TS-129
Failure Rate Analysis Of 1000 Hp Main Engines Installed On Small General Cargo Ships:
A Proof Of Wear-Out Period Of Installed Main Engines
Agoes A. MASROERI1, Dwi PRIYANTA2, Ketut B. ARTANA3
ABSTRACT
Most of general cargo ships operated in Indonesia are more than fifteen years old. intuitively, one can conclude that the failure rate of main engines Installed onboard ships fall into the wear-out period of widely known bath up curve. This paper is intended to obtain and to prove the failure rate pattern of main engines installed onboard ship. Seven different diesel engines, which delivered 1000 hp each and were installed onto different ships, are analyzed.
The failure rate function of each analyzed diesel engine is derived based upon the fittest distribution representing the failure. The maximum likelihood estimate (MLE) method is employed to obtain the appropriate parameter for each distribution.
The results of the analyses showed that five out of seven diesel engines fall into wear-out period while the others two start entering wear-out period.
Key Words: Reliability, Failure Rate, Failure Analysis, Bathup Curve, Diesel Engines
1. INTRODUCTION
As an archipelago country, Indonesia needs more ships to transport either passengers or commodities from one place to another. In the case of cargo transportation, most of them are shipped by private shipping line range from small to big company. Most of the operated cargo ships are used ships that were imported from European countries, such as Germany and Netherlands, and from Japan. Although the government has ran the program to build a series of ships; such as CARAKA JAYA SERIES for general cargo ship that was started around 80's and PAX 500 for passenger ship that was started around 90's; but they are not sufficient enough to fulfill the ship demand. Beside that, the ships might be bought before the government ran the program and also the budget constraint might also force the ship owners to import the used ships. The imported ships were built around 80's, and sometimes they were built around 60's and 70's. Consequently, most of main engine installed onboard ships are too old and need to be repowered. But, some ship owners still kept the original main engine installed.
This paper discussed the results of the failure pattern analyses of seven diesel engines installed on seven imported ships. Each ship is operated by different shipping lines. Among of them, five diesel engines were built in Japan and the other two were built in Hungary and Holland respectively. Each diesel engine delivered at the average of 1000 HP and propelled the ships at the designed speed at the range of 12 to 13 knots. The investigated diesel engines are LANG/SLD 315 RPT. DEUTZ/RBV 6 M 545, HANSHlN / 6 LU 28, NIIGATA / 6 S 32 F. MAKITA / GNL H 6275, and OTSHUKA / 50 D 629 C. They were built in the year 1965, 1972, 1976, 1977, 1982, 1983, and 1987 respectively.
Due to the limitation of the available data as the consequences of ships were bought as used-ship, then only the newest data recorded on ships were used as a basis of analysis. In order to the data could be categorized into one of the three regions in the bath up curve, then the data were collected at least at the interval of one complete cycle operation, i.e. at least between two overhauls.
The analysls was performed by comparing several points among the analyzed diesel engines. The points compared are number of maintenance activities performed and maintenance frequency based upon categorized items.
Failures modeling for each diesel engine were also performed. Random variable of the model must be defined first. A time elapsed by the component from the component is put into operation until it fails known as a time to failure (TTF) is important variable in failure analysis. Consequently, TTF is chosen as random variable and symbolized as T.
The results of the analysis are presented in section 4, while section 2 and 3 discuss the failure modeling theory and the probability distribution utilized to model the failure pattern for each diesel engine respectively. The results of the analysis are presented in section 4 and the conclusions of the analysis are presented in section 5.
2. FAILURE MODELING
A component can either be in up state or in down state condition. A time elapsed by the component from the component is put into operation until it fails known as a time to failure (TTF).
1 Dept. of Marine Systems Engineering, Institute of Technology Sepuluh Nopember (ITS), Surabaya 60111
INDONESIA, FAX: +62-31-5994754,
E-mail: mare_its@surabaya.wasantara.net.id
2 Dept. of Marine Systems Engineering, ITS
3 PhD student, Kobe University of Mercantile Marine
