Machine Risk Assessment

Copyright © 2010 Rockwell Automation, Inc. All rights reserved.

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SafeDesign: Machine

Risk Assessment

Host: Dan Hornbeck

Rockwell Automation

Safety Business Development Manager

2

Today’s Agenda

1. Review of previous SafeDesign webinar

2. The value and necessity of risk assessment

3. The risk assessment process

4. Task and hazard identification

5. Risk mitigation and evaluation

6. The Rockwell Automation Safety Community and Future

Educational Opportunities

7. Questions

3

Today’s Speaker

Michael Kingsley, CFSEMachine Safety Consultant Rockwell Automation

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Highlights from the Last Session

� Safety as a Core System Function

� Functional Safety Life Cycle

� Emerging Design Philosophies

SafeDesign: Modern Safety Designs for Improved Safety &

Productivity

5Copyright ©

2010 Rockwell Automation, Inc. All rights reserved. 5

Safety as a Core System Function

� Safety continues to emerge as core

system function

� Value –

Safety as a Key Differentiator

–

Global Compliance

–

Common Designs

–

Reduced Costs

–

Increased Productivity –

•

Systematic MTTR Reduction

•

Improved Competitiveness

–

Reduced Floor Space and Direct Labor

–

Improved Ergonomics

6Copyright ©


Functional Safety Life Cycle

Safety Life Safety Life

CycleCycle

STEP 5STEP 5MAINTAIN & IMPROVE

SAFETY SYSTEM

STEP 1STEP 1RISK OR HAZARD

ASSESSMENT

STEP 4STEP 4SAFETY SYSTEM

INSTALLATION &

VALIDATIONSTEP 3STEP 3

SAFETY SYSTEM

DESIGN & VERIFICATION

STEP 2STEP 2SAFETY SYSTEM

FUNCTIONAL

REQUIREMENTS

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Emerging Design Philosophies

� Passive

System Design

–

Ensures the safe

way is the easy

way

� Configurable

System Design

–

Ensures the necessary functionality to accommodate complex and variable

maintenance procedures –

by design

–

Helps to limit exposure to hazards while removing the need or incentive to bypass

� Lockable

Safety Systems

–

ANSI Z244-1 Compliant

–

Systems that systematically reduce MTTR/downtime

Safety AND ProductivitySafety AND Productivity

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The Foundation:

Begins with a Risk Assessment

� Provides Safety Performance Level –

Design Target

� Creates the Foundation of the Safety System Functional

Requirements, System Design and Validation Protocol.

� Shows “Due Diligence”

and Global Compliance to Global standards

S1

S2

F2

F1

Performance

Level, PLr

Performance

Level, PLr

a

a

b

b

P1

P2

e

e

c

c

d

d

P1

P2

P1

P2

P1

P2

F2

F1

S = SeverityF = Frequency or Duration of ExposureP = Avoidance Probability

Task/Hazard

Contribution

to Risk

Reduction

Contribution

to Risk

Reduction

Low

High


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SafeDesign: Machine

Risk Assessment

Michael Kingsley, CFSEMachine Safety Consultant Rockwell Automation

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The Purpose of Risk Assessment

•

The process serves as an effective tool for properly identifying

and assessing the real

hazards

involved in operating a particular machine.

•

Risk assessment provides a method for determining equivalent levels of protection

when designing safeguards and stating OSHA’s minor service exception.

•

The process takes away the guesswork

when estimating risk and prescribing safety

system performance.

•

Risk assessment is an active, documented process

that can be filed and maintained

for the entire life of the machine, and serves as documented proof of your “due

diligence.”

•

Risk assessment establishes the foundation and

early

framework for the design and

implementation of an effective machine safety program.

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As Referenced in U.S. Standards

•

Risk assessment is often referenced

throughout mainstream U.S. machinery

safety standards:

ANSI Z244.1

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•



safety standards:

ANSI B11.19

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•



safety standards:

ANSI / RIA R15.06 This standard provides a detailed risk assessment methodology

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•



safety standards:

NFPA 79

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In Europe

•

Risk assessment is a requirement for machinery directive compliance (2006/42/EC). Applies to those delivering CE compliant machinery

to Europe.

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Why?

•

It is quite common for any group, whether it be a new equipment OEM or

a facility end-user, to have a multitude of questions and concerns when

starting at the beginning of the machine safety system lifecycle.

The most valuable attribute of a risk assessment process is thatThe most valuable attribute of a risk assessment process is that

it it

answers most of these questions for us.answers most of these questions for us.

––

What does the word safety really mean, and What does the word safety really mean, and

how is it achieved? how is it achieved?

–– What is risk? How is it measured? What is risk? How is it measured?

––

Do I need a Ph.D. in mathematics to analyze Do I need a Ph.D. in mathematics to analyze

probability and risk?probability and risk?

–– How safe do I need to make this machine?How safe do I need to make this machine?

–– How do I go about identifying hazards?How do I go about identifying hazards?

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What is “Safety”

Exactly?

•

Before we can understand what exactly we achieve through risk

assessment, it will be important to provide an answer for the first few

questions.

–

What does the word safety

really mean, and how is it achieved?

–

Safety, with respect to machinery operation is defined in IEC 62061:2005 as:

…Safety is freedom from unacceptable risk

–

This immediately gives us a definition for safety in terms of risk,

so it now starts to

become more clear how risk assessment plays a part in achieving safety?!?

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What is Risk?

•

Now we must define risk? Under the same standard, risk can be defined as:

Risk is the combination

of the Severity of harm, and the probability of

occurrence of that harm (Frequency of Exposure + Avoidability).

What severityseverity

of harm

would come to the skydiver if his parachute did not open?

+What is the probabilityprobability

that the parachute(s) will not open and the skydiver will experience this harm?

Probability factors might be:

How frequentfrequent

does the person skydive?

+If the parachute(s) do not open, is the skydiver able to avoidavoid

or limit the harm from the fall?

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Defined Risk Scale

•

If we can then define risk in terms of parameters that can be easily selected

and summed

together, then we will have a simple method for estimating risk

relative to machine hazards.

•

Risk assessment methodologies provided in machine standards provide this method through risk graphs and matrices, as we will see later.

Risk = Severity of Harm + Probability of Occurrence of Harm

Negligible

Low

Medium

High

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Acceptable Risk

•

Acceptable risk may differ from organization to organization, and therefore this value is not purely defined in any standard or methodology. The

important thing is that your organization (and the risk assessment team) determine this threshold prior to starting the risk assessment.

•

Since safety is freedom from unacceptable risk, we will need to establish a value on our range that determines a threshold between acceptable, and unacceptable. Various standards will provide guidance on how to

determine when acceptable risk has been achieved.

Negligible

Low

Medium

High

Acceptable Risk

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Fundamental Process

Risk Evaluation

Hazard Identification

Risk Reduction

Risk

Reduction

Complete for

Particular Hazard

OK

Unacceptable

Define all known machine characteristics and limits

Risk Estimation

Next Hazard

22

Typical Worksheet

A typical risk assessment worksheet will look similar to the one

below, with

a column provided for each item of data that will be collected and/or

determined.

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Risk Evaluation


Risk Reduction

Risk

Reduction

Complete for

Particular Hazard

OK

Unacceptable

Risk Estimation

Next Hazard

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•

The first pass of hazard identification is performed on the machine

while ignoring all current safeguards that may be in place.

–

All risks must be identified and estimated

–

It needs to be determined whether or not the existing safeguard and its

performance are applicable and appropriate for the level of risk.

•

All tasks are broken down into individual steps

–

Allows each step to be assessed more thoroughly for exposure to hazards.

–

Provides a flow and outline for the risk assessment process


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•

Operators and helpers, maintenance personnel

•

Quality control, material handlers

•

Engineers, technicians, sales personnel

•

Trainees, supervisors, safety personnel

•

Administrative personnel, passers-by


Considers ALL affected personnel

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•

Packing, transportation, unloading, unpacking

•

System installation, start up, commissioning

•

Set up, try out, teach, operation (all modes)

•

Tool change, planned and unplanned maintenance

•

Troubleshooting, house cleaning, accident recovery

•

And for CE, risk must be assessed entirely through to de-commissioning and disposal of the machine!


Considers ALL tasks being performed on the machine

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Mechanical hazards:

•

Crushing / Shearing / Cutting / Severing / Stabbing

•

Entanglement / Drawing in / Trapping / Impact / Abrasion

•

High pressure fluid injection / part ejection

As well as other hazards such as

•

Electrical, thermal, noise, vibration, radiation, dangerous substance handling, bad ergonomics, etc.


Considers ALL reasonably foreseeable hazard scenarios

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•

Unexpected start-up

•

Over-run, over-speed, or variations in operating speed (or any similar malfunction)

•

Variations in the rotational speed of tools

•

Failure of power supplies and various control circuits

•

Systematic errors in software code / Specifications

•

Effects of EMC / EMI

•

Effects of the installed environment (Temp, moisture, etc.)

•

Operator “mode confusion”

•

Lack of proper procedures and/or training


Considers ALL reasonably foreseeable hazard scenarios

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Typical Worksheet

With a task and hazard identified, we enter this data into our worksheet

Task

Step

Hazard:

a.

Details of potential hazard

b.

Event leading to hazard or failure

mode

c.

Hazardous Energy Source(s)

d.

Reference to a supporting photo or

drawing.

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Risk Estimation

Risk Evaluation


Risk Reduction

Risk

Reduction

Complete for

Particular Hazard

OK

Unacceptable

Risk Estimation

Next Hazard

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Risk Graphs/Matrix/Chart

For example purposes, we will utilize the ISO 13849-1:2006 Risk Graph

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Risk Graphs/Matrix/Chart

But depending on our objectives, we could use various other methods.

We should consider that one objective is to define our safety performance,

and that our risk graph should provide a method for doing so…..

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ISO 13849 Risk Estimation

•

Step 1: Select

Severity of the hazard.

–

S1: Slight

(normally reversible

injury)

–

S2: Serious

(normally irreversible

injury or death)

* Note:

Annex A

will

provide more detailed

guidance on the selection

of this parameter.

S1

S2

F2

F1

Performance

Level, PLr

Performance

Level, PLr

aa

bb

P1

P2

ee

cc

dd

P1

P2

P1

P2

P1

P2

F2

F1

13849-1/Annex A, Figure A.1

Step 1

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•

Step 2: Select

Frequency and/or exposure to hazard.

–

F1: Seldom to less often and/or exposure time is short

–

F2: Frequent to continuous and/or exposure time is long

* Note:

Annex A

will provide more detailed guidance on the selection of this parameter.

S1

S2

F2

F1

Performance

Level, PLr

Performance

Level, PLr

aa

bb

P1

P2

ee

cc

dd

P1

P2

P1

P2

P1

P2

F2

F1


Step 2


35

•

Step 3: Select

Possibility of avoiding

the hazard or limiting

harm.

–

P1: Possible under

specific conditions

–

P2: Scarcely possible

* Note:

Annex A

will

provide more detailed

guidance on the selection

of this parameter.

S1

S2

F2

F1

Performance

Level, PLr

Performance

Level, PLr

aa

bb

P1

P2

ee

cc

dd

P1

P2

P1

P2

P1

P2

F2

F1


Step 3


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We now enter the risk estimation parameter selections into our worksheet

Risk Parameters:

•

Severity

•

Frequency and/or Exposure

•

Probability of avoiding hazard or limiting harm


Safety Function Performance Level

(Determined from graph)

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Risk Evaluation

Risk Evaluation


Risk Reduction

Risk

Reduction

Complete for

Particular Hazard

OK

Unacceptable

Risk Estimation

Next Hazard

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We now enter the risk estimation parameter selections into our worksheet


1. We evaluate the initial risk

Risk Evaluation

3. We then adjust risk parameters affected by the existing and installed safeguards

2. If risk is unacceptable, we must then evaluate the application of our existing and newly recommended safeguards and mitigation measures

4. Then evaluate the residual risk to determine if it is acceptable

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Design it out

Fixed enclosing guard

Interlocked guard and safety

devices

Awareness means

Training & supervision

Personal protective

equipment

Hierarchy of Risk Reduction Measures

More Details in Future SafeDesign Webinars

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Risk Evaluation

Risk Evaluation

Risk Reduction

Risk

Reduction

Complete for

Particular Hazard

OK

Unacceptable

The process of risk reduction may have to be implemented several

times

before the risk is mitigated to an acceptable value.

Risk Estimation

Once the risk is acceptable, we can then move on to the next hazard.

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Each step of a task will result in a completed worksheet (example below)


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Documentation

•

Risk assessment documentation should contain the following information:

� Information relevant for the machinery being assessed (machine limits, specs)

�Any relevant operational or design assumptions (loads, strengths, safety factors)

� Identified hazard scenarios

�The information on which the risk assessment was based;

•

The data used and the sources (accident histories, experience through

safeguarding similar machinery, etc.)

•

The uncertainty associated with the data used and its impact on the risk

assessment.

•

Photos, video, and other supporting data.

�Risk reduction measures assessed and applied in the determination of risk reduction

�Residual risks associated with the machinery

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Summary

•

Risk Assessment is the foundation for your machine safety program.

•

Risk Assessment considers:

–

The machine operating parameters and limits

–

Task / Hazard identification

–

Risk Estimation

–

Risk evaluation / risk reduction measures

•

Risk Assessment establishes the required safety performance for

machine safeguards.


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Next Steps

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Where to Begin

Rockwell Automation Can Help You Get Started

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2010 SafeDesign Webinar Series

May 4th, 2010

SafeDesign: Risk Mitigation Techniques•

Hierarchical approach to safeguarding•

Designing out hazards and risks•

Engineered solutions

*Invitations and announcements with all the details will be forthcoming. Exact time

subject to change.

Rockwell Automation is hosting an ongoing series of educational webinars to provide the most

current information on Functional Safety Directives and Practices.

Our next webinar will be:

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Join our Safety Community

http://discover.rockwellautomation.com/Safety

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Safety Automation Forum group

http://www.linkedin.com/groups?gid=1950912

Rockwell Automation

Safety Portal

Rockwell Automation Safety Solutions

November 2, 2010

Orlando, FL

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Questions?

Documents

Machine Risk Assessment