Fundamental%20Concepts%20

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Fundamental Concepts Terms

• IENG 331
• Safety Engineering

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Assignment

• Read Chapter 3 Brauer
• Do the Review Questions
• Even numbered
• P. 32-33

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Why Safety?

• Give reasons why a company would have a safety
  program?
• Humanitarian Reasons
• Regulatory Reasons
• Economic Reasons

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What is an Accident?

• An event that is not expected or intended
• Could cause
• injury
• loss
• Implies chance

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Fundamental Accident Causes

• Unsafe Acts
• Unsafe Conditions
• Both
• Not necessarily a chance event

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Types of Losses

• Injury
• illness
• disease
• death
• damage to property, equipment, materials
• cost of replacement
• legal medical services

• Loss of time, production, sales
• time to complete forms
• recordkeeping
• investigations
• cleanup
• hospitalization, rehab
• public image damage

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Losses Direct vs. Indirect Costs

• Direct (Obvious)
• medical expenses, WC, repair or replace damages
• Indirect (Not Obvious)
• 41 Ratio (Iceberg Theory)
• Injured workers wages, lost supervisory time,
  co-workers lost time during emergency, damaged
  equipment, ruined product, overtime for
  production to catch back up, learning curve for
  replacement worker, clerical costs, payments made
  to injured under benefits program

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Unsafe Acts vs Unsafe Conditions

• Heinrich analyzed 75,000 accidents
• 88 10 2 ratio
• 88 unsafe acts
• 10 unsafe conditions
• 2 unpreventable causes
• Engineers can attack unsafe conditions
• Must understand human behavior and management
  principles to attack unsafe acts

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Accident - Injury Relationship

• Heinrichs 300 29 1 ratio
• For 330 accidents
• 300 result in no injury
• 29 produce minor injuries
• 1 produces major, lost-time injury
• Opportunities to improve are great
• Many accidents are rehearsed many times

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Accident - Costs Relationship

• Pareto Relationship
• 80 - 20 rule
• 80 of the costs are related to 20 of the
  injuries
• for example, low back lifting injuries represent
  20 of all accidents, but represent 80 of the
  costs
• if you can manage and control that 20 of
  accidents, you can control 80 of the costs
• Figure 3-1 shows 50 of the costs are related to
  2 of the injuries
• the powerful few

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Pareto Analysis The Vital Few
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Terms

• Safety being relatively free from harm, danger,
  damage, injury
• Risk measure of both frequency and severity of
  hazards
• Hazard unsafe condition, the potential for an
  activity or condition to produce harm
• Safety Engineering application of engineering
  principles to the recognition and control of
  hazards

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Accident Theories

• Domino Theory
• Energy Theory
• Single Factor Theories
• Multiple Factor Theories

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Domino Theory (Heinrich)

1. Injury is caused by
2. Accidents which are caused by
3. Unsafe acts or conditions which are caused by
4. Undesirable traits (e.g., recklessness,
   nervousness, temper, lack of knowledge, unsafe
   practices) which are caused by
5. Social environment

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Domino Theory Cont.

• Stop the sequence by removing or controlling
  contributing factors
• Strong emphasis is placed on the middle domino
  unsafe acts or conditions

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Energy Theory (Haddon)

• Accidents Injuries involve the transfer of
  energy, e.g., fires, vehicle accidents,
  projectiles, etc.
• Transfer of energy from a potential to
  kinetic
• Attack problems in parallel rather than serial
  (as is presumed in Domino Theory)

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Energy Theory Cont.10 Strategies to Prevent or
Reduce

• 1. Prevent the marshalling of energy.
• - dont produce the energy
• - dont let kids climb above floor level
• - dont produce gun powder
• 2. Reduce the amount of energy marshalled.
• - keep vehicle speeds down
• - reduce chemical concentrations
• - dont let kids climb above 3

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3. Prevent the release of energy - elevator
brakes 4. Modify the rate at which energy is
released from its source or modify the spatial
distribution of the released energy. - reduce
the slope on roadways 5. Separate in space or
time the energy being released from the structure
that can be damaged or the human who can be
injured. - separate pedestrians from vehicles
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6. Separate the energy being released from a
structure or person that can suffer loss by
interposing a barrier. - safety glasses, highway
median barriers 7. Modify the surfaces of
structures that come into contact with people or
other structure. - rounded corners, larger
surface areas for tool handles 8. Strengthen the
structure or person susceptible to damage. -fire
or earthquake resistant structures, training,
vaccinations
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9. Detect damage quickly and counter its
continuation or extension. - sprinklers that
detect heat - tire tread wear bands 10. During
the period following damage and return to normal
conditions, take measures to restore a stable
condition. - rehab an injured worker - repair a
damaged vehicle
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Single Factor Theories

• Assumes that when one finds a cause, there is
  nothing more to find out.
• Weak theory, there can be so much more to learn!

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Multiple Factor Theories

• Accidents are caused by many factors working
  together
• The theory and the analysis is more complex, but
  more realistic than Single Factor Theory
• Consider the Four Ms
• management, man, media, machine
• And their interactions

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Preventative Strategies

• Proactive vs. Reactive
• Frequency strategies
• Severity strategies
• Cost strategies
• Combinations
• Three Es of Safety engineering, education,
  enforcement

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Three Lines of Defense

1. Engineering Controls
2. Administrative Controls
3. Personal Protective Equipment

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Safety Factors

• Since there is a chance element in safety, we can
  improve our chances by implementing a safety
  factor
• Scaffolding 41
• Designed to withstand 4 times the intended load
• Overhead crane hoists 51
• Scaffold ropes 61
• Why not use 101 as a standard??
• Beware when using field tables or computer
  programs. Are the safety factors applied or not??

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Fail-Safe Principles

• General fail-safe principle
• The resulting status of a system, in event of
  failure of one of its components, shall be in a
  safe mode.
• Read Case Studies 3.5 and 3.6
• Fail-safe principle of redundancy
• A critically important function of a system,
  subsystem, or components can be preserved by
  alternative parallel or standby units.
• Principle of worst case
• The design of a system should consider the worst
  situation to which it may be subjected in use.
• Murphys Law If anything can go wrong, it will.

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Engineering Pitfalls

• False sense of security in technology
• Recommendation for Reading
• Set Phasers on Stun And Other True Tales of
  Design, Technology, and Human Error. Steven
  Casey. Aegean Publishing Company, Santa Barbara,
  CA. 1993. ISBN 0-9636178-7-7

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How Safe is Safe Enough?

• Can absolute safety be achieved?
• Remember the concept of risk.
• What is acceptably safe?
• Remember the Risk Assessment Matrix Severity vs
  Frequency