1. HAZOP Guidewords Base Set

2. HAZARD AND OPERABILITY STUDY GUIDEWORDS FOR FLUID SYSTEMS
For each system:
1. Describe function in plant
2. Describe operating conditions
3. Clarify any questions from team

3. HIGH FLOW HIGH LEVEL Control System Failure Operator Error
Downstream/Upstream Pressure Change
Two-Phase Flow
Power Failure

4. LOW FLOW LOW LEVEL Control System Failure
Operator Error
Pump Failure
Pipe / Vessel Failure
Downstream / Upstream Pressure Change
Two-Phase Flow
Power Failure

5. REVERSE FLOW Control System Failure Pump Failure Operator Error
Downstream / Upstream
Pressure Change
Pump Failure
Power Failure
Zero Flow
Backflow Source

6. HIGH PRESSURE Control System Failure Operator Error
Inadequate Pressure Relief / Venting
Flashing / Boiling
Blockages / Freezing Sedimentation
External Fire
Decomposition / Gas Evolution
Runaway Reaction

7. LOW PRESSURE Control System Failure Operator Error
Condensation / Cooling
High Outflow
Inadequate Vacuum Relief
Power Failure

8. HIGH TEMPERATURE Control System Failure Operator Error
Exothermic Reaction
Weather Conditions
Heat Source / External Fire
Runaway Reaction
Power Failure

9. LOW TEMPERATURE Control System Failure Operator Error
Weather Conditions
Power Failure

10. PROCESS CONTROL Adequate? Automatic vs Manual
Interlocks, Limits and Trips
Critical Variable Monitoring
Location

11. CONTAMINATION Corrosion Products (eg. Salt) Air Ingress Water Ingress
Backflow
Sediments
Biological Activity
Raw Material Impurities
Reaction By-Products
Dust

12. LOSS OF CONTAINMENT Flanges and Fittings Equipment Failure Sampling
Burst
Relief Device
Human Error
Eg. Valve, Cover, Blank etc. left open.

13. ELECTRICAL SAFETY
Area Classification
Earthing
Static Discharge

14. MAINTENANCE Isolation Access Delousing / Purging
Inspection and Testing
Washdown / Cleanup
Spares & Availability
Experienced Personnel

15. ISOLATION Method / Hardware Procedures Shutdown Maintenance
Breakdown Maintenance
Testing
Removal / Re-commissioning
Lock out procedure when working on equipment

16. HAZARD AND OPERABILITY STUDY GUIDEWORDS FOR NON FLUID SYSTEMS
For each system:
1. Describe function in plant
2. Describe operating conditions
3. Clarify any questions from team

17. POSITION
Too High
Too Low
Too Far
Misaligned
Wrong Position

18. MOVEMENT High Speed Vibration Low Speed Friction No Movement Slip
Reverse Movement
Jamming & Un-Jamming
Vibration
Friction
Slip
Obstacles

19. LOAD
High Load
High Flow
Low Load
Low Flow
Loss of Containment

20. (ELECTRICAL, PNEUMATIC, HYDRAULIC, STEAM)
ENERGY
(ELECTRICAL, PNEUMATIC, HYDRAULIC, STEAM)
Low Energy (Flow, pressure, voltage, current, temperature)
High Energy (Flow, pressure, voltage, current, temperature)
Energy Failure
Reverse (Current, voltage, flow, vacuum)

21. TIMING
Too Late
Too Early
Too Short
Too Long
Incorrect Sequence

22. CONTAMINATION
Water
Oil
Dust
Flammables
Corrosives
Vermin
Cleaning

23. SIZE
Too Large
Too Small
Too Long
Too Short
Too Wide
Too Narrow

24. PROCESS CONTROL Adequate? Automatic vs Manual
Interlocks, Limits and Trips
Critical Variable Monitoring
Location

25. MAINTENANCE Isolation Access Delousing / Purging
Inspection and Testing
Spares & Availability
Experienced Personnel

26. HAZARD AND OPERABILITY STUDY GUIDEWORDS FOR OVERVIEW

27. TOXICITY Handling Procedures Precautions Exposure Monitoring
Emergency Procedures
Ventilation

28. PHYSICAL DAMAGE Degradation of Belt Impact Dropped Objects
Transportation Collision
Vibration
Corrosion
Weight (Including Product)

29. FIRE/EXPLOSION Prevention Systems Detection Systems Fire Protection
Emergency Isolation Systems
Inert Atmosphere
Emergency Procedures

30. ENVIRONMENTAL IMPACT Vapour Emissions Dust Emissions Effluent Noise
Ground Seepage
Waste Minimisation

31. MATERIALS OF CONSTRUCTION
Vessels
Pipes
Pumps
Valves
Gaskets / Seals
Structures
Protective Coatings

32. ACCESS
Operation
Maintenance
Emergency Escape

33. UTILITIES AND SERVICES
Lighting
Instrument Air
Compressed Air
Breathing Air
Nitrogen
Cooling Water
Process Water
Steam
Fuel Gas
Electricity
Oxygen
Water

34. COMMISSIONING
Requirements
Sequence
Procedures

35. START UP First Routine Procedures Philosophy of Control
(Supervisory, Automatic, Manual with Interlocks, Manual without Interlocks, Local)

36. SHUTDOWN
Planned
Emergency

37. SAFETY EQUIPMENT Personnel Protection Gas Monitors Breathing Apparatus
Safety Showers
Barriers / Guards

38. NATURAL HAZARDS Earthquake Flooding
Thunderstorm (Lightning Protection)
High Winds

39. INSPECTION AND TESTING
Alarms and Trips
Emergency Isolation Valves
Gas / Fire Detectors
Fire Protection Systems

40. DEVELOPMENT AND DOCUMENTATION
PROCEDURES
DEVELOPMENT AND DOCUMENTATION
Operations
Maintenance
Inspection and Testing
Confined Space
Emergency
Engineering Drawings
Modification Control

41. QUALITY CONTROL
Inspection and Testing
Quality Assurance