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2014 Hazards - Linking task analysis with other process safety activities


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IChemE Hazards conference. How to link task analysis with other process safety activities and the benefits of doing so.

Published in: Engineering
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2014 Hazards - Linking task analysis with other process safety activities

  1. 1. Tel: (+44) 01492 879813 Mob: (+44) 07984 284642 1 Linking task analysis with other process safety activities Andy Brazier
  2. 2. Working in silos 2 QRA HAZOP Human factors
  3. 3. 3 Risk profile Hazard detail Engineered Human Hierarchy Task or activity 1. Instrument 2. Alarm 3. Trip 4. Mechanical Task analysis 1. HMI 2. Deviation response 3. Emergency 4. Generic competence 5. One-off risk assessment 6. Automated Prioritise according to risk of MAH QRA, HAZID Identify deviations leading to MAH HAZOP, PHR ALARP HSE Roadmap Barriers Bowtie?
  4. 4. HAZOP and human factors Safeguards with human component Monitoring and control Alarm response Training or procedure??? Safeguard maintenance Tasks considered as potential causes of deviation Recommendations. 4
  5. 5. 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 factors But creating good links between HAZOP and human factors could be very beneficial. 5
  6. 6. Use HAZOP to structure task analysis HAZOP nodes Focus on deviations that can result in Major Accident hazards (MAH) Use causes of deviations to identify tasks Consistent reference to causes and consequences. 6
  7. 7. Identifying tasks Planned deviations - pressure 7 Pressure Time Start-up Normal Optimise Shutdown
  8. 8. Unplanned deviations - pressure 8 Pressure Time Start-up Controlled excursion Failure HazardUn-controlled excursion
  9. 9. 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 9
  10. 10. Principles to apply Area where MAH identified = safety critical Safety Critical Task (SCT) There is a clear start and finish There are discrete steps A change of status occurs Safety Critical Activity (SCA) where the critical aspects are: Timing (when to perform the task) Tools and equipment to be used Information presentation Decision making 10
  11. 11. Examples of SCT Node start-up and shutdown Starting main items of equipment Stopping same equipment often simpler Remove, calibrate and replace relief valve or bursting disk Leak or pressure test. 11
  12. 12. Examples of SCA & how to address Control/optimise process Human Machine Interfaces (EEMUA 191/201) Emergency response Emergency planning/staffing assessment Routine maintenance/inspection Planning and scheduling Competence of personnel, permit to work One-off tasks (e.g. temporary repair) Risk assessment and management of change. 12
  13. 13. SCT or SCA depends on circumstance Changing operating mode Manual stop or trip Check/calibrate transmitter Function test trip Maintain process equipment Contractor management Prepare plant for maintenance Normal shutdown? 13
  14. 14. 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 forward Needs to be continuous and iterative Changing the approach to human factors is not the only requirement Process safety studies need to be modified to provide better date for human factors studies. 14
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