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Process equipment leak frequency data for use in QRA
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PROCESS EQUIPMENT LEAK FREQUENCY DATA FOR USE IN QRA
failure frequency guidance
DNV SERVING THE PROCESS INDUSTRYquantified risk assessment
02 I PROCESS INDUSTRY I quantified risk assessment I
■■ Asset risk management ■■ Enterprise risk management■■ Offshore classification■■ Safety, health and environmental risk management
■■ Ship classification■■ Technology qualification ■■ Verification
GLOBAL SERVICES TO THE MARITIME, OIL & GAS AND ENERGY INDUSTRIES
I quantified risk assessment I PROCESS INDUSTRY I 03
CONTENTS
The world must lean on new sources to create a sustainable energy system. Wind energy is one of the most important. But technical, environmental, and financial barriers must be removed to release its full-blown potential.
With over 25 years experience in wind energy, DNV understands the industry and what is required for success throughout the entire lifecycle of wind energy projects. Through our services and competent people, we can help get more out of wind energy projects.
THE POWER TO GENERATE RESULTS
04 1. Introduction05 2. Background on HCRD06 3. Application of Data08 4. Methodology
12 5. Calculating Release Rate16 6. Leak Frequency Datasheets38 7. References
04 I PROCESS INDUSTRY I quantified risk assessment I
Frequency estimates are recognised as one of the largest sources of uncertainty in Quantitative Risk Assessment studies.
1. INTRODUCTION
There are a few sources of data for failure frequency data for
process equipment loss of containment: Netherlands and
Belgium have issued two different onshore frequency data-
sets for use in Seveso Directive risk assessments, and some
companies and consultants have their own data. In many
cases the provenance of these data is uncertain and exam-
ples exist of frequencies that are too low and do not match
historical accident frequencies. It is detrimental to QRA
methodology that such old or inconsistent data is routinely
used. DNV is therefore publishing this booklet in order to
put best practice process equipment leak frequency data
into the public domain.
DNV’s data is derived from the Hydrocarbon Release
Database (HCRD) which has been compiled by the UK
Health and Safety Executive (HSE) over a 20 year period.
The database [2] contains details of over 4000 leak events at
oil and gas installations in the UK Continental Shelf. It
identifies 78 different types and size categories of process
equipment, and records the quantity of the release and the
release hole size. This is considered the most extensive
dataset of its type and superior to current published datasets
which often have much smaller and older data which do not
reflect current integrity management programs. DNV has
assessed this data for several years on behalf of a major oper-
ator. While the data is ‘noisy’, typical for real data, DNV has
applied a smoothing function to cover all leak sizes. Leaks
are differentiated for 17 equipment types. This analysis and
interpretation is complex: considerable effort is required to
obtain generic leak frequency data that are suitable for use
in Quantified Risk Assessment (QRA).
DNV believes that process industry will benefit from consist-
ent application of these generic leak frequencies in QRA,
and is therefore publishing its preferred dataset in order to
encourage standardisation across different users.
The booklet describes DNV’s methods for interpreting the
HCRD and describes its application to offshore, onshore
and LNG plant. The booklet also presents tabulations of
generic leak frequency data for different equipment types.
The booklet compares the DNV dataset against some alter-
native sources of leak frequency data and describes some
important reasons why the DNV interpretation of the HCRD
should be preferred.
DNV was commissioned by Statoil to define the model pre-
sented in this document, involving contractors Scandpower
and Safetec in the work.
I quantified risk assessment I PROCESS INDUSTRY I 05
The Piper Alpha incident occurred in 1988 and resulted in 167 people losing their lives. As a result of this disaster Lord Cullen conducted an inquiry [1].
2. BACKGROUND ON HCRD
The inquiry made 106 recommendations including the
requirement to report leaks to the HSE through the report-
ing of injuries, diseases and dangerous occurrences regula-
tions (RIDDOR). The HSE organises this data and makes it
publically available through the Hydrocarbon Release
Database (HCRD). The database started to be compiled in
October 1992 and now contains 20 years of experience in
hydrocarbon releases from the UK Continental Shelf.
Figure 1 shows the number of recorded leaks per year since
1992. (For each bar in the graph, the reporting period for
leaks is between April 1st and March 31st in the following
year. The first bar contains data for a six month period 1st of
October 1992 and the 31st of March 1993).
Figure 2 shows the breakdown of these leaks into three
categories as defined by HSE: minor, significant and major.
The average number of minor leaks per year between April
1st 1993 and March 31st 1998 is 82, whereas there were an
average of 109 minor leaks per year between April 1st 2006
and March 31st 2010. This increase may be due to an actual
increase in minor leaks or an improvement in the reporting
of these leaks. Detection of smaller leaks may also have
improved. The number of significant and major leaks has
decreased over the period, particularly major leaks which
have decreased by a factor of 12. In 2010 in the UK the oil
and industry committed to reducing its number of hydrocar-
bon emissions by 50% in 3 years. Two years into the three
year programme there has been a 40% reduction in the
number of leaks [1].
Determining the number of leaks that have occurred off-
shore provides only one part of the data that is required to
calculate leak frequency. The number of different types of
equipment offshore has also been recorded and quantified
since 1992, although HSE has recorded no change in the
equipment count since 2003 (Regarding system and equip-
ment population data, HSE notes that the responsibility for
maintaining the currency of this data rests with duty holders.
The population data in HCRD is provided by duty holders
on a voluntary database and it is not HSE’s role to update,
or verify this particular data. Use of this population data
would need to be made with caution). It is questionable that
the amount of equipment has remained the same offshore
since 2003. Maintaining an accurate equipment count is not
straightforward, for example the count of equipment on
mobile rigs would require the database operators to keep
track of the position of MOUs and their movements. The
equipment count on the UKCS is provided by the operators
on a voluntary database and it is not part of HSE’s role to
monitor or verify the equipment count. Therefore there are
uncertainties associated with the equipment count.
200
250
300
350
No. of
Leaks
Year
150
100
50
0
1993 1995 1997 1999 2001 2003 2005 2007 2009
1994 1996 1998 2000 2002 2004 2006 2008 2010
200
250
150
100
50
0
1993 1995 1997 1999 2001 2003 2005 2007 2009
1994 1996 1998 2000 2002 2004 2006 2008 2010
Minor Significant Major
Figure 1 Number of Leaks per year Figure 2 Number of leaks per leak category per year
06 I PROCESS INDUSTRY I quantified risk assessment I
3. APPLICATION OF DATA
3.1 OFFSHORE
The data in this booklet is based upon data from the UK
sector of the North Sea which has been collected by the HSE
in the hydrocarbon release database (HCRD). The data is
based on approximately 4000 recorded leaks recorded
between October 1992 and March 2010. This database has
been analysed by DNV to produce generic leak frequencies
applicable for use with offshore installations that are oper-
ated to UK North Sea standards. The methodology of DNVs
approach is presented in the 2009 HAZARDS XXI�
Conference [4].
3.2 ONSHORE
DNV normally also use these data for QRA at onshore facili-
ties. In general, the HSE data set gives higher leak frequen-
cies than most of the onshore sources of data. There are
several possible explanations for this.
Process equipment on offshore installations might experi-
ence higher leak frequencies than on onshore plants.
Possible reasons might be extra external corrosion from
salt-water spray, internal erosion from entrained sand, or
impacts resulting from the more compact equipment lay-
outs. However, offshore installations have safety manage-
ment systems that would be expected to counter such evi-
dent hazards. The HSE data set on leak causes shows that
corrosion/erosion is a minor contributor, with operational/
procedural faults and mechanical defects being the primary
causes. Table 1 indicates the causes of leaks offshore
between the 1st October 1992 to the 31st of March 2002.
Another possible explanation could be differences in data
quality. The HSE offshore data set is a high-quality database,
collected recently, covering a large population, with well-
defined hole sizes, comprehensive equipment counts, and
open for scrutiny by the operators and their consultants. Most
of the available onshore leak frequencies come from small
sample sizes. In fact in the case of onshore pipe leak frequen-
cies it is concluded that the most widely accepted data set is of
eight leaks in U.S. nuclear plants in 1972, or earlier collec-
tions whose size and origin are now unknown. [3].
A third factor affecting the comparison is that the HSE
offshore data set includes some leaks that occurred while
the equipment was depressurised, and others that were
quickly isolated. The onshore frequencies are applicable to
holes with process fluid at the full operating pressure. The
frequencies based on HCRD data should be used with out-
flow models that take account of the variation in operating
circumstances at the time of the leak.
A further complicating factor is that onshore and offshore
management systems in the UK must address different regu-
latory requirements. The Offshore Safety Case requirements
are more onerous than those required of onshore refineries
(e.g. offshore requirements for identification of safety criti-
cal elements, performance standards and written schemes,
plus the rigorous leak reporting requirements).
Overall, it is considered that the HSE offshore data provides
the best available estimate of leak frequencies for both
Category Causation Factor Instances Category Totals
Design fault – 321 321
Equipment Fault Corrosion/Erosion 277
1362
Mechanical Defect 920
Material Defect 76
Other 89
Operational Fault Incorrectly fitted 267
1116
Improper Operation 495
Dropped/Impact 36
Left Open/Opened 237
Other 81
Procedural Fault Noncompliance 231
588
Deficient Procedure 323
Other 34
Table 1: Causation factors in HSE offshore data [2]
I quantified risk assessment I PROCESS INDUSTRY I 07
onshore and offshore process equipment. However, it does
require that the outflow model should take account of the
possibility of the equipment being depressurised or quickly
isolated at the time of the leak.
3.3 LNG FACILITIES
The main risk drivers on an LNG site are events that are
unlikely to be within the direct experience of individual
plants and terminals. Establishing the frequency of such
events is difficult, precisely because of their rarity. It requires
systematic data collection, for leaks and the exposed equip-
ment population, over many plants for many years. Such
data collection is time-consuming and hence unusual.
Alternative methods such as fault tree analysis are possible
for plant-specific applications, but have not yet delivered
generic leak frequencies suitable for routine use in QRA
studies.
Data sets exist that attempt to provide failure rates for cryo-
genic pipework, or for LNG-specific operating experience in
general, but these are not considered to be sufficiently
robust to justify any modification to the generic data derived
from the HCRD. That is, any argument that offshore data
such as the HCRD is not relevant to LNG facilities is consid-
ered to be compensated for by the weight of statistical data
supporting the derived failure rates for specific equipment
items, compared to the very limited data supporting any
specific cryogenic / LNG failures that have occurred.
Given the perceived risks associated with LNG it is often the
case that fully welded pipelines and connections are
employed, at least for the cryogenic part of the facility.
Hence, where QRA of a ‘typical’ facility would assume that
all valves are flanged (even where not shown on the P&IDs)
this may not be the case for LNG facilities. It is important to
confirm the extent to which this applies for any given facility
– the default should be to assume flanged connections.
A common aspect of uncertainty in QRA is associated with
the frequency of inter-unit pipework / pipeline releases. It is
widely accepted that the application of process pipework
failure data will tend to give overly conservative values with
respect to longer inter-unit pipe segments. This can be of
particular relevance to LNG facilities, where the loading
lines are often several kilometers long. In the course of
conducting a large number of QRA studies, DNV has had
the opportunity to draw on the experience of a range of
operators. On the basis of these discussions, it is considered
appropriate to apply a factor of 10 reductions in the pipe-
work failure frequency for inter-unit piping. It should be
recognised that this is an engineering judgement assump-
tion, based on acknowledging operational experience that
inter-unit pipework fails very rarely (in comparison to the
process pipework within the main process areas). This
revised basis can be of particular relevance to loading lines,
although should not substitute for consideration of all
potential loads (and hence potential frequency modification
factors) that may apply to a particular facility, or particular
loading line.
In summary:
■■ The DNV analysis of HCRD is recommended as the basis
for the process and pipework failure data – as per all QRA
studies.
■■ There is no statistically sound basis for modifying the
source failure data to account for cryogenic or LNG-
specific application.
■■ It is considered justifiable – albeit by engineering judge-
ment – to reduce the process pipework failure rates by a
factor of 10 for inter-unit piping.
■■ It should not be assumed that valves are flanged but this is
an area where LNG applications may have the opportu-
nity to reduce the parts count and hence the calculated
leak frequency.
08 I PROCESS INDUSTRY I quantified risk assessment I
4. METHODOLOGY
4.1 GENERAL
This booklet provides hole size frequency data for use in
Quantified Risks Assessment (QRA) of process facilities. The
methodology shown in this document was developed as in
conjunction with Statoil and was presented in the 2009
HAZARDS XXI conference. The frequency data highlighted
in this document uses the same methodology but uses data
up to 2010 from the database. The booklet contains generic
leak frequencies for each of the following process equip-
ment types:
1. Compressors
•Centrifugalcompressors •Reciprocatingcompressors2. Filters
3. Flanges
4. Heat Exchangers (Including Coolers, Heaters
and condensers)
•AirCooledHeatExchangers •Plateheatexchangers •Shellsideheatexchangers •Tubesideheatexchangers
5. Pig traps
6. Process Pipes
7. Pumps
•Centrifugalpumps •Reciprocatingpumps8. Instruments
9. Valves
•Actuatedvalves •Manualvalves10. Pressurized process vessels
11. Atmospheric storage tanks
This analysis represents the leak size distribution by an ana-
lytical frequency function, which ensures non-zero leak
frequencies for all holes size ranges between 1 mm and the
diameter of the inlet pipe to the equipment. In the follow-
ing paragraphs a short presentation of the analysis is given.
The methodology for obtaining leak frequencies from
HCRD consists of three main steps:
■■ Grouping data for different types and sizes of equipment,
where there is insufficient experience to show significant
differences between them.
■■ Fitting analytical leak frequency functions to the data, in order
to obtain a smooth variation of leak frequency with equip-
ment and hole size.
■■ Splitting the leak frequencies into different leak scenarios, in
order to promote compatibility with different approaches
to outflow modelling in the QRA.
Grouping data
The DNV analysis covers 17 different types of process equip-
ment. Wellhead equipment, drilling equipment, pipelines
and risers are all excluded from the analysis, since other
more extensive data sources are available for these types of
equipment. The remaining types of equipment are charac-
terized as “process equipment”.
The HCRD and the Statistics Report [2] allow 78 separate
types and sizes of process equipment to be distinguished.
In some cases, there is relatively little leak experience, and
differences in leak frequencies between certain types and
sizes of process equipment have no statistical significance.
Analysis of results where there are only few reported results
may be misleading. To avoid this, it is desirable to combine
equipment types and sizes with relatively little leak
experience.
DNV equipment type HCRD equipment types
Steel pipes Piping, steel (3 sizes)
Flanged joints Flanges (3 sizes)
Manual valves Valve, manual (10 types & sizes)
Actuated valves Valve, actuated (18 types & sizes)
Instruments Instruments (including connect-ing tubing, valves and flanges)
Process vessels Pressure vessel (14 types)
Atmospheric vessels Vessels at atmospheric pressure
Centrifugal pumps Pumps, centrifugal (2 seal types)
Reciprocating pumps Pumps, reciprocating (2 seal types)
Centrifugal compressors Compressors, centrifugal
Reciprocating compressors Compressors, reciprocating
Shell side heat exchangers Heat exchangers, HC in shell
Tube side heat exchangers Heat exchangers, HC in tube
Plate heat exchangers Heat exchangers, plate
Air cooled heat exchangers Fin fan coolers
Filters Filters
Pig traps Pig launchers & pig receivers (4 sizes)
Table 2: Equipment Type Groups
I quantified risk assessment I PROCESS INDUSTRY I 09
Most HCRD equipment types have been used as defined by
HSE, but some, with relatively little leak experience, have
been combined into the following groups:
■■ All types of manual valves (bleed, block, check and
choke).
■■ All other types of non-pipeline actuated valves (block,
blowdown, choke, control, ESDV and relief, but not pipe-
line ESDV and SSIV).
■■ All types of pressure vessel (horizontal/vertical adsorber,
KO drum, other, reboiler, scrubber, stabiliser, separator
and stabiliser).
Leak frequency function
HCRD data, being real data, is very noisy as can be seen in
Figure 3. DNV overlays a realistic distribution function that
fits the data to obtain average leak frequencies. In raw data
there are gaps (e.g. a particular equipment dimension may
have zero leak events, but we would not predict zero for its
actual leak likelihood) forcing a distribution of results in
realistic predictions.
A feature of the distribution function is that it allows any
hole size distribution to be employed without biasing the
result. In early coarse risk assessments we may only choose
two hole sizes – small and large, whereas in detailed studies
we may choose to employ 5 hole sizes for greater resolu-
tion. The equations allow any number of hole sizes to be
selected and the total release frequency will always stay the
same. The actual hole size feeds the consequence mod-
eling and the more sizes used the greater the computa-
tional effort.
The analysis represents the variation of leak frequency with
equipment and hole size by the following general leak fre-
quency function:
F(d) = f(D)dm + Frup for d = 1 mm to D Eqn 1
where:
F(d) = frequency (per year) of holes exceeding size d
f(D) = function representing the variation of leak
frequency with D
D = equipment diameter (mm)
d = hole diameter (mm)
m = slope parameter
Frup = additional rupture frequency (per year)
Hence the frequency of holes within any range d1 to d2 is:
F(d1) – F(d2) = f(D)(d1m – d2
m) for d = 1 mm to D Eqn 2
The frequency of full-bore ruptures, i.e. holes with diameter
D, is:
F(D) = f(D) Dm + Frup Eqn 3
For pipes, flanges, valves and pig traps, HCRD provides data
for different equipment size groups. Analysis of these
showed significant variations in leak frequency with equip-
ment size for pipes, flanges valves, whereas the population
was too small to show any significant variation of leak fre-
quency with equipment size for pig traps. Size dependence
is represented in the leak frequency function using the
following general form:
f(D) = C(1 + aDn) Eqn 4
where:
C, a, n = constants for each equipment type
The HCRD provides sufficient data to determine estimates
for the a and n parameters for f(D) for pipes, flanges, man-
ual valves and actuated valves. For the other equipment
types, f(D) is equal to the constant C.
It is important to be aware that the leak frequency form is
imposed on the data and that this is a mathematical repre-
sentation of historical data. The data itself does not directly
support a separate frequency for ruptures. The historical
data related to releases from large hole sizes is very limited
and the uncertainty related to estimation of such leaks is
therefore considerable The additional rupture frequency
Frup and the slope parameter m are assumed to be constants,
i.e. not to be dependent on equipment size, for any equip-
ment type.
The function is used to calculate separate hole size frequen-
cies for three types of leak scenario:
■■ Total leak frequency
■■ Full pressure leak frequency
■■ Zero pressure leak frequency
using separate parameters for C, a, n, m and Frup. These
variables are used in DNVs software LEAK to produce the
leak frequencies that are presented in the datasheets of this
report.
4.2 LEAK SCENARIOS
Analysis of the HCRD reveals a large number of scenarios
with a significant difference between the recorded released
mass and the mass that would be estimated by using a
standard QRA methodology based on the recorded inci-
dent data. The HCRD includes many leaks that have
occurred at very low system pressures. In order to account
for this the analysis divides the leaks in HCRD into 2 main
scenario categories: “full pressure leaks” and “zero pressure
leaks”.
10 I PROCESS INDUSTRY I quantified risk assessment I
Full pressure leaks
This scenario category is intended to be consistent
with QRA models that assume a leak through the defined
hole, beginning at the normal operating pressure, until
controlled by isolation and blowdown, with a probability
of isolation/blowdown failure. This is subdivided as
follows:
■■ Full leaks which are intended to be consistent with QRA
models that assume a leak through the defined hole,
beginning at the normal operating pressure, until con-
trolled by ESD1 and blowdown, with a small probability of
ESD/blowdown failure. These are subdivided as follows
– ESD isolated leaks, which are defined as cases where the
outflow quantity is comparable with that predicted for
a leak at the operational pressure.
– Late isolated leaks, presumed to be cases where there is
no effective ESD of the leaking system, resulting in a
greater outflow quantity. Late isolated leaks are defined
as cases where the outflow is greater than predicted for
a leak at the operational pressure controlled by the
slowest credible ESD and no blowdown.
■■ Limited leaks, presumed to be cases where the outflow
quantity is significantly less than from a leak at the opera-
tional pressure controlled by the quickest credible ESD
(after 30 seconds) and blowdown (according to API)
initiated 60 seconds later. This is presumed to be cases
where there exist restrictions in the flow from the system
inventory, as a result of local isolation valves initiated by
human intervention or process safety systems other that
ESD and blowdown.
Normally a quantitative risk assessment will assume that all
leaks are full leaks because these have the potential of devel-
oping into serious events endangering personnel and criti-
cal safety functions. From these leak frequencies the analyst
can use a standard event tree approach for the subsequent
consequence assessment. This includes probabilities for ESD
and BD failure.
Limited leaks may be of as much concern for personnel risk
as full leaks in the period immediately following the start of
the release, but they will have a shorter duration. Hence the
potential for them developing into any major concern for
other safety functions, such as structural integrity, evacua-
tion means, escalation, etc. Any consequence calculations
should be modelled as for ESD and late isolated leaks, but
reflect that these events involve reduced release mass and
durations.
Zero pressure leaks
This scenario includes all leaks where the pressure inside
the leaking equipment is virtually zero (0.01 barg or less).
This may be because the equipment has a normal operating
pressure of zero (e.g. open drains), or because the equip-
ment has been depressurised for maintenance, but not
de-inventoried.
These leaks may typically be very small gas releases, short
lasting oil spills, or liquid releases from atmospheric tanks.
Most likely they represent a significantly reduced major
accident risk potential relative to a pressurised release
through the same hole size (although they do pose occupa-
tional safety issues) and the contribution to the overall risk
level as predicted in QRA studies is considered negligible.
4.3 UNCERTAINTIES
There are several significant uncertainties in fitting a curve
to the available leak data. Some uncertainties are due to the
way that leak data is reported to the HSE and the lack of
data for larger events. Other sources of uncertainty include
issues about an accurate population count and the accuracy
with which the operator records the data. The sources of
uncertainty are illustrated in Figure 3.
4.4 ALLOCATION OF LEAK EVENTS
The method of allocating leak records in HCRD into the
scenarios is as follows:
■■ Identify the zero pressure leak events in order to dis-
count them from the analysis
■■ Estimate the initial release rate Qo from the hole, based
on parameters recorded in HCRD,
■■ Estimate a range of plausible release quantities, REmin to
REmax, based on typical ESD and blowdown response
■■ Compare the recorded release quantity in HCRD to the
estimated release quantity range to determine the
scenario.
The scenario allocation criteria are (in order):
■■ Zero pressure leaks – actual pressure in HCRD < 0.01
barg.
■■ Limited leaks – recorded release quantity in HCRD <
REmin·/ D
■■ ESD isolated leaks – recorded release quantity in HCRD
in the range REmin / D to REmax·
■■ Late isolated leaks – recorded release quantity in HCRD
> REmax·
1 With the assumption that process shutdown (PSD) is the shutdown of a particular section rather than the whole platform the PSD system may have
the same effect as far as QRA modelling of release rates is concerned.
I quantified risk assessment I PROCESS INDUSTRY I 11
Figure 3 Uncertainties in applying curve to data
HCRD Leak(Total)
Full pressure leaks
Full leak
Zero pressure leaks
Limited leak
Late isolated
ESD isolated
3%
94%
49%
51%
93%
7%
6% 6%
43%
48%
Figure 4: Event Tree of Leak Scenarios [4]
Release Type Total GAS LEAK OIL LEAK CONDEN-SATE LEAK
2-PHASE LEAK
NON- PROCESS
Zero Pressure leak 6% 6% 7% 7% 2% 8%
Full pressure leak
Limited leak 48% 33% 75% 64% 67% 53%
Full leaks
ESD isolated 43% 57% 16% 27% 30% 36%
Late Isolated 3% 4% 2% 2% 1% 3%
Total 100% 100% 100% 100% 100% 100%
Table 3 Proportion Distribution of leak incidents in the HCRD database2 (%)3 [4]
2 The figures take account of HCRD data until March 2010.
3 The data that supports the distribution of 2-Phase leaks and condensate leaks are not very comprehensive and the uncertainty in these numbers is
therefore larger than for the other phases e.g. gas and oil leaks. The given distribution for 2-phase leaks and condensate leaks represents a best
estimate.
D is a disproportion factor. It is used to ensure that the clas-
sification of limited leaks is appropriate. The value given to D
is typically 4 and this is the value which has been used in the
calculation of the tables in this document.
As a simple indication of the relative importance of each leak
scenario using the methods and criteria above, Figure 4
shows the breakdown of all leaks in HCRD for the period
1992-2010. This shows that approximately 6% of leaks are at
zero pressure, and that 48% are
limited leaks. Of the remaining
46% leaks, 3% are consistent
with late isolation.
Figure 4 can be further sub-
divided to produce Table 3. This
indicates the effects that each
individual fluid has on the leak
type. Table 3 can be used in
conjunction with the data sheets
to obtain an estimate of the
frequencies of limited leaks.
1.E-03
Holes<1mm only reported since 2001
Holes1-2mm probably under reported
Exposed population declines as d approaches D
Holes >100mm not specified since 2001
Uncertainty increases for largest events probably under reported
Freq
uen
cy E
xceed
ing
(/y
ear)
Hole Diameter (mm)
1.E-04
1.E-05
1.E-06
1.E-07
0.1
All releases LEAK Function
1 10 100
12 I PROCESS INDUSTRY I quantified risk assessment I
In order to estimate the initial release rate Qo from the hole and a range of plausible release quantities REmin to REmax a series of equations are used.
5. CALCULATING RELEASE RATE
The phase of the fluid refers to the initial state of fluid in
the equipment before a leak.
For gas releases the initial release rate from high pressure
equipment is given by:
Eqn 5
Where:
Qg = initial gas release rate (kg/s)
CD = discharge coefficient
A = hole area (m2)
PO = initial pressure of gas (N/m2) absolute
M = molecular weight of gas
g = ratio of specific heats
R = universal gas constant = 8314 J/kg mol K
To = initial temperature of gas (K)
Rearranging the above and noting that gives:
Eqn 6
Approximating the gauge pressure to absolute pressure,
substituting g = 1.31, CD = 0.85, and converting the units of
pressure to bar and noting that the units of the diameter are
in mm we have:
Eqn 7
Where:
d = hole diameter (mm)
rg = initial density of gas (kg/m3)
Pg = initial pressure of gas (bar gauge)
For liquid releases, the initial release rate is given by:
Eqn 8
Where:
QL = initial liquid release rate (kg/s)
CD = discharge coefficient
A = hole area (m2)
rL = liquid density (kg/m3)
Po = initial pressure of liquid (N/m2) (absolute)
Pa = atmospheric pressure = 105 N/m2
g = acceleration due to gravity = 9.81 m/s2
h = height of liquid surface above hole (m)
By neglecting the liquid head, h, and replacing the pressure
term with the gauge pressure of the liquid this can be simpli-
fied to:
Eqn 9
As a simple approximation, substituting CD = 0.61 and
neglecting the liquid head h, the equation can be simplified
to:
Eqn 10
where:
d = hole diameter (mm)
rL = liquid density (kg/m3)
PL = initial pressure of liquid (bar gauge)
This equation may be used for oil, condensate and non-
process releases.
Two-phase releases are less amenable to simple approxima-
tion, but since they form a small proportion of HCRD, they
are represented by:
Eqn 11
where:
Qo = initial release rate (kg/s)
Qg = release rate (kg/s)
QL = release rate (kg/s)
GOR = gas oil ratio (kg gas per kg oil)
The initial release rate is assumed to continue at a constant
rate until the inventory is isolated. After isolation, the
release rate declines as the isolated section is depressurised
through the leak. Blowdown of isolated sections can then
further increase the rate at which the section is depressur-
ized and hence decrease the release rate through the hole.
!! = !!!!! !"!!! !!!! !+!!!!
Where:
γ
!!!! = !!!! !! = !! !!!! ! !!!! !+!!!! !! !!!!
γ
!! = 1.4 x 10!!!! !!!!ρ
!! = !!! 2!! !! − !! !!!ℎ
ρ
!! = !! !!!! 2 !!!!
!! = 2.1 x 10!!!! !!!!ρ
!! = !"#!"#!!!! !!"#!!!!
ρ
!! = !! !!!! 2 !!!!!! = 2.1 x 10!!!! !!!!
ρ
!! = !"#!"#!!!! !!"#!!!!
ρ
!! = !! !!!! 2 !!!!!! = 2.1 x 10!!!! !!!!ρ
!! = !"#!"#!!!! � !!"#!!!!
!! = !!!!! !"!!! !!!! !+!!!!
γ
!!!! = !!!! !! = !! !!!! ! !!!! !+!!!! !! !!!!
Approximating the gauge pressure to absolute pressure, substituting γ
!! = 1.4 x 10!!!! !!!!ρ
!! = !!! 2!! !! − !! !!!ℎ
!! = !!!!! !"!!! !!!! !+!!!!
γ
!!!! = !!!! !! = !! !!!! ! !!!! !+!!!! !! !!!!
γ
!! = 1.4 x 10!!!! !!!!
Where:
ρ
!! = !!! 2!! !! − !! !!!ℎ
!! = !!!!! !"!!! !!!! !+!!!!
γ
!!!! = !!!! !! = !! !!!! ! !!!! !+!!!! !! !!!!
γ
!! = 1.4 x 10!!!! !!!!ρ
!! = !!! 2!! !! − !! � !!!ℎ
!! = !!!!! !"!!! !!!! !+!!!!
γ
!!!! = !!!! gives:
!! = !! !!!! ! !!!! !+!!!! !! !!!!γ
!! = 1.4 x 10!!!! !!!!ρ
!! = !!! 2!! !! − !! !!!ℎ
I quantified risk assessment I PROCESS INDUSTRY I 13
Rele
ase
Rate
Time
Isolation
Leak Flow
Blowdown
QT
QO
QB
t I tB
HPSectionScrubber
HP GasCompressor
Cooler
KEY
Manual Valve
Actuated Valve
Flange
Small Bore Fitting
Figure 5 Decline of release rate with timeTable 4 Parts Count of Isolatable System
The expected release quantity is calculated as follows:
Eqn 12
Where:
Eqn 13
Eqn 14
Eqn 15
QB = release rate through leak when blowdown starts
(kg/s)
QT = total release rate through leak and blowdown
valve when blowdown starts ( kg/s)
I = inventory in isolated section (kg)
MB = mass remaining when blowdown starts
t = time from start of leak (s)
tI = time from start of leak to isolation (s)
tB = time from start of leak to blowdown (s)
rd = density factor
RE = expected ESD-limited outflow (kg)
b = blowdown valve diameter
The density factor is set to 1 for gas and 2-phase releases,
but for liquid releases the following formula is used:
Eqn 16
Where:
f = density number (0.5)
rg = gas density (kg/m3)
rl = liquid density (kg/m3)
Once the frequency of a hole size occurring is determined
the release rate for that particular diameter of hole can be
calculated thereby finding the frequency of that release rate.
5.1 SAMPLE CALCULATION
Figure 6 shows a sample isolated section and Table 4 displays
the part count for this simplified system. Process pipe is
length in metres, not number of pipes. There are 2 pipe
sizes in the system. The 6” pipe connects the scrubber to the
compressor and on to the cooler. The remaining pipework
is 8”. The leak analysis is being conducted on a gas stream.
There are a number of assumptions that are made in count-
ing the parts:
■■ For parts that are independent of equipment size (all
items except for valves, pipe and flanges) the largest pipe
diameter that is connected to the piece of equipment is
taken to be the size.
■■ Only half the scrubber is counted since only the top half
is in contact with gas under normal operating conditions.
(The lower half of the scrubber is included in a separate
count for the liquid stream).
Equipment No. Size
Process Vessel 0.5 8”
Centripetal Compressor 1 6”
Shell and Tube Heat Exchanger 1 6”
Flange 11 8”
Flange 5 6”
Actuated Valve 2 8”
Small Bore Fittings 2 ½”
Manual Valve 3 8”
Process Pipe 10 8”
Process Pipe 5 6”
!! = !!!! � I 1− !!!! �!! !!!!
Where: !! = !!exp !!! !!!!!I!! = I !!!!!!!! = !!!!!!!!!
ρ
!! = ! !!!!
ρρ
!! = !!!! I 1− !!!! !! !!!! !! = !!exp !!! !!!!!I
!! = I !!!!
!!!! = !!!!!!!!!
ρ
!! = ! !!!!
ρρ
!! = !!!! + I 1− !!!! +!! !!!!!! = !!exp !!! !!!!!I
!! = I !!!!
!!!! = !!!!!!!!!
ρ
!! = ! !!!!
ρρ
!! = !!!! + I 1− !!!! +!! !!!!!! = !!exp !!! !!!!!I!! = I !!!!
!!!! = !!!!!!!!!
Q = release rate through leak when blowdown starts (kg/s)
ρ
!! = ! !!!!
ρρ
!! = !!!! + I 1− !!!! +!! !!!!!! = !!exp !!! !!!!!I!! = I !!!!!!!! = !!!!!!!!!
ρ
!! = ! !!!!
Where:
ρρ
Figure 6: Sample Isolatable Section
14 I PROCESS INDUSTRY I quantified risk assessment I
■■ Two flanges are counted on each valve. (The base leak
frequency of the valve does not account for flange
connections).
■■ The actuated valves at the boundaries of the system are
ESDVs. These isolate the section. Only half these valves
are counted and one flange connection.
The results are shown in Table 3.
Then by applying Eqn 1 to each type of equipment, the
contribution of each hole size can be examined.
Equipment No. Size Frequency [ /equipment year] Total [Leaks/year]
Process Vessel 0.5 8” 2.155 x 10-3 1.077 x 10-3
Centrifugal Compressor 1 6” 1.061 x 10-2 1.061 x 10-2
Shell and Tube Heat Exchanger 1 6” 3.446 x 10-3 3.446 x 10-3
Flange 11 8” 1.286 x 10-4 1.414 x 10-3
Flange 5 6” 1.117 x 10-4 5.585 x 10-4
Actuated Valve 2 8” 5.921 x 10-4 1.184 x 10-3
Small Bore Fittings 2 ½” 5.894 x 10-4 1.178 x 10-3
Manual Valve 3 8” 1.437 x 10-4 4.311 x 10-4
Process Pipe 10 8” 6.945 x 10-5 6.945 x 10-4
Process Pipe 5 6” 7.349 x 10-5 3.674 x 10-4
Total 0.021
Table 5 Sample Calculation
5.2 ALTERNATIVE SOURCES OF LEAK FREQUENCY
DATA
The leak frequency data and methodology presented in this
document are based on analysis and application of data in
the HSE Hydrocarbon Release Database. A number of other
data sources and methodologies have been published, but
DNV considers the HSE database to be the best available for
most QRA applications.
Other available databases include the handbook for failure
frequencies which was developed by the Flemish (Belgian)
Government [5], and the Reference Manual Bevi Risk
Assessments which was developed by the Dutch National
Institute of Public Health and the Environment[5] [6].
DNV has compared the leak frequency result from these
sources against the DNV methodology. A comparison of
results based on the sample isolatable section is shown in
Table 4.
The comparison of results shows that the leak frequency
estimated using DNV’s method for this case is greater than
that obtained by the Dutch and Belgian methodologies. The
Belgian and Dutch methodologies present leak frequency
data for equipment systems; and omit any explicit counts of
the flanges, valves and instruments associated with major
equipment items. This is the main reason why the Dutch
and Belgian methodologies produce lower estimate of leak
frequency.
The experience base of the Dutch and Belgian methodolo-
gies does not match the large experience of leaks contained
in the HCRD; leak frequencies derived from the HCRD are
more accurate primarily because HCRD is the largest data-
base with information for over 70 different sizes and types of
equipment, collected systematically over the last 20 years.
DNV notes that the absence of separate frequencies for
flanges, valves and instruments in the Belgian and Dutch
methodologies also means that risk assessments performed
using these methods are insensitive to some design deci-
sions, such as the benefits of all-welded designs.
Figures 7 and 8 illustrate these points. They show the ratios
of frequencies for each type of equipment obtained by divid-
ing the DNV frequency by the Dutch/Belgian frequency for
each type of equipment. The figures show for the majority
of equipment types the DNV methodology quotes higher
frequencies. The figures highlight the large difference
between the frequencies. The explanations of the differ-
ences are as discussed in Section 3.2.
Data source & methodology Leak frequency (per year)
HCRD (DNV) 0.021
Dutch government 0.006
Belgian government 0.012
Table 6: Comparison of Estimated Leak Frequencies
I quantified risk assessment I PROCESS INDUSTRY I 15
Figure 7: Ratio of frequencies - DNV data to Belgium tabulation
Figure 8: Ratio of frequencies - DNV data to Netherlands tabulation
0.1 1
Storage Vessel
Centrifugal Compressor
Heat Exchanger Plate
Heat Exchanger (HC in tube)
Heat Exchanger (HC in shell)
Recipricating Compressors
Centrifugal Pump
Process Vessel
20(in.), Im in LengthProcess Pipeline
6(in.), Im in LengthProcess Pipeline
2(in.), Im in LengthProcess Pipeline
10 100 1000
Storage Vessel
Centrifugal Compressor
Recipricating Pump
Recipricating Compressors
Centrifugal Pump
Process Vessel
20(in.), Im in LengthProcess Pipeline
6(in.), Im in LengthProcess Pipeline
2(in.), Im in LengthProcess Pipeline
0.01 10.1 10 100 1000
16 I PROCESS INDUSTRY I quantified risk assessment I
6. LEAK FREQUENCY DATASHEETS
The following pages include leak frequency data for 17 types
of process equipment. These process equipment types are
split into two categories:
■■ Diameter Dependent
■■ Diameter Independent
As explained in section 4.1 there is enough information in
the HCRD to determine all the constants of the leak fre-
quency data equation for the diameter dependent equip-
ment types (Process pipe, Flanges, Manual and Actuated
Valves). Leak frequencies for other types of equipment are
considered to be independent of equipment size. For equip-
ment considered independent of equipment size the leak
frequencies are quoted to an equipment size of 6 inches.
This is because the leak frequencies remain the same for the
larger diameters.
Typically the parts count is multiplied by the total leaks to
determine the overall leak frequency. For a more in-depth
analysis the parts count may be multiplied by the values in
the full, limited and zero pressure leak columns, but for
most purposes it will be sufficient to use only the “full” leak
frequencies. The frequency of limited leaks can be obtained
using data in Table 3. It may be noted that the sum of fre-
quencies for full, limited and zero pressure leaks do not
necessarily equal the total leaks. The small difference is due
to total, full and zero pressure leaks being determined using
different equations.
The tables presented in this section have been gener-
ated using commercially available DNV LEAK software
which implements the methodology described in this
document.
I quantified risk assessment I PROCESS INDUSTRY I 17
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Centrifugal Compressors Source: HCRD 10/92 – 03/10
Definition: The scope includes the compressor itself, but excludes all attached valves, piping, flanges, instruments and fittings beyond the first flange. The first flange itself is also excluded.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 5.802E‐03 5.583E‐03 1.324E‐04 3 ‐ 10 mm 2.462E‐03 2.316E‐03 1.052E‐04 10 ‐ 50 mm 1.435E‐03 1.300E‐03 2.624E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 9.699E‐03 9.199E‐03 5.000E‐04
1 in
1 ‐ 3 mm 5.802E‐03 5.583E‐03 1.324E‐04 3 ‐ 10 mm 2.462E‐03 2.316E‐03 1.052E‐04 10 ‐ 50 mm 1.435E‐03 1.300E‐03 2.624E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 9.699E‐03 9.199E‐03 5.000E‐04
2 in
1 ‐ 3 mm 5.802E‐03 5.583E‐03 1.324E‐04 3 ‐ 10 mm 2.462E‐03 2.316E‐03 1.052E‐04 10 ‐ 50 mm 1.057E‐03 9.686E‐04 9.519E‐05 50 ‐ 150 mm 3.772E‐04 3.309E‐04 1.672E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 9.699E‐03 9.199E‐03 5.000E‐04
4 in
1 ‐ 3 mm 5.802E‐03 5.583E‐03 1.324E‐04 3 ‐ 10 mm 2.462E‐03 2.316E‐03 1.052E‐04 10 ‐ 50 mm 1.057E‐03 9.686E‐04 9.519E‐05 50 ‐ 150 mm 3.772E‐04 3.309E‐04 1.672E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 9.699E‐03 9.199E‐03 5.000E‐04
6 in
1 ‐ 3 mm 5.802E‐03 5.583E‐03 1.324E‐04 3 ‐ 10 mm 2.462E‐03 2.316E‐03 1.052E‐04 10 ‐ 50 mm 1.057E‐03 9.686E‐04 9.519E‐05 50 ‐ 150 mm 2.257E‐04 2.008E‐04 4.428E‐05 > 150 mm 1.516E‐04 1.300E‐04 1.229E‐04
Total 9.699E‐03 9.199E‐03 5.000E‐04
18 I PROCESS INDUSTRY I quantified risk assessment I
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Reciprocating Compressors Source: HCRD 10/92 – 03/10
Definition: The scope includes the compressor itself, but excludes all attached valves, piping, flanges, instruments and fittings beyond the first flange. The first flange itself is also excluded.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 3.641E‐02 3.685E‐02 0.000E+00 3 ‐ 10 mm 1.581E‐02 1.512E‐02 0.000E+00 10 ‐ 50 mm 9.572E‐03 8.324E‐03 0.000E+00 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.179E‐02 6.029E‐02 0.000E+00
1 in
1 ‐ 3 mm 3.641E‐02 3.685E‐02 0.000E+00 3 ‐ 10 mm 1.581E‐02 1.512E‐02 0.000E+00 10 ‐ 50 mm 9.572E‐03 8.324E‐03 0.000E+00 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.179E‐02 6.029E‐02 0.000E+00
2 in
1 ‐ 3 mm 3.641E‐02 3.685E‐02 0.000E+00 3 ‐ 10 mm 1.581E‐02 1.512E‐02 0.000E+00 10 ‐ 50 mm 6.973E‐03 6.238E‐03 0.000E+00 50 ‐ 150 mm 2.599E‐03 2.085E‐03 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.179E‐02 6.029E‐02 0.000E+00
4 in
1 ‐ 3 mm 3.641E‐02 3.685E‐02 0.000E+00 3 ‐ 10 mm 1.581E‐02 1.512E‐02 0.000E+00 10 ‐ 50 mm 6.973E‐03 6.238E‐03 0.000E+00 50 ‐ 150 mm 2.599E‐03 2.085E‐03 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.179E‐02 6.029E‐02 0.000E+00
6 in
1 ‐ 3 mm 3.641E‐02 3.685E‐02 0.000E+00 3 ‐ 10 mm 1.581E‐02 1.512E‐02 0.000E+00 10 ‐ 50 mm 6.973E‐03 6.238E‐03 0.000E+00 50 ‐ 150 mm 1.532E‐03 1.275E‐03 0.000E+00 > 150 mm 1.067E‐03 8.107E‐04 0.000E+00
Total 6.179E‐02 6.029E‐02 0.000E+00
I quantified risk assessment I PROCESS INDUSTRY I 19
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Filters Source: HCRD 10/92 – 03/10
Definition:
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 1.870E‐03 1.608E‐03 2.453E‐04 3 ‐ 10 mm 9.307E‐04 7.559E‐04 1.605E‐04 10 ‐ 50 mm 7.187E‐04 5.259E‐04 2.232E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.520E‐03 2.890E‐03 6.290E‐04
1 in
1 ‐ 3 mm 1.870E‐03 1.608E‐03 2.453E‐04 3 ‐ 10 mm 9.307E‐04 7.559E‐04 1.605E‐04 10 ‐ 50 mm 7.187E‐04 5.259E‐04 2.232E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.520E‐03 2.890E‐03 6.290E‐04
2 in
1 ‐ 3 mm 1.870E‐03 1.608E‐03 2.453E‐04 3 ‐ 10 mm 9.307E‐04 7.559E‐04 1.605E‐04 10 ‐ 50 mm 4.820E‐04 3.661E‐04 1.150E‐04 50 ‐ 150 mm 2.367E‐04 1.598E‐04 1.082E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.520E‐03 2.890E‐03 6.290E‐04
4 in
1 ‐ 3 mm 1.870E‐03 1.608E‐03 2.453E‐04 3 ‐ 10 mm 9.307E‐04 7.559E‐04 1.605E‐04 10 ‐ 50 mm 4.820E‐04 3.661E‐04 1.150E‐04 50 ‐ 150 mm 2.367E‐04 1.598E‐04 1.082E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.520E‐03 2.890E‐03 6.290E‐04
6 in
1 ‐ 3 mm 1.870E‐03 1.608E‐03 2.453E‐04 3 ‐ 10 mm 9.307E‐04 7.559E‐04 1.605E‐04 10 ‐ 50 mm 4.820E‐04 3.661E‐04 1.150E‐04 50 ‐ 150 mm 1.258E‐04 8.894E‐05 4.219E‐05 > 150 mm 1.109E‐04 7.089E‐05 6.598E‐05
Total 3.520E‐03 2.890E‐03 6.290E‐04
20 I PROCESS INDUSTRY I quantified risk assessment I
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Flange Source: HCRD 10/92 – 03/10
Definition: The following frequencies refer to a flanged joint, comprising two flange faces, a gasket (where fitted), and two welds to the pipe. Flange types include ring type joint, spiral wound, clamp (Grayloc) and hammer union (Chicksan)
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 3.725E‐05 3.538E‐05 1.156E‐06 3 ‐ 10 mm 1.364E‐05 1.239E‐05 8.773E‐07 10 ‐ 50 mm 1.227E‐05 1.031E‐05 2.367E‐06 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.316E‐05 5.808E‐05 4.400E‐06
1 in
1 ‐ 3 mm 4.037E‐05 3.771E‐05 1.156E‐06 3 ‐ 10 mm 1.479E‐05 1.320E‐05 8.774E‐07 10 ‐ 50 mm 1.279E‐05 1.066E‐05 2.367E‐06 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.795E‐05 6.156E‐05 4.400E‐06
2 in
1 ‐ 3 mm 4.628E‐05 4.229E‐05 1.157E‐06 3 ‐ 10 mm 1.695E‐05 1.480E‐05 8.780E‐07 10 ‐ 50 mm 6.126E‐06 5.076E‐06 7.519E‐07 50 ‐ 150 mm 7.661E‐06 6.269E‐06 1.616E‐06 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 7.701E‐05 6.844E‐05 4.403E‐06
4 in
1 ‐ 3 mm 5.745E‐05 5.133E‐05 1.171E‐06 3 ‐ 10 mm 2.104E‐05 1.797E‐05 8.891E‐07 10 ‐ 50 mm 7.605E‐06 6.161E‐06 7.614E‐07 50 ‐ 150 mm 8.062E‐06 6.540E‐06 1.630E‐06 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 9.415E‐05 8.200E‐05 4.452E‐06
6 in
1 ‐ 3 mm 6.816E‐05 6.028E‐05 1.241E‐06 3 ‐ 10 mm 2.496E‐05 2.110E‐05 9.420E‐07 10 ‐ 50 mm 9.023E‐06 7.235E‐06 8.067E‐07 50 ‐ 150 mm 1.594E‐06 1.206E‐06 3.550E‐07 > 150 mm 6.852E‐06 5.603E‐06 1.343E‐06
Total 1.106E‐04 9.542E‐05 4.687E‐06
I quantified risk assessment I PROCESS INDUSTRY I 21
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Flange Source: HCRD 10/92 – 03/10
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
10 in
1 ‐ 3 mm 8.880E‐05 7.801E‐05 1.884E‐06 3 ‐ 10 mm 3.252E‐05 2.731E‐05 1.430E‐06 10 ‐ 50 mm 1.176E‐05 9.362E‐06 1.225E‐06 50 ‐ 150 mm 2.077E‐06 1.560E‐06 5.388E‐07 > 150 mm 7.110E‐06 5.780E‐06 1.779E‐06
Total 1.423E‐04 1.220E‐04 6.856E‐06
14 in
1 ‐ 3 mm 1.088E‐04 9.559E‐05 4.148E‐06 3 ‐ 10 mm 3.984E‐05 3.346E‐05 3.148E‐06 10 ‐ 50 mm 1.440E‐05 1.147E‐05 2.696E‐06 50 ‐ 150 mm 2.544E‐06 1.912E‐06 1.186E‐06 > 150 mm 7.360E‐06 5.956E‐06 3.316E‐06
Total 1.729E‐04 1.484E‐04 1.449E‐05
20 in
1 ‐ 3 mm 1.379E‐04 1.218E‐04 1.454E‐05 3 ‐ 10 mm 5.051E‐05 4.263E‐05 1.103E‐05 10 ‐ 50 mm 1.826E‐05 1.462E‐05 9.450E‐06 50 ‐ 150 mm 3.226E‐06 2.436E‐06 4.158E‐06 > 150 mm 7.724E‐06 6.218E‐06 1.037E‐05
Total 2.176E‐04 1.877E‐04 4.955E‐05
22 I PROCESS INDUSTRY I quantified risk assessment I
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Fin Fan Heat Exchanger Source: HCRD 10/92 – 03/10
Definition: The scope includes the heat exchanger itself, but excludes all attached valves, piping, flanges, instruments and fittings beyond the first flange. The first flange is also excluded.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 7.997E‐04 7.997E‐04 0.000E+00 3 ‐ 10 mm 3.802E‐04 3.802E‐04 0.000E+00 10 ‐ 50 mm 2.700E‐04 2.700E‐04 0.000E+00 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 1.450E‐03 1.450E‐03 0.000E+00
1 in
1 ‐ 3 mm 7.997E‐04 7.997E‐04 0.000E+00 3 ‐ 10 mm 3.802E‐04 3.802E‐04 0.000E+00 10 ‐ 50 mm 2.700E‐04 2.700E‐04 0.000E+00 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 1.450E‐03 1.450E‐03 0.000E+00
2 in
1 ‐ 3 mm 7.997E‐04 7.997E‐04 0.000E+00 3 ‐ 10 mm 3.802E‐04 3.802E‐04 0.000E+00 10 ‐ 50 mm 1.866E‐04 1.866E‐04 0.000E+00 50 ‐ 150 mm 8.339E‐05 8.339E‐05 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 1.450E‐03 1.450E‐03 0.000E+00
4 in
1 ‐ 3 mm 7.997E‐04 7.997E‐04 0.000E+00 3 ‐ 10 mm 3.802E‐04 3.802E‐04 0.000E+00 10 ‐ 50 mm 1.866E‐04 1.866E‐04 0.000E+00 50 ‐ 150 mm 8.339E‐05 8.339E‐05 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 1.450E‐03 1.450E‐03 0.000E+00
6 in
1 ‐ 3 mm 7.997E‐04 7.997E‐04 0.000E+00 3 ‐ 10 mm 3.802E‐04 3.802E‐04 0.000E+00 10 ‐ 50 mm 1.866E‐04 1.866E‐04 0.000E+00 50 ‐ 150 mm 4.600E‐05 4.600E‐05 0.000E+00 > 150 mm 3.740E‐05 3.740E‐05 0.000E+00
Total 1.450E‐03 1.450E‐03 0.000E+00
I quantified risk assessment I PROCESS INDUSTRY I 23
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Plate Heat Exchanger Source: HCRD 10/92 – 03/10
Definition: The scope includes the heat exchanger itself, but excludes all attached valves, piping, flanges, instruments and fittings beyond the first flange. The first flange is also excluded.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 5.164E‐03 5.008E‐03 1.482E‐04 3 ‐ 10 mm 2.847E‐03 2.792E‐03 9.695E‐05 10 ‐ 50 mm 2.688E‐03 2.699E‐03 1.348E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 1.070E‐02 1.050E‐02 3.800E‐04
1 in
1 ‐ 3 mm 5.164E‐03 5.008E‐03 1.482E‐04 3 ‐ 10 mm 2.847E‐03 2.792E‐03 9.695E‐05 10 ‐ 50 mm 2.688E‐03 2.699E‐03 1.348E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 1.070E‐02 1.050E‐02 3.800E‐04
2 in
1 ‐ 3 mm 5.164E‐03 5.008E‐03 1.482E‐04 3 ‐ 10 mm 2.847E‐03 2.792E‐03 9.695E‐05 10 ‐ 50 mm 1.664E‐03 1.655E‐03 6.948E‐05 50 ‐ 150 mm 1.023E‐03 1.044E‐03 6.535E‐05 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 1.070E‐02 1.050E‐02 3.800E‐04
4 in
1 ‐ 3 mm 5.164E‐03 5.008E‐03 1.482E‐04 3 ‐ 10 mm 2.847E‐03 2.792E‐03 9.695E‐05 10 ‐ 50 mm 1.664E‐03 1.655E‐03 6.948E‐05 50 ‐ 150 mm 1.023E‐03 1.044E‐03 6.535E‐05 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 1.070E‐02 1.050E‐02 3.800E‐04
6 in
1 ‐ 3 mm 5.164E‐03 5.008E‐03 1.482E‐04 3 ‐ 10 mm 2.847E‐03 2.792E‐03 9.695E‐05 10 ‐ 50 mm 1.664E‐03 1.655E‐03 6.948E‐05 50 ‐ 150 mm 4.940E‐04 4.981E‐04 2.549E‐05 > 150 mm 5.293E‐04 5.461E‐04 3.986E‐05
Total 1.070E‐02 1.050E‐02 3.800E‐04
24 I PROCESS INDUSTRY I quantified risk assessment I
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Shell Side Heat Exchanger Source: HCRD 10/92 – 03/10
Definition: Shell & tube type heat exchangers with hydrocarbon in the shell side. The scope includes the heat exchanger itself, but excludes all attached valves, piping, flanges, instruments and fittings beyond the first flange. The first flange itself is also excluded
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 2.011E‐03 1.827E‐03 2.339E‐04 3 ‐ 10 mm 1.035E‐03 9.847E‐04 1.027E‐04 10 ‐ 50 mm 8.532E‐04 8.876E‐04 6.340E‐05 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.900E‐03 3.700E‐03 4.000E‐04
1 in
1 ‐ 3 mm 2.011E‐03 1.827E‐03 2.339E‐04 3 ‐ 10 mm 1.035E‐03 9.847E‐04 1.027E‐04 10 ‐ 50 mm 8.532E‐04 8.876E‐04 6.340E‐05 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.900E‐03 3.700E‐03 4.000E‐04
2 in
1 ‐ 3 mm 2.011E‐03 1.827E‐03 2.339E‐04 3 ‐ 10 mm 1.035E‐03 9.847E‐04 1.027E‐04 10 ‐ 50 mm 5.583E‐04 5.603E‐04 4.590E‐05 50 ‐ 150 mm 2.949E‐04 3.272E‐04 1.749E‐05 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.900E‐03 3.700E‐03 4.000E‐04
4 in
1 ‐ 3 mm 2.011E‐03 1.827E‐03 2.339E‐04 3 ‐ 10 mm 1.035E‐03 9.847E‐04 1.027E‐04 10 ‐ 50 mm 5.583E‐04 5.603E‐04 4.590E‐05 50 ‐ 150 mm 2.949E‐04 3.272E‐04 1.749E‐05 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.900E‐03 3.700E‐03 4.000E‐04
6 in
1 ‐ 3 mm 2.011E‐03 1.827E‐03 2.339E‐04 3 ‐ 10 mm 1.035E‐03 9.847E‐04 1.027E‐04 10 ‐ 50 mm 5.583E‐04 5.603E‐04 4.590E‐05 50 ‐ 150 mm 1.521E‐04 1.616E‐04 1.023E‐05 > 150 mm 1.428E‐04 1.656E‐04 7.264E‐06
Total 3.900E‐03 3.700E‐03 4.000E‐04
I quantified risk assessment I PROCESS INDUSTRY I 25
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Tube Side Heat Exchanger Source: HCRD 10/92 – 03/10
Definition: Shell & tube type heat exchangers with hydrocarbon in the tube side. The scope includes the heat exchanger itself, but excludes all attached valves, piping, flanges, instruments and fittings beyond the first flange. The first flange itself is also excluded.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 1.721E‐03 1.473E‐03 1.665E‐04 3 ‐ 10 mm 7.729E‐04 6.618E‐04 1.089E‐04 10 ‐ 50 mm 5.462E‐04 4.749E‐04 1.515E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.040E‐03 2.610E‐03 4.270E‐04
1 in
1 ‐ 3 mm 1.721E‐03 1.473E‐03 1.665E‐04 3 ‐ 10 mm 7.729E‐04 6.618E‐04 1.089E‐04 10 ‐ 50 mm 5.462E‐04 4.749E‐04 1.515E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.040E‐03 2.610E‐03 4.270E‐04
2 in
1 ‐ 3 mm 1.721E‐03 1.473E‐03 1.665E‐04 3 ‐ 10 mm 7.729E‐04 6.618E‐04 1.089E‐04 10 ‐ 50 mm 3.548E‐04 3.038E‐04 7.807E‐05 50 ‐ 150 mm 1.914E‐04 1.711E‐04 7.343E‐05 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.040E‐03 2.610E‐03 4.270E‐04
4 in
1 ‐ 3 mm 1.721E‐03 1.473E‐03 1.665E‐04 3 ‐ 10 mm 7.729E‐04 6.618E‐04 1.089E‐04 10 ‐ 50 mm 3.548E‐04 3.038E‐04 7.807E‐05 50 ‐ 150 mm 1.914E‐04 1.711E‐04 7.343E‐05 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 3.040E‐03 2.610E‐03 4.270E‐04
6 in
1 ‐ 3 mm 1.721E‐03 1.473E‐03 1.665E‐04 3 ‐ 10 mm 7.729E‐04 6.618E‐04 1.089E‐04 10 ‐ 50 mm 3.548E‐04 3.038E‐04 7.807E‐05 50 ‐ 150 mm 8.138E‐05 6.968E‐05 2.864E‐05 > 150 mm 1.100E‐04 1.014E‐04 4.479E‐05
Total 3.040E‐03 2.610E‐03 4.270E‐04
26 I PROCESS INDUSTRY I quantified risk assessment I
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Pig Trap Source: HCRD 10/92 – 03/10
Definition: Includes pig launchers and pig receivers. The scope includes the pig trap itself, but excludes all attached valves, piping, flanges, instruments and fittings beyond the first flange. The first flange itself is also excluded.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 3.253E‐03 3.271E‐03 4.815E‐05 3 ‐ 10 mm 1.814E‐03 1.591E‐03 4.936E‐05 10 ‐ 50 mm 1.753E‐03 1.178E‐03 6.825E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.820E‐03 6.039E‐03 7.800E‐04
1 in
1 ‐ 3 mm 3.253E‐03 3.271E‐03 4.815E‐05 3 ‐ 10 mm 1.814E‐03 1.591E‐03 4.936E‐05 10 ‐ 50 mm 1.753E‐03 1.178E‐03 6.825E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.820E‐03 6.039E‐03 7.800E‐04
2 in
1 ‐ 3 mm 3.253E‐03 3.271E‐03 4.815E‐05 3 ‐ 10 mm 1.814E‐03 1.591E‐03 4.936E‐05 10 ‐ 50 mm 1.075E‐03 8.021E‐04 6.082E‐05 50 ‐ 150 mm 6.783E‐04 3.756E‐04 6.217E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.820E‐03 6.039E‐03 7.800E‐04
4 in
1 ‐ 3 mm 3.253E‐03 3.271E‐03 4.815E‐05 3 ‐ 10 mm 1.814E‐03 1.591E‐03 4.936E‐05 10 ‐ 50 mm 1.075E‐03 8.021E‐04 6.082E‐05 50 ‐ 150 mm 6.783E‐04 3.756E‐04 6.217E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.820E‐03 6.039E‐03 7.800E‐04
6 in
1 ‐ 3 mm 3.253E‐03 3.271E‐03 4.815E‐05 3 ‐ 10 mm 1.814E‐03 1.591E‐03 4.936E‐05 10 ‐ 50 mm 1.075E‐03 8.021E‐04 6.082E‐05 50 ‐ 150 mm 3.235E‐04 2.034E‐04 3.838E‐05 > 150 mm 3.547E‐04 1.722E‐04 5.833E‐04
Total 6.820E‐03 6.039E‐03 7.800E‐04
I quantified risk assessment I PROCESS INDUSTRY I 27
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Process Pipe Source: HCRD 10/92 – 03/10
Definition: Includes pipes located on topsides (between well and riser) and subsea (between well and pipeline). The scope includes welds but excludes all valves, flanges, and instruments.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 9.169E‐04 9.409E‐04 7.564E‐06 3 ‐ 10 mm 3.435E‐04 3.294E‐04 5.300E‐06 10 ‐ 50 mm 1.680E‐04 1.442E‐04 1.084E‐05 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 1.428E‐03 1.414E‐03 2.371E‐05
1 in
1 ‐ 3 mm 2.725E‐04 2.851E‐04 4.768E‐06 3 ‐ 10 mm 1.021E‐04 9.979E‐05 3.341E‐06 10 ‐ 50 mm 5.310E‐05 4.577E‐05 7.575E‐06 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 4.277E‐04 4.307E‐04 1.568E‐05
2 in
1 ‐ 3 mm 9.989E‐05 1.032E‐04 3.551E‐06 3 ‐ 10 mm 3.742E‐05 3.611E‐05 2.488E‐06 10 ‐ 50 mm 1.389E‐05 1.238E‐05 1.936E‐06 50 ‐ 150 mm 8.424E‐06 6.095E‐06 4.216E‐06 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 1.596E‐04 1.578E‐04 1.219E‐05
4 in
1 ‐ 3 mm 5.363E‐05 5.270E‐05 3.022E‐06 3 ‐ 10 mm 2.009E‐05 1.845E‐05 2.117E‐06 10 ‐ 50 mm 7.457E‐06 6.325E‐06 1.647E‐06 50 ‐ 150 mm 6.607E‐06 4.581E‐06 3.886E‐06 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 8.779E‐05 8.205E‐05 1.067E‐05
6 in
1 ‐ 3 mm 4.454E‐05 4.248E‐05 2.864E‐06 3 ‐ 10 mm 1.669E‐05 1.487E‐05 2.007E‐06 10 ‐ 50 mm 6.192E‐06 5.098E‐06 1.561E‐06 50 ‐ 150 mm 1.127E‐06 8.497E‐07 6.230E‐07 > 150 mm 5.123E‐06 3.425E‐06 3.165E‐06
Total 7.366E‐05 6.672E‐05 1.022E‐05
28 I PROCESS INDUSTRY I quantified risk assessment I
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Process Pipe Source: HCRD 10/92 – 03/10
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
10 in
1 ‐ 3 mm 3.967E‐05 3.688E‐05 2.749E‐06 3 ‐ 10 mm 1.486E‐05 1.291E‐05 1.926E‐06 10 ‐ 50 mm 5.516E‐06 4.427E‐06 1.498E‐06 50 ‐ 150 mm 1.003E‐06 7.378E‐07 5.980E‐07 > 150 mm 5.055E‐06 3.369E‐06 3.118E‐06
Total 6.610E‐05 5.833E‐05 9.890E‐06
14 in
1 ‐ 3 mm 3.880E‐05 3.587E‐05 2.723E‐06 3 ‐ 10 mm 1.454E‐05 1.255E‐05 1.907E‐06 10 ‐ 50 mm 5.395E‐06 4.305E‐06 1.484E‐06 50 ‐ 150 mm 9.814E‐07 7.174E‐07 5.922E‐07 > 150 mm 5.043E‐06 3.359E‐06 3.107E‐06
Total 6.475E‐05 5.680E‐05 9.813E‐06
20 in
1 ‐ 3 mm 3.792E‐05 3.482E‐05 2.691E‐06 3 ‐ 10 mm 1.420E‐05 1.219E‐05 1.885E‐06 10 ‐ 50 mm 5.272E‐06 4.179E‐06 1.466E‐06 50 ‐ 150 mm 9.591E‐07 6.965E‐07 5.852E‐07 > 150 mm 5.030E‐06 3.348E‐06 3.094E‐06
Total 6.338E‐05 5.523E‐05 9.722E‐06
I quantified risk assessment I PROCESS INDUSTRY I 29
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Centrifugal Pump Source: HCRD 10/92 – 03/10
Definition: Centrifugal pumps including single‐seal and double‐seal types. The scope includes the pump itself, but excludes all attached valves, piping, flanges, instruments and fittings beyond the first flange. The first flange itself is also excluded.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 4.204E‐03 4.044E‐03 1.566E‐04 3 ‐ 10 mm 1.575E‐03 1.432E‐03 1.073E‐04 10 ‐ 50 mm 7.497E‐04 6.242E‐04 1.681E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.529E‐03 6.099E‐03 4.320E‐04
1 in
1 ‐ 3 mm 4.204E‐03 4.044E‐03 1.566E‐04 3 ‐ 10 mm 1.575E‐03 1.432E‐03 1.073E‐04 10 ‐ 50 mm 7.497E‐04 6.242E‐04 1.681E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.529E‐03 6.099E‐03 4.320E‐04
2 in
1 ‐ 3 mm 4.204E‐03 4.044E‐03 1.566E‐04 3 ‐ 10 mm 1.575E‐03 1.432E‐03 1.073E‐04 10 ‐ 50 mm 5.846E‐04 4.973E‐04 8.119E‐05 50 ‐ 150 mm 1.652E‐04 1.269E‐04 8.688E‐05 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.529E‐03 6.099E‐03 4.320E‐04
4 in
1 ‐ 3 mm 4.204E‐03 4.044E‐03 1.566E‐04 3 ‐ 10 mm 1.575E‐03 1.432E‐03 1.073E‐04 10 ‐ 50 mm 5.846E‐04 4.973E‐04 8.119E‐05 50 ‐ 150 mm 1.652E‐04 1.269E‐04 8.688E‐05 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.529E‐03 6.099E‐03 4.320E‐04
6 in
1 ‐ 3 mm 4.204E‐03 4.044E‐03 1.566E‐04 3 ‐ 10 mm 1.575E‐03 1.432E‐03 1.073E‐04 10 ‐ 50 mm 5.846E‐04 4.973E‐04 8.119E‐05 50 ‐ 150 mm 1.063E‐04 8.411E‐05 3.151E‐05 > 150 mm 5.880E‐05 4.276E‐05 5.537E‐05
Total 6.529E‐03 6.099E‐03 4.320E‐04
30 I PROCESS INDUSTRY I quantified risk assessment I
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Reciprocating Pump Source: HCRD 10/92 – 03/10
Definition: Reciprocating pumps including single‐seal and double‐seal types. The scope includes the pump itself, but excludes all attached valves, piping, flanges, instruments and fittings beyond the first flange. The first flange itself is also excluded.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 2.848E‐03 2.331E‐03 2.347E‐04 3 ‐ 10 mm 1.644E‐03 1.457E‐03 1.625E‐04 10 ‐ 50 mm 1.708E‐03 1.812E‐03 2.627E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.200E‐03 5.600E‐03 6.600E‐04
1 in
1 ‐ 3 mm 2.848E‐03 2.331E‐03 2.347E‐04 3 ‐ 10 mm 1.644E‐03 1.457E‐03 1.625E‐04 10 ‐ 50 mm 1.708E‐03 1.812E‐03 2.627E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.200E‐03 5.600E‐03 6.600E‐04
2 in
1 ‐ 3 mm 2.848E‐03 2.331E‐03 2.347E‐04 3 ‐ 10 mm 1.644E‐03 1.457E‐03 1.625E‐04 10 ‐ 50 mm 1.014E‐03 9.886E‐04 1.247E‐04 50 ‐ 150 mm 6.934E‐04 8.236E‐04 1.380E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.200E‐03 5.600E‐03 6.600E‐04
4 in
1 ‐ 3 mm 2.848E‐03 2.331E‐03 2.347E‐04 3 ‐ 10 mm 1.644E‐03 1.457E‐03 1.625E‐04 10 ‐ 50 mm 1.014E‐03 9.886E‐04 1.247E‐04 50 ‐ 150 mm 6.934E‐04 8.236E‐04 1.380E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 6.200E‐03 5.600E‐03 6.600E‐04
6 in
1 ‐ 3 mm 2.848E‐03 2.331E‐03 2.347E‐04 3 ‐ 10 mm 1.644E‐03 1.457E‐03 1.625E‐04 10 ‐ 50 mm 1.014E‐03 9.886E‐04 1.247E‐04 50 ‐ 150 mm 3.186E‐04 3.428E‐04 4.908E‐05 > 150 mm 3.748E‐04 4.807E‐04 8.894E‐05
Total 6.200E‐03 5.600E‐03 6.600E‐04
I quantified risk assessment I PROCESS INDUSTRY I 31
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Small Bore Fittings Source: HCRD 10/92 – 03/10
Definition: Includes small‐bore connections for flow, pressure and temperature sensing. The scope includes the instrument itself plus up to 2 valves, 4 flanges, 1 fitting and associated small‐bore piping, usually 25mm diameter or less.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 3.092E‐04 2.998E‐04 1.092E‐05 3 ‐ 10 mm 1.373E‐04 1.287E‐04 7.144E‐06 10 ‐ 50 mm 8.644E‐05 7.643E‐05 9.935E‐06 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 5.330E‐04 5.050E‐04 2.800E‐05
1 in
1 ‐ 3 mm 3.092E‐04 2.998E‐04 1.092E‐05 3 ‐ 10 mm 1.373E‐04 1.287E‐04 7.144E‐06 10 ‐ 50 mm 8.644E‐05 7.643E‐05 9.935E‐06 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 5.330E‐04 5.050E‐04 2.800E‐05
2 in
1 ‐ 3 mm 3.092E‐04 2.998E‐04 1.092E‐05 3 ‐ 10 mm 1.373E‐04 1.287E‐04 7.144E‐06 10 ‐ 50 mm 6.220E‐05 5.601E‐05 5.119E‐06 50 ‐ 150 mm 2.424E‐05 2.042E‐05 4.815E‐06 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 5.330E‐04 5.050E‐04 2.800E‐05
32 I PROCESS INDUSTRY I quantified risk assessment I
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Actuated Valves Source: HCRD 10/92 – 03/10
Definition: Includes all types of actuated valves (block, blowdown, choke, control, ESDV and relief), but not actuated pipeline valves (pipeline ESDV and SSIV). Valve types include gate, ball, plug, globe and needle. The scope includes the valve body, stem and packer, but excludes flanges, controls and instrumentation.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 5.587E‐04 5.421E‐04 6.077E‐06 3 ‐ 10 mm 1.767E‐04 1.681E‐04 4.209E‐06 10 ‐ 50 mm 7.507E‐05 7.023E‐05 7.804E‐06 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 8.105E‐04 7.804E‐04 1.809E‐05
1 in
1 ‐ 3 mm 5.594E‐04 5.427E‐04 7.710E‐06 3 ‐ 10 mm 1.769E‐04 1.683E‐04 5.340E‐06 10 ‐ 50 mm 7.515E‐05 7.030E‐05 9.633E‐06 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 8.114E‐04 7.813E‐04 2.268E‐05
2 in
1 ‐ 3 mm 5.611E‐04 5.444E‐04 9.926E‐06 3 ‐ 10 mm 1.774E‐04 1.688E‐04 6.875E‐06 10 ‐ 50 mm 5.404E‐05 5.030E‐05 5.276E‐06 50 ‐ 150 mm 2.131E‐05 2.018E‐05 6.838E‐06 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 8.138E‐04 7.837E‐04 2.891E‐05
4 in
1 ‐ 3 mm 5.656E‐04 5.487E‐04 1.293E‐05 3 ‐ 10 mm 1.788E‐04 1.702E‐04 8.957E‐06 10 ‐ 50 mm 5.447E‐05 5.070E‐05 6.873E‐06 50 ‐ 150 mm 2.140E‐05 2.026E‐05 8.606E‐06 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 8.202E‐04 7.898E‐04 3.737E‐05
6 in
1 ‐ 3 mm 5.711E‐04 5.540E‐04 1.517E‐05 3 ‐ 10 mm 1.805E‐04 1.718E‐04 1.050E‐05 10 ‐ 50 mm 5.500E‐05 5.119E‐05 8.060E‐06 50 ‐ 150 mm 8.033E‐06 7.292E‐06 3.172E‐06 > 150 mm 1.347E‐05 1.307E‐05 6.748E‐06
Total 8.281E‐04 7.974E‐04 4.365E‐05
I quantified risk assessment I PROCESS INDUSTRY I 33
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Actuated Valves Source: HCRD 10/92 – 03/10
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
10 in
1 ‐ 3 mm 5.843E‐04 5.669E‐04 1.861E‐05 3 ‐ 10 mm 1.847E‐04 1.758E‐04 1.289E‐05 10 ‐ 50 mm 5.628E‐05 5.238E‐05 9.891E‐06 50 ‐ 150 mm 8.220E‐06 7.462E‐06 3.892E‐06 > 150 mm 1.356E‐05 1.314E‐05 8.053E‐06
Total 8.471E‐04 8.157E‐04 5.334E‐05
14 in
1 ‐ 3 mm 6.000E‐04 5.821E‐04 2.134E‐05 3 ‐ 10 mm 1.897E‐04 1.805E‐04 1.478E‐05 10 ‐ 50 mm 5.778E‐05 5.378E‐05 1.134E‐05 50 ‐ 150 mm 8.440E‐06 7.661E‐06 4.463E‐06 > 150 mm 1.365E‐05 1.323E‐05 9.088E‐06
Total 8.695E‐04 8.373E‐04 6.102E‐05
20 in
1 ‐ 3 mm 6.269E‐04 6.082E‐04 2.471E‐05 3 ‐ 10 mm 1.982E‐04 1.886E‐04 1.712E‐05 10 ‐ 50 mm 6.038E‐05 5.620E‐05 1.313E‐05 50 ‐ 150 mm 8.819E‐06 8.005E‐06 5.169E‐06 > 150 mm 1.381E‐05 1.337E‐05 1.037E‐05
Total 9.081E‐04 8.745E‐04 7.050E‐05
34 I PROCESS INDUSTRY I quantified risk assessment I
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Manual Valves Source: HCRD 10/92 – 03/10
Definition: Includes all types of manual valves (block, bleed, check and choke). Valve types gate, ball, plug, globe, needle and butterfly. The scope includes the valve body, stem and packer, but excludes flanges, controls and instrumentation.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 5.166E‐05 5.247E‐05 3.030E‐07 3 ‐ 10 mm 2.401E‐05 2.278E‐05 2.222E‐07 10 ‐ 50 mm 1.837E‐05 1.479E‐05 4.241E‐07 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 9.404E‐05 9.004E‐05 9.494E‐07
1 in
1 ‐ 3 mm 5.180E‐05 5.260E‐05 5.840E‐07 3 ‐ 10 mm 2.407E‐05 2.284E‐05 4.283E‐07 10 ‐ 50 mm 1.841E‐05 1.483E‐05 8.172E‐07 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 9.428E‐05 9.027E‐05 1.829E‐06
2 in
1 ‐ 3 mm 5.262E‐05 5.344E‐05 1.146E‐06 3 ‐ 10 mm 2.446E‐05 2.320E‐05 8.403E‐07 10 ‐ 50 mm 1.169E‐05 1.023E‐05 6.906E‐07 50 ‐ 150 mm 6.986E‐06 4.814E‐06 9.129E‐07 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 9.575E‐05 9.169E‐05 3.590E‐06
4 in
1 ‐ 3 mm 5.760E‐05 5.850E‐05 2.269E‐06 3 ‐ 10 mm 2.677E‐05 2.540E‐05 1.664E‐06 10 ‐ 50 mm 1.279E‐05 1.120E‐05 1.368E‐06 50 ‐ 150 mm 7.459E‐06 5.176E‐06 1.808E‐06 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 1.046E‐04 1.003E‐04 7.110E‐06
6 in
1 ‐ 3 mm 6.876E‐05 6.984E‐05 3.393E‐06 3 ‐ 10 mm 3.196E‐05 3.032E‐05 2.489E‐06 10 ‐ 50 mm 1.527E‐05 1.337E‐05 2.045E‐06 50 ‐ 150 mm 3.658E‐06 2.938E‐06 8.630E‐07 > 150 mm 4.859E‐06 3.047E‐06 1.840E‐06
Total 1.245E‐04 1.195E‐04 1.063E‐05
I quantified risk assessment I PROCESS INDUSTRY I 35
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Manual Valves Source: HCRD 10/92 – 03/10
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
10 in
1 ‐ 3 mm 1.163E‐04 1.181E‐04 5.640E‐06 3 ‐ 10 mm 5.405E‐05 5.128E‐05 4.137E‐06 10 ‐ 50 mm 2.583E‐05 2.261E‐05 3.400E‐06 50 ‐ 150 mm 6.185E‐06 4.968E‐06 1.435E‐06 > 150 mm 6.834E‐06 4.462E‐06 3.059E‐06
Total 2.092E‐04 2.014E‐04 1.767E‐05
14 in
1 ‐ 3 mm 2.067E‐04 2.099E‐04 7.888E‐06 3 ‐ 10 mm 9.607E‐05 9.114E‐05 5.785E‐06 10 ‐ 50 mm 4.591E‐05 4.020E‐05 4.754E‐06 50 ‐ 150 mm 1.099E‐05 8.830E‐06 2.006E‐06 > 150 mm 1.059E‐05 7.154E‐06 4.278E‐06
Total 3.703E‐04 3.573E‐04 2.471E‐05
20 in
1 ‐ 3 mm 4.436E‐04 4.506E‐04 1.126E‐05 3 ‐ 10 mm 2.062E‐04 1.956E‐04 8.257E‐06 10 ‐ 50 mm 9.852E‐05 8.627E‐05 6.786E‐06 50 ‐ 150 mm 2.360E‐05 1.895E‐05 2.864E‐06 > 150 mm 2.044E‐05 1.421E‐05 6.107E‐06
Total 7.924E‐04 7.656E‐04 3.527E‐05
36 I PROCESS INDUSTRY I quantified risk assessment I
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Process Vessel Source: HCRD 10/92 – 03/10
Definition: Includes all types of pressure vessel (horizontal/vertical absorber, knock‐out drum, reboiler, scrubber, stabiliser, separator and stabiliser), but not the HCRD category “other”, which are mainly hydrocyclones. The scope includes the vessel itself and any nozzles or inspection openings, but excludes all attached valves, piping, flanges, instruments and fittings beyond the first flange. The first flange itself is also excluded.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 8.884E‐04 7.859E‐04 1.600E‐04 3 ‐ 10 mm 5.946E‐04 4.093E‐04 1.393E‐04 10 ‐ 50 mm 8.768E‐04 3.448E‐04 5.117E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 2.360E‐03 1.540E‐03 8.110E‐04
1 in
1 ‐ 3 mm 8.884E‐04 7.859E‐04 1.600E‐04 3 ‐ 10 mm 5.946E‐04 4.093E‐04 1.393E‐04 10 ‐ 50 mm 8.768E‐04 3.448E‐04 5.117E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 2.360E‐03 1.540E‐03 8.110E‐04
2 in
1 ‐ 3 mm 8.884E‐04 7.859E‐04 1.600E‐04 3 ‐ 10 mm 5.946E‐04 4.093E‐04 1.393E‐04 10 ‐ 50 mm 4.379E‐04 2.236E‐04 1.408E‐04 50 ‐ 150 mm 4.389E‐04 1.211E‐04 3.709E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 2.360E‐03 1.540E‐03 8.110E‐04
4 in
1 ‐ 3 mm 8.884E‐04 7.859E‐04 1.600E‐04 3 ‐ 10 mm 5.946E‐04 4.093E‐04 1.393E‐04 10 ‐ 50 mm 4.379E‐04 2.236E‐04 1.408E‐04 50 ‐ 150 mm 4.389E‐04 1.211E‐04 3.709E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 2.360E‐03 1.540E‐03 8.110E‐04 1 ‐ 3 mm 8.884E‐04 7.859E‐04 1.600E‐04 3 ‐ 10 mm 5.946E‐04 4.093E‐04 1.393E‐04 10 ‐ 50 mm 4.379E‐04 2.236E‐04 1.408E‐04
6 in 50 ‐ 150 mm 1.652E‐04 6.181E‐05 7.316E‐05 > 150 mm 2.736E‐04 5.930E‐05 2.977E‐04 Total 2.360E‐03 1.540E‐03 8.110E‐04
I quantified risk assessment I PROCESS INDUSTRY I 37
Process Equipment Leak Frequencies
Rev.: 1
Date: 26/9/2012
Equipment Type: Atmospheric Storage Vessel Source: HCRD 10/92 – 03/10
Definition: This datasheet applies to offshore atmospheric tanks. Includes types of vessel at atmospheric pressure (oil storage tanks). The scope includes the vessel itself and any nozzles or inspection openings, but excludes all attached valves, piping, flanges, instruments and fittings beyond the first flange. The first flange itself is also excluded.
Frequency Data: Equipment Size Category Total Full Pressure Zero Pressure
0.5 in
1 ‐ 3 mm 1.462E‐03 1.177E‐03 3.081E‐04 3 ‐ 10 mm 1.084E‐03 8.152E‐04 2.593E‐04 10 ‐ 50 mm 2.144E‐03 1.318E‐03 8.126E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 4.690E‐03 3.310E‐03 1.380E‐03
1 in
1 ‐ 3 mm 1.462E‐03 1.177E‐03 3.081E‐04 3 ‐ 10 mm 1.084E‐03 8.152E‐04 2.593E‐04 10 ‐ 50 mm 2.144E‐03 1.318E‐03 8.126E‐04 50 ‐ 150 mm 0.000E+00 0.000E+00 0.000E+00 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 4.690E‐03 3.310E‐03 1.380E‐03
2in
1 ‐ 3 mm 1.462E‐03 1.177E‐03 3.081E‐04 3 ‐ 10 mm 1.084E‐03 8.152E‐04 2.593E‐04 10 ‐ 50 mm 9.034E‐04 6.255E‐04 2.514E‐04 50 ‐ 150 mm 1.240E‐03 6.922E‐04 5.612E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 4.690E‐03 3.310E‐03 1.380E‐03
4in
1 ‐ 3 mm 1.462E‐03 1.177E‐03 3.081E‐04 3 ‐ 10 mm 1.084E‐03 8.152E‐04 2.593E‐04 10 ‐ 50 mm 9.034E‐04 6.255E‐04 2.514E‐04 50 ‐ 150 mm 1.240E‐03 6.922E‐04 5.612E‐04 > 150 mm 0.000E+00 0.000E+00 0.000E+00
Total 4.690E‐03 3.310E‐03 1.380E‐03
6 in
1 ‐ 3 mm 1.462E‐03 1.177E‐03 3.081E‐04 3 ‐ 10 mm 1.084E‐03 8.152E‐04 2.593E‐04 10 ‐ 50 mm 9.034E‐04 6.255E‐04 2.514E‐04 50 ‐ 150 mm 3.866E‐04 2.462E‐04 1.253E‐04 > 150 mm 8.537E‐04 4.461E‐04 4.359E‐04
Total 4.690E‐03 3.310E‐03 1.380E‐03
38 I PROCESS INDUSTRY I quantified risk assessment I
7. REFERENCES
1. Department of Energy, The Public Inquiry into the Piper
Alpha Disaster, 1990
2. Health and Safety Executive (HSE), Hydrocarbon release
reporting and statistics (www.hse.gov.uk/offshore/
hydrocarbon.htm) accessed 2012
3. Spouge, J. (2005), New generic leak frequencies for
process equipment, Process Safety Progress, 24, 4,
pp249-257
4. Falck, A., Bain, B., & Rødsætre, L. (2009) Leak frequency
modeling of offshore QRA based on the Hydrocarbon
Release Database, Hazards XXI Conference, IChemE,
Nov. 2009.
5. Flemish Government. (2009) Handbook Failure
Frequencies 2009 for drawing up a safety report. LNE
Department. Environment, Nature and Energy Policy
Unit. Safety Reporting Division.
6. RIVM. (2009). Reference manual BEVI risk assessments.
v3.1, Jan 1st 2009. Centre for External Safety,
Netherlands National Institute of Public Health and the
Environment
DISCLAIMER: This document describes certain of DNV’s
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opportunities, profits or otherwise.
I quantified risk assessment I PROCESS INDUSTRY I 39
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