Proceedings of the 2nd Int. Symposium on “Ship Operations, Management and Economics”, The Greek Scetion of the Society of Naval Architects and Marine Engineers (SNAME), Athens, Sep. 17-18, 2008
Impact of ship age on tanker accidents A. Papanikolaou1), E. Eliopoulou2) 1
Ship Design Laboratory-NTUA, Greece,
[email protected] Ship Design Laboratory-NTUA, Greece,
[email protected]
2)
Hull and Non-Double hull configurations) and of ship’s building year and age with marine accidental oil pollution. Calculations of accident rates were conducted on the basis of historical data for the period 1990-2007 by category of accidents, ship’s hull type configuration and building year in order to identify underlying trends. In particular, the paper focuses on the impact of tanker’s hull type and age on the accident statistics, considering the introduction of a variety of regulatory developments since the early 90ties (OPA 90 and MARPOL amendments), phase-out schemes of single-hull tankers, enhanced class survey programs and 2nd hand tanker ship trading patterns.
Abstract There is a strong general believe that ship accidents and particularly tanker accidents leading to marine pollution are mainly related to ship’s age, namely the older the ship the more likely her involvement in at least non-accidental structural failure accidents. The paper presents results of a comprehensive analysis of recorded large tanker accidents of DWT greater than 60,000 that occurred in the period between 1990 and 2007. The analysis enables the identification of clear trends with respect to the accident rates per shipyear for all major accident categories. It also relates the impact of ship’s hull design, namely of the double hull and the various non-double hull configurations, as well as the impact of ship’s age on non-accidental structural failure accidents. Results of the latter analysis were partly unexpected, showing that more than ship’s age, the actual condition of ship’s structure in terms of maintenance and building quality are the decisive factors for non accidental structural failure accidents.
Oil Tanker Casualties, Historical data Collision
Contact
Grounding
Fire
Explosion
NASF
Frequency per shipyear
1.40E-01 1.20E-01 1.00E-01 8.00E-02 6.00E-02 4.00E-02 2.00E-02
Fig. 1:
Keywords
2007
2006
2004 2005
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1982 1983
1981
1980
0.00E+00
Frequency per shipyear
2. Approach
Tanker accident rates; marine pollution; tanker hull design; impact of ship’s age on accidents
2.1 Field Data Model
Nomenclature
Casualty databases are potentially important tools for the evaluation of tanker safety and the environmental performance of the shipping industry. The investigation of historic accident scenarios could lead to the identification of vulnerable operational or design problems and also provide guidance to regulatory process to ship safety and environmental protection. There are many casualty databases available nowadays, enabling the conduct of this type of analysis; the most prominent and complete ones are believed to be the Lloyd’s Register Fairplay (LRFP) and Lloyd’s Maritime Intelligent Unit (LMIU). Although these databases contain a significant amount of data (even though it is believed that a series of data related to near-misses and underreporting are missing), they were originally not designed for potential application to rational risk assessment procedures, making their usage in engineering studies, if not post-processed, quite problematic.
DH Double hull ships LOWI Loss of Watertight Integrity NASF Non-Accidental Structural Failure
1. Introduction The introduction of OPA90 and the more recent amendments to the MARPOL convention by IMO, first mandating double hulls for new tankers and second accelerating the phase-out of single hull tankers, were conceived in order to minimize oil pollution caused by tanker accidents. As a result of this and of other measures, a remarkable decrease of tanker accidents of all types could be observed, Fig.1. The main scope of the present paper is to identify possible relationships between the tanker hull design (Double
1
Proceedings of the 2nd Int. Symposium on “Ship Operations, Management and Economics”, The Greek Scetion of the Society of Naval Architects and Marine Engineers (SNAME), Athens, Sep. 17-18, 2008 seeable future. In (Delautre et al., 2005) it was found that there was a significant reduction of accidents occurrence in the post-90 period (Fig. 1) due to the introduction of a series of regulations (with the most prominent one being OPA 90) on the prevention and mitigation of accidents (Fig. A1, Appendix) 3. In the post-1990, more and more double hull ships were built and are operating, displacing single hull ships (Fig. A2, Appendix). With respect to the studied tanker subcategories and sizes, large oil tankers - Oil Tankers, Crude Tankers, Shuttle Tankers, Product Carriers and Chemical/Oil Tankers- of DWT greater than 60,000 were selected for the herein presented investigation. Considering the above, in total 814 incidents large tanker accidents were investigated, Table 1.
This post-processing may be achieved by a second round of evaluation of these casualty data transforming first the source information, i.e. textual information, into a proper format to be directly applicable in risk assessment studies. Therefore, for setting-up proper tanker ship risk evaluation models, the casualty information of the LRFP and LMIU databases were imported into a purposely designed database of NTUA-SDL (Papanikolaou et al., 2005) enabling the further processing towards the quantification of detailed event categories and the direct extract of conditional probabilities of identified accident scenarios in terms of frequency and consequence models. In Fig. 2, the herein applied field data model for this assessment is illustrated (Eliopoulou et al., 2008).
2.
Table 1:
Fig. 2:
Field Data Model
Casualty data2, Covered period 1990-2007
Category
No of incidents
%
Collision
265
33%
Contact
93
11%
Grounding
192
24%
Fire
77
9%
Explosion
39
5%
NASF
148
18%
Total
814
100%
2.2 Sampling plan
2.3 Fleet at risk
The applied full evaluation model of ships’ casualties, independently of ship type, shall include all possible incident categories that may lead to an undesired event (as a consequence of identified hazards), as indicated in Fig. 3. The particular study focuses on the six (6) events that potentially lead to ship’s Loss Of Watertight Integrity (LOWI), namely collision, contact, grounding, fire, explosion, non-accidental structural failure and to accidental oil pollution.
Relevant fleet at risk was based on LRFP data (Loer & Hamann, 2007), see Appendix, Fig. A2.
Fig. 3:
3. Navigational events 3.1 Collision events Collision events refer to incidents where two vessels accidentally come into contact with each other. The investigated scenarios contain collisions when the tanker vessel is striking or being struck by another ship. The collision probability is highly related to the traffic density. According to the statistics, most collisions take place within congested waters with dense ship traffic, crossing routes and areas with large ship speed variations. The basic causes are bad visibility, navigational or technical failures. Concerning the degree of event’s severity as coded in LRFP/LMIU databases, 25% of them are characterised by serious degree of severity, from which 8% resulted to ship’s total loss. In 8 events out of 265 (Table 1), there were 2 nonserious injuries and 55 fatalities (39 missing persons and 16 deaths). In 11 cases out of the 265 recorded accidents (4%), fire occurred during the accident. In all these cases, except for one, the accident was of serious degree of severity.
Generic Casualty Categorization
The time period of 1990-20071 was selected for the present investigation, aiming at looking at the present state of affairs and into the foreseeable future. This was done for the following reasons. 1. The sample of ship accidents to be analyzed should be representative for the present status and the fore1
Results of a similar study on AFRAMAX ship accidents for the period 1978-2003, in which the share of double hull ships was limited, may be found in (Papanikolaou et al., 2006).
2
2
Excluded incidents happened in Shipyards & Drydocks
Proceedings of the 2nd Int. Symposium on “Ship Operations, Management and Economics”, The Greek Scetion of the Society of Naval Architects and Marine Engineers (SNAME), Athens, Sep. 17-18, 2008 Collision events, followed by fire/explosion, are events with very severe consequences. According to the setup database, in cases when collision was followed by fire/explosion, the expected crew fatality rate is about 40% of ship’s crew number, when there is ship’s total loss and 14%, when there is no total loss but severe ship damage. With respect to the oil spill occurrence, in 27 collision events (10% of registered collisions) there was oil release to the sea, resulting to 126,532 tonnes of oil spilt within the studied period.
3.4 Frequency of navigational events In Figs 4-6, the frequency of each navigational event is presented for the two basic ship hull types (DH and non DH). Tanker hull type appears not to be related to the occurrence of navigational accidents. This conclusion could be expected, because the main causes of such events are related to human operational errors or/ and technical failures. Thus, the frequency assessment of navigational events could be considered as independent of the hull type. However, the consequences of navigational accidents are expected to be different in terms of environmental oil cargo release, because there is a certain probability of inner hull non-breaching for DH ships, resulting to no environmental pollution.
3.2 Contact events Contact events refer to scenarios where the vessel accidentally comes into contact with a floating object or a fixed installation. The likelihood of contacts is higher in congested waters than in open sea operation. In fact, the majority of the contact scenarios takes place during maneuvering operations or approach/sailing in rivers and canals. The basic causes for contacts are poor visibility, navigational, technical or human failures. In total, 93 accidents were registered as contacts, Table 1, from which 67% were contacts with a fixed installation and 33% with a floating object. Concerning the degree of the event’s severity, as coded in LRFP/LMIU databases, 25% were characterised by serious degree of severity. No ship’s total loss was registered in the particular incident category. No injuries or fatalities were recorded during the studied period in such events. With respect to the oil spill occurrence, in 16 contact events (17% of registered contacts) there was oil release to the sea, resulting to 13,162 tonnes of oil spilt within the studied period.
Collision events
Frequency per shipyear
Non-DH ships
DH ships
3.00E-02 2.50E-02 2.00E-02 1.50E-02 1.00E-02 5.00E-03 0.00E+00 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Incident Year
Fig. 4:
Frequency of collision events
Contact events
Frequency per shipyear
Non-DH ships
3.3 Grounding events
DH ships
2.00E-02 1.75E-02 1.50E-02 1.25E-02 1.00E-02 7.50E-03 5.00E-03 2.50E-03 0.00E+00 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Incident Year
Grounding events refer to scenarios where the vessel accidentally comes into contact with the sea bed or shore. Grounding is predominantly caused by navigational failure (powered grounding) or by propulsion, power or steering failure (drift grounding). The main causes for grounding accidents are related to ground topology and environmental conditions, technical failures (steering or machinery failures) and human factors. In total, 192 accidents were registered as groundings, of which 83% were powered groundings and 17% were drift groundings. Concerning the degree of event’s severity as coded in LRFP/LMIU databases, 41% are characterised by serious degree of severity, from which 5% resulted to ship’s total loss. Concerning all grounding scenarios, in only one accident there was one reported fatality (missing person). With respect to the oil spill occurrence, in 17 grounding events (9% of registered groundings) there was oil release to the sea, resulting to 245,942 tonnes of oil spilt within the studied period.
Fig. 5:
Frequency of contact events
Grounding events
Frequency per shipyear
Non-DH ships
DH-ships
2.50E-02 2.00E-02 1.50E-02 1.00E-02 5.00E-03 0.00E+00 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Incident Year
Fig. 6:
Frequency of grounding events
3.5 Navigational events & ship’s age The frequency of navigational events increases when ships turn 15 years and older, whereas high frequencies are observed for the collisions and groundings of young ships (0-5 years), Fig. 7. Although there is a small reservation on the estimation of the employed fleet at risk in calculating the event frequencies, slightly underestimating the number of newbuildings entering the fleet at risk at the year of census, the observed high frequencies
3
Proceedings of the 2nd Int. Symposium on “Ship Operations, Management and Economics”, The Greek Scetion of the Society of Naval Architects and Marine Engineers (SNAME), Athens, Sep. 17-18, 2008 serious degree of severity, from which 28% resulted to ship’s total loss. In 17 accidents out of 39, Table 1, there were 65 fatalities. With respect to the oil spill occurrence, in 3 explosion events (8% of registered explosions) there was oil release to the sea resulting to 278,770 tonnes of oil spilt within the studied period.
for the navigational events of young ships may be related to crew’s proper training, communication problems and to crew’s ability to handle new technology equipment. Navigational Events, Covered Period 1990-2007 Oil Tankers >60,000 DWT, Frequency per shipyear
Collisions
Contacts
Groundings
2.50E-02 2.00E-02
4.3 Frequency of fire, and explosion events
1.50E-02 1.00E-02
In Figs 8-9, the frequency of fire and explosion event is presented for each basic hull type. Tanker hull type seems to be unrelated to the occurrence of fire and explosion accidents. Thus, frequency assessment could be considered as independent of hull type.
5.00E-03 0.00E+00 0-5 years
Fig. 7:
6-10 years
11-15 years
16-20 years
> 20 years
Frequency of navigational events vs. Ship’s age
Fire events Non-DH Frequency per shipyear
4. Fire and Explosion events 4.1 Fire events Fire events refer to scenarios where the fire is the first, initiative event. Fire can start due to internal sources, external sources (unlawful acts, spread of fire from other ship) or due to atmospheric conditions (by lighting). Fire due to internal source can be initiated in ship’s aft area, on deck, in Cargo/Slop tanks area, in Ballast/Void spaces or in the Fore Peak area. Fire in the aft area can occur in the accommodation area (above main deck) because of electrical faults, heating equipment failure, smoking etc., or below the main deck in Engine Room or in the Pump Room. The accident evolution depends on the timing (early/late) of detection and the rate of fire spreading. In total, 77 accidents were registered as fire, 96% were fires due to internal source, 1% by external source and 3% by lightning. Fire due to internal source started in Aft Area (89%), in cargo/slop tanks (5%), in ballast tanks (3%) and on deck (3%). Concerning the degree of event’s severity, as coded in LRFP/LMIU databases, 31% were characterised by serious degree of severity, from which 27% resulted to ship’s total loss. In 10 accidents, there were 22 injuries (21 serious & 1 non serious) and 12 fatalities (5 missing and 7 deaths). With respect to the oil spill occurrence, in 2 fire events (3% of registered fires) there was oil release resulting to 161,000 tonnes of oil spilt within the studied period.
DH ships
2.00E-02 1.75E-02 1.50E-02 1.25E-02 1.00E-02 7.50E-03 5.00E-03 2.50E-03 0.00E+00 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Incident Year
Fig. 8:
Frequency of fire events
Explosion events
Frequency per shipyear
Non-DH
DH ships
1.80E-02 1.60E-02 1.40E-02 1.20E-02 1.00E-02 8.00E-03 6.00E-03 4.00E-03 2.00E-03 0.00E+00 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Incident Year
Fig. 9:
Frequency of explosion events
4.4 Fire, Explosion events & ship’s age Figs 10-11 present the frequency of fire, and explosion occurrence by ship hull type and age. DH ships are a relatively new ships thus there are no representatives in the larger age groups. Independently of the hull type, higher frequencies are observed for higher ship ages. Fires, Covered Period 1990-2007 Oil Tankers >60,000 DWT All ships
4.2 Explosion events
DH ships
1.20E-02 Frequency per shipyear
Explosion events refer to scenarios where the explosion is the first, initiative event. In total, 39 explosions occurred in the operational phase of the studied tanker ships during the period 1990-2007. Explosion started in Aft Area (47%), in cargo/slop tanks (47%), and on deck (6%). Concerning the degree of event’s severity as coded in LRFP/LMIU databases, 69% were characterised by
1.00E-02 8.00E-03 6.00E-03 4.00E-03 2.00E-03 0.00E+00 0-5 years
Fig. 10:
4
6-10 years
11-15 years
16-20 years
> 20 years
Frequency of fire events by group age
Proceedings of the 2nd Int. Symposium on “Ship Operations, Management and Economics”, The Greek Scetion of the Society of Naval Architects and Marine Engineers (SNAME), Athens, Sep. 17-18, 2008 Focusing on the 6 cases where there was ship’s total loss, the following was observed:
Regarding the high frequencies observed for the fire and explosions of young ships (0-5 years), there is a small reservation on the estimation of the employed fleet at risk, not properly capturing the number of newbuildings entering the fleet at risk at the year of census. Explosions, Covered Period 1990-2007 Oil Tankers >60,000 DWT All ships
DH ships
•
All accidents happened while the ship was en route in Open Sea, in heavy weather conditions.
•
In all cases the involved tanker ships were of NonDH construction.
•
In 5 cases, external hull damage was the starting point of NASF. The ship was loaded in 4 cases out of 5, causing significant oil spill in the majority of cases.
4.50E-03 4.00E-03 3.50E-03 3.00E-03 2.50E-03
•
In the remaining one case, deck damage was the starting point of NASF. With respect to the oil spill occurrence, in 38 nonaccidental structural failures (26% of registered NASF) there was oil release to the sea resulting to 170,538 tonnes of oil spilt within the studied period.
2.00E-03 1.50E-03 1.00E-03 5.00E-04 0.00E+00 0-5 years
Fig. 11:
6-10 years
11-15 years
16-20 years
> 20 years
Frequency of explosion events by group age
5.2 NASF recordings of Double Hull ships
5. Non-accidental structural failures, NASF
Focusing on Double Hull ships, 20 non-accidental structural failures were registered in the period 1990-2007. Concerning the degree of event’s severity as coded in LRFP/LMIU database, in 11 cases the event was characterised by serious degree of severity and in 9 cases there were non serious degree of severity. According to the recorded data, the weather condition was an important factor in 6 cases out of 20. Practically, no oil spill occurred due to NASF for DH ships in the study period (in 1 case there was a minor release of oil, around 1 tonne).
Non-accidental structural failure events refer to scenarios where the hull presents cracks and fractures, affecting ship’s structural integrity and seaworthiness. Damage to a vessel rudder, or rudder-adjoining parts are herein also counted as structural damage. However, damages related to ship’s hull-fitting equipments, like vessel propeller, propeller portion or propeller adjoining parts are not included in the particular categorisation. Non-accidental structural failures may potentially lead to the Loss Of Watertight Integrity (LOWI); they occur because of structural degradation, overstressing due to excessive loading or due to poor design and/or construction. Such accidents mainly happen while the tanker ship is in en-route in Open Sea/Archipelagos, or during loading or discharging operations.
5.3 Weather relation Based on the NASF registered data for all ships, regardless the hull type, many incidents happened in heavy weather conditions (about 35%, 52 cases out of 148 incidents). This does not mean that the weather condition is the main cause of non-accidental structural failures. Large tanker hulls are typically designed to handle a wide range of weather conditions. In case of poor hull structural design or corrosion due to poor maintenance, however, the structure becomes weak to handle heavy weather conditions and this naturally leads to nonaccidental structural failures. Focusing on Double Hull ships, the relation of NASF to weather conditions was found to be almost the same as for the overall fleet (about 30%, 6 cases out of 20 incidents). This could be actually more related to structural design problems because the particular tanker fleet has a relatively small age up to date and maintenance problems should come second. Looking into detailed data, according to the setup database, in all weather related accidents, the DH ships involved were at the group age of less than 5 years. Table 2 presents the age distribution of Double Hull ships involved to NASFs during the studied period 1990-2007.
5.1 NASF recordings independent of ship’s hull type Non-accidental structural failure events present 18% of all registered initial causes in the setup database involving large tanker ships for the studied period 1990-2007. In total, 148 accidents were registered as non-accidental structural failures, Table 1. The degree of event’s severity as coded in LRFP/LMIU databases is presented in Fig. 12. NASF, Historical data, Covered period 1990-2007 Degree of severity, 148 incidents
No of accidents
100
92
80 60
46
40 20
6
4
0 Total loss
Fig. 12:
Serious
Not serious
Unknown
NASF, accidents’ severity
5
Proceedings of the 2nd Int. Symposium on “Ship Operations, Management and Economics”, The Greek Scetion of the Society of Naval Architects and Marine Engineers (SNAME), Athens, Sep. 17-18, 2008 Table 2:
Non-accidental structural failures, DH ships, covered period 1990-2007 Group age
Number of ships
up to 5 years
15
6-10 years
1
11-15 years
2
>16 years
2
NASFs, Covered Period 1990-2007 Oil Tankers >60,000 DWT PANAMAX
0-5 years
Fig. 15:
With respect to Non-DH ships, the majority of NASFs started at the external hull (59%), Fig. 13. In contrary, DH ships found to present higher structural problems in the internal structural hull (40%).
Percentage of events
V&ULCC
All ships
6-10 years
11-15 years
16-20 years
> 20 years
NASF Frequency by tanker size & age NASFs, Covered Period 1990-2007 Oil Tankers >60,000 DWT All ships
NASF events, Structural damage initiation Covered Period 1990-2007
AFRAMAX
SUEZMAX
1.20E-02 1.00E-02
DH ships
8.00E-03
70
6.00E-03
60 50
4.00E-03
40
2.00E-03
30
0.00E+00
20
6-10 years
10
11-15 years
16-20 years
> 20 years
0 Deck damage
Internal damage
Fig. 13:
Hull damage
Rudder damage
Unknown
Fig. 16:
NASF, damage initiation
Fig. 14 presents the NASF frequency per shipyear for each basic hull type. Non Accidental Structural failures Non-DH
NASF Frequency of AFRAMAX & SUEZMAX by group age
Regarding these two notable observations, the following reasoning is offered for discussion. 1. Failures of young aged ships (0-5 years): this is alarming for the quality of recently delivered DH ships3. It is hoped that the ongoing discussion about Goal Based Standards (IMO MSC76/5/10) and the recently introduced Common Structural Rules by IACS (IACS, 2006) effectively address this. The related NASF status for the AFRAMAX and SUEZMAX DH ships in age group of 0-5 years, is shown in Fig.17.
5.5 NASF Frequency per shipyear
Frequency per shipyear
SUEZMAX
2.00E-02 1.80E-02 1.60E-02 1.40E-02 1.20E-02 1.00E-02 8.00E-03 6.00E-03 4.00E-03 2.00E-03 0.00E+00
5.4 NASF damage initiation
Non-DH ships
AFRAMAX
DH
4.00E-02 3.50E-02 3.00E-02 2.50E-02 2.00E-02 1.50E-02 1.00E-02 5.00E-03 0.00E+00 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
NASFs, Covered Period 1990-2007 Double Hull, Oil Tankers
Incident Year
AFRAMAX, DH
Fig. 14:
Frequency of NASF per shipyear
2.00E-02
1.77E-02
1.75E-02
5.6 NASF and ship’s age
SUEZMAX, DH
Frequency
1.50E-02
Taking into account all tanker ships involved in NASFs, the frequency of the particular accident category generally increases, when ship’s age increases after the 6-10 years of built, Fig. 15 (line). There are, however, two very interesting and unexpected observations to note. 1. Young ships of age zero to five years (0-5) show a remarkable structural failure rate for all ship categories, except for VLCC/ULCC. 2. For two tanker categories, namely AFRAMAX and SUEZMAX, with a significant share in the overall fleet at risk, there is a peak at the age group 11-15 years and then the frequency decreases, particularly for the SUEZMAX, whereas for the AFRAMAX the frequency increases sharply only for ages over 20 years (Fig. 16).
1.25E-02 1.00E-02 7.50E-03 5.00E-03
4.64E-03
2.50E-03
0.00E+00
0.00E+00 0-5 years
Fig. 17:
2.
4.96E-04
6-10 years
Frequency of NASF per shipyear
Peak NASF frequency (age group 11-15 years): This might be attributed to a decreased maintenance effort on ship’s hull structure when approaching her assumed design economic life of about 20 years and before the ship changes ownership for her 2nd economic life by another operator. Note that this observation is clearer for single hull ships, as
3 Some reservation might be due here in view of possible slight underestimation of recorded newbuildings in the relevant fleet at risk
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Proceedings of the 2nd Int. Symposium on “Ship Operations, Management and Economics”, The Greek Scetion of the Society of Naval Architects and Marine Engineers (SNAME), Athens, Sep. 17-18, 2008 following individual catastrophic events and such events (fortunately) did not happen yet with large DH oil tankers. It is noted, that one catastrophic accident with a DH ship happened in the study period, namely with the DH Ore/Bulk/Ore AFRAMAX “Aegean Sea” that took place in 1992 in Spanish waters causing 74,000 tonnes of oil spill. The “Ore/Bulk/Ore” tanker subcategory was, however, not included in the present analysis by definition. Despite and even including this accident in the DH assessment, pollution rates of DH ships are still significantly better than those of non DH ship hull types.
shown in Fig. 18 (Papanikolaou et al., 2006) AFRAMAX Tankers, Accident Rates by AGE Collision
Contact
Grounding
Structural Failure
Fire
Explosion
3.00E-02 2.50E-02 2.00E-02 1.50E-02 1.00E-02 5.00E-03 0.00E+00 0-5 years
Fig. 18:
6-10 years
11-15 years
16-20 years
> 20 years
Frequency of NASFs per shipyear by accident category and ship age - AFRAMAX ships
7. Conclusions The undertaken study leads us to the following conclusions: 1. A significant decrease of the frequency of large tanker accidents is noted in the post 1990 period. This is related to the introduction of a series of regulatory measures, changes in ship design and technology and overall improvement of the safety culture of the engaged maritime industry. 2. Double hull ships proved very effective in limiting marine environment accidental pollution, Fig. 19 and Table 3. 3. It was found that non-accidental structural failure accidents (NASF) are generally related to ship’s maintenance and age, however with respect to age in a non-straightforward way. Alarmingly, some young double hull ships show unexpectedly NASF problems, calling for enhanced measures by builders and class societies to improve this unsatisfactory state of affairs.
6. Environmental pollution Based on the investigated sampling plan and the setup database, a total amount of about 1,000,000 tonnes of oil spill was released to the sea environment due to large tanker accidents in the period 1990-2007, Fig. 19. Historical data, Covered period 1990-2007 Amount quantity of oil spilt Total amount = 995,944 tonnes 278770
300000 245942
Tonnes
250000 200000
161000
150000
170538
126532
100000 50000
13162
0 Collision
Fig. 19:
Contact
Grounding
Fire
Explosion
NASF
Oil spill release to the sea environment
Practically, this environmental pollution is entirely attributed to accidents of single hull ships. The environmental pollution due to DH ships’ accidents is less than 2% of the total oil quantity released to the sea, Table 3. Table 3:
Acknowledgements A part of the work presented herein was financially supported by the European Commission under the FP6 Sustainable Surface Transport Programme. This support was given under the scheme of STREP, POP&C project, Contract No. TST3-CT-2004-506193 and under the Integrated Project SAFEDOR, Contract No FP6516278. The European Community and the authors shall not in any way be liable or responsible for the use of any knowledge, information or data of the present paper, or of the consequences thereof. The views expressed in this paper those of the authors and do not necessary reflect the views and policies of the European Community. The authors like to thank their SAFEDOR project partner Germanischer Lloyd AG, especially Drs R. Hamann and K. Loer for their support with data in the presented work.
Environmental pollution by DH ships Covered period 1990-2007
Incident type
Oil release to the sea, in tonnes
Collision
215
Contact
292
Grounding
24
Fire
17000
Explosion
0
NASF
1 17532
Therefore, results of the present study indicate that oil pollution rates of large tankers with Double Hull configuration are nearly zero and orders of magnitude smaller than those of non-double hull tankers. However, before drawing reliable conclusions on the actual impact of tanker hull configuration on pollution, the following should be considered. Pollution rates and relevant statistics change drastically
References Delautre, S, Eliopoulou, E, and Mikelis, N, (2005). "The Influence of Regulations on the Safety Record of the Aframax Tankers", Study carried out within the EU
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Proceedings of the 2nd Int. Symposium on “Ship Operations, Management and Economics”, The Greek Scetion of the Society of Naval Architects and Marine Engineers (SNAME), Athens, Sep. 17-18, 2008 view of AFRAMAX Tankers Incidents", 3rd Int. Conference ENSUS, Newcastle upon Tyne, 13-15 April 2005. Papanikolaou, A, Eliopoulou, E, and Mikelis, N, 2006. "Impact of hull design on tanker pollution", Proc. 9th Int. Marine Design Conference IMDC, Ann Arbor, Michigan, May 16-19. POP&C, “Pollution Prevention and Control.” EU project, 6th Framework Programme, Contract No TST3-CT-2004-506193, 2004-2007. SAFEDOR (2005-2009), “Design, Operation and Regulation for Safety”, EU project, FP6-516278.
funded project POP&C, Contract No TST3-CT2004-506193. Eliopoulou, E, Papanikolaou, A, and Hamann R, (2008). "Risk Analysis of Large Tankers", 2nd Int. Workshop on Risk-Based Approaches in the Maritime Industry, Glasgow, 5-6 May 2008. IACS, 2006. "The Common Structural Rules for Tankers and Bulk Carriers", adopted by the Council of the International Association of Classification Societies, for implementation on 1st April 2006. Loer, K, and Hamann, R, (2007). "HazId of Tanker Operation", EU funded project SAFEDOR, Deliverable D4.7.1. Papanikolaou, A, Eliopoulou, E, Alissafaki, A, Aksu, S, Delautre, S, and Mikelis, N, (2005). "Critical Re-
Appendix Red border: applies to COLLISION incidents Blue border: applies to CONTACT incidents Black border: applies to GROUNDING incidents Green border: applies to all 3 categories Gray shading: applies to newbuildings
Aframax Tankers: Navigational Incident Rates per shipyear Collision
74 SOLAS Nav. Equipm.
7.00E-02
81 SOLAS Nav. Aids
72 COLREG
6.00E-02
Contact
Grounding
81 SOLAS Duplication Steering gear
78 PARIS MOU
72 COLREG
95 SOLAS Routeing Systems
TOKYO MOU VETTING
5.00E-02 72 COLREG
81 SOLAS ARPA
4.00E-02
96 SOLAS ETS
88 SOLAS GMDSS
88 SOLAS GMDSS
88 SOLAS Nav. Aids
OPA 90 78 STCW
95 STCW
3.00E-02 96 ILO C180
94 SOLAS ISM
2.00E-02 1.00E-02 0.00E+00 78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
00
01
02
03
Fig.A1: Impact on regulation on the prevention of navigational events
Oil Tankers of DWT>60,000 Hull type distribution of Fleet at risk DH
Non-DH
Fig. A2: Distribution of Fleet at Risk of Oil Tankers by hull basic configuration.
8
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%
