The document summarizes a risk assessment conducted at the LPG tank truck unloading section of an LPG bottling plant. The objectives were to identify hazards, assess risks through fault tree analysis and event tree analysis, and estimate individual and societal risk. Methodology included HAZOP study to identify hazards, consequence analysis using PHAST Risk software, and calculation of individual risk using thermal radiation exposure models. Key findings were an individual risk of 1x10-4 per year and societal risk within acceptable limits defined by the F-N curve. Recommendations to reduce risk included following standard operating procedures and improving safety systems.

1. RISK ASSESSMENT AT TANK- TRUCK
UNLOADING SECTION OF LPG
BOTTLING PLANT
Presented By:
Gaurav Kumar Singh Rajput (16160019)
Guide: Mr. ANISH JOB KURIAN
1

2. Presentation outline:
Title Justification
Introduction
Objective
Relevance
Methodology
Conclusion
Recommendations
Reference
2

3. TITLE JUSTIFICATION
 LPG tank truck unloading section is the most critical section of
LPG Bottling plant, as LPG is unloaded and delivered to
mounded bullets from the tank truck with the help of liquid
and vapour line using compressor.
 Unloading process is not fully automatic, it includes human
intervention so, there are chances of error.
 It possess various hazards like leakage of LPG, BLEVE, flash
fire, explosion which are disorganized in the level of impact
and perceived risk.
 So a proper identification of hazards and consequence
analysis is necessary to identify hazards and their related risk.
3

4. INTRODUCTION
 India is the second largest consumer of LPG in the world after
China.
 Liquified petroleum gas (LPG) is a clean fuel and during 2017-
18, more than 2.26 crore new LPG connections have been
released.
 LPG is highly flammable, odourless, non toxic and non
corrosive liquid, which causes severe hazards when released
in atmosphere.
 Owing to its very low boiling point and narrow flammability
limit, LPG is extremely hazardous when released into the
atmosphere.
4

5. OBJECTIVES
 Hazard identification
• To find hazards by conducting HAZOP
 Risk assessment
• Fault Tree Analysis
• Find out basic events for various final events like BLEVE, VCE etc.
• To find out various causes and consequences of the scenario.
• Event Tree Analysis
• To find out the various consequences of single basic events.
• To find out the cause, consequence and development of scenarios.
 Consequence Analysis
• Mathematical models provide quantitative estimation of radiation from
BLEVE.
• SAFETI provides graphical representation of the BLEVE, VCE, Jet fire on the
basis of radiation, over pressure, vapour cloud explosion, etc.
 Estimation of risk
• Individual risk by ALARP diagram.
• Societal risk by F-N curve.
5

6. RELEVANCE
 This methodology can be applied to tank- truck unloading
section of LPG Bottling plants where finding risk associated
with BLEVE is of utmost importance. This can enable
precautionary measures to be taken for disaster management
in case of emergency.
 Research on risk analysis of LPG bottling plant is very sparse
and risk analysis of unloading section has not been to the best
of our knowledge.
6

7. Many researches have been done on transportation related accidents of LPG.
One such case study was LPG truck tanker accident in Kannur, Kerala.
(Nilambar Bariha,2016)
 It covers the hazards during transportation of LPG tank truck and analyses the
behavior and effect of different scenarios like jet fire , flash fire, bleve and its
effect on vessel.
 It concluded that BLEVE was most severe phenomena of domino sequence and
its effects are most catastrophic that can affect nearby population and
environment.
 Modeling and simulation results of the fireball, jet flame radiation and explosion
overpressure matches with the actual loss reported from the site.
 The thermal radiation results obtained were used to calculate the probability of
burn injuries due to LPG accident in real scenarios.
 The fireball results show an area of about 200m radius badly affected .
LITERATURE REVIEW
7

8.  Another study was impact assessment of Thermal Radiation hazard from LPG
Fireball
(Bhisham K. Dhurandher, Ravi kumar, 2015)
 It focus on the failure of pressure vessel containing pressure liquified petroleum
gas leads to Boiling Expanding Vapour Explosion.
 Further ignition of released gas results in the formation of fireballs.
 In paper the semi -empirical equations are presented that represent the impact
assessment of thermal radiation hazards from the liquified petroleum gas
fireballs.
 The diameter, duration and height of the fireballs is directly proportional to the
amount of flammable materials present in the tanker at the time of
accident/failure.
 Safe separation distance and the probability of injuries and death varies
depending on the amount of fuel carried by the tanker.
Incident analysis of Bucheon LPG filling station pool fire and BLEVE (Kyoshik Park,
2006)
 An LPG filling station incident in korea has been studied.
 The direct cause of the incident was concluded to the faulty joining of the
couplings of the hoses during the butane unloading process from a tank Lory into
an underground storage tank.
 The faulty connection of a hose to the tank lorry resulted in a massive leak of gas
followed by catastrophic explosion.
8

9. METHODOLOGY
The Risk Assessment involves the following steps
1. Identification of the hazards involved.
2. Analysis of the consequence of hazard.
3. Evaluation of the probability of occurrence of failure.
4. Assessment/Quantification of the risk involved ( for the
property and for the people) within and outside the
area/plant.
5. Suggestions / Recommendations
9

10. 1. Identification of the hazards involved:
 Hazard identification is part of the process used to evaluate if any
particular situation, item, thing, etc may have the potential to cause
harm.
 We choose HAZOP study as hazard identification technique.
2. Analysis of the consequence of hazard:
 Hazard analysis includes: Estimating how often an incident (hazardous
event) will occur; estimating the consequences to persons, environment,
and plant; and deciding the required amount of risk reduction.
 We use FTA & ETA as risk assessment tool.
3. Evaluation of the probability of occurrence:
 The failure frequencies for different types of equipment are estimated
using generic failure rate databases published by organizations such as
International Oil & Gas Producers Association (OGP). OGP Report No.434-
1 “Process Release Frequencies” for equipment & piping.
 Also available from the book HAZARD IDENTIFICATION AND RISK
ASSESSMENT by Geoff wells.
10

11. 4. Assessment/Quantification of the risk involved:
 The quantitative risk analysis is carried out using the renowned software
package PHAST Risk (also known as SAFETI) developed and marketed by
Det Norske Veritas (DNV) of Norway.
 The following input data are required for the risk calculation:
 Process data for release scenarios (material, inventory, pressure,
temperature, type of release, leak size, location, etc.)
 Estimated frequency of each failure case.
 Distribution of people in the plant/adjoining area during the day and
night time.
 Distribution of wind speed and direction (wind rose data).
 Ignition sources.
11

12.  The results of quantitative risk analysis are commonly represented by the
following parameters:
 Individual Risk
 Societal Risk
 Individual risk is the risk that an individual remaining at a particular spot
would face from the plant facility
 The total individual risk at each point is equal to the sum of the individual
risks, at that point and it is called as societal risk
12

13. 13

14. 14
ROV

15. Project: HAZOP study of HPCL LPG
Bottling plant
Session date: Dec 2018
Section
descriptio
n:
LPG receipt from tanker, LPG
compressor, LPG mounded
bullet
Section: ROVs
Design
intention:
To receive and store LPG in
mounded bullets.
Revision date:
-
Ref. No Parameters Guidewor
ds
Cause Consequence Safeguards
1
Flow More 1. ROV-
stuck
open
Possible over
pressurizatio
n of the
mounted
bullet,
leading to
rupture
causing
fire/explosion
1. SOP based operation.
2. Level Transmitters
provided
3. High Level Alarm
provided on bullets
4. Gas detection system.
5. Manned Operation.
6. ESDs on Manual
operation.
7. Sprinklers based on
Quartzoid Bulb (triggers
at 79 Degree)
8. Fire Fighting System.
HAZOP
15

16. Ref. No Parameters Guidewords Cause Consequence Safeguards
2. Change over
from one
storage vessel
to another
failure
1. Process
upset
2. Possible
over
pressurization
of the
mounted
bullet, lading
to rupture
causing
fire/explosion
1.SOP based operation.
2.Level Transmitters
provided
3.High Level Alarm
provided on both bullets
4.Gas detection system.
5.Manned Operation.
6. ESDs on Manual
Intervention.
7. Sprinklers based on
Quartzoid Bulb (triggers at
79 Degree)
8.Fire Fighting System.
1.1
Less/No 1. Empty LPG
tanker
Process offset
loss of
inventory to
bullet.
1.Manned operation
2.SOP
3.Local pressure
2. Compressor
trip
Process upset,
operation
delays
1. High discharge pressure
trip provided
2. Manned Operation.
3. Inspection and
maintenance
4. Dos & DON’T’S
16

17. Ref. No Parameters Guidewor
ds
Cause Consequence Safeguards
3. ROV-fails
close
Possible over
pressurization
upstream,
leading to
fire/explosion
1. Manned operation
2. Inspection and
maintaince
4. Leakage
and rupture
Loss in
inventory,
possible
fire/explosion
1. Excess flow check
valve
2. Gas detection system
3. Manned operation
4. ESD
5. Firefighting system
1.2
Other
than
Water
present in
LPG tanker
Process
offset, No
safety hazard
1. SOP based operation
2. Gas detection system
3. Manned operation
4. Inspection and
maintenance
5. Water draining of
Bullets
17

18. Fault Tree
18

19. Event Tree
19

20. SAFETI- Input data:
 Accident scenarios
 Population data
 Map
 Material
 Ignition sources
 Weather conditions
20

21. SAFETI-Input data:
 Accident scenarios –
 LPG Tanker -
 Material-
S.N
o
Description Data
1 Length (m) 12.5
2 Diameter (m) 1.5
3 Capacity (tonne) 17/18
S.No Description Data
1 Mass inventory (tonne) 12/13
2 Phase to be released Liquid
3 Temperature (oC) 27
4 Pressure (bar) 7-9
21

22. SAFETI- Input data:
 Catastrophic rupture-
 Flammable-
S.No Description
Data
1
Release location – Tank head (m)
Elevation (m)
1.2
1
2 Outdoor release angle (deg) 0
3 Outdoor release direction Horizontal
4 Failure rate (per year) 1.5 x 10-5
S.No Description Data
1 Explosion method TNT
2 Jet fire method Cone model
3 Fireball model TNO model
22

23. SAFETI- Input data:
 Accident scenarios-
 Liquid line rupture-
S.N
o
Description
1 Pipe diameter (mm) 150
2 Hole – Orifice diameter (mm) 25
3 Release height from vessel bottom (m) 0
4 Release location – Tank head (m)
Elevation (m)
1.2
1
5 Outdoor release direction Horizontal
6 Outdoor release angle (deg) 0
7 Frequency of leak (per year) 2.7 x 10-6
23

24. SAFETI- Input data:
 Population data -
S.No. Location 1st shift 2nd shift 3rd shift Gen. shift Total
1 Bullet Area 0 0 0 0 0
2 Pump House 1 1 0 0 2
3 TT Gantry 1 1 0 0 2
4 Valve Changing shed 3 3 0 0 6
5 Filling shed 10 10 0 0 20
6 Storage Shed 3 3 0 0 6
7 Unloading shed 7 7 0 0 14
8 Loading Shed 7 7 0 0 14
9 MCC 2 1 0 0 3
10 Retesting Shed 9 0 0 0 9
11 Admin Building Area 5 0 0 10 15
12 Security Cabin 5 5 5 1 16
Total shift wise 53 38 5 11 107
24

25. SAFETI- Input data:
 Map-
 Google earth
 Plant layout
 Material-
 LPG (liquefied petroleum gas)
 Mixture of Propane(60%) and Butane (40%)
 Ignition sources-
 Open flame ( Kitchen)
 Spark from electrical cable (Electrical switchgear room and
transformer)
 Spark from another vehicle (Vehicles moving on the road)
 Diesel generator
 Intentionally done
25

26. SAFETI- Input data:
 Weather conditions
Month Max. Temperature (°C) Min. Temperature (°C) Precipitation
(inches)
January 31.6 22.0 0
February 32.0 23.4 0
March 32.7 25.0 1
April 33.1 26.1 4
May 32.4 25.8 10
June 29.4 24.0 25
July 28.4 23.5 25
August 28.3 23.5 23
September 29.5 24.0 13
October 30.6 24.0 11
November 31.3 23.6 7
December 31.6 22.7 1
Description #1 #2 #3
Temperature (°C) 23 27 30
Wind speed (m/s) 2 3 5
Atmospheric Stability D D D
Monthly average weather data
Weather Parameters for Risk Analysis
26

27.  Wind rose diagram
Wind rose diagram for distribution of direction from which wind is
blowing and wind speed
Wind Rose Diagram for Kochi
27

28. 28

29. 29

30. 30

31. 31

32. 32

33. 33
Ellipse @4kw/m2
Ellipse
@12.5kw/m2
Intensity Radii for BLEVE/Fireball

34. 34
Category 5D
Category 3D
Category 2D

35. RISK CALCULATION:
INDIVIDUAL RISK
Individual risk is defined by as risk to a person in the vicinity of a hazard.
This includes the nature of the injury to the individual, the likelihood of the
injury occurring and the time period over which the injury might occur. The
individual risk is a frequency of fatality, usually chances per million per year.
35
IRx,y = Total individual risk of fatality at geographic location x,y.
IRx,y,i = Individual risk of fatality at geographical location x,Y from the
incident outcome case i.
n = Total number of individual outcome cases from the industrial area.

36. 36
IRx,y,i = fi * pf,i
fi = frequency of incident outcome case i. (from the frequency
analysis)
pfi = probability that that incident outcome case i will result in a
fatality at location x,y. (from the consequence and effect models)
The upper limit of tolerable risk to public, 1 x 10-4 per year is in
the range of risk due to transport accidents. The upper limit of
acceptable risk, 1 x 10-6 per year, is in the range of risk due to
natural hazard such as lightning.

37. INDIVIDUAL RISK CALCULATION
The probit functions are used to calculate the percentage of lethality and first degree
burns respectively that will occur at a particular thermal load and period of exposure
of a unprotected body.
Pr = -36.38 + 2.56ln (tq4/3)
Pr = -39.83 + 3.0186(tq4/3)
Pr = probit, the measure for the percentage of people exposed who incur a particular
injury
q = Thermal load (w/m2)
t = exposure time in minutes
Assumes t = 20 and q = 37.5kw/m2
So,
Pr = 7.24
37

38. % 0 1 2 3 4 5 6 7 8 9
0 - 2.67 2.95 3.12 3.25 3.36 3.45 3.52 3.59 3.66
10 3.72 3.77 3.82 3.87 3.92 3.96 4.01 4.05 4.08 4.12
20 4.16 4.19 4.23 4.26 4.29 4.33 4.36 4.39 4.42 4.45
30 4.48 4.50 4.53 4.56 4.59 4.61 4.64 4.67 4.69 4.72
40 4.75 4.77 4.80 4.82 4.85 4.87 4.90 4.92 4.95 4.97
50 5.00 5.03 5.05 5.08 5.10 5.13 5.15 5.18 5.20 5.23
60 5.25 5.28 5.31 5.33 5.36 5.39 5.41 5.44 5.47 5.50
70 5.52 5.55 5.58 5.61 5.64 5.67 5.71 5.74 5.77 5.81
80 5.84 5.88 5.92 5.95 5.99 6.04 6.08 6.13 6.18 6.23
90 6.28 6.34 6.41 6.48 6.55 6.64 6.75 6.88 7.05 7.33
% 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
99 7.33 7.37 7.41 7.46 7.51 7.58 7.65 7.75 7.88 8.09
Probit to Percentage Conversion:
38

39. From conversion table
pfi =0.99
Frequency of Bleve fire ball LPG = 1*10-6
i Rx,y = fi*pfi
= 1*10-6 *0.99*4 (considering 4 unloading operations at the same
time)
=3.96 *10-6
The values of maximum individual risk to plant personnel in comparison
with the risk tolerance criteria are shown in Figure.
39

40. Max. Individual
Risk: 3.96 x 10-6
40

41. SOCIETAL RISK:
Societal risk is a measure of risk to a group of people. It is most often expressed in
terms of the frequency distribution of multiple casualty events. (FN curve)
Ni = number of fatalities resulting from incident outcome case i.
Px,y = number people at locations x,y.
pf,i = probability that that incident outcome case i will result in a fatality at location x,y.
Estimation of societal risk
N= Px,y *pf
Px,y = 107
pf V = 0.99
N = 107*0.99
= 106
41

42. EVENT BASE
FREEQ
UENCY
DIREC
TION
DAY/NIGHT OUTCOME
FREEQUENCY
OUTCOME CUMMU
LATIVE
FREEQ
UENCY
NW-day 1.0E-6 0.15 1 1.5E-7 40 1.5E-7
SW-day 1.0E-6 0.2 0.8 1.6E-7 25 3.1E-7
SW-night 1.0E-6 0.2 0.2 4.0E-8 5 1.0E-6
SE-day 1.0E-6 0.25 1 2.5E-7 15 9.6E-7
NE-day 1.0E-6 0.4 1 4.0E-7 22 7.1E-7
EVENT BASE
FREEQUEN
CY
DIRECTION DAY/NIGHT OUTCOME
FREEQUENCY
(PER YEAR)
OUTCOME
(FATALITI
ES)
EXPECTATION
VALUE(FATALITIES
PER YEAR)
NE-day 1.0E-6 0.4 1 4.0E-7 22 8.8E-6
SE-day 1.0E-6 0.25 1 2.5E-7 15 3.8E-6
SW-day 1.0E-6 0.2 0.8 1.6E-7 25 4.0E-6
NW-day 1.0E-6 0.15 1 1.5E-7 40 6.0E-6
SW-Night 1.0E-6 0.2 0.2 4.0E-7 5 2.0E-7
1.0E-6 2.3E-5
42

43. 1.50E-07
3.10E-07
7.10E-07
9.60E-07
1.00E-06
1.00E-07
1.00E-06
1.00E-05
1 10 100
CUMMULATIVE
FREQUENCY
(PER
YEAR)
NUMBER OF FATALITIES (N)
F-N curve
43

44. 1.50E-07
3.10E-07
7.10E-07
9.60E-07
1.00E-06
1.00E-04
1.00E-06
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
1.00E-02
1 10 100
CUMMULATIVE
FREQUENCY
(PER
YEAR)
NUMBER OF FATALITIES (N)
F-N curve
The FN curves for societal risk are shown in figure. s The resulting values of fatalities
(N) are plotted against cumulative frequency (F) conventionally on a log/log plot.
44

45. CONCLUSION
 Maximum individual risk to personnel working in the LPG bottling plant
is 3.96E-06 per year, which is in the tolerable part of ALARP region.
 Societal risk due to LPG bottling plant is in Broadly Acceptable region
 Based on the above results it is concluded that the LPG storage &
bottling plant of HPCL at Kochi conform to the specified risk tolerance
criteria.
 Results of consequence analysis indicate that significant fire radiation
and explosion overpressure effects for maximum credible leak scenarios
are mostly within the plant boundary.
45

46. RECOMMENDATIONS
The following recommendations are made to ensure that the risks at HPCL
Kochi LPG storage and bottling plant are maintained at low level.
1. Emergency push buttons for closing the remote-operated shut-off valves
(ROSOVs) and stop LPG pumps/compressors are to be provided in control
room and other safe locations.
2. Flange joints are potential source of leakage. Raised face flanges with
metallic spiral wound gaskets or tongue & groove type flanges should be used
in LPG service as specified by OISD.
3. Prevention of ignition
 The flame-proof electrical equipment should be properly maintained by
competent and trained personnel to ensure their integrity.
 The spark arrestors used for vehicles should be maintained by regular
checking.
 Use of cell phones should not be allowed in the LPG installation.
46

47. REFERENCES
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