Risk assessment


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From Professor Sa'ari Bin Mustapha's class on Risk Assessment and EIA. Postgraduate class.

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Risk assessment

  1. 1. ESC 5714 Dr. Sa’ari
  2. 2. RISK ASSESSMENT IS REQUIRED IN SOME EIA REPORTS 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 hectares vi) Petroleum vii) airport viii) Land reclamation ix) Fisheries – increase 50% or more landing facility/yr x) Infrastructure
  3. 3. HAZARD
  4. 4. What are hazards? IChemE 1)
  5. 5. Hazards Hazards effect
  6. 6. Answer
  7. 7. 2) What are hazards entering for sewer? Hazards Hazards effect
  8. 8. Answer
  9. 9. Cynide release LPG explosion Mexico Lagos munitions explosion MIC release Bhopal Nigeria Pipeline
  10. 10. Prepare For Risk?
  11. 11. 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 or occurring as a result of exposure to one or more stressor
  12. 12. Risk = Exposure x Effect Exposure is the interaction of stressors with receptors. Measures of exposure can include concentrations of contaminants or physical habitat. Effects is measured from the changes in the nature and magnitude of effects as exposure changes. 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.
  13. 13. Exposure 1) Duration 2) Frequency 3) Dose (Concentration) or M agnitude(force, pressure or damage) Effect( or consequence) 1) Health 2) Ecosystem 3) Property ( or quality of life) Risk 1) Casualty (ill or fatality) 2) Damage ( cost or lost e.g.RM /hectare) 3) Price or standard of living (decrease or increase)
  14. 14. RISK EXPRESSION 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.
  15. 15. An example of Qualitative Risk Assessment Intolerable region Risk cannot be justified on any ground (except in extraordinary circumstances) -----------------------------------------------------------------------------------------Tolerable region Tolerable region if risk reduction is not reasonable or its cost is not proportional to the improvement gained. ---------------------------------------------------------------------------Acceptable region Broadly acceptable region
  16. 16. An example of Qualitative Risk Assessment Intolerable Risk cannot justified on any ground: 10-4 fatlity/year Tolerable Only reduction is impracticle or if cost is grossly disproportionate to the improvement gained : 10-5 fatlity/year Tolerable If the cost of reduction would exceed the improvement gained: 10-6 fatlity/year Negligible risk 10-7fatlity/year Trivial risk NOTE: Acceptable industrial risk by DOE and DOSH in Malaysia 10-6 fatlity/year Summarised from Higson (1998). Diagram adapted from HSE. Reference VRJ Individual Risk Criteria for Critical exposed group
  17. 17. An example of Semi-Qualitative Risk Assessment Risk is grading into A, B and C
  18. 18. HAZARD EFFECT X PROBABILITY=RISK Risk is grading into: High, Medium and Low
  19. 19. 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
  20. 20. Example GRASS CUTTING
  21. 21. Minimise risk Residual risk 1) Wearing stout boots or better still safety shoes 2) Do not mow in the wet 3) Clear lawn of stones etc. Keep children away Wear eye protection 4) Mow away from cable Install ELCB( earth leakage circuit breaker) Answer NIL, NIL, L, NIL
  22. 22. 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).
  23. 23. RISK MATRICES (for risk criteria apply) FREQUENCY Very unlikely unlikely 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 Extremely unlikely Catastrophic (5) E F F E C T improbable probable 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
  24. 24. CONCEPT OF DEVELOPMENT ( continue) • the highest value of the risk is 25 and the lowest value is 1.
  25. 25. Determine hazard effect, risk level and propose suitable mitigation for the hazards, frequencies and effects ( in tabulated form) as follows: No. Hazard Hazard Effect Frequenc y Effect 1. Chlorine leak 2 3 2. LPG Explosion Contaminated sea water 1 5 3 2 4. Poor communicati ons 3 5 5. Occurrence of tsunami 4 5 3. Risk Risk Level Propose Mitigation
  26. 26. Parameters of Study 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
  27. 27. Contoh Keputusan Hasil Bengkel :Anggaran Risiko Terhadap Sumber Asli Pinggir Laut (risk of coastal area) 20 18 16 14 Risk 12 10 Kualiti Perkhidmatan Kump Sasaran 8 Keadaan A Sekitar 6 4 2 0 1 2 3 4 5 Parameter 6 7
  28. 28. •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, or the 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 group of accidents or Risk = Probability x Severity of Consequence
  29. 29. Exposure of toxic chemicals cause casualty; fatality, injury and health effect Exposure; Time-weight average (TWA), Lethal concentration (LC50) RISK MEASURES is based on methodology and data Example of RISK MEASURES Major Accident Human Health Financial Ecosystem Fatality/year or injury( ist or 2nd degree of burn air drum rupture, building burn, collapse etc) Cases (reported) incident (rate cases) Life loss expectancy Money loss (lost) Ruin Drop of population of indicator species Lost species Destroy of community diversity
  30. 30. Risk Perception and Acceptable Risk Voluntary risk and Involuntary Risk Smoker 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 car driving football Examples of Involuntary risk Leukemia falling aircraft (UK) 500 x 10 10-5 17 x 1010 -5 4 x 1010-5 2,000 x 10 -7 0.5 x 10-5
  31. 31. A selection of published risk criteria for population at risk Authority Intolerable risk (per year) negligible risk ( per year) EPA, W Australia (new plant) 10-5 10-6 UK HSE (new housing) 10-4 10-6 Hong Kong 10-5 Malaysia 10-5 -
  32. 32. Acceptability can based on ALARP Intolerable region RISK CANNOT BE JUSTIFIED ON ANY GROUND --------------------------------------------------------------------------------------- Tolerable region Tolerable region if risk reduction is not reasonably or economically practicable and achievable ---------------------------------------------------------------------------Acceptable region Acceptable region
  33. 33. 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)
  34. 34. The process of risk assessment involves: 1)Identification of potential harmful hazards 2) Measurements to estimate the consequences of the hazards 3) Estimation of the probability of the occurrence of each hazard consequence 4) Quantitative calculation of risks and comparison with potentially acceptable hazard levels 5) Characterisation of the hazard risks to be managed, along with the assumptions and uncertainties 6) Ranking of the risk hazards for management decision making
  36. 36. Method: e.g Checklist, Hazard Operability Study (HAZOP), Historical, deductive HAZARD IDENTIFICATION SCENARIO IDENTIFICATION e.g leak, ignition, fire Historical data, Fault Tree Analysis (FTA),Event Tree Analysis (ETA Potential adverse effect FREQUENCY(PROBABLITY) ANALYSIS Frequency x consequence=risk: Effected area Risk assessment flowchart CONSEQUENCE ANALYSIS RISK DETERMINATION RISK AND OR HAZARD ACCEPTANCE Acceptable risk 5x10-6 fatality/y INPUT TO RISK MANAGEMENT Radiation(kW/m2), Explosion (pressure)
  37. 37. 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 section of experiences plant and lab people. A typical team might involve the following personnel: Team leader Team secretary Process engineer Project/design engineer Plant/operation manager Operator One or ,ore, as and when required, from:  SHE expert Research chemist Control/instrumentation engineer Maintenance/mechanical engineer Other specialist
  38. 38. 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 achieved More (more of, higher) Quantitative increase in a parameter Less (less of, lower) Quantitative decrease in a parameter As well as 9more than) An additional activity occurs Part of Only some design intention is achieved Reverse Logical opposite of the design intention occurs Other than (other) Complete substitution-another activity takes places ___________________________________________________ Other useful guidewords include: Where else applicable for flows, transfers, sources and destinations Before/after The step (or some part of it) is effected out of sequence Early/late The timing is different from the intention Faster/slower The step is done/not done with the right timing
  39. 39. 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 as Temperature Higher, lower Pressure higher, lower, reverse Level Higher, lower, none Mixing Less, more, none Reaction Higher (rate of), lower (rate of), none, reverse, as well as/other than , part of Phase other, reverse, as well as Composition Part of, as well as Communication None, part of, more of, less of, other, as well as
  40. 40. Ref no Parameter Deviation Possible cause Consequence 1 Flow No I)no power II)valve closed III)connection slip No flow •2 •Flow •More •Valve opened too far •Filling the storage tank fast •3 •Flow •Less I)Less power II)Pump failure III)Valve choked IV)Tube or connection leak 1)–3) Filling of the slow 2)LPG spilled Safeguard/protection Action 1)Installed alarm 2)install flow meter 3)Inspect valve regularly •Operator regulate the valve to normal position 1)improve maintenance schedule; 2)change failure parts/pump 1)Operator need to stop operation immediately and make inspection; 2)Installed low level alarm for flowrate
  41. 41. Video LNG SPILL
  42. 42. Recording Format For the Detailed Examination Minimum column Deviation Cause Consequence Action Include number, parameter, protection (safe guard), on (person in-charge) No Parameter Deviation Cause Consequence Action on
  43. 43. mass & heat discharge conduction radiation to vapour evaporation total incident flux (radiation, convection) convection or nucleate boiling to liquid re-emitted radiation stratified hot layer
  44. 44. Fireball RELEASE
  45. 45. Loading Bay A LPG tank Bottling Plant
  46. 46. Vapor line FA Lorry tanker LPG tank P1 Liquid line LPG Loading
  47. 47. LPG loading
  48. 48. Hazard category Source of Hazard Site Hazards Nature of Hazard Potential Consequences Mitigation Factors Possible Escalation Escalation Controls Release of LPG on-site. LPG may become ignited by compressors pumps , trucks , switchgear room , static etc .. : Jet fire Pool/cloud fire Flash fire. Fire detection system Gas detection system Isolation Intrinsically 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 fire Pool/cloud fire Flash fire. Fire detection system Gas detection system Isolation Intrinsically 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 fire Flash fire Fire detection system Gas detection system Isolation Deluge system Wall between Compressor shed and storage bullet. Ongoing jet fire if isolation fails. Automatic deluge system over spheres in case wall fails. 1. Bullet rupture fracture, leak.
  49. 49. Hazard category Source of Hazard 4. Filling equipment rupture, fracture, leak. 5. LPG cylinder valve leak. 6. Manual Handling. 7. Transportatio n Site Hazards Nature of Hazard Potential Consequence s Mitigation Factors Possible Escalation Release of LPG in filling hall. LPG may become ignited by spark, static etc . : Jet fire Flash fire Pool/cloud fire Fire detection system Gas detection system Isolation Intrinsically safe equipment to be used Deluge system (manual). Missile (cylinder) damage if cylinders overheat. Release of LPG from cylinder. LPG may become ignited by spark, static etc.: Jet fire Fire detection system Gas detection system Intrinsically safe equipment to be used. Missile (cylinder) damage. Dropped LPG cylinder. Damage to LPG cylinder with possible LPG release. Valve protection Possibility of automatic handling system. Missile (cylinder) damage if LPG ignited. Truck impact to pipework causing release of LPG. LPG may become ignited by truck, static etc.: Jet fire Pool fire/fire cloud Transportation/truck procedures Isolation. Continuing jet fire if isolation not possible. Escalatio n Controls Automatic deluge system over bullet.
  50. 50. Representative set of incidents(OHS, 1996) Failure Rate Plant Component Catastrophic/guillotine Vessel above ground Pipework Fittings Partial 2.0x10-6 per year 1.0x10-6 per year 8.8x10-7 per meter per year 8.8x10-6 per meter per year Gasket/flange 8.8 x10-4 per year Isolation valve 5.6 x10-6 per year
  52. 52. Effect of thermal radiation on construction Thermal radiation Effect m  37.5 23-25 25 18-20 12.5 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. Distance kW m2  286 346-360 346 385-405 481 488 491
  53. 53. Buffer zones for probability of 1st. degree of burn
  54. 54. 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. ?
  55. 55. mitigation Relate to: pandemic diseases, Tindakbalas Kecemasan Emergency response Passive protection (e.g. bund) Perlindungan pasif ( e.g. ‘bund’) Perlindungan aktif e.g. injap pelega) System peralatan keseamatan Campurtangan operator System kawalan incident trip Active protection (e.g. relief valve) Safety instrument system Operator intervention alarm Process value Control system loss of e-system, power failure, sabotage, financial crisis etc.
  56. 56. Risk Management Is an output of risk assessment Involves: 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