Risk Assessment Work Place

8/9/2019 Risk Assessment Work Place

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Risk Assessment &

Management

Health & Safety Management for Quarries

Topic Five


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Objectives of this Section

• Introduce the concept of risk assessment andrisk management and its role within UK health

and safety legislation.

•To define the principle components of riskmanagement.

• To outline advanced risk assessment

methodologies for use in QRAs.

• To outline a practical risk assessmentprocess.


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Principals of Risk Management

Risk management can !e defined as"

The eradication or minimisation of the adverseaffects of risks to which an organisation is

exposed.


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Stages in Risk Management

• Identifying the ha#ards.

• $valuating the associated risks.

• %ontrolling the risks.


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Activity%haracterisation

&a#ard Identification

Risk $stimation

Implementation

Monitoring

Audit or Review

'ption Analysis

(ecision )aking

RI*K )A+A,$)$+T

RI*K A**$**)$+T

RI*K R$(U%TI'+


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Regulation -/0 of the 1)anagement of &ealthand *afety at 2ork Regulations /334 states"5

• ‘very mployer shall make a suita!le and efficientassessment of"#

a$ The risks to the health and safety of his employees to

which they are exposed whilst they are at work.!$ The risks to the health and safety of persons not in his

employment arising out of or in connection with the conduct !yhim or his undertaking%

• or the purpose of identifying the measures he needs

to take to comply with the re'uirements and prohi!itions imposed on him !y or under the relevantstatutory provisions.(


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Risk assessment can !e a

1very straightforward process !ased on

)udgement re'uiring no specialist skills orcomplicated techni'ues.

This approach is commonly known as'alitative or s'bjective risk assessment(


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Major )a*ar+s

• )a6or ha#ards associated with comple7chemical or nuclear plants8 may 1warrant the

need of such techni'ues as Quantitative *isk

+ssessment .

• In Quantitative Risk Assessment ,-RA. a

numerical estimate is made of the pro!a!ility

that a defined harm will result from the

occurrence of a particular event.


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The Risk Management Process

)a*ar+ I+entification

Hazard :

The potential to cause harm. Harm including ill

health and in)ury, damage to property, plant,

products or the environment, production losses

or increased lia!ilities.


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)a*ar+ I+entification

• Comparative Methods. e.g. checklists andaudits.

• Fundamental Methods" e.g. (eviation Analysis8 &a#ard and 'pera!ility *tudies8$nergy Analysis8 9ailure )odes : $ffects

Analysis.

• Failure Logic " e.g. 9ault Trees8 $vent Trees :%ause5 %onse;uence diagrams


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Assessing the Risks

Risk:

The likelihood that a specified undesired

event will occur due to the realisation of aha-ard !y, or during work activities or !ythe products and services created !ywork activities.


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Assessing the Risks

Quantitative risk assessment

• %ommonly used in the high technology

industries

• QRA tends to deal with the avoidance of

low pro!a!ility events with serious

conse;uences to the plant and the

surrounding environment.


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Assessing the Risks

Su!)ective risk assessment

•Qualitative risk assessment involves making a formal 6udgement on the conse;uence and pro!a!ility using"

*isk Severity x /ikelihood


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Assessing the Risks

$7ample"The likely effect of a ha#ard may for e7ample !e rated"

/( Major

(eath or ma6or in6ury or illness causing long term disa!ility

0( Serio's

In6uries or illness causing short5term disa!ility

1( Slight

All other in6uries or illnesses


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Assessing the Risks

The likelihood of harm may !e rated

/( )igh

2here it is certain that harm will occur

0( Me+i'm

2here harm will often occur

1( !o2

2here harm will seldom occur


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Assessing the Risks

Risk

<

*everity of &arm

7=ikelihood of occurrence

• This simple computation gives a risk value of !etween / and 3

ena!ling a rough and ready comparison of risks.• In this case the lower the num!er8 the greater the risk8 and soprioritises the ha#ards so that control action can !e targeted athigher risks.


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3ontrolling Risk

• Risk Avoi+ance > This strategy involves aconscious decision on the part of the organisation to

avoid completely a particular risk !y discontinuing the

operation producing the risk e.g. the replacing a

ha#ardous chemical !y one with less or no risk

potential.

• Risk Retention > The risk is retained in theorganisation where any conse;uent loss is financed

!y the company. There are two aspects to consider

here8 risk retention with knowledge and risk retention

without knowledge.


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3ontrolling Risk

• Risk Transfer > This refers to the legalassignment of the costs of certain potential losses

from one party to another. The most common way is!y insurance.

• Risk Re+'ction > &ere the risks aresystematically reduced through control measures8

according to the hierarchy of risk control descri!ed inearlier sections.


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A!ARP

• =egislation re;uires employers to reducerisks to a level that is as low as is reasona!lypractica!le sometimes a!!reviated as

A=AR?0.

• To carry out a duty so far as is reasona!ly practica!le means that the degree of risk in aparticular activity or environment can !e!alanced against the time8 trou!le8 cost andphysical difficulty of taking measures to avoidthe risk.


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T4pes of Risk Assessment

0ithin 1ndustry, three types of riskassessment can !e distinguished"

• Assessments of large scale comple7 ha#ard sites8

such as those found in the process and nuclear

industries. These re;uire QRAs• ,eneral assessments of the complete range of

workplace risks > as re;uired under the )anagement

of &ealth : *afety at 2ork Regulations8 /333.

• Risk Assessments re;uired under specific legislation > for e7ample for ha#ardous su!stances %'*&&

Regulations8 /33@08 )anual &andling )anual

&andling 'perations Regulations8 /3340.


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-'antitative Risk Assessment ,/.

• In+ivi+'al Risk is defined as 1the fre;uency atwhich an individual may !e e7pected to sustain a

given level of harm from the realisation of specificha#ards.

• Societal Risk


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Usually e7pressed as risk contours"

%&='RI+$

I+*TA==ATI'+

/5BCyear

risk contour

.-D/5BCyearrisk contour

*ite for

proposed

developmen

EI==A,$

/5FCyear

risk contour

/ km


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-'antitative Risk Assessment5

Acceptance 3riteria

• The &*$ state that 1!roadly, a risk of death of 2 in

2333 42x23#5

$ per annum is a!out the most that isordinarily accepted under modern conditions for

workers in the 67 and it seems to !e the dividing line

!etween what is tolera!le and what is intolera!le( .


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Fail're Mo+es an+ #ffect Anal4sis

The system is divided into su! systems that

can !e handled effectively.

1t involves"• Identification of the component and parent system.

• 9ailure mode and cause of failure.

• $ffect of the failure on the su!system or system.

• )ethod of detection and diagnostic aids availa!le.


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A typical format"

%omponent 9unction 9ailure

)ode

9ailure

Rate

9ailure

$ffect

%riticality (etection

)ethod

?reventative

)easures


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• 9or each components functions8 every conceiva!lemode of failure is identified and recorded.

• It is also common to rate the failure rate for each

failure mode identified.• The potential conse;uences for each failure must !e

identified along with its effects on other e;uipment8components within the rest of the system.

• It is then necessary to record preventative measuresthat are in place or may !e introduced to correct thefailure8 reduce its failure rate or provide someade;uate form of detection.


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)a*ar+ & Operabilit4 St'+ies

• &a#ard and 'pera!ility *tudies&AG'?0 have !een used for manyyears as a formal means for the reviewof chemical process designs.

• A &AG'? study is a systematic searchfor ha#ards which are defined asdeviations within these parameters thatmay have dangerous conse;uences.

• In the process industry8 these deviations

concern process parameters such asflow8 temperature8 pressure etc.


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The process is as follows"

The system is divided into suita!le parts or su!5systems8which are then analysed one at a time.

9or each su!5system each parameter flow8 temperature8pressure8 volume8 viscosity etc.0 that has an influence on it8is noted.

,uidewords are applied to each parameter in eachsu!system. The intention is to prompt creative discussion ofdeviations and possi!le conse;uences

9or each significant deviation8 possi!le causes are

identified.



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+' or +'T +o part of the design intent occurs8 such as no flow in a

pipeline due to !lockage.

)'R$ or =$** A ;uantitative increase or decrease of some parameter8 such

as flow8 temperature etc.

A* 2$== A* All the design intentions are fulfilled and something happens

in addition

?ART '9 'nly part of the design intention is fulfilled

R$E$R*$ The logical opposite of the design intention occurs

,uideword (efinitions

'T&$R T&A+ *omething completely different than attended occurs


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#6ample• %onsider the simple process diagram !elow. It

represents a plant where su!stances A and H react

with each other to form a new su!stance %. If there is

more H than A there may !e an e7plosion.

A

H

E/E4

E-

E

EF

A 7 8 9 #6plosion %

$7ample from &arms Ringdahl = /33F08 *afety Analysis" ?rincipals and ?ractice in

'ccupational *afety8 $lsevier Applied *cience.


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The &AG'? sheet for the section of the plant from A to % will !e as

follows"

,uide 2ord (eviation ?ossi!le %auses %onse;uences ?roposed

)easures

+'8 +'T +o A Tank containing A is empty.

E/ or E4 closed.

?ump does not work.

?ipe !roken

+ot enough A <

$7plosion

Indicator for low

level.

)onitoring of flow

)'R$ Too much A ?ump too high capacity

'pening of E/ or E4 is too

large.

% contaminated !y

A. Tank overfilled.

Indicator for high

level.

)onitoring of flow

=$** +ot enough A

E/8E4 or pipe are partially!locked. ?ump gives low flow or

runs for too short a time.

+ot enough A <$7plosion

*ee a!ove

A* 2$== A* 'ther

su!stance

E- open > air sucked in +ot enough A <

$7plosion

9low monitoring

!ased on weight

R$E$R*$ =i;uid

pumped

!ackwards

2rong connector to motor +ot enough A <

$7plosion

A is contaminated

9low monitoring

'T&$R

T&A+

A !oils in

pump

Temperature too high +ot enough A <

$7plosion

Temperature and

flow0 monitoring.




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Fa'lt Tree Anal4sis

#6ample• %onsider the simple circuit diagram shown !elow"

J

5

=A)?

*2IT%&9U*$

HATT$R

?'2$RU+IT




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Fa'lt Tree Anal4sis

• The corresponding fault tree for the a!ove circuit8 with the top

event or ha#ard0 !eing the lamp not working is as follows"

=amp does notlight

+o currentthrough the lamp

+o power supplyto the lamp

Hroken circuit+o power feed

9aulty=amp

+o ?ower from !attery

+o ?ower from unit

Hroken%ircuit

(efectiveswitch

(efectivefuse



Practical Risk Assessment


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Practical Risk Assessment

,from 8S::;;.

%lassify work activities

Identify ha#ards

(etermine risk

(ecide if risk is tolera!le

?repare risk control action plan

if necessary0

Review ade;uacy of action plan


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I+entif4 )a*ar+s

Broad categories of hazard To help with the process of identifying

ha#ards it is useful to categorise ha#ards in

different ways8 for e7ample !y topic8 e.g."

• )echanical.

• $lectrical.

• Radiation.

• *u!stances.• 9ire and e7plosion.

H*@@"/33B


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Hazards prompt-list

8uring work activities could the followingha-ards exist9

• Slips:falls on the level.

• alls of persons form heights.

• alls of tools, materials, etc., from heights.

• 1nade'uate headroom.

• Ha-ards associated with manual lifting:handling oftools, materials, etc..

• Ha-ards from plant and machinery associated withassem!ly, commissioning, operation, maintenance,modification, repair and dismantling.

H*@@"/33B


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Hazards prompt-list

• ;ehicle ha-ards, covering !oth site transport, and travel!y road.

• ire and explosion.

• ;iolence to staff.

• Su!stances that may !e inhaled.• Su!stances or agents that may damage the eye.

• Su!stances that may cause harm !y coming intocontact with, or !eing a!sor!ed through, the skin.

• Su!stances that may cause harm !y !eing ingested4i.e., entering the !ody via the mouth$.

• Harmful energies 4e.g., electricity, radiation, noise,vi!ration$.

H*@@"/33B


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Hazards prompt-list

• 0ork#related upper lim! disorders resulting from

fre'uently repeated tasks.

• 1nade'uate thermal environment, e.g. too hot.

• /ighting levels.

• Slippery, uneven ground:surfaces.

• 1nade'uate guard rails or hand rails on stairs.

•


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=etermine risk

The risk from the ha#ard should !e

determined !y estimating the potential

severity of harm and the likelihood that harmwill occur.


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Severit of harm

Information o!tained a!out work activities is avital input to risk assessment. 2hen seeking

to esta!lish potential severity of harm8 the

following should also !e considered"

• ?arts0 of the !ody likely to !e affectedM• +ature of the harm8 ranging from slightly to e7tremely

harmful"

> /0 *lightly harmful8 e.g."

• *uperficial in6uriesM minor cuts and !ruisesM eye irritationfrom dust.

• +uisance and irritation e.g. headaches0M ill5health leading

to temporary discomfort.

H*@@"/33B


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Likelihood of harm

2hen seeking to esta!lish likelihood of harmthe ade;uacy of control measures already

implemented and complied with needs to !e

considered.

Issues considered"•+um!er of personnel e7posed.

•9re;uency and duration of e7posure to the ha#ard.

•9ailure of services e.g. electricity and water.

•9ailure of plant and machinery components and safety devices.•$7posure to the elements.

H*@@"/33B


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=eci+e if risk is tolerable

'ne simple method for estimating risk levels and for

deciding whether risks are tolera!le. Risks are

classified according to their estimated likelihood and

potential severity of harm.

Slightly harmful

Harmful

Extremely

harmful

Highly unlikely

TRIVIAL RIS

T!LERA"LE

RIS

#!DERATE

RIS

$nlikely

T!LERA"LE

RIS

#!DERATE

RIS

S$"STA%TIAL

RIS

Likely

#!DERATE

RIS

S$"STA%TIAL

RIS

I%T!LERA"LE

RIS

H*@@"/33B


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A simple risk5!ased control plan.


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RISK !#$#! A3TIO A= TIM#S3A!#

TRI$IA! +o action is re;uired and no documentary records need to !e kept.

TO!#RA8!# +o additional controls are re;uired. %onsideration may !e given to

a more cost5effective solution or improvement that imposes no

additional cost !urden. )onitoring is re;uired to ensure that the

controls are maintained.

MO=#RAT# $fforts should !e made to reduce the risk8 !ut the costs of

prevention should ! e carefully measured and limited. Risk

reduction measures should !e implemented within a defined time

period.2here the moderate risk is associated with e7tremely harmful

conse;uences8 further assessment may !e necessary to esta!lish

more precisely the likelihood of harm as a !asis for determining the

need for improved control measures.

S%8STATIA! 2ork should not !e started until the risk has !een reduced.

%onsidera!le resources may have to !e allocated to reduce the risk.

2here the risk involves work in progress8 urgent action should !e

taken.

ITO!#RA8!# 2ork should not !e started or continued until the risk has !een

reduced. If it is not possi!le to reduce risk even with unlimited

resources8 work has to remain prohi!ited.

H*@@"/33B


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Prepare risk control action plan

The action plan should !e reviewed !efore

implementation8 typically !y asking"

• 2ill the revised controls lead to tolera!le risk levelsN

• Are new ha#ards createdN• &as the most cost5effective solution !een chosenN

• 2hat do people affected think a!out the need for8 and

practicality of8 the revised preventive measuresN

• 2ill the revised controls !e used in practice8 and notignored in the face of8 for e7ample8 pressures to get

the 6o! doneN

H*@@"/33B


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Changing Conditions and Revising

Risk assessment should !e seen as a

continuing process. Thus8 the ade;uacy of

control measures should !e su!6ect tocontinual review and revised if necessary.

H*@@"/33B

Risk Assessment Work Place

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