HAZARD IDENTIFICATION METHODS /Part 1 Antony Thanos Ph.D. Chem. Eng. antony.thanos@gmail

1. This project is funded by the European Union Projekat finansira Evropska Unija HAZARD IDENTIFICATION METHODS /Part 1Antony ThanosPh.D. Chem. Eng.antony.thanos@gmail.com

2. Hazard • State, action or physical-chemical characteristic with potential of harm to equipment, human health or the environment • Examples: • Work at height – Hazard of fall

3. Hazard examples : (cont.) • Toxic material handling (e.g. production of NH3) • Toxic release (e.g. failure of pipe) • Dispersion of released NH3 to the atmosphere • Toxic effects to human via inhalation of toxic substance

4. Hazard examples : (cont.) • Flammable material handling (e.g. storage of gasoline) • Release of substance (e.g. hole in tank wall) • Subsequence ignition leading to fire or explosion (vapour ignition in congested space –” certain circumstances”) • Effects to human and equipment due to : • heat radiation (cause of burns or equipment failure) for fire • overpressure/missiles for explosion

5. Hazard source examples: • Failures of control systems, such as : • instrument failure, e,g. LIT (Level Indicator Transmitters) stuck to place failing to show overfilling of tank • level controller (LC) failure • control valve failure, e.g. LCV (Level Control Valve) failure lead to overfill and overpressure with failure of pipe/pressure vessel

6. LC LIT FI • Hazard source examples • Failures of control /protection systems PRV HV LCV Ομάδα HAZOP

7. Hazard source examples : (cont.) • Failures of protection/“emergency” systems, such as : • Pressure Relief Valve (PRV) failure, e,g. valve fails to open in high pressure case, leading to vessel failure • Mechanical failures, e.g. corrosion, weld defects, human error in design • Operator errors, e.g. hand operated valve (HV) closes when pump is in operation

8. Hazard source examples : (cont.) • External sources, e.g. earthquakes, missiles from accidents in other equipment • Management failures, as lack of operating / maintenance procedures

9. Accident : The event that leads to harm to human, environment or equipment • Consequence : The outcome (effect) of an accident, as for example: • Injury from fall from height • Pulmonary damage due to inhalation of released NH3 • Burns from thermal radiation of fire in gasoline tank • Consequence analysis : the procedure applied for calculation of the extent of accidents effects

10. Hazard Identification : Use of techniques for identifying hazards, causes of accidents and effects • Techniques do not automatically reveal hazards, but facilitate the systematic examination of hazards, taking into advantage of existing knowledge of systems examined • “Few accidents occur because the design team lack knowledge; Most errors in design occur, because the design team fail to apply their knowledge”, Trevor Kletz

11. Hazard Identification (cont.) • Not all hazards or causes/effects are guarantied to be found • Results quality are strongly dependent on personnel experience • High subjectivity in hazard importance evaluation

12. Hazard Identification (cont.) • Team work leads to higher quality in results • The prudent application of Hazard Identification Techniques can identify important accidents, their causes and effects • Do not consider Hazard Identification only as requirement for Legislation compliance, but as essential tool for safety improvement

13. Safety reviews/audit/inspections • Evaluation of information from : • Visits to workplaces • Review of drawings, operation procedures • Interviews with personnel (defensive response ?) • Records of events

14. Safety reviews/audit/inspections (cont.) • Advantages : • Very simple • Applicable during the whole lifecycle of establishment • Allows compliance checks with company procedures/practices • Disadvantage : • Not strictly formed technique • Not to be considered as suitable for Safety Reports

15. Checklists • Written list of questions (usually require answers in YES/NO form) • Response to questions via : • Document review • Walk-arounds (verification of actual situation –existing installations)

16. Checklists (cont.) • Level of detail strongly depends on author experience on process examined • Minimal : Too generic, easily applied in different processes within a company • Very detailed: • focusing in a specific process only • not applicable in other type of processes (e.g. LPG checklists not suitable to Heavy Fuel Oil depots)

17. Checklists (cont.) • Typical areas to be addressed : • Storage/handling of materials • Process equipment, procedures • Control and emergency provisions • Sampling facilities • Personnel protection • Maintenance • Emergency response • Wastes management

18. Checklists (cont.) • Example : • Is there quality control on raw materials ? • Are SDS available for raw materials ? • Are there incompatible materials in close areas ? • What is the flash point of raw/intermediate materials, products ?

19. Checklists (cont.) • Examples : • Are there shift hand-over procedures ? • Are there equipment isolation procedures ? • Are there reactions with runaway characteristics ?

20. Checklists (cont.) • Examples for safety valves : • Are there available and valid test certificates for each safety valve ? • Are there the required marking on each safety valve ? • Are all safety valves depicted in P&IDs? • Do all safety valve discharge to safe location? • Are there isolation valves in safety valves limiting their operation ?

21. Checklists (cont.) • Examples for pumps : • Are there dry-run protection provisions for pumps ? • Can pump shut-off pressure exceed downstream pipe design pressure ? • ……. Please contribute……

22. Checklists (cont.) • Examples for pumps : (cont.) • Are there strainers at suction ? • Are there check valves at discharge to prevent back flow ? • Are there protection guards at pump/motor couplings ? • Is there minimum flow recirculation line ?

23. Checklists (cont.) • Examples for furnaces : • Is there protection for acid dew point corrosion ? • Are there fail-closed valves at fuel supply lines ? • ……. Please contribute……

24. Checklists (cont.) • Examples for furnaces : (cont.) • Is manual reset required for fail-closed fuel supply lines ? • After failure in ignition of burners are there interlocks for sufficient purging air before re-ignition ? • Are there fast acting blow-off panels in furnace ?

25. Checklists (cont.) • Advantages • Very useful in compliance checking with standards, legislation requirements etc. • Can be used by non-experience personnel • Adaptable to analysis depth desired • Minimal time requirements (in the order of 7 days for large processes) • Known hazards are fully explored

26. Checklists (cont.) • Disadvantages • No info for causes, consequences, prevention/mitigation • Not effectively applicable to novel processes (as checklist heavily rely on past experience) • Hazards not foreseen by questions cannot be identified • Not to be considered as suitable for Safety Reports

27. Preliminary Hazard Analysis • Applied usually in initial design of layout planning • Examines basic characteristics for : • Raw materials, intermediates/final products, wastes • Equipment: high pressure systems, reactors • Factors causing accidents and safety equipment • Procedures for operation, control, maintenance

28. Preliminary Hazard Analysis (cont.) • First step forfurther refinement of hazard identification by more detailed technique when project is more mature • Rather experienced personnel on safety is required, as judgment is necessary • Hazard attributed to ranking scheme, such as : • I, Insignificant • II, Limiting • III, Critical • IV, Catastrophic

29. Preliminary Hazard Analysis (cont.) • Results presented usually in sheet form Example of resultsforLPG road tanker HazardCauseEffects Cat. Mitigation/Prevention measures Flammable 1. Hose rupture Uncontrolled leak, III a. Procedures require release due to tanker potential off-site handbrake on movement consequences during loading

30. Preliminary Hazard Analysis (cont.) • Advantages: • Rather limited information and time (in the order of 12 days for large processes) • Applicable even in early stage of design • permits interventions for risk control with minimum cost, e.g. identification of intermediate products with special hazards (Bhopal accident), • permits examination of different production process

31. Preliminary Hazard Analysis (cont.) • Disadvantage : • Not strictly defined technique. Information collected within discussions without systematic structure • Not to be considered as suitable for Safety Reports (design is expected to be fixed and mature when Safety Report is submitted)

32. Relative Ranking • Calculation of qualitative or quantitative index of hazard, based on characteristics of hazardous processes (quantities, operating conditions etc.) • Examples : • DOW F&EI (Fire and Explosion Index) • DOW CEI (Chemical Exposure Index) • MOND Toxicity index

33. Relative Ranking (cont.) • Examples of required information: • Material properties • Process conditions/characteristics • System design and construction • Support systems • Purging, ventilation, cooling, heating etc • Equipment fire proofing, layout, corrosion resistance etc • Operation, training • Maintenance, inspection

34. Relative Ranking - DOW F&EI • Index calculation F&EI= MF*(1+GPH)*(1+SPH) MF: Material factor, based on NFPA flammable and reactivity ranking, or calculated on physicochemical properties (at ambient conditions) GPH : General Process Hazard SPH: Specific Process Hazard GPH, SPH : Calculated as Sum of penalties of partial values availablein tables GPH=ΣGPHi, SPH=ΣSPHi

35. Relative Ranking - DOW F&EI (cont.)

36. Relative Ranking - DOW F&EI (cont.) • MF table values adjusted, if necessary, depending on process conditions (e.g. material used at temperature over flash point) • GPHi cases : • Exothermic reactions • Endothermic reactions • Material handling and transfer • Enclosed or Indoor process units • Access • Drainage and Spill control

37. Relative Ranking - DOW F&EI (cont.) • Example GPHi values for Exothermic Reaction : • Mild exotherms : GPH=0.3 (isomerisation, hydrogenation) • Moderate exothems : GPH=0.5 (alkylation) • Extremely sensitive exotherm reactions : GPH=1.25 (nitration)

38. Relative Ranking - DOW F&EI (cont.) • Example GPHi values for indoor units : • Dust filters in enclosed area : GPH=0.5 • LPGs, or flammables above flash point : GPH=0.6 (in case of quantity over 1000 gal, GPH=0.9) • For mechanical ventilation GPHs reduced by 50%

39. Relative Ranking - DOW F&EI (cont.) • SPHi cases : • Toxic materials • Vacuum conditions • Operation near flammable range • Dust explosion • Pressure • Low temperature • Quantities of flammable/unstable material

40. Relative Ranking - DOW F&EI (cont.) • SPHi cases : (cont.) • Corrosion/erosion • Leakage (joints-packings • Fired equipment • Hot-Oil heat exchangers • Rotating equipment

41. Relative Ranking - DOW F&EI (cont.) • Examples of SPHi values for pressure : • 1000 psig, SPH=0.86 • 2500 psig, SPH=0.98 • >10000 psig, SPH=1.5 • Quantity of flammable material : graph based on potential heat release • Fired equipment : graph based on distance from flammables leakage locations (SPH max =1 for flammables heated in fired equipment)

42. Relative Ranking - DOW F&EI (cont.) • Examples of SPHi values for leakage : • Process with regular leakage problems at pumps, compressors, flanges, SPH=0.3 • Abrasive slurries with sealing problems, along with rotating shafts (i.e. pumps) SPH=0.4 • Use of sight glasses, expansion joints, bellows assemblies, SPH=1.5

43. Relative Ranking - DOW F&EI (cont.) • DOW F&EI values : • 1-60,Light • 61-96,Moderate • 97-127, Intermediate • 128-158, Heavy • 159, Severe • And then ???

44. Relative Ranking - DOW F&EI (cont.) • DOW F&EI method is supplemented by similar calculation of : • Exposure area(function of DOW F&EI value) • Base Maximum Property Damage • Loss Control Factor using credits for prevention/mitigation measures, such as : • Emergency power, Cooling, Computer control, Isolation features • Actual MaximumProperty Damage and Maximum outage time expected • and finally Business interruptionloss (capital units)

45. Relative Ranking - DOW F&EI (cont.)

46. Relative Ranking in legislation • Italian legislation for LPGs and for very flammable and toxic storage • Incorporation of safety measures in ranking calculation • Result (classes) used in risk acceptance criteria • TNO subselection method for scenarios selection (used in Netherlands within legislation requirements for Safety Reports –RIVM Reference Manual BEVI Risk Assessments)

47. Relative Ranking • Advantages of Risk Ranking techniques: • Strictly defined (easy to apply) • Rather limited data required • Limited time requirements (in the order of 10 days for large processes) • Can be applied even (and preferably) by 1 person • Scalable (application in either Unit or Site level) • Applicable in early design phase

48. Relative Ranking (cont.) • Advantages of Risk Ranking techniques: (cont). • Very useful in evaluation/comparison of : • alternative processes and sitings, • comparison of different sites, • ranking of hazardous areas within a Site • Effective decision making and screening tool

49. Relative Ranking (cont.) • Disadvantages : • Strong dependence of outcome from penalties/equations used and assumptions used • Procedural issues not prorely taken into account • Not to be considered as suitable for Safety Reports for other thanscreening purposes

50. END OF PART 1