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November 24,

2010

Process Safety Assessment Process Safety Assessment

Different Techniques Different Techniques ––

Beyond ComplianceBeyond Compliance

Private and Confidential

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


Inventory of 1800 Incidents World wideInventory of 1800 Incidents World wide

Source DNV

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


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]


CASE STUDY OF RAILWAY CASE STUDY OF RAILWAY

SPUR LINESSPUR LINES


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.


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


EVENT TREE ANALYSIS


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


containing MS 65 M3 Atm

Not

Possible Possible Possible


Damage Limits Identification and mapping on the layout


THREE STEPS OF CONSEQUENCE MODELLING


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


containing LPG 795.16 505.68 461.42

807.4

8 545.81 504.10

2


containing MS 573.00 445.86 402.87

477.7

1 334.00 286.94


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


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


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.


INDIVIDUAL RISK – CONSEQUENCE ANALYSIS


SOCIETAL RISK


INDIVIDUAL RISK CONTOUR – Domino effects for simultaneous unloading of Rail wagons of LPG & MS.


SOCIETAL RISK F-N CURVE – Domino effects for simultaneous unloading of Rail wagons of LPG & MS.


INDIVIDUAL RISK CONTOUR – Domino effects for simultaneous Domino effects for simultaneous

unloading of two MS Rail wagonsunloading of two MS Rail wagons


SOCIETAL RISK F-N CURVE – Domino effects for simultaneous Domino effects for simultaneous

unloading of two MS Rail wagonsunloading of two MS Rail wagons


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


ALARP


RISK ACCEPTANCE CRITERIA


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


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)


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


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,


RISK REDUCTION MEASURES – SUGGESTED


RISK REDUCTION MEASURES – SUGGESTED CONTD.,


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


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


Heat Flux models for design Power PlantHeat Flux models for design Power Plant-- Evacuation Evacuation

Transformer locationTransformer location


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


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


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


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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