Fuel Data Visualization & Piston Ring Breakage – What Viswa Lab has to Say?
Viswa Lab has been studying the piston ring breakage problem in-depth. With more than 200 cases and with all the data available, it has been a very interesting study all these days. Viswa Lab has many algorithms and advanced fuel study where PFIN (Problem Fuel Identification Number) and POMP (Peace of Mind Package) have been accepted by many ship owners and managers to prevent/protect/mitigate problems from bad fuels.
The main reason a lubricating oil is analyzed is to check the machinery condition based on wear rate and oil degradation. Analyzing used lube oils are acclaimed as a part of condition monitoring under shipboard maintenance management. Can fuels used on board ships be monitored where apart from regular testing, can the potential to cause machinery damage be determined?
It can be very well determined – says Viswa Lab.
MFAME asked Viswa Lab about some frequently experienced machinery problems, where Viswa Lab commented that the piston ring breakage is one among the most fuel problems which often causes ships to drift when at mid sea.
Comments from Viswa Lab:
While analyzing the mechanism of the piston ring breakage, it was clear that high MCR(Carbon Residue) and high asphaltene packed the gap between the piston ring and groove with carbonaceous material rendering the piston ring immobile, leading to high wear rate and eventual fracture of piston rings.
First of all, Viswa Lab generated a PFIN (Problem Fuel Identification Number) mainly to identify fuels with potential to cause piston ring breakage. The PFIN algorithm considered the following 5 parameters:
CCAI greater than (>848),
Asphaltene (> 10.5%),
Xylene Equivalent number (greater than >30) and
Reserve Stability Number (>5).
An algorithm was built around these 5 values. Using the PFIN algorithm, Viswa Lab is able to predict with 85 to 90% certainty, the fuels that are likely to cause piston ring breakage. There is enough statistical data to confirm the findings. More work is going on and Viswa Lab says that many ship owners and managers have recently subscribed their ships under PFIN/POMP testing to have a real peace of mind from the bunker fuel problems.
Another interesting observation made by Viswa Lab was that though UEC engines command an estimated 10% of the marine engine market, they accounted for over 40% of the piston ring breakage case studies. This meant that a UEC engine carries the potential for piston ring breakage at a level more than 4 times that of other marine diesel engines. Many reasons can be attributed to this. It could be that this Japanese engine is machined to much finer clearances making it intolerant of excess carbon, asphaltene etc in the fuel.
We further studied the recommended values of the fuel properties at entrance engine for the three major engine makers, Wartsila, MAN B&W and UEC as listed by a Class NKK document. The striking difference was the MCR is limited to 12% in the case of UEC engine while Wartsila permits 15% and MAN permits 14% MCR. Interestingly, UEC and Wartsila engines were more tolerant of presence of used lube oil at levels of Zinc 15 ppm, Phosphorus 15 ppm and Calcium 30 ppm. The MAN engine had limits of Zinc 5 ppm, Phosphorous 5 ppm and Calcium 10 ppm.
What is the benefit of this study?
It is better to measure these 5 parameters (MCR, CCAI, Asphaltene, Xylene Equivalent and Reserve Stability Number) and use the algorithm to get PFIN. If it exceeds the number indicated by the algorithm, you must take precautions to prevent piston ring breakage. In addition to this, you have also take into consideration the engine make.
Thus, to summarize, it is very much possible to mitigate or prevent piston ring breakage than to suffer engine damage and thereby commercial loss due to ship delay.
We welcome ship managers and owners to share with us if a ship is experiencing piston ring breakage or other fuel related problems. At the least, you can check for the pattern in fuels which are causing problems and let us know your thoughts on it.
Do not hesitate to write to us at: [email protected]
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Source: Viswa Lab