ASSESSMENT OF THE 15-YEAR SERVICE OF THE LNG CARRIER BISHU MARU LE NAVIRE METHANIER BISHU MARU : COMPTE-RENDU DE SES 15 ANS DE SERVICE

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ASSESSMENT OF THE 15-YEAR SERVICE OF THE LNG CARRIER BISHU MARU LE NAVIRE METHANIER BISHU MARU : COMPTE-RENDU DE SES 15 ANS DE SERVICE N. Tsutsumi K. Takahashi T. Igarashi Kawasaki Kisen Kaisha, Ltd.

1 ASSESSMENT OF THE 15-YEAR SERVICE OF THE LNG CARRIER BISHU MARU LE NAVIRE METHANIER BISHU MARU : COMPTE-RENDU DE SES 15 ANS DE SERVICE N. Tsutsumi K. Takahashi T. Igarashi Kawasaki Kisen Kaisha, Ltd. M. Ohyama Y. Saitoh I. Kaku M. Nakamura K. Saeki Kawasaki Heavy Industries, Ltd. ABSTRACT The 125,000m3 LNG carrier Bishu Maru, the first Japanese flag vessel of this kind, has been transporting 2.5 million m3 of LNG annually from Indonesia to four Japanese Buyers. The vessel, having delivered 35 million m3 of LNG in about 290 voyages since 1983, is one of the most successful LNG carriers in the world. The authors first briefly introduce the vessel outline and the transportation scheme, and describe operations in which the vessel is engaged. They then discuss the long term effects of time on the vessel s performance with regard to speed, steam turbine plant, and cargo tank insulation, and finally conclude that the effects of aging on performance are negligible and the ship is almost as workable as new, capable of serving much longer terms ahead under proper management. RESUME D une capacité de m3, le Bishu Maru, premier méthanier naviguant sous pavillon japonais, transporte, chaque année jusqu à quatre terminaux japonais, 2,5 millions de m3 de GNL en provenance d Indonésie. Ayant déjà livré plus de 35 millions de m3 de GNL au cours de ses 290 voyages depuis 1983, ce navire est l un des méthaniers les plus performants du parc mondial. Les auteurs présentont, tout d abord, les principaux traits caractéristiques de ce navire ainsi que l organisation du trafic qu il effectue. Ils examinent ensuite les effects du vieillissement du navire sur sa capacité de propulsion, la performance de ses équipements E.8 1

2 de bord. Enfin, ils concluent que les effects du vieillissement sont négligeables sur les performances du navire et que ce dernier est presque aussi exploitable que s il était neuf, c est-à-dire qu il peut encore être utilisé pendant longtemps avec une bonne gestion. 1. Outline Description of Bishu Maru and its Operational Structure 1.1 Project description The project in which Bishu Maru (the Ship) has been engaged is called Badak Expansion Project (the Project), where now 3.5 million tonnes of LNG are transported yearly from Indonesia to four Japanese utility companies, Chubu Electric Company, Kansai Electric Company, Osaka Gas, and Toho Gas. The Project, an expansion of the preceding Indonesia Project (Ex-Ship basis), supplies LNG produced in the Badak plant of Pertamina for 20 years from 1983 on FOB-basis first in Japan. A fleet of three 125,000 m3 LNG carriers of Japanese flag was constructed to serve the Project. The Ship is vessel No.1 of the fleet and the first Japanese flag LNG carrier. It was constructed by Kawasaki Heavy Industries (KHI) in 1983 and has been in service for 15 years. 1.2 Outline of the Ship In the Project, as often followed in later Japanese projects, ownership of the fleet vessel was shared by three shipping companies, Kawasaki Kisen Kaisha (K Line), Nippon Yusen Kaisha and Mitsui O.S.K. Lines. The Ship has been operated and managed by K Line successfully since At the initial planning of the Ship, its major characteristics were coordinated with those of its two sister ships. Particular attention was given to : Compatibility with preceding Indonesia Project (Terminal facilities, etc.) Adoption of Moss spherical tanks to follow the preceding fleet Adequate margin in speed and power of the main engine to carry contracted volume The outlines of the Ship are shown in Table 1 and Fig Operational structure General. Operation of each fleet vessel is comprehensively controlled by Badak LNG Transport, Inc. (BALTRA) with an individual time charter contract with each of the three shipping companies, who cooperate to provide the safe and stable delivery of LNG. The Ship is operated on the annual schedule and scheme agreed upon between BALTRA and K Line, with 20 ~ 22 round trips per year. The Ship leaves Japan in the morning, takes 6 to 9 days on the ballast voyage to enter Bontang at dawn, and takes 6 days loaded with LNG to be back in Japan in the morning to close a cycle. LNG is discharged at Chita, Yokkaichi, Senboku, and Himeji. E.8 2

3 Maintenance and repair. Maintenance and repair of the LNG carrier is characterized by a long term plan to keep the ship workable during its long service, and is especially dependent on drydocking as the ship requires specialized skill and know-how regarding systems not seen in ordinary vessels. The Ship s first drydocking was a year after delivery. The docking interval was then extended to 2 years, and will be 2.5 years owing to an amendment of the Japanese law. All 8 drydockings of the Ship were made in the Sakaide Works of KHI, its mother yard. This has proved to be a success, as the Ship could enjoy KHI s profound knowledge about it, together with the experienced and skilled work offered by the yard. 1.4 LNG transportation In 14 years, the Ship has logged 290 round voyages between Indonesia and Japan, carrying 35 million m3 of LNG. It is now transporting 2.5 million m3 per year, one of the highest figures in the world. The Ship s stable transportation is illustrated in Fig.2, which shows well managed operation free from any interruptions to the service. 290 discharges include 106 at Chita, 102 at Senboku, 75 at Yokkaichi and 7 at Himeji. 2. Operational Experience 2.1 Operation in general With the increasing number of LNG projects, delay of one LNG carrier has a big impact on the shipping schedules of other projects in Japan. Delivery of LNG on schedule, in addition to safety, is becoming more important. In this context, K Line has been concentrating on the safe and punctual operation of the Ship with a full internal back-up organization, which has worked well to avoid any delays in service. Port operation. The Ship enters Bontang early in the morning and starts loading at noon, which lasts 12 hours. As this port is operational 24 hours a day, the Ship leaves the port soon after loading has finished, at around 1 to 3 am. In Japan, due to restrictions on port traffic to the day-time only and to ease of watching en route along the passage, navigation in the bay to and from the port is carried out in the day-time. Table 2 shows a typical example of the time scheme for LNG discharging in Japan. Speed. Fig.3 shows speed profiles of the Ship. On the laden voyage, the speed profile has a rather simple distribution around an average speed of about 17.0 knots. The ballast voyage has a widely distributed speed profile due to the schedule adjustment. Fuel selection during navigation. After early trials to make the best use of B.O.G. for fuel, it is now utilized in the established way. During laden voyages, the main boiler burns generated B.O.G. with additional fuel oil, the latter being dominant as there is less B.O.G. On ballast voyages, B.O.G. is dominant as its quantity can be adjusted by cooling E.8 3

4 of the tanks, and fuel oil is used only supplementally. The Ship s speed is also often adjusted to match the total fuel. 2.2 Cargo operation Loading / discharging. Almost all the established and identical procedures of cargo operation are consistently followed in loading and discharging at ports. After berthing, these begin with arm connection, followed by cargo measurement, trip test, arm cooling, and then LNG transfer. When the transfer is completed and necessary procedures such as cargo measurement, arm disconnection, etc. are all finished, in Bontang the Ship leaves the port immediately. In Japanese ports, the departure is put off till daylight. During navigation. During laden voyages, control of vapor pressure in the tanks is the most important aspect and prevails in the cargo operation. Soon after departure, B.O.G. tends to increase due to the residual effect of loading. After stabilization, the limited vapor space in the tanks sometimes causes a rapid increase in pressure, requiring careful attention. As part of the heat leakage into the tank is used to raise the cargo temperature during the voyage, actual B.O.R. is 0.12 ~ 0.16 %/d with an average figure of about 0.14%/d in 14 years, much lower than the official 0.25%/d. During ballast voyages, cooling-down of the cargo tanks occupies the major part of cargo operation. It is mainly carried out in the day-time, during which part of the B.O.G. accumulates in the tanks. This B.O.G. storage is used as fuel during the night. The Ship s speed is sometimes reduced to adapt to the available B.O.G. 2.3 Troubles in 15 years During the early days after commissioning, the Ship experienced several troubles including typical initial ones. Some of them were due to human errors. In each case, back-up systems on board covered the troubles as designed, and none of them seriously affected the Ship s operation or cargo handling. Table 3 shows the total operation hours up to 1995 and the availability of machinery and equipment. All of them show nearly 100% availability. In particular, the main turbine, main boiler and cargo pump show a perfect record. The excellent design of the Ship and its systems, together with well-planned and good maintenance work at each drydocking seem to have contributed to this remarkable achievement. 3. Long Term Effects of Aging on the Ship s Performance 3.1 Effects of aging on LNG carrier The effects of aging over 14 years were studied regarding the three main items of propulsive performance, steam turbine plant, and cargo tank insulation. These were chosen because they collectively represent the general performance of the Ship. Results of the study are also applicable to the assessment of the longevity of the Ship. E.8 4

5 3.2 Propulsive performance Long term effects of aging. To measure the long term effects on the Ship s propulsive performance, average speeds were plotted against the lapse of time over 13 years as shown in Fig.4. The speeds were measured on more than 200 laden voyages on the second day after leaving Bontang, when sea states are generally mild. The figure shows that, though somewhat scattered, the drop in average speed is around 0.7 ~ 0.9 knots after 13 years, when it stabilizes. At the initial planning of the Ship, the drop in speed was estimated to be 1.0 knots after 10 years. This estimation seems appropriate when compared with the above results. Effects of bottom fouling. The Ship is also affected by bottom fouling in addition to the long term drop in speed. This adverse effect proceeds with days at sea after drydocking and is generally reversed after the bottom has been cleaned in the next drydocking. Fig. 5 shows a worst example of drop in speed during the 2 years dock-to-dock period of May 1989 to April It is estimated that the effect of fouling on the speed is about 1.0 knots in 2 years at maximum. 3.3 Steam turbine plant Plant description and operation. The main turbine of the Ship is a Kawasaki UC type, impulse marine steam turbine, and is supplied with steam from two Kawasaki UMG type main boilers. The main boilers have always been operated in dual fuel mode of fuel oil and B.O.G. Although the ratio of fuel oil and B.O.G. differs on each voyage, it is relatively stable on laden voyages, while fuel oil tends to be minimized during ballast voyages. The burners are observed to ensure stable burning in the boiler. Main turbine output and fuel consumption rate. Fig. 6 shows the main turbine output and rpm of the propeller. The output is mostly 30,000 PS or lower, with the maximum around 33,000 PS. The effects of aging on the steam turbine plant are collectively measured by fuel consumption rate. Fig. 7 shows the consumption rate at around 25,000 PS, the most frequently recorded level. No trace of degradation is detected. Fig.8 shows another set of data at 30,000 ~ 33,000 PS, measured after each drydocking in fuel oil burning mode. The fuel consumption rate shows only a slight increase. Overall assessment. Other data such as the main condenser vacuum and the main boiler exhaust gas temperature showed no clear degradation. Such mechanical aspects as clearances of labyrinths in main turbine and pipe thickness of super heater in the main boiler have not changed and they are almost completely intact after 14 years of operation. The reasons for the good condition may be the relatively low output levels experienced, mostly 30,000 PS or below despite the maximum output rating of 40,000 PS, and periodic maintenance at the drydocking. Overall assessment of the steam turbine E.8 5

6 plant is that it is almost as operable as new, and is well-suited for much longer service under good and careful maintenance. 3.4 Cargo tank insulation Outline of tank insulation and its aging. Cargo tank insulation is a Kawasaki Panel System consisting of small panels of two insulation layers. Aging is believed to take place whereby the gas in the cells in the outer layer of polyurethane foam are gradually replaced by environmental nitrogen. Long term change in B.O.R. B.O.R. on the laden voyage is the best measure for assessing the performance of the tank insulation. To calculate the B.O.R. based on the actual heat leakage into the tank, part of the heat used to raise the temperature of the cargo was added to the heat used to vaporize the cargo during voyage. Fig. 9 shows B.O.R. over 14 years, at IMO condition (air 45ºC, sea water 32ºC). The average value of B.O.R. is about %/d, against the estimated value of 0.214%/d at the design stage of the insulation. The figure shows no sign of aging. 4. Conclusion 4.1 Reflection on the past 15 years service During the past 15 years, the Ship has been able to perform successful shipping of LNG without suffering any major troubles, which, the authors believe, is to the satisfaction of the buyers and other parties concerned. The long period of operation and ship management has also enabled K Line to accumulate various kinds of know-how in this field. Reflecting on 15 years, the authors can specify several reasons for the success: Adoption of the proven systems of Moss type spherical tank and steam turbine plant Good service records of major machinery and equipment as planned, owing to good initial planning of the Ship and to its excellent design/construction. Cooperation and exchange of information with sister ships and parties concerned. Maintenance and repair work based on a long-term planning, and the excellent work done by the shipyard which constructed the Ship. After 15 years, the steam turbine plant and the cargo tank insulation of the Ship are judged to have remained intact, almost as new. Although a drop in average speed of 0.7 ~ 0.9 knots is detected, it seem to be corrected by complete recoating of the bottom. 4.2 A view for the future The Ship s spherical cargo tanks, with their simple structure and adequate tolerance in cargo operation, are very easy to handle. The steam turbine plant, as the means of propulsion and B.O.G. disposal, has proven reliability, requires far less maintenance than a diesel engine, and shows no signs of aging even after long service. LNG carriers with spherical tanks and a steam turbine plant seem to remain one of the best options in the future. E.8 6

7 In some fields, improvements are required, such as a lower B.O.R., less power for propulsion, improved shipping through a smaller number of tanks, etc. The authors see, however, that these are already incorporated in the recent generation of LNG carriers. After 15 years, as discussed in this paper, the Ship still remains as new regarding major performances. The authors believe the Ship can serve not only the remaining 5 years, but also more years beyond that under good and careful maintenance. A study for the possible longevity of the Ship has been undertaken and is almost completed. K Line is determined to contribute to the safe and stable supply of LNG, making the best use of 15 years experience. KHI, in the mean time, will incorporate the valuable data from the Ship s long service into its design and construction of LNG carriers in the future. Fig. 1 Profile of Bishu Maru E.8 7

8 Table 1 Principal Particulars of "Bishu Maru" Delivery : August 16, 1983 Builder : Kawasaki Heavy Industries, Ltd. Class/Flag : Nippon Kaiji Kyokai /Japanese Loa m Table 2 LNG Discharging Schedule ( YOKKAICHI Terminal ) Lpp m Bm m Events Approx. time Dm m Navigation in ISE Bay dm(design service) m Arrival IRAGO pilot station 05 : 15 dext(summer) m Passing IRAGO traffic route 06 : 00 D.W.(Summer) 70,546 t Cleared out above traffic route 06 : 15 Gross tonnage 100,296 T Harbour pilot on board 08 : 30 Main engine Entering YOKKAICHI No.2 passage 09 : 10 1x Kawasaki UA steam turbine Cargo Handling in port Max.cont.output(shp) 40,000 PS Arrival berth 10 : 28 Normal output(shp) 36,000 PS Flanging 10 : 40 ~ 11 : 30 Boiler : 2x Kawasaki UMG 66/57 O 2 check 10 : 35 ~ 10 : 40 Generator : Gauging before discharging 11 : 00 ~ 11 : 05 Turbo generator 2 x 2,500 kw Opening vapor line 11 : 05 Diesel generator 1 x 1,200 kw Trip test 11 : 40 ~ 11 : 50 Service speed 19.3 knt Cooling down arms 12 : 00 ~` 13 : 30 Discharging cargo 13 : 50 ~ 01 : 10 Cargo tank system Loading utilities 12 : 00 ~` 16 : 30 Type, No. : Moss type spherical, 5 (bunker oil, diesel oil, etc.) Volume (100%,-163ºC) 125,660 m 3 Unflanging 01 : 20 ~ 03 : 00 Insulation : Kawasaki Panel System Closing vapor line 02 : 05 B.O.Rate (IMO Cond.) 0.25 %/d Gauging after discharging 02 : 35 ~ 02 : 40 Cargo pump : 10 x 1,100m 3 /h x135 m Meetring between ship / shore 07 : 30 ~ 08 : 00 Spray pump : 2 x 50m 3 /h x135 m Pilot on board (all lines aboard) 08 : 45 Departure berth Table 3 Service Performance of Major Machinery/Equipment Machinery/Equipment Operation Time (hr) Availability (%) Main turbine 82, Main boiler 102, Propeller/Prop.shaft 82, Turbo generator 132, Feed water pump 101, Steering gear 83, Cargo pump 28, Spray pump 16, L/D gas compressor 92, H/D gas compressor 8, IGG blower 1, Remarks : Operation time shows total hours of the set at the end of E.8 8

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Year Book 2016 : Progress of Marine Engineering Technology in the year General Shipbuilding

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