Hazard Control

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Hazard Control
IENG 331, Safety Engineering Fall 2009
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Assignment

• Read Chapter 9 from Brauer Text
• Do the odd numbered Review Questions
• P. 109
• Due ?

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Hazards

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

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Murphys Law Whatever Possibly Can Go Wrong,
Will

• 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
• Even though Murphys Law sounds pessimistic, it
  is a motivating safety concept

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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
• Sustain (Shitsuke) Focus on defining a new
  status quo and standard of workplace
  organization Dont revert to old ways
• Sometimes a 6th S is added to represent
  Safety

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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

• Identification
• Evaluation
• Control
• Engineering Controls
• Administrative Controls
• Personal Protective Equipment (PPE)

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Knowledge Recognition of Hazards

• No one person can be fully knowledgeable about
  all hazards
• Several disciplines and people 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 (2006)
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Hazard Control Priorities

• Eliminate the hazard (engineering)
• Reduce the hazard level (engineering or
  administrative)
• Provide safety devices (engineering or
  administrative)
• Provide warnings (administrative)
• Provide safety procedures (administrative)
• 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

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Assignment

• Read Chapter 9 from Brauer Text
• Do the odd numbered Review Questions
• P. 109
• Due ?