Case Studies Flashcards
1
Q
Formosa
- Incident Analysis
A
- VCM explosion
- Operator opened wrong valve
- Human error emphasized by reactor layout, lack of communication (no radios), and staff changes which got rid of specialized group leader who had knowledge on supervising valve by-pass
2
Q
Formosa
- Hazard Recognition
A
- Human error lead to wrong valve being opened. Recommended that the supervisor should be present to override the valve interlock and air hose system should be changed to one which requires supervisor key.
- Only safeguard was the operating procedure and interlock which is not suitable for high consequence hazards
- Reactor cleaning procedure may lead to wrong reactor being opened, key lock system should be implemented
- By-Pass control too easily accessible such as wooden blocks (prevented inadvertent activation of deluge system) and VCM gas detection switch.
- Lack of Emergency Preparedness (HAZWOPER should have been used)
3
Q
Formosa
- Key Findings
A
- Borden Chemical did not implement 1992 PHA recommendations
- New organisational structure that reduced staffing
- There was a lack of communication in the plant
- By-Pass of the valve interlock was too accessible
- Lack of emergency procedure
- Safety offices close enough to be heavily damaged
4
Q
Piper Alpha
- Incident Analysis
A
- Two modes of operation included Phase 1 where excess gas was flared, and Phase 2 where excess gas was exported. Piper was switched to Phase 1 mode 3 days before the accident due to maintenance.
- Condensate pump B tripped, gas alarms activated, first stage gas compressors tripped, and flare was observed much larger than usual.
- High pressure gas line ruptured, releasing gas at initial rate of 3 tonnes/sec
- Most likely cause of initial explosion was small amount of propane condensate released through a blind flange where a PRV was removed for maintenance.
5
Q
Piper Alpha
- Hazard Recognition
A
- Inadequate transfer of information between crews (Handover)
- Poor emergency response (Safety Culture)
- (Management of change) - new facilities near important rooms such as control room, radio room
- Fire pumps were set to manual to avoid divers from getting sucked into the pipes, therefore the fire protection system didn’t activate to cool the plant and significantly delay the secondary explosion rupture of pipeline
- The permit to work on piper alpha seemed to rely heavily on informal communication
6
Q
Piper Alpha
- Key Findings
A
- Pump A had been stopped for maintenance along with the Pump A PRV, When Pump B tripped, the operators may have chosen to reinstate Pump A, not realizing that the PRV had been removed and that the blind flange had not been pressure or leak tested.
- Because of the way the work permits were organised on piper alpha, operators would have had no way of realizing that the pump A PRV was missing.
- The first explosion was then followed by an oil pipe rupture and a rapid escalation of the disaster.
7
Q
T2 Laboratories
- Incident Analysis
A
- Runaway reaction
- The most likely cause of the explosion was a failure within the cooling system as it was susceptible to single-point failure.
- The event could have been stopped if the rupture disc pressure relief valve was set at a lower pressure to it could relieve the pressure before the secondary reaction had started.
8
Q
T2 Laboratories
- Hazard Recognition
A
- Cause of single point failure of water cooling system: Water supply valve failing closed or partially closed, water drain valve failing open or partially open, failure of pneumatic system, blockage or partial blockage, faulty temperature indication, Mineral scale build up.
- Cooling system maintenance needed had been reported but never acted upon
- Secondary exothermic reaction occurred once there was not sufficient cooling, causing a drastic rise in temperature and pressure which lead to the reactor bursting.
- Proper research was not conducted on the hazardous components of the process, the reaction when tested was not observed at higher temperatures than what would have been expected in the process.
9
Q
T2 Laboratories
- Key Findings
A
- Killed 4, injured 32, and destroyed many businesses
- Explosion due to thermal runaway reaction of MCMT
- Thermal runaway because of a cooling system failure
- Cooling system lacked design redundancy, subject to single point failure and there was no emergency cooling system.
- PRV was designed for normal operating conditions and could not relieve the second exothermic reaction
- Owner and operators likely unaware that the secondary reaction would occur.
- There was a lack of reactive chemistry experience
- Chem Eng curriculum did not include reactive hazard recognition or management
- (SCALE UP)
10
Q
MGPI
- Incident Analysis
A
- Wrong connection used when delivering chemicals
11
Q
MGPI
- Key Findings
A
For fixed facilities that receive chemicals:
- must identify and address all possibilities that may lead too human error.
- Interlocks and safeguards should be implemented where feasible to ensure safe operations when unloading chemicals. The control system should monitor hazardous process conditions.
- Modify transfer equipment so the transfer of incompatible fill lines is not possible. (Shape of fittings and colours)
- Make sure that the loading areas for different chemicals is separate. For example separating acids and bases.
- The markings on fill lines should be very clear so they operator knows exactly which line they are filling.
- Chemical distributors should be worked with closely so the unloading and emergency procedures are agreed upon. Periodic refresher training
- Important that design considerations are made to make sure near by buildings are safe in the event of a spill or reaction.
- Emergency protocol should be very clear with consistent training. emergency exits and respirators (not locked up) also emergency escape respirators.
12
Q
Bhopal
- Incident Analysis
A
- Bhopal disaster happened due to a number of reasons as it failed to follow the inherent safety principals
- Budget cuts
- Methyl isocyanate released killing thousands of people and injuring many more
- two leaks prior that were fatal yet still ignored
- 61 safety regulation violations
- all three safety nets were offline at the time of disaster
- bad emergency protocol
- water has highly exothermic reaction with methyl isocyanate
- flare tower ‘ being repaired’
- scrubber did not work due to lack of caustic soda
13
Q
Hoeganaes (INCOMPLETE)
- Incident Analysis
A
- Iron dust flash fire
14
Q
Hoeganaes
- Key Findings
A
- Significant amounts of accumulated iron dust fueled fatal flash fires when lofted near ignition point
- Facility management knew about the hazard 2 years prior but did not act on it
- Hoeganaes did not institute procedures, such as combustible gas monitoring or training for employees to avoid flammable gas fires or explosions
- OSHA did not include iron or steel mills in its combustible dust national emphasis program
- The international fire code that was used in the city did not require the jurisdictions to enforce rigorous standards to prevent dust fires and explosions
- Fire brigade had inspected two dust fire incidents weeks prior but did not formally address the combustible dust hazard.
15
Q
Imperial Sugar (INCOMPLETE)
- Incident Analysis
A
- Sugar dust explosion
- SCALE UP
16
Q
Imperial Sugar
- Key Findings
A
- Imperial sugar had been aware of sugar dust explosion hazard since 1925
- The importance of properly designed dust handling equipment and housekeeping was emphasized but never implemented.
- There were no major incidents up until 2008
- Managers and operators did not recognize the significant hazards posed by the sugar dust despite the history of continuous near misses
- A confined environment was created where the minimum explosible concentration was easily surpassed.
- Explosion vents were not fitted (used to safely vent a dust explosion)
- There was a secondary explosion that caused a rapid spreading fire which then caused fatalities which would not of happened with correct dust precautions and housekeeping
17
Q
Barton Solvents
- Key Findings
A
Several factors combined to produce initial explosion:
Tank contained ignitable air-vapor mix in head space, stop-start filling and sediment/water present in the tank caused a rapid static charge accumulation, loose linkage on liquid level gauging system separated created a spark. The explosive hazard was not properly communicated
18
Q
Williams Olefins Plant (INCOMPLETE)
- Incident Analysis
A
- Management of change was not used properly
- Reboiler explosion
19
Q
Williams Olefins Plant
- Key Lessons
A
- Over pressure protection is very important, at a minimum pressure relief devices
- Robust isolation methods should be used to protect offline equipment from process fluids as block valves (Gate Valve) are susceptible to leaking.
- Companies should ensure that action items have been effectively implemented and field verified before closing them out.
- Robust management of change should be implemented
- PSSR (Pre startup safety reviews)
- Extensive training required on detailed operating procedure for operators
20
Q
LOPA (Layer Of Protection Analysis) (7)
most likely unnecessary
A
- More rigorous approach than qualitative method to determine whether a risks safeguards are suitable.
- Method for classifying consequences
- Criteria for determining risk tolerance
- Scenario development procedure
- Rules for considering independence of safeguards
- Procedures and calculating risk
- Procedures to determine whether risk is adequately safeguarded
21
Q
Buncefield
- Analysis
A
- Tank was being filled with petrochemicals
- Level alarm high did not sound
- Vapour released
- Congestion from trees was overlooked
- Overpressure occurred and found ignition source for the vapour
- hydrocarbon based sealant was melted by the initial explosion and released other vapour and liquid which further fueled the disaster ( flexible sealant between concrete tanks failed upon fire exposure)
22
Q
‘Phast’ Modelling software
A
- A computer program for simulating groundwater flow, solute transport, and multi component geochemical reactions.
- ‘Process hazard analysis simulation tool’
23
Q
Factors that effect the dispersion of a toxic/flammable cloud (6)
A
- Velocity of release
- Buoyancy of release
- Amount/Duration of release
- Temperature of release
- Weather conditions
- Local land and terrain
24
Q
Inputs required for ‘Phast’ (5)
A
- Map
- Materials information
- Items of equipment to be analysed
- Weather conditions
- Obstructions on site
25
Q
Possible flammable outcomes (fires and explosions) (6)
A
- Fireballs
- Jet fires
- Pool fires
- Flash fires
- BLEVE blast
- Vapour cloud explosion
25
Q
How should toxic chemicals be stored? (8)
A
- Ensure the storage area is clearly identified with warning signs, clear of obstructions, and is only accessible to authorized/trained personnel
- Before storing toxic materials, inspect all incoming containers to ensure they are undamaged and properly labelled.
- Do not accept delivery of defective containers, be sure to store toxic materials in the containers recommended by suppliers.
- Keep the minimum amount possible
- Inspect storage containers regularly
- Ensure containers are tightly closed
- Store in correct conditions (Temperature)
- Containers should be stored in trays made of compatible materials so spills and leaks can be contained
26
Q
What does ‘COSHH’ abbreviate
A
‘Control of Substances Hazardous to Health’
27
Q
What substances does ‘COSHH’ cover?
A
- Chemicals
- Products containing chemicals
- Fumes
- Dust
- Vapours
- Nanotechnology
- Gases and asphyxiating gases
28
Q
Pure hazard identification
A
- Checklists
- What if study
- Hazard identification (HAZID)
- Hazard and operability study (HAZOP)
29
Q
Supplementary hazard identification techniques
A
- Relative ranking
- Fault tree analysis
- Event tree analysis
- (FMEA) failure modes and effects analysis
- (LOPA) layers of protection analysis
30
Q
Fire triangle components
A
- Fuel
- Oxidiser
- Ignition source
31
Q
Types of fires
A
- Pool fires
- Jet fires
- Fireballs
- Pyrophoric fires
- Flash fires
- Dust fires
32
Q
What does BLEVE abbreviate?
A
Boiling Liquid Expanding Vapour Explosion
33
Q
Pool fires
A
- When liquid on the ground or in water is ignited
- fire burns steady as the fuel is provided by the evaporating liquid caused by the heat of the flames
- height of the flames is approx twice the diameter of the pool
- storage tank fires have similar characteristics
- never put fire water in pool fire as water turns into steam
34
Q
Jet fires
A
- generally from a small hole in a pipe or pressure vessel
- long flame that is stable and usually unaffected by wind
- release induces large amounts of air and burns with intense radiation
- Jet fires should be extinguished by turning off the gas supply otherwise unburned gas could accumulate and lead to an explosion
