HAZARD IDENTIFICATION EXAMPLE CASES IN LPG AND OIL STORAGE Antony Thanos Ph.D. Chem. Eng. [e-mail]

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HAZARD IDENTIFICATIONEXAMPLE CASES IN LPG AND
OIL STORAGEAntony ThanosPh.D. Chem.
Eng.antony.thanos_at_gmail.com
This project is funded by the European
Union Projekat finansira Evropska Unija

Project implemented by Human Dynamics
Consortium Projekat realizuje Human Dynamics
Konzorcijum
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• HAZOP technique, liquid phase LPG line from tank
  to pump. Examine deviations for
• NO FLOW, LESS FLOW
• MORE TEMPERATURE
• LOSS OF CONTAINEMENT

LPG Tank
V-1
V-2
P-2
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• HAZOP in LPG (cont.), HAZOP form for use

No Deviation Causes Consequences Safeguards Comments, Recommendations
1 No flow
2 Less flow
3 More Temperature
4 Loss of Containment
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• HAZOP in LPG (cont.), answers example

No Deviation Causes Consequences Safeguards Comments, Recommendations
1 No Flow V1 or V2 closed and P2 starts Cavitation in pump, potential pump failure, as seal failure with LPG release, in prolonged or repeated cases No remote pump start capability (local only) and V2 very close to pump Closed suction results in excessive noise, operator will immediately identify incident Develop written procedure to require check of proper line-up before pump start. Installation of limit switches for V1 position with position signal to pump house.
2 Less Flow Level in tank very low (reduced suction to pump) As in No.1 Procedures require check for adequate level in tank before pump start. Examine installation of level transmitter with level indication to pump-house, along with visual alarm, forcing pump trip in very low level.
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• HAZOP in LPG (cont.), answers example

No Deviation Causes Consequences Safeguards Comments, Recommendations
3 More Temperature V1 and V2 closed in summer conditions Thermal expansion increases pressure, potential for pipe rupture Piping test pressure according to standards Install Thermal Relief Valve (TRV) between V1 and V2
4 Loss of Containment Piping mechanical failure Collision of vehicle in piping Release of LPG from tank, uncontrolled if V1 cannot close (failure close to V1) or failure upstream of V1 Manual isolation of V1 Install Fail-Safe remote operated isolation valve at valve outlet (internal if possible) Establish protection of piping routing from collisions
?µ?da HAZOP
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• Accident scenarios
• Define some worst-case scenarios for LPG
  installation

LPG Road Tanker 20 tn
2 in, gas phase
to other tanks, compressor
LPG BEST S.A.
LPG Tank 200 m3
LPG Tank 120 m3
2 in hose
to other tanks
Supply pipeline from refinery
6 in, liquid phase
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• Accident scenarios (cont.), answers example
• Storage area (tanks)
• Catastrophic failure of 200 m3 tank
• Movement facilities
• Catastrophic failure of road tanker
• Catastrophic failure (FBR) of 6 inch pipeline
  from refinery

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• Top event scenarios
• Initial event Catastrophic failure of 200 m3
  LPG tank, complete top events in event tree

PHASE IGNITION CONFINEMENT TOP EVENT
DIRECT

2-PHASE DELAYED NO CONFINEMENT
CONFINEMENT
NO IGNITION
DIRECT

LIQUID DELAYED NO CONFINEMENT
PHASE CONFINEMENT
NO IGNITION
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• Top event scenarios (cont.), answer
• Initial event Catastrophic failure of 200 m3
  LPG tank

PHASE IGNITION CONFINEMENT TOP EVENT
DIRECT FIREBALL (BLEVE)

2-PHASE DELAYED NO CONFINEMENT FLASH FIRE
CONFINEMENT UVCE
NO IGNITION SAFE DISPERSION
DIRECT POOL FIRE

LIQUID DELAYED NO CONFINEMENT FLASH FIRE
PHASE CONFINEMENT UVCE
NO IGNITION SAFE DISPERSION
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• HAZOP technique, Diesel tank in Refinery. Examine
  deviations for tank
• MORE TEMPERATURE
• LESS/MORE LEVEL
• LESS/MORE PRESSURE

Pressure/Vacuum Vent
LAH LAL
PVV
Emergency Relief Vent
EV
EV
MOtorized Valves
To pumpstations
MOV1
From harbour
MOV2
M
From refinery unit
Mixer
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• HAZOP in Diesel Tank (cont.), HAZOP form for use

No Deviation Causes Consequences Safeguards Comments, Recommendations
1 More Temperature
2 Less Level
3 More Level
4 Less Pressure
5 More Pressure
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• HAZOP in Diesel Tank (cont.), answers example

No Deviation Causes Consequences Safeguards Comments, Recommendations
1 More Temperature High temperature in feed from refinery (potential loss of cooling water at production unit exit) High pressure Vapour pressure exceeding flash point (elevated ignition hazard) TI (local Temperature Indicator) Mixer dampens temperature variations from feeds Installation of remoteTemperature Transmitter at production unit exit with Temperature Indication and Alarm High (TIAH) Installation of remote Temperature Transmitter with multiple temperature measurements (TITs) at various levels
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• HAZOP in Diesel Tank (cont.), answers example

No Deviation Causes Consequences Safeguards Comments, Recommendations
2 Less Level Unattended withdrawal from tank via pumpstation Potential loss of suction in pumps, with seal damage Mixer exposed, potential damage in mixer seal and leak/ignition LT, LAL (remote Level Transmitter with low level alarm) Install dedidated Low Low Level Switch (LLLS) with Alarm (LLLA) and automatic stop of mixer
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• HAZOP in Diesel Tank (cont.), answers example

No Deviation Causes Consequences Safeguards Comments, Recommendations
3 More Level Unattended feed from refiner or port Potential overpessure with overflow via EV or tank failure and leak to bund LT, LAH (remote Level Transmitter with Level Alarm High) Dedicated Level Switch High High (LSHH) with remote Level Alarm High High and automatic closure of feed MOVs Examine the potential of water hammer effects upstream harbour MOV1 during closure of MOV1
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• HAZOP in Diesel Tank (cont.), answers example

No Deviation Causes Consequences Safeguards Comments, Recommendations
4 Less pressure Excessive withdrawal flowrate from pump station Rapid temperature drop in ambient temperature (cooling of vapour space) Potential failure of tank shell with leak to bund PVVs prevent vacuum conditions Verify that PVV sizing for vacuum is set according to standards for max flow to pumpstations
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• HAZOP in Diesel Tank (cont.), answers example

No Deviation Causes Consequences Safeguards Comments, Recommendations
5 More Pressure High feed rate Wrorg component feed to tank (high volatile substance, (e.g. gasoline) Failure of PVVs External fire Potential vapour release via EV and ignition Tank failure and leak to bund in case of EV failure PVVs EV Verify capacity of PVV according to standards for max feed rate (either ship or production unit) Verify capacity of EV according to standards Verify that connections to tank originate only from diesel units and diesel loading arms from harbour