Presentation on theme: "Process Safety in Chemical Plants with Focus on HAZOP"— Presentation transcript:
1 Process Safety in Chemical Plants with Focus on HAZOP Title: HAZOP in Practice09-10 December 2008Second World Congress on Disaster ManagementProcess Safety in Chemical Plants with Focus on HAZOPbyS. S PIPARAFaculty at AVVIARE Educational Hub, NoidaandEx. Joint President GRASIM Industries Ltd., Nagda (India)Chilworth Safety & Risk Management P. Ltd.
2 Process Safety Management Root cause analysis of incidentsThe hazards associated with Unit processes and Unit operationsProcess Safety and Equipment Health
3 Hazard Identification Techniques Techniques in use are in one of three categories:Techniques123Experience BasedChecklists and What-If / ChecklistsIndices and Layers of Protection Analysis (LOPA)AnalyticalFailure Mode and Effects Analysis (FMEA)Fault Tree Analysis and Event Tree AnalysisCreativeBrainstormingHAZOPS
4 Definitions Process Hazard Analysis Catastrophic Release An organized and systematic effort to identify and determine the significance of the hazards associated with the handling and processing of highly hazardous chemicals and assess the effectiveness of safeguards.Catastrophic ReleaseMajor uncontrolled emission, fire or explosion that causes serious danger to employees in the workplaceHighly Hazardous Chemicala substance that has toxic, flammable, explosive or reactive properties.ProcessAny activity including use, storage, manufacturing, handling or on-site movement of a highly hazardous chemicalSafeguardProcedures and devices used to control process hazards and manage risk.PreventionsProcedures and devices intended to stop the initiation of an undesired event or interrupt the escalation of an event sequence.MitigationsProcedures and devices intended to respond to events and reduce the magnitude of undesired consequences.
5 Experience Based Hazard Identification Techniques Title: HAZOP in Practice09-10 December 2008Experience Based Hazard Identification TechniquesChecklistWhat-If/ ChecklistNatural extension of simple checklistBegins to introduce a customization of the checklist to better fit the processBest if done by experienced personnelMost effective in early design stage of new projects.Most often guided by a checklist of topicsCan be applied to a limited scopeIndividual (of most limited value)Informed Individual (safety specialist)Outside standards such as:Center for Chemical Process Safety (CCPS)National Fire Protection Association (NFPA)Chilworth Safety & Risk Management P. Ltd.5
6 What-If Spreadsheet Example Process UpsetCausesConsequencesSafeguardsAction ItemsWhat if sample is spilled on operatorBottle breaksOperator errorOperator burned, LTI Procedures and trainingPPEModify procedures to stress issueWhat if batch temperature is too high?Control failureNo issue, material is thermally stableProcedures and trainingDCSWhat if reactor leaks?CorrosionMaintenance ErrorClean up costs onlyPM ProgramERP Ensure adequate spill clean up materials are on handWhat if spill ignites and pool fire occurs indoors?Leak plus spark from equipmentOperator fatality possible Big $$$ lossFixed SprinklersAdequate drainageEnsure adequate PM of electrical devicesNote: Action items are often abbreviated during the review and expanded to includeadditional explanation in the final report.
7 Fault Tree Analysis Analytical Hazard Identification Techniques Title: HAZOP in Practice09-10 December 2008Analytical Hazard Identification TechniquesFault Tree AnalysisUse of a logic diagram to plot the path from an undesired outcome back to the basic equipment, systems and human failures, the Basic Events;Predominantly used for high consequence, low frequency events, to determine the adequacy of safeguards;Graphical representation of the combination of faults leading to a predefined undesired eventThis methodology uses logic gates to show all the credible paths from where the undesired event could occurA top down approach where each level is required to allow the next;The analyst asks what is required for the upper event or condition to exist?The pathway is plotted on the diagram using standard symbolsChilworth Safety & Risk Management P. Ltd.7
9 Title: HAZOP in Practice 09-10 December 2008Event Tree AnalysisAn event tree is a graphical representation of the logic model that identifies and quantifies the possible outcomes following an initiating event.Use of a logic diagram to plot the path from a single initiating event through each decision point where consequences can be altered to arrive at the final potential consequence. At each decision point success or failure diverts the path.Event trees are used to identify the various accidents that can occur in a complex processCan be used with FMEA to develop safety oriented mechanical integrity programs.Chilworth Safety & Risk Management P. Ltd.9
10 Event Tree Analysis Example Quantified Incident development pathOutcome FrequencyYES 50%Vapor CloudExplosion0.5%YES 10%NO 50%Pool Fire0.5%FlammableLiquid isReleasedDelay?NO 10%ReportableEnvironmentalIncidentNO 90%9.0%Ignition?Minor in-houseincidentYES 90%90%
11 Failure Mode Effect Analysis Title: HAZOP in Practice09-10 December 2008Failure Mode Effect AnalysisFailure Modes and Effects Analysis (FMEA) is methodology for analyzing potential reliability problems early in the development cycle where it is easier to take actions to overcome these issues, thereby enhancing reliability through design.FMEA is used to identify potential failure modes, determine their effect on the operation of the product, and identify actions to mitigate the failures.An assessment of equipment, components and systems to determine the way in which failures can occur and the consequences of component failure on systems and units.Most often qualitative but a quantitative assessment can be made.A “Bottom Up” approachSpreadsheet style documentationChilworth Safety & Risk Management P. Ltd.11
12 FEMA Title: HAZOP in Practice 09-10 December 2008 Chilworth Safety & Risk Management P. Ltd.12
13 Selecting a Hazard Identification Technique Title: HAZOP in Practice09-10 December 2008Selecting a Hazard Identification TechniqueConsiderationsInformation availableProject stagePersonnel requirementsPersonnel skill levelSystem complexitySystem typeSchedule and time restrictionsChilworth Safety & Risk Management P. Ltd.13
14 Selecting Technique Title: HAZOP in Practice 09-10 December 2008 Chilworth Safety & Risk Management P. Ltd.14
15 Creative Hazard Identification Techniques Brainstorming Title: HAZOP in Practice09-10 December 2008Creative Hazard Identification TechniquesBrainstormingAn unstructured technique used by a team to gather all ideas about a topic, without specific analysis of those ideas.The scribe will typically write down all that is said by the team members for later analysis. (Flip Chart)May be leader or checklist driven:“How can the pump fail?”Common method within a PHA teamThe classic method encourages free thinking and creativity, no idea is turned away.Only after the team’s brainstorming has reached a logical end, are documented ideas analyzed, and possibly discarded.Brainstorming can be a good way of encouraging team participation.Chilworth Safety & Risk Management P. Ltd.15
16 HAZOP - HAZard & OPerability Title: HAZOP in Practice09-10 December 2008HAZOP - HAZard & OPerabilityFirst developed at ICI in the UK in 1964 this method is a natural extension of standardized checklists.Where checklists count on past experience, HAZOPs develops ‘synthetic experience’ by hypothesizing deviations from desired performance.Most applicable to new and novel processes where experience is lacking.Chilworth Safety & Risk Management P. Ltd.16
17 HAZOP - HAZard & OPerability Title: HAZOP in Practice09-10 December 2008HAZOP - HAZard & OPerabilityThe basic premise of HAZOPS is:All hazardous material incidents are instigated by a deviation from the desired operating state or condition.If we can predict all deviations and analyze them before we operate a new process then we can head off the undesired consequences.Forewarned is ForearmedChilworth Safety & Risk Management P. Ltd.17
18 HAZOP Approach Define Intended Process Repeat Parameter + Guided words Deviation CauseConsequenceSafeguardActionDefine Intended ProcessRepeat
19 Title: HAZOP in Practice 09-10 December 2008HAZOP APPROACHIntention:The Intention defines, How the selected section/unit is expected to operateParameters:Aspects of a process that describe it physically or in terms of what is happeningSome Parameters:FlowPressureTemperatureLevelPhaseViscosityConcentrationLoss of containment is a critical consideration and must be included.Flow RateFlow AmountAgitationAgingPhConductivityCatalyst ActivityTimeChilworth Safety & Risk Management P. Ltd.
20 Title: HAZOP in Practice 09-10 December 2008HAZOP APPROACHGuidewords:These are simple words, which are used to qualify the intentions in order to guide and stimulate the thinking process and so discover deviations.Some Guidewords:No/NoneMoreLessReverseOther thanAs well asPart ofMore = High for example High Pressure, High Temp etc.Similarly, Less = LowChilworth Safety & Risk Management P. Ltd.
21 HAZOP APPROACH Guideword Meanings Title: HAZOP in Practice09-10 December 2008HAZOP APPROACH Guideword MeaningsGuidewordMeaningExampleParameter: FlowNo/NoneNone of design intent is achievedNo FlowMoreQuantitative increase in a parameterMore FlowLessQuantitative decrease in a parameterLess FlowReverseLogical opposite of the design intent occursReverse FlowOther thanComplete substitution – another activity takes placeBoilingAs well asAn additional activity occursChemical ReactionPart ofOnly some of the design intent is achieved-----Chilworth Safety & Risk Management P. Ltd.
22 Title: HAZOP in Practice 09-10 December 2008HAZOP APPROACHDeviations:Deviation means departure from the design intentThese are discovered by systematically applying the guidewordsCauses:Reasons for deviationsConsequences:Results of deviationsChilworth Safety & Risk Management P. Ltd.
23 Title: HAZOP in Practice 09-10 December 2008HAZOP APPROACHSafeguards:Procedures or devices exists to control causes or mitigate consequencesPrevention measures orMitigation measures orCombination of bothChilworth Safety & Risk Management P. Ltd.
24 Title: HAZOP in Practice 09-10 December 2008HAZOP APPROACHSUMMARYHAZOPS uses a standard list of “Guidewords” as modifiers to process Parameters to hypothesize Deviations from the desired intent.Deviation = Guideword + ParameterThe Deviations are analyzed by the team to determine if a hazardous condition would occur, or if an important operating upset is discovered.Chilworth Safety & Risk Management P. Ltd.
25 Title: HAZOP in Practice 09-10 December 2008HAZOP APPROACHSUMMARYChilworth Safety & Risk Management P. Ltd.
26 Title: HAZOP in Practice 09-10 December 2008HAZOP Study TeamLeaderInstrumentationsupervisorOperatorChemistChemical EngineerMaintenanceSupervisorSpecialistOperationsDesign TeamMemberCommon Team Size:4-7 peopleScribeIt is important to select right composition of HAZOP team.Chilworth Safety & Risk Management P. Ltd.
27 Hazard StudiesHAZID - To identify hazards and potential accident scenarios to be performed at the initial stage of a projectHAZOP - To identify specific hazards arising from process deviation, to evaluate adequacy of existing safeguards and to identify additional mitigating measures to be performed at different stages throughout the entire project lifeQRA - To assess personnel risk posed by potential hazard scenarios to be performed at the initial stage of the project with further updating at a later stage/
28 Risk Identification Techniques Identifying the RiskRisk Identification TechniquesWhen you might use themSafety ReviewChecklistPreliminary Hazard AnalysisWhat-IfAbbreviated HAZOP StudyUsed in preliminary hazard evaluation studies to provide a general overview of existing risks(Usually not too time consuming)What-If/ChecklistDetailed and complete HAZOP StudyFailure Mode and Event AnalysisUsed to develop a more detailed analysis of potential risksFault Tree AnalysisEvent Tree AnalysisCause Consequence AnalysisHuman Reliability AnalysisUsed in conjunction with quantitative risk analysis to establish a high level detail about risks(Usually used for specific area or Unit Operations)
29 Hazard identification Scenario identification Risk Assessment ProcedureHAZARD IDENTIFICATION METHODS:- Process hazard checklist- Hazard survey: DOW index- HAZOP hazard & operability study- Safety reviewSystem descriptionHazard identificationScenario identificationAccidentprobabilityconsequencesRisk determinationRisk &Hazardacceptable?Modify designAccept systemYNRISK ASSESSMENT:- What can go wrong & how ?- What are the chances ?- Consequences ?EXTREMES- Low probability- Minimal consequences