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Mining and Petroleum Training Service Basics of Equipment Guarding Presented by David Spann Presentation Developed by Rene Azzara. Basics of Machine Safeguarding Crushed hands and arms, severed fingers, blindness - the list of possible machinery-related injuries is as
Presented by David Spann
Presentation Developed by Rene Azzara
Crushed hands and arms, severed fingers, blindness -
the list of possible machinery-related injuries is as
long as it is horrifying.
There seem to be as many hazards created by moving
machine parts as there are types of machines.
Safeguards are essential for protecting workers from
needless and preventableinjuries.
Any machine part, function, or process which
many cause injury must be safeguarded.
When the operation of a machine or accidental
contact with it can injure the operator or others
in the vicinity, the hazards must be either
controlled or eliminated.
Following an organized and logical approach, risk assessment and risk reduction can achieve a tolerable risk.
Determine Equipment Limitations
Hazards and Task Hazards
Catastrophic: Permanent Disabling
Serious: Severe Disabling
Moderate: Significant Disabling
Minor: Sligh Disabling
Determine Whether Risk
Very Likely to Occur
Likely, May Occur
Unlikely, Not Likely to Occur
Remote: Very Unlikely
Risk Reduction Measures
Must Be Implemented
Eliminate and Reduce
Hazards by Design
Keep machines repaired, lubricated and adjusted.
Clean up excess lubricants.
Clearly mark control switches and valves that control machines.
Check machines for emergency stop switches; they should be located on or near the machine so the machine can be turned off quickly if a malfunction occurs.
Dangerous moving parts in
three basic areas require safeguarding:
Power transmission apparatus
All components of the mechanical system which transmit energy
to the part of the machine performing the work. These components
include flywheels, pulleys, belts, connecting rods, couplings, cams,
spindles, chains, cranks, and gears.
Other moving parts
All parts of the machine which move while the machine is working.
These can include reciprocating, rotating, and transverse moving
parts, as well as feed mechanisms and auxiliary parts of the machine.
The point where work is performed on the material, such as cutting, shaping, boring, or forming of stock.
The human hand can move at
63 inches per second!
Example: A device located 2 inches from a
grinder must be able to sense the hand and
stop the grinder in under 0.03 seconds.
Hazardous spots where loose clothing or body parts
could be caught and squeezed in rotating parts.
All pulleys, belts, sprockets and chains, flywheels, shafting
and shaft projections, gears, and couplings, or other rotating
or reciprocating parts.
If it moves, it merits your attention!
Do not wear gloves around reciprocating or rotating machine parts.
Note: A nip point entry permit system is intended for observation of hazardous
machinery while at a safe distance.
It is not a "Permit to Work" in a nip point zone.
Permit to Work activity must only be undertaken with the machine shut down
and locked out.
may be hazardous because, during the
back-and-forth or up-and-down motion,
a worker may be struck by or caught
between a moving and a stationary part.
Transverse motion (movement
in a straight, continuous line) creates
a hazard because a worker may be
struck or caught in a pinch or shear
point by the moving part.
Never step across a rotating power shaft.
Equipment operators should wear close-fitting clothes and slip-resistant footwear. Rotating parts catch loose clothing easily.
Never allow children around the equipment or work area.
Good maintenance and repair procedures contribute significantly to the safety of the maintenance crew as well as that of machine operators.
In addition to guarding, you need to understand:
LOTO - Lockout/Tagout (aka)
CHE - Control of Hazardous Energy
In shops where several maintenance persons might be working on the same machine, multiple lockout devices accommodating several padlocks are used. The machine cannot be reactivated until each person removes his or her lock. As a matter of general policy, lockout control is gained by the procedure of issuing personal padlocks to each maintenance or repair person; no one but that person can remove the padlock, thereby each worker controls the power systems.
Guards are barriers which prevent
access to dangerous areas.
There are four general types of guards:
Fixed - A fixed guard is a permanent part of the machine.
Interlocked - When this type of guard is opened or removed, the tripping mechanism and/or power automatically shuts off or disengages, and the machine cannot cycle or be started until the guard is back in place.
Adjustable - Adjustable guards are useful because they allow flexibility in accommodating various sizes of stock.
Self-Adjusting - The openings of these barriers are determined by the movement of the stock. Self-adjusting guards offer different degrees of protection.
Today many builders of single-purpose machines provide point-of-operation and power transmission safeguards as standard equipment.
However, not all machines in use have built-in safeguards
provided by the manufacturer!
A conveyor attendant with 5 years mining
experience was fatally injured at an open
pit copper operation. The victim became
entangled in a tripper conveyor pulley.
experience was fatally injured at a sand and gravel operation.
The victim made a splice on a conveyor belt and was making
adjustments to the belt.
He was found
entangled in the
tail pulley of the
On February 7, 2002, a 37-year-old male laborer (the victim) was fatally injured when he became caught between a conveyor belt and an idler pulley of a rock crushing machine.
The victim's job consisted of sweeping and shoveling
the area around the rock-crushing machine.
Approximately 20 minutes after the victim
arrived at work he was found underneath
the rock crushing machine with his
arm caught between a conveyor belt
and an idler pulley.
investigator note that
should have been taken
that would have
prevented this fatality?
Is a person likely to get close to the idler roller face?
Is the nip point directly accessible?
An effective guard is required
- had not been installed
- no steps had been taken to block/secure this
component against hazardous motion.
The pitman assembly shifted and fatally pinned
the victim against the crusher framework.
with 2 years mining experience was fatally injured at a crushed
The victim was using a steel bar to dislodge a blockage in an
impact crusher. The bar contacted a moving crusher component causing it to be propelled and strike the victim's neck.
The accident occurred because the procedures used to dislodge the blockage of rock were inadequate.
and lock out the crusher before attempting to dislodge the rock.
Never attempt to remove jammed material while machinery is in operation.
Shut down, isolate, and block all forms of hazardous energy before performing machine maintenance.
Do not allow employees to position themselves directly over the intake of a horizontal impactor while it is actively crushing rock.
Viewing decks should be designed and installed where worker's can safely access the equipment to observe operation.
The worker had reversed his truck up to the primary hopper in order to discharge a load of quarried material.
He then walked to the rear of his truck, before falling into the hopper.
In order to discharge the load, it was not necessary to leave the truck. It is unknown why the driver did so.
Nothing can protect you from senseless acts.
As he was oiling a moving conveyor, a worker's pant leg became entangled
in the part of the conveyor, causing his right foot to be dragged in and
crushed between the head sprocket and the side of the conveyor.
His right leg had to be amputated
below his knee.
The worker usually oiled the
conveyor from a relatively safe
position from underneath the
For some reason, on this day,
he decided to oil the conveyor
from an unstable position above
the conveyor without locking out.
His pant legs also hung down
below his boots.
Lesson: Follow task procedures every time!
A machine tender was found pinned in the ingoing nip point of a press.
He died from massive crush injuries. There was no witness to this
accident. Guardrails were in place around the machine.
It is unclear how the victim fell into the nip point of the press.
He may have been reaching into or over top of one of the guardrails.
Lesson: Never reach through
or over top of a guardrail of
Do not defeat guards and place body
parts, tools or pry bars in equipment
that is not deenergized or LOTO.
Develop and follow written procedures for checking the
well-being of a worker working alone or in isolation, including
establishingcontact at predetermined intervals and at the end
of the shift.