaffold. It's wide enough. It has the ladder, like access
tool. It's properly braced. It's fully planked on the working
surfaces, solid wood, not plywood. And it has here, in this case, it
has something that looks like a guard rail, and mid rail here. So
this is this looks like a good scaffold. Access must be provided
when platforms are two feet or more above or below a point of
access. So if the point of access, for example, is this roof slab,
and you're going to be working on this scaffold, and there's a
difference in elevation between the two levels of two or more
feet, then you must provide some access, which is going to be
something like a ladder or something like that.
The methods of access can be either ladders, which could be
portable, hook on, attachable, or stair type. It could also be ramps
and walkways or prefabricated access leather frame type scaffold
like the one that we can see here on this slide. This is the leather
frame
or direct access from another scaffold, and may use building
stairs and come out windows. These are all valid ways of access to
the scaffold. Never use cross bracing. This is the cross bracing
some people would climb on this cross braking. It's not designed
for that, so it may collapse. So never use the cross bracing to
access the scaffold.
Here we have a good.
Frame that has the ladder type,
and the bottom rung has a maximum height of 24 inches. So the
maximum height for this rung is two feet.
Another way of access, as we mentioned, is hook on or detach or
attachable. Ladders must be installed as soon as safe
installation permits
for any damaged pieces you have either to repair them or take them
out of service immediately. You don't want to keep them on site so
that people might use them. It can cause injuries or damage.
One of the major issues here is power lines. And again, scaffolds
are used to access higher elevations, which might be very
close to power lines. So do not erect scaffolds too close to power
lines. The good practice is to stay at least 10 feet away, 10
feet away from the power line. Check clearance requirements.
You're going to find these in the code book that talk about the
different voltage of the different cables and any additional distance
that should be kept above and beyond the 10 feet.
So do not erect scaffold. Need scaffolds. Need power near. Power
lines. Stay three feet away from insulated lines less than 300
volts. Stay 10 feet away from non insulated lines, or insulated
lines greater than 300 volts, and if it's greater than 50 kilovolts,
which is 50,000 volts, stay away 10 feet plus point four inch per
kilovolt over 50 kilovolts. So for example, if it's 55 kilovolts,
then is going to be
five times point four inches. That's a total of an additional
two inches plus the 10 feet. The increments going to be very small,
but again, at least we are keeping the 10 feet safe distance.
Never overload scaffolds, because there's going to be the risk of
collapsing. Platforms must not deflect more than 1/60
of span when loaded, and that's going to show you if it's
overloaded or not, if it sags or Deflects More than one over 60 of
the span. So if the span, for example, is 60 feet, which is very
rare, you will never see an unsupported span of 60 feet. Just
for the sake of illustration. If it's 60 feet, the sag should not
exceed one foot, and that's going to be a very big sag. So if it's
10 feet, for example, which is a very normal span for a scaffold,
it should not exceed 1/6 of a foot,
which is basically two inches.
Ladders may not be used to increase working height, except
when so if you're working already on top of a scaffold, and you want
to reach a higher elevation, you should not work on a ladder,
except if the ladder is placed against structure which provides
stability other than the scaffold, leather legs must be on the same
plank again to make sure that it's stable, it's not going to shake.
Scaffold is secured against the force of the ladder. So because
that's going to create a concentrated load on the planks of
the scaffold, planks are secured to prevent their movements, and
the ladder legs are secured to prevent slippage. So if you do not
have all of these conditions, you cannot work on the ladder on top
of a scalpel
from time to time. And for certain kinds of work, we're going to have
mobile scaffolds for painting, for example, and similar other work.
So here you can see the worker. It has the guardrails and the
midrail. It might have a tool board as well to prevent falling
debris. It has the ladder type access on both sides. It's
properly fully planked on both working surfaces. It has some
braces here. It has the casters at the bottom, and it has outriggers
to increase the width of the base of the scaffold. Now, if you're
going to be working on top a mobile scaffold like this, the
surface must be level. The surface on which the scaffold is going to
be moving must be level. The maximum height to base is going to
be two to one. Remember, in other platforms or scaffolds, we talked
about four to one. In this case, since this is going to be mobile
or movable, then we're going to reduce that by twofold. So it's
going to be only two to one. And our triggers must be used on both
sides. In this case, a competent person must be on site to
supervise
the casters, as we have seen on the previous slide, must be on a
firm search.
Like concrete. You cannot use them on dirt, which is going to be
uneven. You must inspect surfaces first for holes, etc, because
again, if that caster hits a hole or falls into a hole, it might
destabilize the whole scaffold and cause it to collapse. You must
lock casters prior to scaffold use. You must lock the casters
prior to scaffold use, and no one should be on that scaffold while
it's being moved.
Apply the force low, no more than five feet above the base when
moving a scaffold if you're gonna be pushing it, for example, or
something like that, not nothing above five feet from the base when
moving it, diagonal bracing is going to be required to prevent
racking or collapse of the scaffold.
If you have employees on the scaffold, employees must not ride
on scaffolds, unless the rolling surface, if you moving it or
pushing it from one place to another while the employees are on
top of it, you can only do that in very limited conditions if the
rolling surface has more, no more than three degrees out of level,
so it's almost 100% level and flat. If the running surface is
free of pits, holes and obstructions, if it has any holes
or debris or pits, then the employees should descend this
mount from that scaffold until it's moved, and then they can
mount it again. The maximum height to base, as we agreed before, for
mobile scaffold is going to be two to one. Our trigger frames when
used, are on both sides of the scaffold. No employee or any part
of the scaffold extend beyond the wheels or casters, because that's
going to create a cantilever effect which might cause
destabilization of that and overturning of the scaffold make
employee aware of the move before we move, so that they are alert
and they are paying attention that the scaffold is going to be moved.
In case of scaffolds, remember, in general, in general, for fall
protection, our magic number was six feet in case of
in case of scaffolds, since we're going to have either PFAs or we're
going to have guardrails, then the number is increased to 10 feet,
because usually scaffolds are going to be needed for more than
six feet, so the fall protection is going to be required that 10
feet of scaffolds either PFAs, personal fall arrest system, or
guardrails or netting. You might have a safety net.
If the employees are going to be wearing the PFAs as their fault
protection measure, they must be trained in PFAs on scaffolds,
including the Anchorage. What is it going to be anchored to the
lifeline, the lanyard and the body harness? They must be trained on,
how to wear them, how to maintain them, how to inspect them, and how
to discard the defective components. If they have been
used before and they have been extended, for example, if the
lanyard has been extended already, then it has to be discarded.
Use PFAs instead of guard drills on some scaffolds, because, again,
if the worker needs to work
again, here you can see the distance between the worker, the
employee, and the facade of the building that should not exceed,
as we agreed before, anywhere between 14 to 18 inches.
So you can use PFAs instead of guardrails on some scaffolds, use
PFS and guardrails on suspension scaffolds if it's going to be a
suspension so far, we're talking about platform scaffolds. We have
not discussed suspension yet, but if you're going to be working on a
suspension scaffold, use both of them, PFAs and guardrails.
Erectors and dismantlers use PFAs when feasible, because by that
time you have not yet installed the guardrails. So the only mode
of protection is going to be the PFAs.
You can notice here that the ends of this scaffold are not properly
guarded. We don't have any guard any guard rails on the sides of
that scaffold, so it's not properly guarded.
The personal far rest systems on scaffolds must be attached by
lanyard, either to a lifeline, either vertical order, horizontal,
and we have seen these in fault protection or to a scaffold
structural member. Do not attach to scaffold member unless the
manufacturer has designed a specific fault anchorage point
location or device for this purpose, because that's going to
take a lot of load. We.
Remember the 1800 pounds that we talked about before. So if it's
not designed for that purpose, then you cannot attach to it.
The clause in the code, in the code here says,
For all scaffolds not otherwise specified in paragraphs g1, I
through g1, six or G, 1g
i One through G, i Six of the section, each employee shall be
protected by the use of fall RS system or guardrail systems
meeting the requirements of g4, of this section, PFAs is not needed
in other fault protect if other fault protection is provided.
The guardrail, as we have learned about it before, is going to be 42
inches plus or minus three. Here it says it can be as low as four
inches below the 42 inches must be installed along all open sides and
ends of the platforms before work begins for the slide that we
showed that we have seen a couple of slides ago. This one,
basically,
it has not been provided on the ends or of that platform,
therefore it's not properly guarded.
The mid rails are going to be screens, mesh, etc, must run
between the top edge of the guardrail system and the scaffold
platform
for overhand brick laying, which is a very specific task, guardrail
or PFAs required on all sides. Expect the size where the work is
being done. So here we have the guardrails, and he should be
wearing PFAs, but on the side of the opposite side where is laying
the bricks, you cannot have the guardrail because that defeats the
purpose
laying units such that the work is on the opposite side of the wall
from the Mason required in the Mason to lean over the wall to
complete the work. Then in this case, you don't need to have the
guardrails,
tool boards, screens and nets, etc, are going to be required or
use barricades to restrict access below. So either you're gonna have
the proper tool boards and screens and nets to prevent falling debris
from hitting someone who's standing or walking underneath the
scalpel. Or you're gonna have a barricade at the lower level
preventing anyone from being there while work is being done on top of
the scaffold,
if the tool boards are not high enough. And we mentioned before
that the height, the proper height of the toolbar, is going to be
four inches, so a two by four is going to be acceptable use
screening from toolbar to top rail, or use canopies or nets to
catch fawning objects or barricade area below. That's if the material
is stacked higher than the tool board, like bricks or blocks which
might fall
above the tool board.
Now, for another type of scaffolds, the man lifts train
operators. Requirement
operators must be trained on the type of equipment being used keep
the operators manual nearby to identify, again, the proper
height, to identify the proper loading, etc. Inspect equipment
prior to use,
inspect area above and around, especially for
inconsistencies in the flatness and the level of the ground, or
for the existence of power lines and things like that, set up on
the level and firm soil and move with platform lowered. So if
you're going to move the man lift, which is what it's used for, you
have to lower it and not move it while it's still at the high
level.
The main lift is not a crane. Do not use it as one. So don't use as
a material. Voice to lift material to someone working at an upper
level.
It has to be at least 10 feet from the power line.
Fault protection is going to be required. Fall arrest equipment
must be utilized, and you must observe the weight capacity of
that man lift not to overload it.
Permissible types of loads on the main lifts are going to be solid
loads, not fluid loads. So it's going to include personnel, tools
and materials only.
You can modify the equipment only with the written consent of the
manufacturer, because, again, these men lifts are manufactured
according to certain specs. So if you want to change these specs,
you have to contact the manufacturer who can tell you
whether you can do that change or not. So.
Another form is going to be the man basket. The employee must
stand firmly in the basket. No sitting, no climbing on the edge
of the basket, no Jerry rigging for extra height. You cannot add
any additional platforms using planks or ladders or anything on
demand. Lift. You cannot do that. And no tying off, because, again,
tying off might cause an additional hazard on its own. You
can you should not tie off to adjacent structures, etc, while
working from the lift, because if the lift moves, that's going to
cause that person to lose his or her balance and fall, probably to
their death.
Here's an example. This is a man lift. This is the cage where
they're going to be working. It has, as you can see, guardrails on
all sides.
This is a fact. This is an example of an accident. Employee was on a
fully extended man lift, ran over some bricks because the ground was
not level. The boom flexed and sprung by breaking effect. Worker
was thrown from the basket, fell 37 feet to concrete floor. You can
imagine what happened. It shows here fatal fact.
The third type of scaffolds is the suspension scaffolds, as you can
see here, this is suspended from the top instead of being built
from the bottom up
the rope suspending the scaffold must hold six times the load.
Remember, for the scaffolds, we had the platform scaffolds, we had
a factor of safety of four. Now for the suspended scaffold is
going to be even more strict. It's going to be six times the load.
Train workers to recognize the hazards, secure the scaffold to
prevent sway swaying, especially if working in a windy condition,
inspect the roofs by a competent person before each and every shift
and anchor PFAs independently of the scaffold, because you want to
have another anchorage point separate from the scaffold itself.
So
up. You need a competent person for rigging.
You need to inspect the equipment before each shift, because
conditions might change.
It must be tied to a structurally sound member capable of supporting
four times the rated load. So the ropes six times. The support
system four times. Lifelines, cables to the ground, independent
lifelines and hoist cables must reach completely to the ground if
you want to move that scaffold or balance the scaffold, especially
in case of strong winds and things like that.
Also special scaffolds we're going to use, PFAs at all times, with
independent life lines attached to Anchorage point capable of
supporting 5000 pounds. The key number here is, here is 5000
pounds. So
if you want to use counterweights used on our trigger beams, they
must be of a non flowable material. So you cannot use sand,
you cannot use a liquid, you cannot use cement. It can be
something like bricks or blocks or every any solid weight, they must
be permanently marked with weight and securely attached. That's to
give stability to that platform. No fuel powered equipment,
because, again, the fuel itself is a flowable material, so you cannot
use any fuel powered equipment on a suspension scaffold.
Some of the hazards for suspended scaffolds include high winds, poor
foundation, and use of screening can cause the scaffold to
collapse. Use of screening is very interesting, because the screening
is going to offer certain resistance to the wind, so it's
going to increase the surface area that's exposed to the wind,
increasing the wind load on the scaffold, which might cause it to
collapse.
So here
you have the screening, which creates a special wind load
hazard. Don't work on ice or snow covered platforms because of issue
of slipping. Don't work during storms or high wind because it can
destabilize it. Use taglines on swinging load protect suspension
droves from heat and acid, because that can corrode them and make
them lose part of their cross section, reducing their loading
capacity.
Again. Here the main hazards of scaffolds falls from elevation,
bad planking, if it's not properly supported with proper overlap.
Uh, assembly or structural scaffold collapse, if it's not
properly braced, or it does not have the proper loading capacity
or is not properly tied, struck by falling tools or debris,
especially for those who are standing around the scaffold and
electrocution, if you're going to be working near power lines.
So that basically is our discussion about scaffolds. We
have identified three different types, the platform, the suspended
and the man lifts. And now we have a few questions for review.
At what height must fall protection begin on scaffolds.
Remember, again, in the under normal condition, it was six feet
on scaffold. The magic number is 10 feet.
What are the elements of a proper scaffold? Footing on frame
scaffolds, base plate, mud, sills and casters that are got to
provide stability at the bottom, that's the most important part.
Which type of man lift requires the use of fault protection,
scissor lifts or boom lifts, the answer is, each and every one of
them, all of them, any kind of man lift requires fault protection.
How far away must scaffolds be from overhead power lines? Again,
remember another magic number, which happens to be the same
thing, 10 feet, minimum is going to be 10 feet.
That's basically our lecture about scaffolds. I hope you have learned
about the proper installation, the proper maintenance and the proper
use of scaffolds, and I'll see you in another lecture.