Tel: (+44) 01492 879813 Mob: (+44) 07984 284642andy@abrisk.co.ukwww.abrisk.co.uk 1

Linking task analysis with other process safety activities

Andy Brazier

Working in silos

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QRA

HAZOP

Human factors

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Risk profile

Hazard detail

Engineered Human

Hierarchy Task or activity

1. Instrument2. Alarm3. Trip4. Mechanical

Task analysis

1. HMI2. Deviation response3. Emergency4. Generic competence5. One-off risk assessment6. Automated

Prioritise according to risk of MAHQRA, HAZID

Identify deviations leading to MAHHAZOP, PHR

ALARP

HSE Roadmap

Barriers

Bowtie?

HAZOP and human factors

Safeguards with human componentMonitoring and controlAlarm responseTraining or procedure???

Safeguard maintenanceTasks considered as potential causes of deviationRecommendations.

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Issues with HAZOP and human factors

Not a systematic study of human factors Human factors principles not always applied (correctly)HAZOP is already demanding without adding human factorsBut creating good links between HAZOP and human factors could be very beneficial.

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Use HAZOP to structure task analysis

HAZOP nodesFocus on deviations that can result in Major Accident hazards (MAH)Use causes of deviations to identify tasksConsistent reference to causes and consequences.

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Identifying tasks Planned deviations - pressure

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Pre

ssur

e

Time

Start-up Normal Optimise Shutdown

Unplanned deviations - pressure

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Pre

ssur

e

Time

Start-up Controlled excursion

Failure

HazardUn-controlled excursion

Safety critical task analysis

What does ‘safety critical’ mean?What is a task?What about non-tasks?Prioritise to get the maximum benefit from the effort put in

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Principles to apply

Area where MAH identified = safety criticalSafety Critical Task (SCT)

There is a clear start and finishThere are discrete stepsA change of status occurs

Safety Critical Activity (SCA) where the critical aspects are:

Timing (when to perform the task)Tools and equipment to be usedInformation presentationDecision making

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Examples of SCT

Node start-up and shutdownStarting main items of equipment

Stopping same equipment often simpler

Remove, calibrate and replace relief valve or bursting diskLeak or pressure test.

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Examples of SCA & how to address

Control/optimise process Human Machine Interfaces (EEMUA 191/201)

Emergency responseEmergency planning/staffing assessment

Routine maintenance/inspection Planning and schedulingCompetence of personnel, permit to work

One-off tasks (e.g. temporary repair)Risk assessment and management of change.

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SCT or SCA depends on circumstance

Changing operating modeManual stop or tripCheck/calibrate transmitterFunction test tripMaintain process equipment

Contractor management

Prepare plant for maintenanceNormal shutdown?

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Conclusions

Linking human factors with other process safety activities has great benefits

Linking all process safety activities should be the aim

Differentiating SCT and SCA helps clarify the way forwardNeeds to be continuous and iterative

Changing the approach to human factors is not the only requirementProcess safety studies need to be modified to provide better date for human factors studies.

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