Paper PS7-3
LNG INCIDENT IDENTIFICATION—A COMPILATION AND
ANALYSIS BY THE INTERNATIONAL LNG IMPORTER’S GROUP
IDENTIFICATION DES INCIDENTS GNL UNE COLLECTE ET UNE
ANALYSE REALISEE PAR LE GROUPE INTERNATIONAL
DES IMPORTATEURS DE GNL
A. Acton
BG Group U.K
GIIGNL Study Group Chairman
F. Katulak
Tractebel LNG North America
J. L. Deveautour
Gaz de France
K. Sakamoto
Osaka Gas Company, Ltd.
M. Kan
Tokyo Gas Co., Ltd.
ABSTRACT
Safety in LNG Operations has been of utmost importance to the industry since its
inception. The International LNG Importer’s Group (GIIGNL) first began a
comprehensive study of incidents relating to the global LNG industry in 1992 and has
recently updated its work during 2001 to include all incidents reported up to that time.
The work has been undertaken by a Study Group comprising representatives from
GIIGNL Member companies in the USA, Europe and Japan who obtained data from all
the GIIGNL Members. The goals of the study were as follows:
• To identify actual incidents of LNG or vapor release for possible inclusion in the
hazard analysis of new, modified, or existing facilities.
• To advise on the severity of the identified LNG incidents to assist in evaluation of
their importance and potential consequences.
• To provide information on the circumstances under which the identified LNG
incidents occur (and their frequency where possible) to assist in the evaluation of
their relevance to the particular LNG facility under review.
Incidents have been categorized by type, function being performed, and severity. A
frequency and trend analysis has been performed on the data presented in order to
identify trends and draw conclusions.
The general trend is for a decrease in the relative number of events where significant
amounts of hydrocarbons are released. This indicates continual improvement in
mitigation measures and procedures at facilities.
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The most important fact drawn from this comprehensive study for the global LNG
industry is that there have been no reports of offsite damage resulting from an incident at
an LNG facility. This is important both in demonstrating the industry’s commitment to
safety and is demonstrable evidence of the adequacy of design and procedures employed
by the industry, as well as the codes and regulations which govern LNG facilities.
RESUME
La sécurité dans l’exploitation des installations de GNL a toujours été de la plus haute
importance dans cette industrie depuis sa création. Le Groupe International des
importateurs de GNL (GIIGNL) a initié en 1992 une étude détaillée des incidents qui se
sont produits dans l’industrie du GNL. Ce travail a été mis à jour en 2001 pour prendre en
compte tous les incidents enregistrés jusqu’à cette date. Cette étude a été réalisée par un
groupe de travail comprenant des représentants des compagnies membres du GIIGNL des
USA, d’Europe et du Japon qui eux-mêmes ont pu récolter des données en provenance de
tous les membres du GIIGNL. Les objectifs de cette étude sont les suivants :
• Identifier les incidents avec fuites de GNL ou rejets de gaz pour les inclure dans
les études de dangers des installations nouvelles, modifiées ou existantes.
• Conseiller sur la sévérité des incidents GNL identifiés pour permettre une
évaluation de leur ampleur et de la gravité de leurs conséquences.
• Fournir des informations sur les circonstances dans lesquelles ces incidents de
GNL se sont produit (et leur fréquence si possible) afin d’aider à l’évaluation de
leur occurrence pour les installations de GNL à étudier.
Les incidents ont été classés par type, fonction et par gravité. Une analyse de leur
occurrence et des tendances a été réalisée dans le but d’identifier les évolutions et de
pouvoir tirer de premières conclusions.
La tendance générale est une diminution relative des incidents conduisant à une fuite
significative de GNL. Cette constatation souligne les améliorations constantes dans les
mesures de prévention et dans les procédures d’exploitation.
Du point de vue de l’ensemble de l’industrie du GNL, cette étude détaillée établit
qu’il n’y a pas eu de conséquence à l’extérieur du site suite à un incident survenu sur les
installations GNL. Ce constat est à souligner à double titre. D’une part cela démontre
l’engagement de l’industrie dans la sécurité des installations et d’autre part cela souligne
l’adéquation des procédures utilisées ainsi que des codes et des réglementations qui
régissent les installations de GNL.
1. INTRODUCTION
The International LNG Importer’s Group (GIIGNL) has developed a database of
incidents of LNG release or vapour release at the LNG facilities their Members own and
operate. The key objective of the work is to provide real data for use in future hazard
assessments. The database covers the period from the beginning of the commercial LNG
Industry in 1965 up until late 2000.
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The study covers 38 (mainly) receiving terminals and peak-shaving plants belonging
to GIIGNL members. The scope includes all LNG incidents with the potential to cause
damage to equipment or injury to personnel. We have not sought to provide a unique list
of LNG incidents to be included in all hazard assessments because of the site-specific
nature of some LNG plant and equipment and also because operators or regulators may
wish to include scenarios for incidents that have not occurred due to the potential severity
of their consequences. Other incidents that are well-known within the LNG industry but
are outside the scope of this study were reviewed but were not included in the
quantitative analysis because they were already reported and also because the available
information was insufficiently detailed.
The work was led by the Permanent Technical Study Group of GIIGNL which, at the
time, comprised representatives from BG, CMS Energy, Tractebel LNG North America,
ENAGAS, Fluxys, Gaz de France, Gastransport services, Osaka Gas, GNL Italia, and
Tokyo Gas. BG provided the Secretariat for the Study Group. Regional co-ordinators
from within the Study Group communicated with companies within their regions and also
provided a single source of contact for the collection and distribution of incident
information. Tokyo Gas and Osaka Gas acted as Far-Eastern Regional Co-ordinators to
collect and process data from about half each of the 11 companies in their region.
Tractebel LNG North America and Gaz de France acted as American and European
Regional Co-ordinators respectively. Advantica Technologies of the UK prepared the
comparative analysis for the Study Group.
2. THE GIIGNL SURVEY
Information on incidents was first collected from previous GIIGNL studies and also
on recent incidents known to the Study Group Members that had not featured in those
studies. This was used to initiate the work but it was immediately recognised that more
details were required for any useful analysis of results to be performed. Reports of events
considered to be routine operational incidents were disregarded. Information was also
reviewed for a number of incidents in the public domain that were technically outside the
scope of this study because the plants concerned did not belong to GIIGNL members.
Detailed information on incidents was then obtained by a questionnaire that was
developed by the Study Group and then circulated by the regional co-ordinators to all of
the GIIGNL companies in their regions. Incidents were divided into three categories
based on definitions developed for the study, as follows:
Category 1 - Releases of Hazardous Material
Any release of LNG, LPG, NGL, Liquid Nitrogen or related
hydrocarbon gases leading to, or with the potential to lead to, injury to
personnel or damage to equipment or buildings either on or off site.
Category 2 - Near Misses
Any incident involving a hazardous material system where there was no
actual release of hazardous material but which had the potential to lead
to a release of hazardous material as described in Category 1.
Category 3 - Other Incidents of Concern
Any incident, not involving a hazardous material system in the LNG
plant, but, for example, with the potential to escalate to Category 1
release.
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Companies were asked to report the Immediate and Primary Causes of the incident in
order to distinguish between the precipitating event and its basic cause. Companies were
also asked to provide a summary of the key points of the incident.
It was recognised that a definition of the Immediate and Primary Causes of incidents
can be a subjective view so this was supported by detailed reviews of each incident by the
Study Group and a final consistency check between similar types of incident by a sub-
group of European Study Group Members.
One of the most important points in the incident reports was an estimate of the total
quantity released. This had proved difficult to specify in the past and so three quantity
bands were defined:
A: Less than 100 kg
B: Greater than 100 kg but less than 1 000 kg
C: Greater than 1 000 kg
Extra information such as date and time of the incident, sequence of events, extent of
consequences, details of any casualties, effect on plant production, size of vapour cloud
or liquid pool and actions taken to prevent it from happening again, were all obtained
where historical records were accurate enough for it to be provided.
The study was undertaken in two phases, initially covering the period from the start of
LNG importation in 1965 to Q1, 1994 and subsequently from Q2, 1994 to 2000.
3. INCIDENT DATA AND ANALYSIS
The incident database currently contains 144 ‘Previous’ incidents for the period 1965
to 1994 and 102 ‘New’ incidents from 1994 to 2000 making an ‘All’ incident total of
246.
3.1 Analysis by Function
The following groupings were used for the definition of equipment functions:
Unloading: LNG Ship, Jetty & Unloading Facilities.
Storage: LNG Tanks, In-Tank Pumps & BOG Facilities.
Send-out: Pumps, Vaporisers & Send-out Facilities (including LPG equipment)
External: Equipment outside the control of the terminal, other than the LNG ship.
Other: Utility equipment & any other equipment not included above.
The breakdown of incidents by function is shown in Figure 1 below. There is no
appreciable change in this data from the ‘Previous’ to ‘New’ periods and so only ‘All’
data is shown.
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By Function
'All'
Others
Storage
12%
21%
External
6%
Sendout Unloading
34% 27%
Figure 1. Incident Analysis by Function
The major functions, unloading, storage and sendout account for the majority of the
incidents. However, (ship) unloading is a discontinuous function at conventional import
terminals so the frequency of incidents as a function of operational time for this function
is the most significant of the three, see Section 3.4.
3.2 Analysis by Category
The three Incident categories are:
Category 1: Releases of Hazardous Material
Category 2: Near Misses
Category 3: Other Incidents of Concern
The breakdown of incidents by category is shown in Figure 2 below. There is no
appreciable change in this data from the ‘Previous’ to ‘New’ periods and so only ‘All’
data is shown.
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By Category
'All'
Category 3
18%
Category 2
14%
Category 1
68%
Figure 2. Incident Analysis by Category
3.3 Analysis by Function and Category
The breakdown of incidents by function and category is shown in Figure 3 below.
There is no appreciable change in this data from the ‘Previous’ to ‘New’ periods and so
only ‘All’ data is shown.
By Function for Each Category
'All'
100
80
60 3
2
40
1
20
0
Storage Unloading Sendout External Others
Figure 3. Incident Analysis by Function and Category
(Numbers of Incidents Reported)
The major functions, storage, unloading and sendout account for the majority of the
category 1 incidents (hazardous releases). For the incidents assigned to the Other function
category, the most significant numbers were associated with electrical/control equipment
failures.
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3.4 Frequency Versus Duration for Each Function
For the ‘Previous’ period from 1965 to 1994, estimates were made based on data from
GIIGNL and SIGTTO (Society of International Tanker & Terminal Operators) of the
cumulative operating period of the import terminals and peak-shaving sites included in
the scope of the study as summarised below.
• 533 operating ‘site-years’ (44 for 1965-1974, 179 for 1975-1984 and 310 for
1985-Q1, 1994).
• 3 060 ‘tank-years’ used for storage analysis.
• 20 250 ship voyages used for unloading analysis
• Total throughput of 868 x 109 m3(n) of natural gas sent out by import terminals
used for send-out analysis.
For the ‘New’ period from Q2, 1994 to 2000, operational data was collated via a
survey of terminals as summarised below.
• 208 ‘site-years’
• 1 110 ‘tank-years’
• 12 000 ship voyages
• Total throughput of 607 x 109 m3(n) of natural gas.
For the purpose of analysis, the above operating data has been converted into millions
of operating hours for each of the functions with the exception of sendout. The frequency
of incidents within each function was calculated and the results are shown in Table 1 and
Figure 4 below.
Table 1. Incident Frequencies per Function
Storage Unloading Sendout External Others
(Per million (Per million (Per 109 m3(n) (Per million (Per million
Data hours) hours) of gas) hours) hours)
Previous 1.34 176.95 54.15 1.71 2.14
New 1.64 166.67 60.96 3.31 10.47
All 1.42 173.13 56.95 2.16 4.47
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Frequency per Function Frequency per Function
'Previous' 'New'
200 200
176.95 166.67
150 150
Incident Incident
Frequency Frequency
100 100
(per m illion (per m ilion
hrs) hrs)
50 50
3.31 10.47
1.34 1.71 2.14 1.64
0 0
Storage Unloading External Others Storage Unloading External Others
Frequency per Function
'All'
200
173.13
150
Incident
Frequency
100
(per m ilion
hrs)
50
1.42 2.16 4.47
0
Storage Unloading External Others
Figure 4. Incident Frequencies per Function
The analysis shows that events during Unloading functions are the most frequent
although there is a small decrease in the rate for the “New” data compared with the
‘Previous’ data. These events are approximately 10 times more likely per operating hour
than for any other function. However, it is important to realise that the unloading
operation is relatively infrequent at import terminals, typically 16-20 hours per week.
Small increases in incident rates for Storage, Sendout, External and Other functions
are apparent between the two data collection periods. Whilst factors such as the increased
throughput and ageing equipment could have an influence, the introduction of formal
reporting procedures will likely have increased the number of incidents recorded.
3.5 Analysis by Incident Date & Time
Incident Date. Using the dates provided in the questionnaire report for each incident,
an incident frequency has been estimated for 4 periods of operation since the commercial
LNG industry began 35 years before completion of the present survey: The historical
incident frequencies per site-year are shown in Table 2 below.
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Table 2. Historical Incident Frequencies
Period Incidents Site-years Frequency
(Incidents/Site-
year)
1965 - 1974 15 44 0.34
1975 - 1984 52 179 0.29
1985 - 1994 94 327 0.29
1995 - 2000 85 191 0.45
Total 1965-2000 246 741 0.33
As noted in the previous section, the increase in incident frequency in the most-recent
5-year period may be due to factors such as the increased throughput and ageing of
equipment but is likely to be influenced by improved reporting rates following the
introduction of formal reporting procedures.
Incident Time. Analysis was based on an operational day period from 6:00 a.m. to
10:00 p.m. There is no appreciable change in this data from the ‘Previous’ to ‘New’
periods and so only ‘All’ data is shown in Figure 5 below.
Incide nt by Time of Da y
'All'
Night
19%
Day
81%
Figure 5. Incidents During the Day and Night
3.6 Analysis by Incident Cause
Two levels of incident causality were defined in the study, Major Immediate Cause
and Main Primary Cause in order to distinguish between the precipitating and the
underlying causes of incidents.
Major Immediate Cause. Four Major Immediate Causes were defined as follows:
– Operation (concerning an action, including maintenance)
– Material (concerning equipment, materials or installation)
– External (concerning anything out of the influence of the terminal)
– Unknown (concerning those where the Immediate Cause was never
found)
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The results are shown in Figure 6 below:
Major Immediate Cause Major Immediate Cause
'Previous' 'New'
Unknow n Unknow n
2% 5%
Operation Operation
27% 23%
Material
Material
52%
57%
External
External
14%
20%
Major Immediate Cause
'All'
Unknow n
3%
Operation
25%
Material
56%
External
16%
Figure 6. Incident Analysis by Major Immediate Cause
It can be seen that, in general, there are more incidents with a Major Immediate Cause
that can be attributed to problems with ‘Material’ (including equipment and its
installation) than those that are caused by ‘Operation’ (including maintenance), which is
the second most-important cause. However, there is a reduction in the proportion of
incidents due to ‘Material’ in the ‘New’ data compared with the ‘Previous’ data.
The breakdown of categories of incidents for each Major Immediate Cause is shown
in Figure 7 below:
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Major Immediate Cause v Category of Major Immediate Cause v Category of
Incident 'Previous' Incident 'New'
70 63 70
60 60
46
50 50
1 1
40 40
26 2 2
30 30
3 17 3
20 12 20 10
10
7 5 7 8 8 5
3 0 0 10
7 5 5 5
1 1 2 0 3
0 0
Material External Operation Unknow n Material External Operation Unknow n
Major Immediate Cause v Category of
Incident 'All'
120 109
100
80 1
60 43 2
40 3
13 14 18
20 10 12 9 10 5 0 3
0
Material External Operation Unknow n
Figure 7. Incident Analysis by Major Immediate Cause and Category
(Numbers of Incidents Reported)
The results show that incidents with ‘Material’ as a Major Immediate Cause (i.e.
defective equipment, materials or installation) tend to involve releases of hazardous
substances, and external causes are less likely to bring about an incident involving a
release.
Main Primary Cause. Four Primary Causes were defined as follows:
- Design/Construction,
- Operation/Maintenance,
- External Cause,
- Unknown,
For these causality groupings, the Design/Construction cause was restricted to
incidents caused by a problem with the initial design and installation of the equipment.
Any incidents caused by equipment failure during operation, operator error, poor
procedures and poor maintenance were grouped together under Operation/Maintenance.
In other words, these incidents were caused as a result of the operation of the terminal
and could not be attributed to poor design or installation in the first place. The results are
shown in Figure 8 below:
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Main Primary Cause Main Primary Cause
'Previous' 'New'
External External D/C
8% 16% 12%
Unknow n D/C
3% 27%
Unknow n
7%
O/M O/M
62% 65%
Main Primary Cause
'All'
External D/C
11% 21%
Unknow n
5%
O/M
63%
Figure 8. Incident Analysis by Main Primary Cause
It can be seen that O/M (operation & maintenance) is the biggest Main Primary Cause
of incidents and that the proportion of incidents with design and construction as the Main
Primary Cause has reduced between the ‘Previous’ and ‘New’ periods.
Major Immediate Cause Versus Main Primary Cause
Material. Figure 9 below shows that for the ‘Previous’ data, 51 % of incidents cited
as having ‘Material’ as a Major Immediate Cause had a Primary Cause that was a design
fault or an equipment failure. For the ‘New’ data this has increased to 69 %. This
suggests an improvement in maintenance, better procedures and less operator error.
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Primary Cause for Major Cause as Material Primary Cause for Major Cause as Material
'Previous' 'New'
Poor Maint
Poor Procs Poor Procs
27%
11% Poor Maint 6%
15% Ex/Unknow n
Op Error Ex/Unknow n 4%
Op Error
9% 2% 6%
Design/Equip Design/Equip
51% 69%
Primary Cause for Major Cause as Material
'All'
Poor Procs
9%
Poor Maint Ex/Unknow n
15% 4%
Design/Equip
59%
Op Error
7%
Figure 9. Primary Causes for Material as Major Immediate Cause
Operation. Figure 10, below, shows that for the ‘Previous’ data, 74 % of incidents
cited as having Operation as a Major Immediate Cause had Primary Causes that were due
to human actions (Operator Error and Poor Procedures). For ‘New’ data, this is 100 %.
Therefore, it is clear that these kinds of incidents can be reduced by better training of
operators and an improvement in procedures.
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Primary Cause for Major Cause as Operation Primary Cause for Major Cause as Operation
'Previous' 'New'
Ex/Unknow n Design/Equip
Ex/Unknow n Design/Equip 0% 0%
13% 13% Poor Procs
22%
Poor Maint
Poor Procs 0%
31%
Op Error
43% Op Error
Poor Maint
78%
0%
Primary Cause for Major Cause as Operation
'New'
Ex/Unknow n Design/Equip
8% 8%
Poor Procs
27%
Op Error
Poor Maint 57%
0%
Figure 10. Primary Causes for Operation as Major Immediate Cause
3.7 Analysis by Release Quantity
Analysis of the Category 1 incidents (the only category that includes actual releases
of hazardous material) produced the results shown in Figure 11 below:
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Quantity of Release Quantity of Release
'Previous' 'New'
>1000kg
8%
>1000kg
100-1000kg
36%
1000kg
25%
1000kg 1000kg
Function for each Release Quantity
'All'
100
80
Unloading
60
Storage
40
Sendout
20
0
1000kg
Figure 12. Release Quantity for Unloading, Storage and Sendout Functions
(Numbers of Incidents Reported)
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There is a general trend between the ‘Previous’ and ‘New’ data away from incidents
involving the larger releases of hazardous materials. The improvement for unloading
facilities is particularly striking.
3.8 Incident Analysis by Gravity
Incidents have been classified according to their gravity by cross-referencing the
incidents of release of hazardous material (Category 1 Incidents) against the range of
consequences reported, i.e. Explosion (E), Fire (F) or Rapid Phase Transition
(RPT).There is no appreciable change in this data from the ‘Previous’ to ‘New’ periods
and so only ‘All’ data is shown in Figure 13 below.
Gravity of Event
'All'
11%
No E,F,RPT
E,F,RPT
89%
Figure 13. Incident Analysis by Gravity
4. CONCLUSIONS
• Since the commercial LNG import industry began in 1965, there have been no known
instances of damage outside the LNG facility concerned nor of catastrophic LNG
storage tank failure leading to loss of containment integrity. This study has confirmed
these facts.
• A total of 246 incidents of releases of hazardous material, near misses and other
incidents of concern have been reported and analysed in this comprehensive study of
GIIGNL Member’s facilities covering the 35 year period from 1965 to 2000.
• The frequency of the reported incidents over the whole period is very low, 0.33
incidents per site-year.
• Incidents involving the release of hazardous material (hydrocarbons) are 68 % of all
those reported.
• The gravity of the events reported is variable and only 11 % resulted in an explosion,
fire or rapid phase transition.
• The study has been undertaken over two periods from 1965-1994 and from 1994-
2000 and it has therefore been possible to evaluate safety performance improvements.
There is a trend towards a decrease in the relative number of events where significant
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quantities of hydrocarbon have been released. This demonstrates better mitigation
measures and operational procedures at LNG import facilities.
• The frequency of events reported has increased in some areas. Whilst this is likely to
be influenced by the introduction of formal reporting procedures, factors such as
increased throughput and ageing of equipment could also be responsible.
• The analysis shows that incidents during LNG unloading functions are the most
frequent. These incidents are approximately 10 times more likely per operating hour
than for any other function but do not contribute excessively to the total number
because LNG unloading is a relatively infrequent operation at LNG import facilities.
• The severity of incidents during LNG unloading has deceased dramatically recently,
which shows that LNG Importers have been successful in reducing this risk.
• The relative number of incidents where the cause was considered to be outside of the
influence of the terminal has increased. Nine out of the 20 incidents are related to
shipping, 5 to adverse weather (storms, lightning), 2 to external interference (digging
up pipelines), an electrical supply interruption, a vehicle impact, an adverse pressure
build up in a tank and a World War I bomb discovered during excavation works near
an LNG site.
• Many fewer incidents (19 %) occur during the night than during daytime hours.
• The LNG Importer’s Group (GIIGNL) believes that it has developed a comprehensive
database of incidents that will be useful for the future design and development of safe
LNG facilities. GIIGNL is committed both to improving further the reporting of
incidents and to maintaining its database up-to-date for the general good of the LNG
Industry.
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