Ergonomics
Global Safety Campaign
November 2015
Week 2 – Repetition, Vibration with Powered and
Non-Powered Hand Tools
Since the dawn of time cavemen used tools . .
. How times have changed.
Imagination at work.
Ergonomics Safety Campaign
The Plan
FW 45 – Lifting and Manual Material Handling
An ant can lift 1,000 times it body weight but humans are not ants !
FW 46 – Repetition, Vibration with Powered and Non-Powered Hand Tools
Since the dawn of time cavemen used tools . . . How times have changed.
FW 47 – Awkward Positions and Proper Body Placement
Did the game of Twister prepare us for performing work in awkward
positions?
FW 48 – Ergonomics for Long Drives and Office Safety
It feels like we spend most of our lives behind a steering wheel or behind a
desk. No wonder our bodies complain !
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Since the dawn of time cavemen used tools . .
. How times have changed.
It’s not always complexity
that causes injuries
A simple tool like a screw driver can cause an ergonomic
injury.
While technology has advanced and tools help us to easily perform tasks
that otherwise would be difficult or impossible, the simplest tools have the
potential for causing severe ergonomic injuries.
This weeks focus will be on raising your awareness on the ergonomic
impacts from Repetition and Vibration while using Powered and NonPowered Hand Tools including some solutions to help prevent Ergonomic
injuries.
3
This weeks Focus on Ergonomics
• The right tool for the job
• Understanding vibration
• Ergonomic injuries
Signs and Symptoms
• Reducing exposure to
Vibration
• Injury Case Study
• Preparing your body for tasks
Stretching
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The right tool for the job – If the tool Fits . . .
The best tool is one that:
• Fits the job you are doing
• Fits the work space available
• Reduces the force you need to apply
• Fits your hand
• Can be used in a comfortable work position
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If the tool fits . . . Use it
!
Handle size
The right-sized handle is one that allows the hand to go more than halfway around the handle without the
thumb and fingers meeting. The recommended grip diameter in most cases falls between 2 – 2½ inches (50
and 60 mm). To provide good control of the tool and prevent pain and pressure hot spots in the palm of the
hand, handles should be at least 4¾ inches (120 mm) long. A precision grip (when the tool is pinched
between the tips of the thumb and fingers) is primarily used for work that requires control rather than a lot of
force. Handles for precision tools should be ¼ to ½ inch (8 to 13 mm) in diameter and at least 4 inches (100
mm) long.
Grip surfaces
The grip surfaces of hand tools should be smooth, non-conductive, and slightly compressible to dampen
vibration and better distribute hand pressure. Avoid tools that have grooves for finger — for most people the
grooves are either too big or too widely or closely spaced. The resulting pressure ridges across the hand can
damage nerves or create hot spots of pain. Grooves along the length of the handle are intended to prevent
slipping but can also cut into the hand and create pressure ridges, particularly if the tool is in continuous use.
If a grooved handle is the only choice available, ensure that the grooves are many, narrow and shallow. If it is
available, try a grip shape that is non-cylindrical. Triangular grips measuring approximately 4½ inches (110
mm) around at their widest part can be quite comfortable and help to increase power.
6
Weight
If the tool fits . . . Use it
!
Weight is often a problem with power tools and tools such as axes, hammers, and saws. To
reduce hand, arm, and shoulder fatigue, the hand tool should not weigh more than 5 lbs. (2.3
kg). If the center of gravity of a heavy tool is far from the wrist, this maximum weight should be
reduced. Studies have shown that tools weighing 2 to 3¾ lbs. (0.9 to 1.75 kg) feel “just right”
for most workers. For precision work where the small muscles of the hand support the tool, it
should weigh far less. Lighter is better. Heavy tools can be made easier to use by suspending
or counterweighting them.
Triggers
Many power tools have a trigger that is operated either by the thumb or one or more fingers. To
avoid hand and forearm fatigue, look for tools that can be activated by either hand. Also, the
trigger should have a mechanism that holds or locks it in place while the tool is being used.
Triggers should be at least 1 inch (25 mm long) for single-finger activation and 2 inches (50
mm) long for two-finger activation. Use four-finger activation only with suspended tools.
There is no real definition for an “ergonomic tool”.
Look for hand tools that have features such as the ones described above.
If the tool fits, it’s the right one for the worker and the job, whether or not it’s
called “ergonomic”.
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Understanding Vibration
Vibration can be explained as the back and forth motion
produced by objects such as tools, machinery and
equipment. It has two components:
•
Frequency (or repeat rate)
ƒ
•
Amplitude (or displacement)
ƒ
Some objects vibrate by design, such as impact wrenches
and sanders, while others vibrate due to defects or
malfunctioning.
When a worker uses or handles a vibrating object, the
vibration is transmitted to the hands and arms, resulting in
hand/arm vibration.
Both frequency and amplitude play a role in the injury
process.
Exposure to excessive vibration can result in vibration-related injuries and diseases such as
vibration white finger, Raynaud’s phenomenon and carpal tunnel syndrome.
In extreme cases, these injuries and diseases can even lead to permanent impairment of the
hands and arms.
The adverse effect produced by exposure to vibration is called hand-arm vibration syndrome
(HAVS).
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Reducing exposure to hand-arm vibration
The best way to avoid injury is to work with non-vibrating tools whenever possible.
When that is not possible here are some simple steps to take:
• Identify the tasks that require the use of powered hand tools
• E
ƒ valuate the extent of use of the equipment, with regard to the
duration and intensity of vibration.
• Proper tool selection can eliminate or lessen the issue:
 Utilizing Anti-vibration tools when possible
 Use alternative tools and methods for certain jobs (such as
hydraulic tools in place of vibratory tools).
 Informing and training to workers in the proper use and
handling of tools and equipment and recognizing HAVS
symptoms
 Let the tool do the work. Use as light a grip as possible to
keep the tool under control. A tight grip restricts blood flow
in the hands and fingers and allows more vibration to pass
from the tool to the body.
 Implement rest periods for vibratory tool operators.
 Selection and use of anti-vibration gloves
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How do you know if you have an ergonomic
problem?
You may have a problem if you have any of these
symptoms:
• Tingling
• Swelling in the joints
• Decreased ability to move
• Decreased grip strength
• Pain from movement, pressure, or exposure to cold or
vibration
• Continual muscle fatigue
• Sore muscles
• Numbness
• Change in the skin color of your hands or fingertips
These symptoms may not appear immediately because they develop over
weeks, months, or years.
By then, the damage may be serious.
Take action before you notice any symptoms.
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Case Studies
Recordable – Fatigue and Repetition using Power Tools
Case Number: 2156
Mesquite Creek Wind – Lamesa, TX - USA
JUN
2015
Description:
•
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Wind Technician experienced fatigue in his right shoulder after
performing Thermal reduction retrofit activities on June 8th. The
employee claimed “stiffness “ in in his upper back and right shoulder
on the morning of June 9th which, at the time, he attributed to a bad
night of rest. The employee continued performing thermal reduction
retrofit activities on June 9th and reported experiencing soreness and
discomfort in the evening and the reminder of the night. Due to
increase in the level of pain/soreness/stiffness, the employee reported
the symptoms on June the 10th (Wednesday).
Actions taken:
•
•
•
•
Fact finding was initiated.
Nurse triage was engaged.
The employee was taken to occupational clinic for medical evaluation
which resulted in medical treatment beyond first aid and work
restrictions.
EHS conducted a review of the installation process for improvement.
What I am doing different:
•
•
•
•
•
•
•
•
•
•
Use two hands on the power tools (battery operated drill only).
Use four high quality bits to drill holes: 1/8”, 3/8”, 9/16”, stepper bit.*
Use edge protector on ‘half moon’ cut, or exhaust edge.*
Use high quality blades to cut steel.*
Use Mono-goggle while drilling/cutting.*
Use stool, step, ladder to improve balance and access.*
Use wrist supports, or gloves with wrist support.*
Rotation of tasks on teams.
Minimize using tools with arms extended and above shoulders.
Initiate periodic stretching during task.
*see tooling
slides
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Recommended Drill Bits (Black and Gold)
Recommended Stepper Bit
Recommended SawZall Blade
Recommended Face/Eye Protection
Recommended Wrist Support
Step / Stool Options
CAUTION!
Unprotected points
on
Self Tapping Screws
Edge Protector (pool noodle)
Take breaks during drilling/cutting
tasks to stretch the hands, arms
and shoulders.
Mesquite Creek Wind – Lamesa, TX USA
Fatigue and Repetition using Power Tools
Recordability Rationale: Rx prescribed,
DAFW
Date:
Management system failure: Work Instruction
SEVERITY LEVEL C
Wind Technician experienced fatigue in his right shoulder after performing
Thermal reduction retrofit activities on June 8th. The employee claimed
“stiffness “ in in his upper back and right shoulder in the morning of June
9th which, at the time, he attributed to a bad night of rest. The employee
continued performing thermal reduction retrofit activities on June 9th and
reported experiencing soreness and discomfort in the evening and the
reminder of the night. Due to increase in the level of
pain/soreness/stiffness, the employee reported the symptoms on June the
10th (Wednesday).
Causes (How did it Happen?):
1.
2.
3.
4.
Poor ergonomic posture - reaching out and above shoulders
Poor ergonomic design of the unit
The use of one hand on power tool
Repetitive task (performing same task for weeks, daily)
Lessons Learned:
1. Use two hands on the power tools (battery operated drill only).
2. Use specific tooling/PPE for this work scope.
3. Rotation of tasks on teams.
4. Minimize using tools with arms extended and above shoulders.
5. Periodic stretching and rest during task.
DAFW: Yes RWA: NO
INCIDENT LOCATION: Nacelle of Wind Turbine
Description (What Happened?):
•
Case Number:
2156
Strength of Defenses Matrix
Illustrate existing failed defenses in red text; existing successful defenses in green text; and new defenses in blue text.
Please note it is NOT necessary to have an entry in every cell: just make the matrix reflect reality.
Type
Purpose
Engineered
Defenses
Admin
Defenses
Management
Oversight
Defenses
Personal
Protective
Equipment
Cultural
Defenses
Eliminate
(substitute)
Rotation of tasks on
teams.
Prevent
Catch
Detect
Mitigate
battery operated drill
only.
Minimize using tools
with arms extended
and above shoulders.
Use two hands on
the power tools.
Use specific
tooling/PPE for this
work scope.
Type – What type of defense is it? Engineered is strongest, while Cultural is weakest.
Purpose – Will the defense eliminate, prevent, catch, detect, or mitigate an error and/or
Periodic stretching
during task.
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Preparing your body for tasks - Stretching
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