Machine Safeguarding &
Lockout/Tagout
OSHE 112, Spring 2016
Instructor: Mr. Chris Kuiper, CSP
Email: [email protected]
Phone: 985-549-3751
Energy Forms
Potential
Kinetic
• Thermal
• Chemical
• Mechanical
• Nuclear
• Electrical
• Gravitational
• Sound
• Stored
• Electro-mechanical
Stored to Kinetic Energy
Energy Forms
Energy Source Examples
• Types of energy (Main-1 and Secondary 2)
– E1 = Electrical (electricity)
– P1 = Pneumatic (air – compressors and lines)
– H1 = Hydraulic (fluid – pumps and lines)
– W1 = Water
– G1 = Gas
– C1 = Chemical
– S1 = Steam
Energy Source Example
Energy Source Example
Energy Source Example
Energy Source Example
Energy Isolation
• Lockout and tagout equipment
– Electrical sources
– Rotating mechanical parts
– Shutoff valves
– Hazardous materials
• Blank and bleed pneumatic and hydraulic
lines
• Blank sewer and water flow
• Disconnect mechanical drives and shafts
Introduction
• Common machinery-related injuries
include crushed hands and arms, severed
fingers, and blindness, etc.
• Every machine that has moving parts
presents an energy hazard.
• OSHA lists lockout/tagout (#5) and
machine guarding (#9) most frequently
cited standards. *
* OSHA Fiscal 2015 Top 10 Most Frequently Cited Standards
Therefore …
• Safeguards are essential for protecting workers
from needless and preventable injuries.
• Where the operation of a machine or accidental
contact with it can injure the operator or others in
the vicinity, the hazard must be either controlled
or eliminated.
• Rule of thumb: Any machine part, function, or
process which may cause injury must be
safeguarded.
Guarding Examples
Safeguarding Principles
• Powered machines that must be properly guarded
– gears, sprockets, chains, belts, bands, pulleys, clutches, wheels, shafts, spindles,
couplings, counter-weights, revolving or reciprocating parts and all other
dangerous points, parts or projections
• Roller fed machines presenting hazard to operator’s
hands
• Machines that sheer, press, squeeze, or cut that present
hazard to operator’s hands
Hansen, C. (1914) Universal Safety Standards, Second Edition, New York, Universal Safety Standards Publishing Company.
Standards
• OSHA 29 CFR 1910 Subpart O: Machinery and
Machine Guarding
– For machine operation
• OSHA 29 CFR 1910.147: Lockout/Tagout
– For maintenance and service
• ANSI B11.1, 2, 3, etc.
• https://www.osha.gov/SLTC/machineguarding/st
andards.html
Important Terms
• Safeguarding: Any means of preventing
personnel from coming in contact with the
moving parts of machinery or equipment,
potentially causing physical harm.
• Device: A mechanism or control designed
for safeguarding at the point of operation,
such as presence-sensing, pull-back, twohand-trip, etc. devices.
Important Terms
• Enclosure: A barrier or cover that protects
workers from other danger zones (other
than the point of operation) in the
operation.
• Guard: Barriers exclusively designed for
safeguarding at the point of operation.
Important Terms
• Point of Operation: The area on a machine
where
– Material is positioned for processing, or
– Work is actually being performed on the
material.
• Power Transmission: All mechanical parts
that transmit energy and motion from the
source of power to the equipment or
machine.
Important Terms
• Nip Point: A hazard area created by two or
more mechanical parts rotating in opposite
directions within the same plane and in
close interaction to each other.
• Pinch Point: Any point other than the point
of operation where a body part can be
caught between two or more moving
mechanical parts, or between moving and
stationary parts.
Hazard Sources
• Point of operation
• All moving parts of the machine, including
– Flywheels, pulleys, belts, etc.
– Feed mechanism and auxiliary parts of the
machine
• Nip points
• Flying chips and sparks
Principles Regarding
Point-of-Operation Guarding
• Designing and constructing tools so that guards are not
required
• Providing enclosures, covers and barricades
• Providing mechanical feeding devices
• Providing devices that prevent or interrupt the movement
of tools when the operator’s hands are in the danger
zone
• Providing remote-control operating mechanisms
• Providing mechanical devices that remove the hands
from the danger zone
• Combinations of devices
Heinrich, H. (1959) Industrial Accident Prevention – A Scientific Approach,
Machine, Prime-Mover and Power-Transmission Guarding, New York, McGraw-Hill
Book Company.
Machine Motion and Action
• Motions
– Rotating (including in-running nip points)
– Reciprocating
– Transverse
• Actions
– Cutting
– Punching
– Shearing
– Bending
Machine Motion
• Rotating (including in-running nip points): Turning shafts,
cams, flywheels create gripping hazard where gloves or
clothing pull worker into the machinery or place them in a
dangerous position during machine operation.
Nip Points
Machine Motion
• Reciprocating: The up-and-down or back-and-forth
motion of a machine creates the hazard for the worker
being caught between a moving and stationary part or
being struck by the part in motion.
Machine Motion
• Transverse: The movement in a straight, continuous line
which exposes the worker to being struck by the moving
part or caught in a pinch point or shear point.
Machine Action
• Cutting
– Involves rotating, reciprocating or transverse motion.
– Creates hazards at the point of operation where finger,
head and arm injuries can occur and where flying
chips or scrap material can strike the eyes or face.
– Typical examples of machines with cutting hazards
include band saws, circular saws, boring or drilling
machines, turning machines (lathes) and milling
machines.
Cutting
Machine Action
• Punching
– Power is applied to a slide (ram) for the purpose of
blanking, drawing or stamping metal or other
materials.
– Danger occurs at the point of operation where stock is
inserted, held and withdrawn by hand.
– Typical machines which use punching action are
power presses and metal stamping.
Punching
Machine Action
• Shearing
– Apply power to a slide or knife to trim or shear metal
or other materials.
– Hazard at the point of operation where stock is
actually inserted, held and withdrawn.
– Typical examples of machinery used for shearing
operations are mechanically, hydraulically or
pneumatically powered shears.
Shearing
Machine Action
• Bending
– Power applied to a slide in order to shape, draw or
stamp metal or other materials.
– Hazard at the point of operation where stock is
inserted, held and withdrawn.
– Equipment that uses bending action includes power
presses, press brakes and tubing benders.
Bending
Requirements for Safeguards
• Prevent contact:
– Safeguard must prevent hands, arms or any part of a worker's
body or clothing from making contact with dangerous moving
parts by eliminating the possibility of the operators or other
workers placing parts of their bodies near hazardous moving
parts.
• Provide security:
– Workers should not be able to easily remove or tamper with the
safeguard. Guards and safety devices made of durable material
that will withstand the conditions of normal use and firmly
secured to the machine.
Requirements for Safeguards
• Protect from falling objects:
– Ensure no objects can fall into moving parts and damage the
equipment or become a projectile that could strike and injure
someone.
• Does not create new hazards:
– A safeguard defeats its purpose if it creates a hazard of its own,
such as a shear point, a jagged edge or an unfinished surface.
The edges of guards, for example, should be rolled or bolted in
such a way that they eliminate sharp edges.
Requirements for Safeguards
• Does not create task interference:
– Safeguards which impede workers from performing their jobs
might soon be overridden or disregarded.
• Allow safe lubrication:
– Workers should be able to lubricate machine without
disengaging or removing safeguards.
• For example, locate oil reservoirs outside the guard, with a line leading to
the lubrication point reduces the need to enter the hazardous area.
Methods of Machine Safeguarding
• Types
– Fixed/Built-in; Interlocked; Adjustable; Self-adjusting
• Devices
– Presence sensing; pullback; restraint; safety controls; gates
• Location/Distance
– Position of the operator’s control station; Distance the machine
feeding process is away from operator’s hands
• Feeding and ejection
– Automatic feed; Robotics
• Miscellaneous aids
– Awareness barriers; Protective shields
Fixed Guard
• Permanent part of the machine not dependent on
moving parts to perform its intended function.
• May be constructed of sheet metal, screen, wire cloth,
bars, plastic or any other material substantial enough to
withstand whatever impact it may receive and to endure
prolonged use.
• Fixed guards preferable to other types for simplicity and
permanence.
Fixed Guard
Fixed Guard
• Advantages
–
–
–
–
–
Suits many applications
In-plant construction is often possible
Provides maximum protection
Usually requires minimum maintenance
Suitable to high production, repetitive operations
• Limitations
– May interfere with visibility
– Must be built to specification for the application
– Machine adjustment and repair may require removal
Interlocked Guard
• When interlocked guards are opened or removed, the
tripping mechanism and/or power automatically shuts off
or disengages, and the machine cannot cycle or be
started until the interlock guard is back in place.
– Replacing the interlock guard should not automatically restart the
machine.
• Interlock guards may use electrical, mechanical,
hydraulic or pneumatic power, or any combination of
these.
Interlocked Guard
Interlocked Guard
• Advantages
– Provides maximum protection
– Allows access to machine for removing jams
without time-consuming removal of fixed
guards
• Limitations
– Requires careful adjustment and maintenance
– May be bypassed
Adjustable Guard
• Provides a barrier which may be adjusted
to facilitate a variety of production
operations
• Allows flexibility in accommodating various
sizes of stock
Adjustable Guard
Adjustable Guard
• Advantages
– Can be constructed to suit many specific applications
– Can be adjusted to admit varying sizes of stock
• Limitations
– Operator may enter danger area: Protection may not
be complete at all times
– May require frequent maintenance and/or adjustment
– May be made ineffective by the operator
– May interfere with visibility
Types of Machine Safeguarding
–Fixed
–Interlocked
–Adjustable
–Self-adjusting
What Type of Guard?
Interlocking
What Type of Guard?
Fixed
What Type of Guard?
Adjustable
Type of Guard?
Self Adjusting
Self-Adjusting Guard
• Provides a barrier which moves according to the
size of the stock entering danger area
• May be constructed of plastic, metal or other
substantial material
• Self-adjusting guards offer different degrees of
protection
Self-Adjusting Guard
Self-Adjusting Guard
• Advantages
– Off-the-shelf guards often commercially
available
• Limitations
– Does not always provide maximum protection
– May interfere with visibility
– May require frequent maintenance and
adjustment
Proximity Devices
• Stop the machine when the operator’s hand or other
body part is placed in the danger area
• Restrain or withdraw the operator’s hands from the
danger area during machine operation
• Require the operator to use both hands to operate the
machine or provide a barrier synchronized with the
operating cycle of the machine to prevent the operator
from coming in contact with dangerous parts of the
machine during operation
Presence-Sensing Devices
• Photoelectric, radio frequency or
electromechanical
• Stops machine operation when light field,
capacitance (radio frequency) or probe sensing
mechanisms are tripped or broken
Presence-Sensing Devices
Presence-Sensing devices
• Advantages
– Can allow freer movement for operator
– Can allow access at the point of operation
• Limitations
– Does not protect against mechanical failure
– May require frequent alignment and calibration
– Excessive vibration may cause lamp filament damage and
premature burnout
– Limited to machines that can be stopped without completing
cycle
– Antenna sensitivity must be properly adjusted
– Contact bar or probe must be properly adjusted and maintained
for each application
Pullback Devices
• Utilize a series of cables attached to the
operator's hands, wrists and/or arms and are
primarily used on machines with stroking action.
• When the slide/ram is up, the operator is allowed
access to the point of operation.
• When the slide/ram begins to descend, a
mechanical linkage automatically assures
withdrawal of the hands from the point of
operation.
Pullback Devices
Pullback Devices
• Advantages
– Eliminates the need for auxiliary barriers or other
interference at the danger area
• Limitations
– Limits movement of operator
– May obstruct workspace around operator
– Adjustments must be made for specific operations
and for each individual
– Requires frequent inspections and regular
maintenance
– Requires close supervision of the operator's use of
the equipment
Restraint Devices
• Utilize cables or straps that are attached
between a fixed point and the operator's hands.
• The cables or straps must be adjusted for
individual operators to ensure the operator
cannot access the danger zone of the machine
being operated.
• Hand-feeding tools are usually necessary
because there is no extending or retracting
action associated with this type of safeguard.
Restraint Devices
Guard Construction
• Built-in safeguards
– Advantages
• Usually conform to the design and function of the
machine
• Can be designed to strengthen the machine in
some way or to serve additional functional
purposes
– Disadvantages
• May not be well enough to provide the protection
Guard Construction
• Point-of-Operation guards
– Allow the work to continue with minimum disruption to the
production process.
• Power-transmission guards
– Provide openings for lubrication, adjustment, repair, and
inspection with interlocked covers
– Cover all moving parts in a manner that no part of the operator’s
body can come in contact with them.
Guarding Materials
• Metal best material under many circumstances.
• Wood not recommended because of flammability and
lack of durability and strength.
• Aluminum and plastic are better choices for anti-rust
areas.
• Ample ventilation needs to be provided.
Ergonomic Considerations
• Workplace - requires a minimum amount of strenuous
lifting and traveling
• Work surface height - optimal and flexible
• Controls - readily accessible
• Fatigue and stress - prevent and minimize
Workstation Dimensions
“The controls of a lathe…. are not within easy reach of the average man
[or woman] but are so placed that the ideal operator should be 4.5 feet
tall, 2 feet across at the shoulders, and have an 8-foot arm span.”
[Singleton, Applied Ergonomics, Dec. 1969, p.27]
Maintenance and Servicing
• Apply engineering techniques to reduce or
eliminate the job
• Provide automatic controls
• Isolate the energy sources and implement
lockout/tagout
https://www.osha.gov/SLTC/controlhaz
ardousenergy/index.html
Lockout/Tagout in General
• More citations and more costly fines
• 95% of all lockout/tagout citations involve failure to have
a formal energy control program in place
• Lack of equipment specific procedures
• Remains near the top of OSHA’s list of most frequently
cited standards
• 80% of the violations in a single year are classified as
serious*
* One in which there is substantial probability that death or serious physical harm could
result, and the employer knew or should have known of the hazard.
Purpose
• Requires employers to train “authorized”
employees
–
–
–
–
When and how to shut down machinery
Drain and isolate all energy sources
Verify the absence of energy
Safely restart equipment when maintenance or repair
is complete
• Mandated awareness training of “affected”
workers, such as machine operators,
maintenance crew, etc.
Definition
• Any energy source, be it electrical, hydraulic, mechanical
or any other source that may cause unexpected
movement, must be disengaged or blocked, and
electrical sources must be de-energized and locked in
the off position.
• Preferable if equipment is capable of being locked out
and tagged
• Tag allowed if unit cannot be locked out - if employer can
demonstrate FULL EMPLOYEE PROTECTION
Full Employee Protection?
• Tags attached at the same location as locks
• Full compliance with all tagout provisions in 29
CFR 1910.147
• Additional means when necessary (e.g. removal
of a valve handle)
Requirements
• Written program which includes equipment
specific written procedures
• Employee training (not just maintenance!)
• Periodic procedure review and annual
program implementation audit
Energy Control Program
• Clearly and specifically outline
–
–
–
–
–
–
Scope
Purpose
Authorization
Rules
Techniques for control of energy
Means to enforce compliance
• Intended use of procedure
• Specific procedural steps
• Specific testing requirements
Energy Control Procedure
1.
2.
3.
4.
5.
6.
7.
8.
Notify Personnel: Before controls are applied, and before
they are removed
Prepare for shutdown: Knowledge of the type and
magnitude of energy and methods to control energy
Machine or equipment shutdown: Orderly shutdown to
avoid increased hazard
Machine or equipment isolation: All energy isolation
devices located and operated to isolate machine
Lockout device application: Affixed by authorized
employee holding energy isolating device in the safe or off
position
Relieve stored energy: Relieve all stored energy and
continue to verify if there is a chance of re-accumulation
Verification of isolation: Prior to servicing or maintenance,
authorized employee must verify machine has been deenergized
Confirm lockout
Tag Requirements
• Durable: be able to withstand environment
• Standardized: color, size, etc.
– Tags: print and format
• Substantial: no accidental removal
– Tag attachment means
•
•
•
•
Withstand at least 50 pounds of force
Not re-usable
Self locking
Attachable by hand
• Identifiable: identify the employee who applied
– Tags must include legend such as DO NOT START
Periodic Inspection
• Performed at least annually
• Lockout: include review with authorized
employees
• Tagout: include review with authorized and
affected employees
• Certification record kept
– Identify machine or equipment
– Date of inspection
– Employees performing and included in inspection
Training
• Authorized employees
– Recognition of hazardous energy
– Type and magnitude of hazardous energy
– Methods of isolating energy
– How to verify isolation
• Affected: purpose and use of procedure
• Other: procedure and prohibition from
tampering
• Tagout provisions
Re-Training
• Re-training is required when
– Change in job assignment
– Change in machine or process
– Change in lockout/tagout procedure
– Inadequacies revealed in periodic review
Training Certification
• Certify that the training has been
conducted and kept up to date
– Employee names
– Date(s) of training
Summary
• Written program including written
procedures for each machine
• Training of employees
• Periodic review of program
• ENFORCEMENT