Machine Guarding Risk Assessment

7/21/2019 Machine Guarding Risk Assessment

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Machine Safeguarding Risk Assessment:

Achieving Acceptable Risk

Paul A. Zoubek, CSP, CIH ASSE PDC-June 26, [email protected] 619-677-8682

mailto:[email protected]

mailto:[email protected]



• Recognizing MachineHazards

• Introduction• Why Risk Assessment?

• ANSI B11 ConsensusStandard

• Risk Assessment• ANSI B11-TR3

• ANSI B11-2008

Introduction

Topics

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Understanding Risk

• Hazard• Potential source of

harm• Risk

• Combination ofseverity of harm &probability ofoccurrence of harm

Risk=Severity of Harm X Likelihood



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Why Risk Assessment

• Job Hazard Analysis (JHA)• Generally lists the sequence

of basic job steps, potentialhazards, and recommended

hazard controls• Risk Assessment

• Similar to JHA but containsadditional assessment ofRisk to determine if hazard

controls will reduce the riskof potential harm to anacceptable level



Why Risk Assessment

• A structured process that candiscover the cause for the vastmajority of workplace injuries.

•Focuses on the relationshipbetween the worker, the task,the tools and the workenvironment.

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Why Risk Assessment?

Through the use of a RiskEvaluation Form you look atequipment to identify potentialproblems.

ANSI B11 assists inidentification of machinehazards & uses a quantitativeapproach for identification &

prioritization

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Why Risk Assessment?

ANSI Series of Standards

1. American National Standards Institute (ANSI): ANSIB11.0 – 2010 Safety of Machinery; GeneralRequirements and Risk Assessment . New York: ANSI,2010.

2. American National Standards Institute (ANSI): ANSIB11.19 – 2010 Performance Requirements forSafeguarding . New York: ANSI, 2010.

3. American National Standards Institute (ANSI): ANSIB11.TR3 –2000 Risk Assessment and Risk Reduction – A Guide to Estimate, Evaluate and Reduce Risks Associated with Machine Tools. New York: ANSI,2000.

4. American Industrial Hygiene Association (AIHA®): ANSI/AIHA® Z10 – 2005 Occupational Health andSafety Management Systems . Fairfax, VA: AIHA®,2005.

ANSI B11-TR3

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Question 1

The term that focuses on the relationship between theworker, the task, the tools and the work environment.

A. Risk AssessmentB. Job Hazard AnalysisC. Safety AssessmentD. Height Assessment



Risk Assessment

A numeric risk score is generated for each hazardanalyzed.

The Machine Safeguarding Risk Assessment sequence

adds a third variable, a guarding factor to identify the

potential for contact with the machine hazard. Scores range from:

◦ 5=Low Risk

◦ 160=High Risk

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5

Acceptable

160

Unacceptable

77.5



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Risk Assessment

Evaluations can beaveraged to even out slightdifferences betweenobservers

When completemanagement will have abetter picture of whichareas need guarding

attention





Risk Assessment

2. Observe & understandhow machine operates◦ Watch operators at

work paying

attention to whatthey do and howthey move

◦ Ask questions ofoperators and crew

members◦ Video

tape/photographmachine hazards

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Risk Assessment

5. Assign a hazard type

◦ Type of machine motion

◦ Point of operationhazards

◦ Miscellaneous hazards

6. Location of evaluation

◦ Sketch the location

◦ Photographs

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Point of operations on a table saw



Probability of Contact (P)◦ 2=Lesser (likelihood of injury

low)◦ 4=Greater (likelihood of

injury high)◦ Consider

◦

Do people pass by itfrequently?◦ When they go near it, is it

at close range?◦ Watch operators as they

work and ask questionsabout their contact with

the hazard.◦ If you have any doubts

about which probabilitylevel to choose, pick thegreater probability score.

Risk Assessment

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Risk Assessment

Operator’s position at theoperator control and lack

of guarding puts him atclose range to the point ofoperation. He has reasonto access therefore P could be evaluated at 4.



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Operator’s position atthe operator controldoes not put him at

close range to the pointof operation duringnormal operations. Hehas little/no reason to

access therefore P couldbe evaluated at 2.

Risk Assessment



Risk Assessment

Severity (S)◦ High =4: Involves death

from injury or injuriesinvolving permanentdisability.

◦ Medium =3: Involves injuries resulting

in hospitalization orvariable but limited periodof disability

OSHA recordable injurynot resulting in fatality orpermanent disability

◦ Low =2: Involves injuries not

resulting in hospitalizationand requiring only minorsupportive treatment.

Non-OSHA recordableinjury resulting in first aid

treatment18



Risk Assessment

Guarding Factor (G)◦ Contact with the hazard is not

expected =0.9

Complete guarding in place, littlechance of operator removal ofguards during normal operation;

little chance of guards beingover-ridden during operation.

◦ Contact with hazard is unlikely butconceivable =0.6

Guards permit slight chance of

contact; slight chance ofoperator removal of guardsduring normal operations; slightchance of guards being over-ridden during operation.

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Risk Assessment

Compete enclosureof process &operator controls

outside the point ofoperation makinginaccessible.Therefore G could

be evaluated at 0.9.



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Risk Assessment

Enclosure of process& safety interlockguard. Operator has

slight chance ofaccessing point ofoperation if he leftoperator controlbecause of lack of

guarding on sides.Therefore G could beevaluated at 0.6.



Risk Assessment

Guarding Factor (G)◦ Contact with hazard is possible =0.3

Can/are safeguards missing or be overridden?

Can operator contact point of operation?

◦ Contact with hazard is imminent =0.1 Has there been an injury?

Are safeguards properly used/adjusted properly?

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Operator needsaccess to pistonperiodically

throughout the shift.Guarding over pistonis interlocks, howeverthe interlock is a limitswitch which can be

easily overridden.Therefore G could beevaluated at 0.3.

Risk Assessment



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Risk Assessment

Lack of guarding andoperational controlsputs operator at riskof contact with in-running nip pointsince he has toaccess the point ofoperation with a tool

at close range.Therefore G could beevaluated at 0.1.



Probability (P)

Severity (S)

Guarding Factor (G) Risk= (PxS)/G

Scores range from:

◦ 5=Low Risk

◦ 160=High Risk

Risk Assessment

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Risk Assessment



0 10 20 30 40 50 60

Equipment #1

Equipment #2

Equipment #3

Drill Press

Lathe Machines

Milling Machines

ML11

MP06

ML03

ML06

ML12

Band Saw

Equipment #4

Equipment #5

Equipment #6

E q u i p m e n t

Hazard Ranking

Risk Assessment

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Question 2

Overall risk that would result in score that wouldnecessitate taking the machine out of service.

A. 80B. 26C. 13D. 9



Risk Assessment Exercise

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Question 3

The risk assessment analyzed resulting in a Probabilityof Risk (P) of:

A. 2B. 4



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Question 4

The risk assessment analyzed resulting in a Severity ofInjury (S) of:

A. 4B. 3C. 2



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Question 5

The risk assessment analyzed resulting in a GuardingFactor (G) of:

A. 0.9B. 0.6C. 0.3D. 0.1



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Question 6

As a result of this risk assessment, equipment shouldbe:

A. Removed from serviceB. Additional controls implementedC. Risk is acceptable



Guarding Requirements

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Risk Assessment

Suggested EngineeringControls

Two Hand Control Light Curtain

Adjustable Guard

Robot

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Risk Assessment

Acceptable Risk

◦ Refers to the level at whichfurther risk reduction will notresult in significant reductionin risk

◦ Risk reduction is consideredcomplete when protectivemeasures are applied and

acceptable risk had beenachieved for the identifiedhazards

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Risk Assessment

Achieving Acceptable Risk

◦ Use the hazard controlhierarchy.

◦ Use of engineeringcontrols (guards/devices)mandatory but notsufficient in reducing riskto an acceptable level.

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Risk Assessment

Required element to achieve Acceptable Risk.

Need culture driven combination to balance to achieve Acceptable Risk.Requires at least a combination of two or more administrative controls inaddition to engineering controls.

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Risk Assessment

EngineeringControl

AdministrativeControl

AdministrativeControl

Required Balance to achieve Acceptable Risk.

Can contain more than twoadministrative controls!!

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Suggested for achievingacceptable risk afterengineering controls are in

place: Signage

Training of proper use ofequipment

Energy control procedures PPE

Risk Assessment

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Documents

Machine Guarding Risk Assessment