Hazard Control

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Hazard Control
IENG 331, Safety Engineering Fall 2006
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Assignment

• Read Chapter 9 from Brauer Text
• Do the even numbered Review Questions
• P. 109

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Hazards

• IDENTIFICATION (RECOGNITION)
• EVALUATION
• CONTROL
• Hazards must be attacked in this order

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Murphys Law

• In spite of ones best efforts to prevent
  undesirable events, errors, and
  misunderstandings, accidents will occur.
• Attributed to Captain Ed Murphy
• Air Force Engineer, 1949
• Conducted crash tests
• Found a strain gage bridge wired incorrectly
• If there is any way the technician can do it
  wrong, he will
• His team then adopted this law as a challenge and
  achieved an excellent safety record
• Murphys Law has become a commonly used expression

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Safety Engineering Corollaries of Murphys Law
(Block, Murphys Law . . ., 1980)

• A car and truck approaching each other on an
  otherwise deserted road will meet at the narrow
  bridge
• Hindsight is an exact science
• Only God can make a random selection
• When all else fails, read the directions
• Any system that depends on human reliability is
  unreliable
• If a test installation functions perfectly, all
  subsequent systems will malfunction
• In any calculation, any error which can creep in
  will do so. Any error in any calculation will be
  in the direction of most harm.
• A fail-safe circuit will destroy others
• A failure will not appear until a unit has passed
  final inspection

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Murphys Law as a Safety Concept

• Our goal in Safety Engineering is to prevent
  fulfillment of Murphys Law
• Through planning, design, and analysis, factors
  that contribute to accidents can be eliminated or
  reduced

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What is a Hazard?

• A condition or changing set of circumstances that
  presents a potential for injury, illness, or
  property damage

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What is Hazard Control?

• Any means of eliminating or reducing the risk
  resulting from a hazard

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Hazard Sources

• Planning Design
• Production Distribution
• Maintenance Repair
• Communication

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Hazard Sources Planning Design

• Usually inadvertently, unknowingly, or
  unintentionally, engineers or planners may create
  hazards in sites, buildings, facilities,
  equipment, operations, and environments
• Computational errors, poor assumptions,
  converting units of measure, improper safety
  factors
• Sky Light example

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Sources of Hazards Production Distribution

• Potential unforeseen changes between design and
  construction
• Substitution of materials or fasteners
• Substitution of chemicals
• Poor packaging

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Sources of Hazards Maintenance Repair

• Insufficient, delayed, improper maintenance
• Equipment or operations may be well designed for
  normal use, but no design consideration was given
  for installation, maintenance, housekeeping
• LOTO Lock Out Tag Out
• Preventative Maintenance, 5S

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Preventative Maintenance, 5S

• 5S philosophy focuses on effective workplace
  organization and standardized work procedures.
  It simplifies your work environment, reduces
  waste and non-value activity while improving
  quality, efficiency, and safety.
• All I Really Need to Know I Learned in
  Kindergarten, Robert Fulghum
• Sort (Seiri) eliminate unnecessary items from
  the workplace red-tag items and move out

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5S Continues

• 2. Set in order (Seiton) efficient effective
  storage methods painting floors outlining work
  areas locations shadow boards modular
  shelving cabinets A place for everything and
  everything in its place
• What do I need to do my job?
• Where should I locate this item?
• How many of this item do I really need?
• 3. Shine (Seiso) Thoroughly clean the work
  area daily follow-up cleaning

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5S Continued

• 4. Standardize (Seiketsu) Standardize best
  practice in your work area allow employee
  participation in development
• 5. Sustain (Shitsuke) Focus on defining a new
  status quo and standard of workplace
  organization Dont revert to old ways

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Sources of Hazards Communication

• Changes in design, operations, procedures are not
  communicated adequately to those impacted
• Consider the four components of communication
• Sender
• Medium
• Message
• Receiver
• The gulf between the sender and receiver can be
  great

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Principles of Hazard Control

1. Identification
2. Evaluation
3. Control
4. Engineering Controls
5. Administrative Controls
6. Personal Protective Equipment (PPE)

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Knowledge Recognition of Hazards

• No one person can be fully knowledgeable about
  all hazards
• Several disciplines must work together
• Take a systems approach, understand the context
• Human
• Machine
• Materials
• Environment
• Historical Approach (see next slide)
• See OSHA Website Statistics

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Most Frequently Cited OSHA Violations (2003)
Rank Topic of Citations
1 Scaffolding 8682
2 Hazard Communication 7318
3 Fall Protection 5980
4 Lockout/Tagout 4304
5 Respiratory Protection 4302
6 Electrical Wiring 3337
7 Machine Guarding 3245
8 Powered Industrial Trucks 3130
9 Electrical Systems 2399
10 Mechanical Power 2321
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Hazard Control Priorities

1. Eliminate the hazard (engineering)
2. Reduce the hazard level (engineering or
   administrative)
3. Provide safety devices (engineering or
   administrative)
4. Provide warnings (administrative)
5. Provide safety procedures (administrative)
6. Provide PPE (PPE)

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Reducing Hazards

• Redundancy
• 2 or more parallel subsystems or components
• Backup systems or contingency plans
• Single Point Failure
• A single component or subsystem that can bring
  down the entire system
• Example Dead car battery
• Search for and eliminate

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Redundancy vs. Single Point Failure
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Safety Devices

• Features or controls that prevent people from
  being exposed to a hazard
• Must be automatic
• They do not remove the hazard
• Examples
• Machine guards
• Fail-safe devices (e.g., automatic fire doors,
  dead man switch, air brakes on truck trailers and
  railcars)

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Fail-Safe Devices

• Fail-Passive
• Reduces system to its lowest energy level
• Circuit breaker, fuse, dead man switch
• Fail-Active
• Keep system energized, but in a safe mode
• Battery-operated smoke alarm chirps when low
• Traffic signal blinks yellow or red on
  malfunction
• Fail-Operational
• Allows the system to function safely even when
  the device fails (e.g. aircraft auto-land
  controls)

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Provide Warnings

• How effective are Warnings? See previous lecture.

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Procedures

• Sets of actions that must be executed
• People must learn to use safe procedures
• Must be developed and understood before they are
  used
• Safety procedures are just as important as
  operational procedures