risk assessment
DESCRIPTION
From Professor Sa'ari Bin Mustapha's class on Risk Assessment and EIA. Postgraduate class.TRANSCRIPT
Dr. Sa’ari
ESC 5714
Prescribed activities:
e.g.:
i) Agriculture – covering area 500 hectares
ii) Power generation & transmission - >10 megawatts
iii) Quarries – within 3km of residential or commercial or industrial area
iv) Industry – for products > 100 tonnes/day
v) Housing 50 hectaresvi) Petroleumvii) airportviii) Land reclamationix) Fisheries – increase 50% or more
landing facility/yrx) Infrastructure
RISK ASSESSMENT IS REQUIRED IN SOME EIA REPORTS
HAZARD
What are hazards?
IChemE
1)
Hazards Hazards effect
Answer
2) What are hazards entering for sewer?
Hazards Hazards effect
Answer
MIC releaseBhopal
LPG explosionMexico
Cynide release
Nigeria Pipeline
Lagos munitions explosion
Prepare For Risk?
1) Malaysia: Environmental quality (prescribed activities)(environmental impact assessment) order 1987
Recommended risk 10-6 fatality/year
2) Ecological risk assessment 1991
evaluate the likely-hood that adverse ecological effect may occur oroccurring as a result of exposure to one or more stressor
Stressor
Any physical, chemical or biological entity that can
induce adverse response.
Receptor
A plant, animal, community of organisms, or
ecosystem that is exposed to stressors in environment.
Risk = Exposure x Effect
Exposure is the interaction of stressors with receptors.Measures of exposure can include concentrations of contaminants orphysical habitat.Effects is measured from the changes in the nature and magnitudeof effects as exposure changes.
ExposureExposure1) Duration1) Duration2) Frequency2) Frequency3) Dose (Concentration) or Magnitude(force, pressure or damage)3) Dose (Concentration) or Magnitude(force, pressure or damage)
Effect( or consequence)Effect( or consequence)1)1) Health Health 2)2) EcosystemEcosystem3)3) Property ( or quality of life)Property ( or quality of life)
RiskRisk1)1) Casualty (ill or fatality)Casualty (ill or fatality)2)2) Damage ( cost or lost e.g.RM/hectare) Damage ( cost or lost e.g.RM/hectare) 3)3) Price or standard of living (decrease or increase)Price or standard of living (decrease or increase)
Risk is expressed in three ways:
1) Qualitatively for example high, medium, intolerable and acceptable ;
2) Semi-quantitatively based on likelihood and consequence but then it ranked one against other e.g. major, intermediate and low risks;
3) Quantitatively by calculating the likelihood (frequency) and the potential consequence of event. The result is presented in form of figure e.g. fatality/year.
RISK EXPRESSION
An example of Qualitative Risk Assessment
Intolerable region Risk cannot be justifiedon any ground (except in extraordinary circumstances)
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Tolerable region Tolerable region ifrisk reduction is notreasonable or its cost is not proportional tothe improvement gained.
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Acceptable region Broadly acceptable region
Summarised from Higson (1998). Diagram adapted from HSE. Reference VRJ Individual Risk Criteria for Critical exposed group
Intolerable Risk cannot justified on any ground: 10-4 fatlity/year
Tolerable Only reduction is impracticle or if cost is grossly disproportionate tothe improvement gained : 10-5 fatlity/year
TolerableIf the cost of reduction would exceed the improvement gained: 10-6 fatlity/year
Negligible risk10-7fatlity/year
Trivial risk
An example of Qualitative Risk Assessment
NOTE: Acceptable industrial risk by DOE and DOSH in Malaysia 10-6 fatlity/year
An example of Semi-Qualitative Risk Assessment
Risk is grading into A, B and C
HAZARD EFFECT X PROBABILITY=RISK
Risk is grading into:High, Medium and Low
GUIDELINES
High x High = High
High x Medium or Medium x High = High
High x Low or Low x High = Medium
Medium x Medium = Medium
Medium x Low or Low x Medium = Medium
Low x Low = Low
Example
GRASS CUTTING
Minimise risk Residual risk1) Wearing stout boots or
better still safety shoes2) Do not mow in the wet3) Clear lawn of stones etc.
Keep children awayWear eye protection
4) Mow away from cableInstall ELCB( earth leakage circuit breaker)
Answer NIL, NIL, L, NIL
CONCEPT OF DEVELOPMENT
• Basis for the risk estimate is usually qualitative;• However, it can be quantitative ( for either consequences
or the frequencies, or both);• For this estimation, categories for consequences and frequencies
are divided into 5 categories;• For consequences terms are: catastropic (category 5),
major(category 4), severe (category 3), significant (category 2) and minor(category 1);
• For frequencies terms are: Probable( 5), improbable(4), unlikely (3),very unlikely(2), extremely unlikely(1).
Veryunlikely
unlikely improbable probable
Catastrophic(5)
5 10 15 20 25
Major(4) 4 8 12 16 20
Severe(3) 3 6 9 12 15
Significant(2) 2 4 6 8 10
Minor(1) 1 2 3 4 5
Extremelyunlikely
RISK MATRICES(for risk criteria apply)
FREQUENCY
EFFECT
Values <10–1 can be indicated as medium and low levels of risk
Values >10-25 can be indicated as high level of risk boundary
CONCEPT OF DEVELOPMENT ( continue)
• the highest value of the risk is 25 and the lowest value is 1.
No. Hazard Hazard Effect
Frequency
Effect Risk Risk Level
Propose Mitigation
1. Chlorine leak 2 3
2. LPG Explosion
1 5
3. Contaminated sea water
3 2
4. Poor communications
3 5
5. Occurrence of tsunami
4 5
Determine hazard effect, risk level and propose suitable mitigation for the hazards,frequencies and effects ( in tabulated form) as follows:
1 (flood) Banjir
2 (shipping) Perkapalan
3 (treatment plant) Loji perawatan
4 (non point source waste) Sumber tidak berpunca
5 (Budget/finance) Bajet/keawangan
6 (Short of staff) Kekurangan kakitangan
7 (Finance allocation) Peruntukan Kewangan
Parameters of Study
Risk
Parameter
Contoh Keputusan Hasil Bengkel :Anggaran Risiko Terhadap Sumber Asli Pinggir Laut
02468
101214161820
1 2 3 4 5 6 7
Kualiti PerkhidmatanKump SasaranKeadaan A Sekitar
(risk of coastal area)
•Risk is the potential for realisation of unwanted,adverse consequences to human life, health, property, or the
environment
• RISK is probability of loss and injury to people, property, orthe environment
• RISK is probability of the occurrence times the severity of harmful effect
• For accident ;
Risk = frequency (event per year) and consequence(effects/event) of a single or groupof accidents
or Risk = Probability x Severity of Consequence
Exposure of toxic chemicals cause casualty; fatality, injury and health effectExposure; Time-weight average (TWA), Lethal concentration (LC50)
RISK MEASURES is based on methodology and data
Example of RISK MEASURES
Major Accident Fatality/year or injury( ist or 2nd degree of burnair drum rupture, building burn, collapse etc)
Human Health Cases (reported) incident (rate cases)Life loss expectancy
Financial Money loss (lost)Ruin
Ecosystem Drop of population of indicator speciesLost speciesDestroy of community diversity
Risk Perception and Acceptable Risk
Voluntary risk and Involuntary RiskSmoker may accept risk of a higher risk such as smoke 100 cigarettes a day) but may not accept comparable risks imposed to them an incinerator at their backyard work in chemical plants)
Examples of voluntary risk versus risk death per person per year
smoking 20 cigarettes/day 500 x 10 10-5
car driving 17 x 1010-5
football 4 x 1010-5
Examples of Involuntary riskLeukemia 2,000 x 10 -7falling aircraft (UK) 0.5 x 10-5
AuthorityAuthority Intolerable riskIntolerable risk(per year)(per year)
negligible risknegligible risk( per year)( per year)
EPA, W AustraliaEPA, W Australia(new plant)(new plant)
1010--55 1010--66
UK HSEUK HSE(new housing)(new housing)
1010--44 1010--66
Hong KongHong Kong 1010--55 --MalaysiaMalaysia 1010--55 --
A selection of published risk criteria for population at risk
Acceptability can based on ALARPIntolerable region RISK CANNOT BE
JUSTIFIED ON ANYGROUND
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Tolerable region Tolerable region ifrisk reduction is notreasonably or economically practicable andachievable
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Acceptable region
Acceptable region
Risk Assessment is a structured sequence activities.
It can be divided into 2 : Risk analysis Risk evaluation
It involves answering the following questions:
What can go wrong? (Hazard Identification) What might be the impact? (consequence analysis) What might be the causes? (causal analysis) How likely is it? (Probability analysis) What is the level of risk? (risk determination)
The process of risk assessment involves:
1)Identification of potential harmful hazards2) Measurements to estimate the consequences of the hazards3) Estimation of the probability of the occurrence of each hazard
consequence4) Quantitative calculation of risks and comparison with potentially
acceptable hazard levels5) Characterisation of the hazard risks to be managed, along with
the assumptions and uncertainties6) Ranking of the risk hazards for management decision making
HAZARD IDENTIFICATION
SCENARIO IDENTIFICATION
FREQUENCY(PROBABLITY)ANALYSIS
CONSEQUENCE ANALYSIS
RISK DETERMINATION
RISK AND OR HAZARD ACCEPTANCE
INPUT TO RISK MANAGEMENT
HAZARD IDENTIFICATION
SCENARIO IDENTIFICATION
FREQUENCY(PROBABLITY)ANALYSIS CONSEQUENCE ANALYSIS
RISK DETERMINATION
RISK AND OR HAZARD ACCEPTANCE
INPUT TO RISK MANAGEMENT
Risk assessmentflowchart
Method:e.g Checklist,Hazard Operability Study (HAZOP),
e.g leak, ignition,fire
Radiation(kW/m2),Explosion (pressure)
Acceptable risk5x10-6 fatality/y
Frequency x consequence=risk:Effected area
Historical,deductive
Historical data, Fault Tree Analysis (FTA),Event Tree Analysis (ETA
Potential adverse effect
HAZOP• The method uses guide words such as “too much’, “too little”, which can
be applied to process parameters to generate “ what if” questions such as“ What if there is too much flow”.
• Full HAZOP study is carried out by a team comprises of a cross sectionof experiences plant and lab people.A typical team might involve the following personnel:Team leaderTeam secretaryProcess engineerProject/design engineerPlant/operation managerOperatorOne or ,ore, as and when required, from: SHE expertResearch chemistControl/instrumentation engineerMaintenance/mechanical engineerOther specialist
Generating Deviation
•Meaningful deviation by coupling a guideword and parameter.•List of guidewords and generic meanings___________________________________________________Guideword Meaning___________________________________________________No (not, none) None of the design intent is achievedMore (more of, higher) Quantitative increase in a parameterLess (less of, lower) Quantitative decrease in a parameterAs well as 9more than) An additional activity occursPart of Only some design intention is achievedReverse Logical opposite of the design intention occursOther than (other) Complete substitution-another activity takes
places___________________________________________________Other useful guidewords include:Where else applicable for flows, transfers, sources and
destinationsBefore/after The step (or some part of it) is effected out
of sequenceEarly/late The timing is different from the intentionFaster/slower The step is done/not done with the right timing
Examples of meaningful combination of parameters and guidewords_______________________________________________________________Parameter Guidewords that can give a meaningful combination_______________________________________________________________Flow none, more of, less of, reverse, elsewhere, as well asTemperature Higher, lowerPressure higher, lower, reverseLevel Higher, lower, noneMixing Less, more, noneReaction Higher (rate of), lower (rate of), none, reverse, as well as/other
than , part ofPhase other, reverse, as well asComposition Part of, as well asCommunication None, part of, more of, less of, other, as well as
1)Operator need to stop operation immediately and make inspection;2)Installed low level alarm for flowrate
1)improve maintenance schedule;2)change failure parts/pump
1)–3) Filling of the slow2)LPG spilled
I)Less powerII)Pump failureIII)Valve chokedIV)Tube or connection leak
•Less•Flow•3
•Operator regulate the valve to normal position
1)Installed alarm2)install flow meter3)Inspect valve regularly
•Filling the storage tank fast
•Valve opened too far•More•Flow•2
No flowI)no powerII)valve closedIII)connection slip
NoFlow1
ActionSafeguard/protectionConsequencePossible causeDeviationParameterRef no
Video LNG SPILL
Recording Format For the Detailed Examination
Deviation Cause Consequence Action
Include number, parameter, protection (safe guard), on (person in-charge)
Minimum column
No Parameter Deviation Cause Consequence Action on
total incident flux(radiation, convection)
mass & heatdischarge
re-emitted radiationradiation to vapour
evaporation
convection ornucleate boilingto liquid
conduction
stratified hot layer
Fireball
RELEASE
Loading Bay
Bottling Plant
A LPG tank
LPG Loading
Lorry tanker LPG tank
Vapor line
Liquid line
P1
FA
LPG loading LPG loading
Hazard category Site Hazards
Source of Hazard
Nature of Hazard
Potential Consequences
Mitigation Factors Possible Escalation
Escalation Controls
1. Bullet rupture fracture, leak.
Release of LPG on-site.
LPG may become ignited by compressors pumps , trucks , switchgear room , static etc .. :Jet fire Pool/cloud fireFlash fire.
Fire detection systemGas detection systemIsolationIntrinsically safe equipment to be used.Drainage area from bullet away from site buildings.
BLEVE;Explosion;Missiles.
Automatic deluge system over bullet.
2. KLPGBTHs’pipeworks rupture , fracture , leak.
Release of LPG on-site.
LPG may become ignited by compressors, pumps, trucks, switchgear room , static etc . :Jet firePool/cloud fireFlash fire.
Fire detection systemGas detection systemIsolationIntrinsically safe equipment to be used.
If jet towards bullet;BLEVE;Explosion;Missiles.
Automatic deluge system over bullet.
3.Pump/compressor rupture, fracture, leak.
Release of LPG in compressor shed.
LPG may become ignited by compressors or pumps:Jet fireFlash fire
Fire detection systemGas detection systemIsolationDeluge systemWall betweenCompressor shed and storage bullet.
Ongoing jet fire if isolation fails.
Automatic deluge system over spheres in case wall fails.
Hazard category
Site Hazards
Source of Hazard
Nature of Hazard Potential Consequences
Mitigation Factors Possible Escalation
Escalation Controls
4. Filling equipment rupture, fracture, leak.
Release of LPG in filling hall.
LPG may become ignited by spark, static etc . :Jet fireFlash firePool/cloud fire
Fire detection systemGas detection systemIsolationIntrinsically safe equipment to be usedDeluge system (manual).
Missile (cylinder) damage if cylinders overheat.
5. LPG cylinder valve leak.
Release of LPG from cylinder.
LPG may become ignited by spark, static etc.:Jet fire
Fire detection systemGas detection systemIntrinsically safe equipment to be used.
Missile (cylinder) damage.
6. Manual Handling.
Dropped LPG cylinder. Damage to LPG cylinder with possible LPG release.
Valve protectionPossibility of automatic handling system.
Missile (cylinder) damage if LPG ignited.
7. Transportation
Truck impact to pipeworkcausing release of LPG.
LPG may become ignited by truck, static etc.:Jet firePool fire/fire cloud
Transportation/truckproceduresIsolation.
Continuing jet fire if isolation not possible.
Automatic deluge system over bullet.
Representative set of incidents(OHS, 1996)
Plant ComponentFailure Rate
Catastrophic/guillotine Partial
Vessel above ground 2.0x10-6 per year 1.0x10-6 per year
Pipework 8.8x10-7 per meter per year
8.8x10-6 per meter per year
Fittings Gasket/flange 8.8 x10-4 per yearIsolation valve 5.6 x10-6 per year
CONSEQUENSES
Effect of thermal radiation on construction
2mkW m
Thermal radiation Effect Distance
37.5
23-2525
18-2012.5
12.6
12
Spontaneous ignition of wood after long exposure. Unprotected steel will reach thermal stress temperatures which can cause failures.Non-piloted ignition of wood occurs.Cable insulation degrades.Piloted ignition of wood occurs.Thermal stress level high enough to cause structural failure. Minimum energy required for piloted ignition of wood, melting of plastic tubing.plastic melts.
286
346-360346
385-405481
488491
Buffer zones for probability of 1st. degree of burn
Lines of Defense in Process Industry
Properly Designed/maintained equipment. Control of Releases :
flares, scrubbers, surge tanks, etc
Fixed mitigation systems :fire fighting systems, dikes, drainage etc
Emergency preparedness
? Pandemic diseases,sabotage, loss of e-system,
power failure,Financial crisis etc.
?
Process value
alarm
trip
incident
Operator intervention
Safety instrument system
Active protection (e.g. relief valve)
Passive protection (e.g. bund)
Control system
Tindakbalas Kecemasan
Emergency response
Perlindungan pasif ( e.g. ‘bund’) Perlindungan aktif e.g. injap pelega)
System peralatan keseamatan
Campurtangan operator
System kawalan
mitigationRelate to:
pandemic diseases,
loss of e-system,
power failure, sabotage,
financial crisis etc.
Risk Management
Is an output of risk assessmentInvolves:
application of management policies (regulatory) and practices(R&D, operation and management, public health, politic, social,economy, impact of enforcement) and formal risk assessment or controlling risk in order to protect life, the environment, physical assets and company in cost effective manner to avoid business interruption or for agency decision or actions.
Effective risk management- planning, organizing, implementing, and controlling to achieve
objective- involves all level of personnel (commitment & reward/appreciate) - effective risk communication (information or training)- audit & review
