Process safety leadership
Not publishedof exam
Management of process risk
Not publishedof exam
Process safety hazard control
Not publishedof exam
Operating LimitsSafety-Critical StandardsUtilities + StaticDangerous SubstancesReaction HazardsBulk Storage
Fire and explosion protection
Not publishedof exam
Quick Facts
- Unit
- PSM1 (single unit)
- Questions
- 40 multiple-choice
- Extended
- 10 scenario questions
- Time
- 90 minutes
- Pass
- 60% = 24 of 40
- Grades
- Pass or Refer
- Elements
- 4 syllabus elements
- Hours
- 28 taught + 20 private
- Level
- SCQF 7, 5 credits
- Sittings
- Monthly, 24-hour window
- Results
- 15 working days
- Spec
- October 2023
Case Study Lessons
Piper permits, Flixborough change, Buncefield overfill
Texas City: injury rates misledBhopal: minimise inventorySeveso: off-site information
Process vs Personal Safety
Process safety
- Loss of containment
- Rare, catastrophic outcome
- Engineering plus management
Personal safety
- Slips, trips, handling
- Frequent, lower consequence
- Behaviour and PPE
Catastrophe vs individual injury
PSM1 Syllabus Map
- Element 1
- Process safety leadership4 hours
- Element 2
- Management of process risk9 hours
- Element 3
- Process safety hazard control10 hours
- Element 4
- Fire and explosion protection5 hours
- Taught minimum
- 28 hours tuition
- Private study
- About 20 hours
- Paper coverage
- At least one per element
- Mark weightings
- NEBOSH publishes none
Leading vs Lagging Indicators
Leading
- Checks controls working
- Proactive measurement
- Inspections completed on time
Lagging
- Counts failures occurred
- Reactive measurement
- Losses of containment
Before vs after failure
Process Safety Basics
- Process safety
- Prevents catastrophic loss of containment
- Personal safety
- Prevents individual worker injury
- PSM system
- System preventing major incidents
- Major accident
- Fire, explosion, toxic release
- Loss of containment
- Energy or substance escapes
- Incident (ISO 45001)
- Event causing or risking harm
- Hazard realisation
- Worst-case consequence pathway
- Barrier
- Control between hazard and harm
Leadership + Culture
- Board visibility
- Directors own major accident risk
- PSM-critical roles
- Responsibilities defined and assigned
- Accountability
- Held at every level
- Resources
- Human, financial and physical
- Objectives
- Reviewed and published openly
- Worker consultation
- Committees, groups, safety circles
- Competence
- Knowledge, skills, experience, reliability
- Competency matrix
- Maps training to roles
Performance Indicators
- Leading indicator
- Checks controls before failure
- Lagging indicator
- Counts failures already happened
- Dual assurance
- Pair leading with lagging
- HSG254
- HSE process safety indicatorsHSE
- Benchmarking
- Compare practice between organisations
- Corporate memory
- Design and modification records kept
- Incident investigation
- Find causes, share lessons
- External sources
- HSE, CSB, trade bodies
Major Accident Lessons
- Piper Alpha 1988
- Permit and handover failure
- Buncefield 2005
- Overfill protection must be independent
- Texas City 2005
- Injury rates hid process risk
- Flixborough 1974
- Unassessed temporary plant modification
- Bhopal 1984
- Minimise hazardous inventory
- Seveso 1976
- Drove EU major-hazard law
Management of Change
- Trigger
- Plant, process or people change
- Hazard review
- Proportionate risk analysis first
- Authorisation
- Competent person signs off
- Safety-critical removal
- Senior management sanction required
- Documentation
- Records retain process knowledge
- Consultation
- Inform everyone affected
- Training
- Given where change requires
- Temporary change
- Managed like a permanent one
HAZOP Guide Words
NO | MORE | LESS | REVERSE | OTHER THAN
AS WELL AS: contaminationPART OF: wrong ratioPair with flow/pressure/tempDeviation = word + parameter
Preventive vs Mitigative Barriers
Preventive
- Left of bow-tie
- Stops the top event
- Trips, permits, inspection
Mitigative
- Right of bow-tie
- Limits the consequences
- Bunds, foam, evacuation
Stop it vs limit it
Which Study To Use
- Concept or pre-modification→HAZID(Broad hazards)
- Line-by-line P&ID review→HAZOP(Guide words)
- Test barrier adequacy→LOPA(Count IPLs)
- Show barriers visually→Bow-tie(Threats to consequences)
- Component failure modes→FMEA
- Mitigation after an event→Event tree(Forward branching)
- Quick team brainstorm→What-if
- Numerical societal risk→QRA(Quantitative)
Risk Techniques
- HAZID
- Early broad hazard identification
- HAZOP
- Guide-word deviation study
- Bow-tie
- Barriers around a top event
- Event tree
- Forward from initiating event
- FMEA
- Component failure modes, effects
- What-if
- Structured brainstorm questions
- Qualitative
- Descriptive likelihood and consequence
- Quantitative
- Numerical risk, QRA
- ALARP
- Cost grossly disproportionate to benefit
Bow-tie Shape
Threats -> top event -> consequences
Left: preventive barriersRight: mitigative barriersKnot: loss of containmentEscalation factors weaken barriers
HAZOP vs LOPA
HAZOP
- Finds deviations
- Guide words on nodes
- Qualitative team study
LOPA
- Tests barrier sufficiency
- Counts independent layers
- Semi-quantitative, order-of-magnitude
Find hazards vs size protection
Permit Picker
- Welding, cutting, grinding→Hot work permit
- Non-spark maintenance→Cold work permit
- Work on electrical systems→Electrical permit
- Vessel or tank entry→Entry permit(Gas test first)
- Breaking containment→Isolation certificate(Lock out, tag out)
- Adjacent simultaneous work→Cross-referenced permits
- Routine task, own procedure→No permit needed
HAZOP Guide Words
- NO / NONE
- No flow, no reaction
- MORE
- High flow, pressure, temperature
- LESS
- Low level, low flow
- REVERSE
- Backflow into the supply
- AS WELL AS
- Contamination plus intended flow
- PART OF
- Wrong composition ratio
- OTHER THAN
- Wrong material or activity
- Parameters
- Flow, pressure, temperature, level
- Node
- Section of P&ID studied
- Chair
- Independent leader, mixed team
Control Hierarchy Order
Inherent, eliminate, substitute, segregate, engineer, admin, PPE
Passive beats activePPE is lastEmergency response only mitigates
HAZID vs HAZOP
HAZID
- Concept and early design
- Includes non-process hazards
- Broad and fast
HAZOP
- Detailed design, P&IDs
- Process deviations only
- Slow and thorough
Wide early vs deep later
Bow-tie + LOPA
- Threat
- Cause on the left
- Top event
- Loss of containment
- Consequence
- Outcome on the right
- Preventive barrier
- Stops threat becoming top event
- Mitigative barrier
- Limits consequence after release
- Escalation factor
- Degrades or defeats a barrier
- Escalation control
- Protects the weakened barrier
- IPL
- Independent protection layer
- IPL test
- Independent, effective, auditable
- PFD
- Probability of failure on demand
- Instrumented trip
- Sensor, logic, final element
COMAH Lower vs Upper Tier
Lower tier
- Notify the authority
- MAPP required
- Public information duty
Upper tier
- Safety report required
- On-site emergency plan
- Feeds off-site plan
Inventory decides the duties
Control Hierarchy
- Inherent safety
- Design the hazard out
- Elimination
- Minimise or remove inventory
- Substitution
- Use a less hazardous material
- Segregation
- Spacing between plant items
- Engineering
- Passive preferred over active
- Administrative
- Procedures and behaviour
- PPE
- Last resort only
- Emergency response
- Mitigates after the release
Asset Integrity
- Asset integrity
- Equipment performs as intended
- Design stage
- Maintainable and inspectable
- Planned preventive
- Scheduled before failure
- Condition monitoring
- Act on measured deterioration
- Breakdown maintenance
- Run to failure
- Risk-based inspection
- Effort follows failure consequence
- Calibration
- Risk-based instrument accuracy checks
- Ageing plant
- Life extension and obsolescence
- Records
- Inspection and maintenance evidence
Permit-to-Work (HSG250)
- Purpose
- Controls non-routine hazardous work
- Scope
- Exact task and location
- Duration
- Validity period stated
- Isolation
- Lock out, tag out
- Cross-reference
- Link to other open permits
- Acceptance
- Named person confirms understanding
- Gas testing
- Specific control before entry
- Hot work
- Spark or flame producing
- Cold work
- Non-spark maintenance tasks
- Electrical work
- Own permit type
- Hand-back
- Plant returned, permit closed
- Not required
- Routine work under procedure
Handover + Contractors
- Two-way handover
- Both parties share responsibility
- Face to face
- Verbal plus written log
- Time allowed
- Questions and clarification permitted
- Plant walk
- Demonstrate the actual state
- Selection
- Competence, not lowest price
- Induction
- Site hazards and rules
- Supervision
- Named site representative
- Audit
- Before, during and after
- HSG159
- HSE managing contractors guideHSE
UK Regulatory Frame
- COMAH 2015
- GB major accident hazard rules
- Seveso III
- EU directive COMAH implements
- Lower tier
- Smaller dangerous substance inventory
- Upper tier
- Larger inventory, extra duties
- Competent Authority
- HSE plus environment regulator
- MAPP
- Major accident prevention policy
- Safety report
- Upper tier duty only
- Emergency plan test
- At least every three years
- Public information
- Duty on both tiers
- DSEAR zones
- Classify explosive atmosphere areas
FARSI Performance Standards
Functionality Availability Reliability Survivability Interdependency
F: what it doesA: uptime proportionR: works on demandS: survives the eventI: depends on others
Bonding vs Earthing
Bonding
- Links two conductors
- Equalises potential between items
- Stops sparks across gaps
Earthing
- Links item to ground
- Drains charge away
- Needs low-resistance path
Between items vs ground
Barrier Picker
- Prevent tank overfill→Independent high-level trip
- Contain runaway pressure→Designed reactor containment
- Remove reaction heat fast→Crash cooling
- Relieve overpressure safely→Vent to knock-out drum
- Stop flame travelling→Flame arrester
- Remove the oxygen→Nitrogen blanketing
- Limit spill spread→Bund(110% largest tank)
- Protect steel from fire→Passive fire protection
Operating Limits
- Safe operating envelope
- Upper and lower safe limits
- Operating procedure
- Step-by-step written instruction
- Verification
- Procedures kept current, accurate
- Alarm response
- Alert, inform, guide operator
- Pre-start-up review
- Confirm plant ready for service
- Start-up types
- Planned, unplanned, emergency, staged
- Shutdown
- Follow the written sequence
- Shared services
- Check impact on neighbours
Flashpoint vs Auto-ignition
Flashpoint
- Lowest vapour-producing temperature
- Needs an ignition source
- Classifies flammable liquids
Auto-ignition
- Ignites with no spark
- Hot surface temperature
- Higher than flashpoint
Spark needed vs not
Safety-Critical Standards (FARSI)
- Safety-critical element
- Failure could cause major accident
- Functionality
- What it must do
- Availability
- Proportion of time working
- Reliability
- Performs when demanded
- Survivability
- Works during the event
- Interdependency
- Relies on other systems
- Proof testing
- Shows the standard still met
Utilities + Static
- Saturated steam
- At its boiling temperature
- Superheated steam
- Heated above saturation temperature
- Water hammer
- Condensate slug shocks pipework
- Thermal expansion
- Trapped liquid overpressures pipe
- Draining vacuum
- Collapses tanks and vessels
- Cooling towers
- Legionella and vapour fog
- Inert gas uses
- Purge, blanket, freeze pipelines
- Nitrogen risk
- Asphyxiation without warning
- Bonding
- Equalises charge between items
- Earthing
- Drains charge to ground
- Power outage
- Generators and UPS backup
Dangerous Substances
- Flashpoint
- Vapour ignites momentarily, spark applied
- LEL
- Below it, too lean
- UEL
- Above it, too rich
- Flammable range
- Between LEL and UEL
- Explosive
- Explodes given oxygen, enough energy
- Oxidising
- Readily accepts electrons
- Physical form
- Gas, vapour, liquid, dust
- Dense vapour
- Collects in pits and drains
Reaction Hazards
- Exothermic
- Releases heat
- Endothermic
- Absorbs heat
- Thermal runaway
- Heat generated exceeds cooling
- Typical causes
- Cooling loss, wrong charge, catalyst
- Containment
- Reactor withstands maximum pressure
- Crash cooling
- Rapid emergency heat removal
- Quenching
- Drown or dilute contents
- Emergency venting
- Dump to scrubber or flare
Bulk Storage
- Overfilling
- Buncefield-type ground vapour cloud
- Vacuum collapse
- Emptying without adequate venting
- Brittle fracture
- Cold, sudden shell failure
- Creep
- Slow deformation under stress
- Floating roof
- Rim seal fire risk
- Landing the roof
- Vapour space forms beneath
- Bund capacity
- 110% of largest tankHSE
- Siting
- Distance from people, plant
- Lightning
- Protection and bonding needed
- Warehousing
- Segregate incompatible dangerous goods
Triangle + Dust Pentagon
Fuel + oxygen + ignition (+ dispersion + confinement)
Triangle: first threePentagon: dust needs fiveRemove one, no explosion
Venting vs Suppression
Explosion venting
- Weak panel or disc
- Relieves pressure outward
- Directed to safe place
Suppression
- Detects pressure rise
- Injects extinguishant fast
- Explosion stays inside
Release pressure vs stop it
Fire Scenario Picker
- Pressurised leak ignites→Jet fire(Impingement escalates)
- Liquid pool ignites→Pool fire(Radiant heat)
- Open cloud ignites late→Flash fire(Little overpressure)
- Congested cloud ignites→UVCE(Flame accelerates)
- Cloud inside a building→CVCE(Confinement)
- Flame heats LPG vessel→BLEVE(Fireball)
- Dust cloud in duct→Primary explosion
- Settled dust disturbed→Secondary explosion(Housekeeping)
Fire + Explosion Types
- Fire triangle
- Fuel, oxygen, ignition source
- Heat transfer
- Conduction, convection, radiation
- Jet fire
- Pressurised release, directional flame
- Pool fire
- Spreading liquid, wide radiation
- Flash fire
- Cloud burns, little overpressure
- BLEVE
- Vessel bursts, fireball follows
- UVCE
- Unconfined vapour cloud explosion
- CVCE
- Confined vapour cloud explosion
- Ignition sources
- Sparks, hot surfaces, static
DSEAR Zones
0 continuous, 1 occasional, 2 rare
Zone 0: Category 1GZone 1: Category 2GZone 2: Category 3GDusts: 20, 21, 22
Passive vs Active Fire Protection
Passive
- No power or action
- Coatings, walls, spacing
- Buys escape time
Active
- Needs detection or operation
- Water, foam, sprinklers
- Can fail on demand
Always there vs activated
Detection + Protection
- Gas detection
- Finds leaks before ignition
- Flame detection
- Optical sensing of fire
- Line heat detection
- Temperature rise along cable
- Passive protection
- Coatings, walls, no power
- Active protection
- Water or foam, manual/automatic
- Hazardous area zoning
- Selects ignition-protected equipment
- Flame arrester
- Stops flame passing through
- Explosion venting
- Weak panel relieves pressure
- Suppression
- Injects extinguishant during explosion
- Automatic isolation
- Closes to stop spread
- Atmosphere control
- Inerting below oxygen limit
- Tank farm foam
- Pourers and fixed monitors
Dust Explosions
- Five conditions
- Fuel, oxygen, ignition, dispersion, confinement
- Primary explosion
- Inside vessel or duct
- Secondary explosion
- Settled dust lifted, ignites
- Housekeeping
- Removes settled dust layers
- Extraction
- Captures dust at source
- Substitution
- Granules or paste instead
- Nitrogen inerting
- Prevents explosive dust atmosphere
- Relief venting
- Vents to a safe place
- Strong construction
- Plant siting withstands pressure
Emergency Preparedness
- On-site plan
- Operator's internal response
- Off-site plan
- Local authority prepares it
- Scenarios
- Chosen by likelihood, consequence
- Alerting
- Warn workers, neighbours, services
- Command roles
- Delegated responsibilities, named people
- Accounting
- Muster and headcount system
- Vulnerable people
- Planned for specifically
- Emergency shutdown
- Plant and services stopped
- Media liaison
- Controlled information release
- Table-top test
- Theoretical scenario exercise
- Live drill
- Practical evacuation rehearsal
Common Traps
Process vs personal safety
Personal safety: slips, falls ≠ Process safety: loss of containment
Prevent vs mitigate
Preventive barriers stop initiation ≠ Mitigative barriers limit consequences
HAZOP vs LOPA
HAZOP finds deviations ≠ LOPA counts protection layers
Indicators
Leading indicators check controls ≠ Lagging indicators count failures
Bonding vs earthing
Bonding equalises between items ≠ Earthing drains to ground
Flashpoint vs auto-ignition
Flashpoint needs a spark ≠ Auto-ignition needs no spark
Venting vs suppression
Venting releases pressure outward ≠ Suppression injects extinguishant inside
COMAH tiers
Lower tier: MAPP, notify ≠ Upper tier adds safety report
Jet vs pool fire
Jet fire: pressurised release ≠ Pool fire: spreading liquid
Flammable limits
Below LEL, too lean ≠ Above UEL, too rich
Last Minute
- 1.PSM1 = 40 questions, 90 minutes
- 2.Pass = 60%, 24 of 40
- 3.Grades are Pass or Refer
- 4.10 questions are extended scenarios
- 5.Process safety = loss of containment
- 6.Leading checks controls; lagging counts failures
- 7.HAZOP = deviations; LOPA = layers
- 8.Bow-tie: left prevents, right mitigates
- 9.FARSI grades safety-critical performance standards
- 10.Flixborough = change; Piper Alpha = permits
- 11.Buncefield = overfill; Texas City = start-up
- 12.Bhopal = inventory; Seveso = EU law
- 13.Bund holds 110% largest tank
- 14.Zone 0 continuous; Zone 2 rare
- 15.Upper tier adds safety report
- 16.Emergency plans tested every 3 years
- 17.Bonding equalises; earthing drains away
- 18.Passive protection needs no power
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