Fig. 1 A graph showing failure cases across all engines in the database
The data collected on each engine from the members contains such items as:
Ship type - engine type - bore - stroke - rpm - bmep - fuel type - engine designer - builder
- year into operation
Service type (main propulsion or generator drive) - propeller type - PTO
Serious faults/failure cases - date of failure - engine area - service hours to failure
Short comments about the failure
How cases were solved - by the User or, Builder or, Licensor
Short comments about builder's/licensor's reaction
User's assessment of builder' s/licensor's reaction to the case/fault
Where the engine fault areas are concerned, the engine is divided into 10 basic areas thus simplifying analyses of faults and trends. Those areas are:
1. - Cylinder cover
2. - Piston, piston rod, stuffing box
3 - Cylinder liner and its lubrication
4. - Crosshead and connecting rod
5. - Crankshaft, thrust bearing, and turning gear
6. - Mechanical control gear
7. - Starting air system
8. - Exhaust valve
9. - Fuel system
10 - Turbocharger and system
All these areas can equally be applied to 2-stroke and 4-stroke engines and that has been well proved as the database information input has increased.
2. INITIAL RESULTS
One year after the introduction of the CIMACUSE program more than 544 diesel engines had been reported into the system and, in these, 330 cases of serious abnormalities or failure cases were to be found. The results of the first analyses were reported at the 1998 CIMAC Congress, held in Copenhagen, [1].
It was very clear that the hot components, ie, those surrounding the combustion chamber, continued to be the predominant failure areas with the larger bore engines, those of 800mm bore and above, showing 81% of major failures. The smaller bore engines, of less than 790mm bore showed 62% of major hot component failures. The most dominant failures in the hot components region were seen to be, cracked cylinder liners and cracked piston crowns, alongside poor cylinder conditions leading to scuffing or heavy wear rates.
Where cracked cylinder liners are concerned, there is always the safety aspect of the possibility of the liner breaking down and pieces falling into the liner space - a rarity fortunately. However, the operator has the job of procuring spares and, most importantly, is faced with unscheduled loss of time, which is always costly.
Cracked piston crowns can lead to cooling oil entering the combustion chamber and hence being carried through to the exhaust receiver, possibly leading to uncontrolled burning. In turn that will lead to over speeding of the turbochargers and hence a situation completely out of control by the ship's engineers. Should the flow be in the opposite direction, ie, the combustion gases penetrate into the cooling oil system and possibly then leak to the crankcase, an explosion in that area can be the consequence.
The Users feel that with today's engines being so finely tuned to produce high outputs, there is little left in reserve for the operator, who may be pressed by a charter to run his engine at the highest possible output.
From the initial analyses on the more than 500 engines, it was also clearly seen that although many faults and failures occur during the guarantee period, there are many more major failures occuring in the immediate following years. Such information from the CIMACUSE database has been investigated in some depth and the WG is now looking seriously at the possibility of demanding longer guarantee periods, for the sake of safety and costs for the engine users.
