Transcript safety through design... advances in safety methods

Safety Through Design
Bruce W. Main, PE CSP
design safety engineering, inc.
Ann Arbor, Michigan
10 Sept 2003
Presentation Overview
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Safety through design
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Why you should care
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Risk assessment basics
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designsafe demonstration and hints
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Examples
Safety Through Design...
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Design - optimizing against criteria
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Late changes in criteria - safety
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Getting it right the first time
Familiar Methods
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Government regulations (OSHA, FDA, etc.)
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Industry standards
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Checklists
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Safety factors
“Recent” Advances
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FMEA
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Failure Modes & Effects Analysis
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Component failures
Risk assessment
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People failures
Safety Through Design…
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Getting it right the first time
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How?
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Risk assessment
Why you should care…
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Your professors think it’s a good idea
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Your grade depends on it
Other reasons to care
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Industry standards are requiring risk assessment
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Europe - CE mark requires risk assessment
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Customers are beginning to require risk assessment
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Condition of sale
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Lots of momentum in industry in risk assessment
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Risk assessment works
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Better, cheaper, faster, more productive
The Basics...
The Safety Hierarchy…
Forms the theoretical basis for design safety
The preferred approach to addressing hazards is:
1.
2.
3.
4.
5.
6.
Eliminate the hazard by design
Substitute less hazardous work methods or materials
Incorporate safety devices (guarding systems)
Provide warning systems
Apply administrative controls (work methods, training)
Provide personal protective equipment (PPE)
(Manuele: Innovations in Safety Management 2001)
1. Determine the limits
of the Machine
2. Hazard Identification
3. Risk Estimation
4. Risk Evaluation
5. Risk Reduction
(Countermeasures)
6. Verify Implementation
ANSI B11 TR3
7. Document Results
Hazard Analysis...
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Identify hazards
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Task-based is a very useful approach
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Focuses on what people do
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Users/tasks/hazards
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Brainstorming grounded in reality
Risk Assessment...
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Qualitative / semi-quantitative / quantitative
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Working to achieve acceptable risk
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risk which remains after protective measures
have been taken
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risk which is accepted in a given context
Zero risk does not exist
B11 TR3 Matrix
Probability of
Occurrence
of Harm
Catastrophic
Level of Severity
Serious
Moderate
Minor
Very Likely
High
High
High
Medium
Likely
High
High
Medium
Low
Unlikely
Medium
Medium
Low
Negligible
Remote
Low
Low
Negligible
Negligible
MIL-STD-882D Matrix
CATEGORY
FREQUENCY
(1)
CATASTROPHIC
(2)
CRITICAL
(3)
MARGINAL
(4)
NEGLIGIBLE
(A) FREQUENT
( X > 10-1 )
(B) PROBABLE
( 10-1 > X > 10-3 )
(C) OCCASIONAL
( 10-2 > X 10-3 )
(D) REMOTE
( 10-3 > X > 10-6 )
(E) IMPROBABLE
( 10-6 > X )
UNACCEPTABLE
ACCEPTABLE WITH REVIEW
UNDESIRABLE
ACCEPTABLE WITHOUT REVIEW
R15.06 Matrix
SEVERITY OF INJURY
S2 Serious Injury
More than
First-aid
S1 Slight Injury
First-aid
EXPOSURE
E2 Frequent
exposure
E1 Infrequent
exposure
E2 Frequent
exposure
E1 Infrequent
exposure
AVOIDANCE
RISK REDUCTION
CATEGORY
A2 Not Likely
R1
A1 Likely
R2A
A2 Not Likely
R2B
A1 Likely
R2B
A2 Not Likely
R2C
A1 Likely
R3A
A2 Not Likely
R3B
A1 Likely
Table 2 – Risk reduction decision matrix prior to safeguard selection
R4
HFMEA Hazard Scoring Matrix
Severity
Probability
Catastrophic
Major
Moderate
Minor
Frequent
16
12
8
4
Occasional
12
9
6
3
Uncommon
8
6
4
2
Remote
4
3
2
1
Risk Scoring Systems
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Bringing structure to a subjective analysis
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There is no one right approach
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This is subjective
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Become comfortable with subjectivity
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The goal is acceptable risk
Risk Assessment Results
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New design requirements/criteria !!
Assessment of risk: severity/probability ratings
Road map for risk reduction activities
Framework for solutions (safety hierarchy)
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design changes, guarding systems
warnings, instructions, training, PPE requirements
Risk reduced to acceptable risk
A Demonstration
designsafe…
Key Points about designsafe
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Guides you through the risk assessment
process
Conforms to current standards
Helps you identify hazards
Prompts your risk reduction effort
Creates the documentation
Free demo at www.designsafe.com
Too Much Residual Risk?
What do you do?
Reduce
Transfer
Avoid
Accept
When do we accept risk?
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When it’s insignificantly low.
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When we are sure it is worth it.
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When we do not know it is there.
Tips on using designsafe…
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It is a guide. Use your head.
Keep your eye on the goal
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Risk scoring is not a scientific exercise.
Look for effective shortcuts
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Identify hazards
Reduce risks to an acceptable level
All users, all tasks
Cut, copy, paste
Make it work for you.
Example – Large Oven System
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Oven system to bake finish on parts
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Elevated, overhead location
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Access required from time to time
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Service conveyor, oven
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Retrieve fallen parts
View Inside of Oven
Fallen Parts
Tripping Hazards
Problems
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Lighting insufficient
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Access difficult
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Introduced hazards to the workplace
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Task-based risk assessment finds these
Perishable Goods Processing
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Packaging system to extend food shelf life
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Automated production system in operation
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Sales wants small, manual system
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customers can “try before they buy”
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Prototype hand-held design in development
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Risk assessment performed
New hazards identified
• Electrical equipment in wet environment
• - not hard wired
• Complex/confusing operation
• unmarked/confusing controls
• high probability for operator error
• equipment damage could occur if not
properly done
• Hand puncture – needle stick
Changes Made
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GFI added
Design changes to greatly simplify
procedures
Entirely eliminated need for operator
to adjust controls
Improved user information – manual,
warnings, system ‘package’
Puncture resistant gloves added
Common Themes
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Must identify hazards early
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Early is better, faster, cheaper and more effective
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Task based risk assessment helps identify more
hazards
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Allows engineers to reduce risks
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Risk assessment helps to determine
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What, why, how and how much
Review
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Safety through design
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Why you should care
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Risk assessment basics
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Demonstrated the process - designsafe
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Example risk assessment applications