November 24,
2010
Process Safety Assessment Process Safety Assessment
Different Techniques Different Techniques ––
Beyond ComplianceBeyond Compliance
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AGENDAAGENDA
Process Safety StudiesProcess Safety Studies-- Background Background
Safety Studies as decision making toolsSafety Studies as decision making tools
QRA QRA ––Example Example
Limitations Of StudiesLimitations Of Studies
Points to PonderPoints to Ponder
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Inventory of 1800 Incidents World wideInventory of 1800 Incidents World wide
Source DNV
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Pipework - few thousands
of kms( 270)
Flanges- thousands in
numbers( 55,000)
Valves - thousands in
numbers( 44,000)
Pump seal - 1500 Compressors - 80
Relief valves - 1000
Drains - 1200
Vents - 1000
INVENTORY OF LEAK INVENTORY OF LEAK
SOURCESSOURCES
Source DNV
Source DNV
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Different Process Safety Studies Different Process Safety Studies
» Hazard & Operability [HAZOP] Studies
» Project, Health, Safety & Environment
Review [PHSER]
» Design/Review of Hazardous Area
Classification
» Quantitative Risk Assessment [QRA]
» Layer of Protection Analysis [LOPA]
» Safety Integrity Levels [SIL] Assessment,
Verification & Validation
» Project Quantitative Risk Assessment
[PQRA]
» FMEA/ETA/FTA
» Health Safety Environment Critical
Equipment Systems [HSECS]
» Comprehensive Safety Audits
» Disaster Management Plans
» Safety Training Program’s
» Control Hazard & Operability
Analysis [CHAZOP]
» Process Safety Management
Audits [PSM Audit]
» Pre-Startup Safety Review
[PSSR] / Pre-
commissioning Audits
» SIMOPS
» Fire Risk Assessment / Fire
Safety Audit
» Fire Hazard Management
» Design/Review
» Fire & Gas Detection
System
» Fire Protection System
[Active & Passive]
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CASE STUDY OF RAILWAY CASE STUDY OF RAILWAY
SPUR LINESSPUR LINES
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Utility of Consequence Analysis
The purpose of the consequence analysis is to provide inputs to the Quantitative Risk Analysis which quantifies the risk in terms ofprobabilistic figures.
The effect zone distances given in studies should not be directly taken as the risk levels. They only provide the maximum possibleeffects in case the scenarios which are envisaged to be with in the realms of probability.
In addition to giving the inputs for QRA these distances help inplanning the emergency handling. The output of consequence analysis will help in identifying the safe distances for emergency handling personnel like fire fighters, fixing the emergency control and rescue centres, assembly points, Personal Protective Equipment requirement, protection required for key facilities etc.
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Questions to be answered through Studies areQuestions to be answered through Studies are
Identification of Hazards and Major Loss of Containment (LOC) evIdentification of Hazards and Major Loss of Containment (LOC) events ents
Calculation of physical effects of accidental scenarios, which iCalculation of physical effects of accidental scenarios, which includes ncludes
frequency analysis for incident scenarios leading to hazards to frequency analysis for incident scenarios leading to hazards to people people
and facilities (flammable gas, fire, and smoke, explosion overprand facilities (flammable gas, fire, and smoke, explosion overpressure essure
and toxic gas hazards) and consequence analysis for the identifiand toxic gas hazards) and consequence analysis for the identified ed
hazards covering impact on people and potential escalation.hazards covering impact on people and potential escalation.
Damage limits identification and quantification of the risks andDamage limits identification and quantification of the risks and contour contour
mapping on the layouts.mapping on the layouts.
Individual risk quantification and contour mapping.Individual risk quantification and contour mapping.
Societal risk quantification and contour mappingSocietal risk quantification and contour mapping
Hazard mitigation recommendations based on QRAHazard mitigation recommendations based on QRA
Evaluate the risk levels for simultaneous use of both the spurs Evaluate the risk levels for simultaneous use of both the spurs for for
wagon unloadingwagon unloading
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EVENT TREE ANALYSIS
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INPUT PARAMETERS FOR MODELLING
S. No ScenarioFlowrate / capacity
Pressure Jet Fire
Late Pool Fire
Late Explosion
1
Rupture of Rail wagon
containing LPG 35 MT 7 kg/cm2
Not
Possible
Not
Possible Possible
2
Rupture of Rail wagon
containing MS 65 M3 Atm
Not
Possible Possible Possible
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Damage Limits Identification and mapping on the layout
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Damage Limits Identification and mapping on the layout
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THREE STEPS OF CONSEQUENCE MODELLING
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LATE EXPLOSION CONSEQUENCES
S. No Scenarios
Damage distances in Mtrs3D 5D
0.03 bar 0.1 bar0.3 bar
0.03 bar 0.1 bar 0.3 bar
1
Rupture of Rail wagon
containing LPG 795.16 505.68 461.42
807.4
8 545.81 504.10
2
Rupture of Rail wagon
containing MS 573.00 445.86 402.87
477.7
1 334.00 286.94
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LATE POOL FIRE CONSEQUENCES
S. No Scenarios
Damage distances in Mtrs3D 5D
4 Kw/m2
12.5 Kw/m2
37.5 Kw/m2
4 Kw/m2
12.5 Kw/m2
37.5 Kw/m2
1
Rupture of Rail
wagon containing
LPG NA NA NA NA NA NA
2
Rupture of Rail
wagon containing
MS 131.14 54.53 NR 148.26 54.84 NR
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LPG FIRE BALL CONSEQUENCES
S. No Scenarios
Damage distances in Mtrs
3D 5D
4 Kw/m2
12.5 Kw/m2
37.5 Kw/m2
4 Kw/m2
12.5 Kw/m2 37.5 Kw/m2
1
Rupture of Rail wagon storing
LPG 471.47 242.88 32.40 471.74 242.88 32.40
Jet Fire Consequences – Not Applicable
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Definition of Risks
Individual Risk
The chance that a person staying at a fixed location
permanently is killed as a result of an accident in the
hazard zone (units/ year)
Societal Risk
A chance that in a single accident in the hazard source a certain number of victims is exceeded.
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INDIVIDUAL RISK – CONSEQUENCE ANALYSIS
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SOCIETAL RISK
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INDIVIDUAL RISK CONTOUR – Domino effects for simultaneous unloading of Rail wagons of LPG & MS.
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SOCIETAL RISK F-N CURVE – Domino effects for simultaneous unloading of Rail wagons of LPG & MS.
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INDIVIDUAL RISK CONTOUR – Domino effects for simultaneous Domino effects for simultaneous
unloading of two MS Rail wagonsunloading of two MS Rail wagons
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SOCIETAL RISK F-N CURVE – Domino effects for simultaneous Domino effects for simultaneous
unloading of two MS Rail wagonsunloading of two MS Rail wagons
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SUMMARY OF INDIVIDUAL AND SOCIETAL RISKS
S. No ScenariosIndividual Risk
Societal Risk
1Rupture of Rail wagon containing LPG(Spur I or Spur II with only one in operation) 2.1933 E-5 2.5179 E-5
2Rupture of Rail wagon containing MS(Spur I or Spur II with only one in operation) 6.6569 E-5 1.0709 E-4
3Domino effects for simultaneous unloading of LPG & MS rail wagons(both the spurs in operation) 4.5239 E-4 6.9196 E-4
4Domino effects for simultaneous unloading of MS from both the spurs 3.9066 E-4 6.0587 E-4
5Domino effects for simultaneous unloading of HSD & MS rail wagons(both the spurs) 7.1613 E-5 1.0703 E-4
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ALARP
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RISK ACCEPTANCE CRITERIA
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MAJOR RISK CONTRIBUTORS
S. No ScenariosIndividual Risk
Societal Risk
1Rupture of Rail wagon containing LPG(Spur I or Spur II with only one in operation) 2.1933 E-5 2.5179 E-5
2Rupture of Rail wagon containing MS(Spur I or Spur II with only one in operation) 6.6569 E-5 1.0709 E-4
3Domino effects for simultaneous unloading of LPG & MS rail wagons(both the spurs in operation) 4.5239 E-4 6.9196 E-4
4Domino effects for simultaneous unloading of MS from both the spurs 3.9066 E-4 6.0587 E-4
5Domino effects for simultaneous unloading of HSD & MS rail wagons(both the spurs) 7.1613 E-5 1.0703 E-4
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GENERAL HIERARCHY OF RISK REDUCTION MEASURES
Prevention (by distance or design)
Detection (e.g. fire & gas, leak detection)
Control (e.g. emergency shutdown & controlled depressurization)
Mitigation (e.g. firefighting and passive fire protection)
Emergency response (in case safety barriers fail)
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STANDARDS REFERRED FOR PROVIDING SOLUTIONS
Guidelines for Quantitative Risk Assessment CPR 18 E (Purple
book), Committee for the Prevention of Disasters, Netherlands
(Edition : PGS 3, 2005)
Reference Manual Bevi Risk Assessment, Version 3.2,2009
Guidelines for Hazard Evaluation Procedures, Center for
Chemical Process Safety, American Institute of Chemical
Engineers, New York, New York, 1992.
IS 15656: 2006 Hazard identification and risk analysis - Code of
practice
Applicable OISD Standards
Statutory Requirements
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RISK REDUCTION MEASURES – CREDIT AT QRA
Blocking systems
Excess Flow Valves
Fire Protection systems
Supreession systems accommodated to limit the consequences of a LOC – eg. rerouting/ segregation with fencing, Restriction on new construction, unauthorised movement, Water screens to minimize the dispersion of substances (soluble in water) into the atmosphere and the use of foam to reduce evaporation of pool considering their response time, proven effectiveness by means of periodic testing,
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RISK REDUCTION MEASURES – SUGGESTED
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RISK REDUCTION MEASURES – SUGGESTED CONTD.,
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RISK REDUCTION MEASURES – SUGGESTED CONTD.,
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RISK REDUCTION MEASURES – SUGGESTED CONTD.,
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ADDITIONAL RISK CONTROL MEASURES SUGGESTED
HAZOP needs to be carried out for the existing unloading network before implementing
the additional risk control measures
Location and position of existing water monitors provided on FCI godown side to be
reviewed. In the present arrangement water may not reach the unloading area.
Water spray system to be provided on the second spur also to reduce the risk levels of
unloading of LPG
Fire rated ROV to be provided in the unloading header of petroleum products so as to
remotely control the operations.
Fire water network analysis to be done to determine the adequacy of Fire water storage,
reliability of interconnectivity, to determine whether the fire water network meets the
OISD 117 norms (two simultaneous fires-tank farm and wagon unloading)
Co-ordination between various agencies utilizing the unloading faciltly and Pipeline
control rooms to be strengthened.
Emergency plan to be updated on priority basis and off site emergency plan to be
prepared taking into consideration new housing colonies near wagon unloading area
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ADDITIONAL RISK CONTROL MEASURES SUGGESTED contd.,
Drains on East side to be restored. Most of the places they were found buried
Wagon Unloading area: Slopes on both sides to be strengthened to prevent land slide during
monsoon season.
Road network to be developed on both sides of the wagon unloading area to facilitate
movement of fire brigade vehicles.
Vegetation on both sides of the rail network to be removed to provide easy access to
monitors
Vehicles parked close to the compound wall of neighbouring expanded parking area can roll
over into the wagon unloading area due low height of compound and blast wall. Compound
wall height need to be increased to prevent roll over
Escape route in wagon unloading area: There is only one entry and exit to this area on the
southern side. POL to examine the feasibility of providing an escape route on Northern side
through neighbouring godown area. .
As the second rail network is not used at many places the rails were found bent and sleepers
out of position. POL to get track inspection /certification done by Indian Railways before
putting into use the second spur
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Heat Flux models for design Power PlantHeat Flux models for design Power Plant-- Evacuation Evacuation
Transformer locationTransformer location
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Where R we now ?Where R we now ?
�� After Jaipur fire, all downstream valves are recommended to be SAfter Jaipur fire, all downstream valves are recommended to be SIL IL
3 Rated3 Rated
�� With changing times even the properties are changing. Recently With changing times even the properties are changing. Recently
Ammonia and Butadiene properties and there by consequences Ammonia and Butadiene properties and there by consequences
have been revisedhave been revised
�� It is possible to model the domino effect to some extentIt is possible to model the domino effect to some extent-- for for
example earlier it is just the pin hole leak now it is possible example earlier it is just the pin hole leak now it is possible to to
predict the damage after the pinhole leakpredict the damage after the pinhole leak-- if it causes a pipeline if it causes a pipeline
rupture what will be the individual riskrupture what will be the individual risk
�� Cost of Jaipur fire for insurance companies is 177 croreCost of Jaipur fire for insurance companies is 177 crore
�� One of the reasons mentioned in OISD is that fire would have gonOne of the reasons mentioned in OISD is that fire would have gone e
to ETP and oil and water separator and would have got ignitedto ETP and oil and water separator and would have got ignited-- in in
conventional QRA we donot consider these type of scenarios atallconventional QRA we donot consider these type of scenarios atall
Almost everyone agrees that ignition occurred 75 min after the Almost everyone agrees that ignition occurred 75 min after the
initial leakinitial leak-- where as our modeling talks about 10 min leakwhere as our modeling talks about 10 min leak
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BP Texas refinery QRA had only 85 scenariosBP Texas refinery QRA had only 85 scenarios-- can a refinery QRA can a refinery QRA
be done with 85 scenarios? The leakage of isomer through be done with 85 scenarios? The leakage of isomer through
Chimney was never consideredChimney was never considered
As per the Bruncefield investigation report the real cause is yeAs per the Bruncefield investigation report the real cause is yet to t to
be established as it defies conventional wisdom. As per the latebe established as it defies conventional wisdom. As per the latest st
theory the green belt around the depot would have caused theory the green belt around the depot would have caused
entrapment of dispersing gas entrapment of dispersing gas
Before Buncefield, vapour cloud explosions (VCEs) were not Before Buncefield, vapour cloud explosions (VCEs) were not
considered as aconsidered as a likely scenario at fuel storage sites. The current likely scenario at fuel storage sites. The current
uncertainty regarding the explosionuncertainty regarding the explosion mechanism at Buncefield mechanism at Buncefield
suggests that such an approach may no longer be validsuggests that such an approach may no longer be valid
A blast overpressure inexcess of 500 millibar over a radius of A blast overpressure inexcess of 500 millibar over a radius of 250 250
metres has been assumed to be the magnitude andextent of the metres has been assumed to be the magnitude andextent of the
explosion to be used as the basis of the credible incident explosion to be used as the basis of the credible incident with with
respect to emergencyarrangements.respect to emergencyarrangements.
Safety studies can be used for decision making if you know how tSafety studies can be used for decision making if you know how to o
interpret resultsinterpret results
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The sprinkler flow ratewhich is presently 3 LPM (OISD standard) The sprinkler flow ratewhich is presently 3 LPM (OISD standard)
may be reviewed. The NFPA(US) Standard recommends 10 LPM may be reviewed. The NFPA(US) Standard recommends 10 LPM
where as IPwhere as IP--55 (UK) Standardrecommends much lower figure55 (UK) Standardrecommends much lower figure
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Extensive research was carried out into the Buncefield accident.Extensive research was carried out into the Buncefield accident.
Thisincluded phase (i) modeling and recreation of the blast Thisincluded phase (i) modeling and recreation of the blast
conclusivelyindicated that the presence of extensive greenery i.conclusivelyindicated that the presence of extensive greenery i.e. e.
dense rows of bigtrees along with low level raw vegetation greatdense rows of bigtrees along with low level raw vegetation greatly ly
contributed to acceleratethe contributed to acceleratethe ““DeflagrationDeflagration”” which first occurs in which first occurs in
““Unconfined Vapour CloudFire/flash fireUnconfined Vapour CloudFire/flash fire”” to to ““DetonationDetonation”” due to very due to very
fast acceleration of flame speedbeyond 500 meters per second or fast acceleration of flame speedbeyond 500 meters per second or
higher. Jaipur terminal too hadextensive greenery and rows of trhigher. Jaipur terminal too hadextensive greenery and rows of trees ees
along the plant road leading to MS tank 401along the plant road leading to MS tank 401--A and also good A and also good
growth of large trees both close to tank farmarea as well as neagrowth of large trees both close to tank farmarea as well as near r
portions of the boundary. The concept of providinggreen belt aloportions of the boundary. The concept of providinggreen belt along ng
the periphery of hazardous facility and also encouraginggreenerythe periphery of hazardous facility and also encouraginggreenery
within/close to plant area itself had been a practice for long.within/close to plant area itself had been a practice for long.
However, this practice needs to be reHowever, this practice needs to be re--examined for examined for
petrochemicals,refinery/petroleum terminals and such facilities petrochemicals,refinery/petroleum terminals and such facilities
wherein vapour cloud maywherein vapour cloud may
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Safety
Management
Safe
Technology
The Sprit of SAFETY ’
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