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A modern Cruise Liner with 12 main propulsion alternator engines has a lot of plate heat exchangers.

Each heat exchanger has to be maintained in accordance with the maintenance scheduler and each has the ability of causing major downtime of the engine and resultant passenger dissatisfaction.

It is often the case when the plates are opened that the level of dirt and contamination did not justify the procedure to go ahead. It is also often the case, that a perfectly good operational and leak free exchanger becomes a nightmare of leaking seals and increasing bilge water levels after rebuilding. There has to be a better way!

The situation

James Fisher Mimic were approached by a major Cruise Line operator and asked if our Mimic Condition Monitoring system could be used to reduce the downtime caused by unnecessary maintenance.

The solution

We were able to use the current functionality within Mimic to record heat exchanger operation (In and out) temperatures and pressures.Then, by use of Mimic’s calculation engine, we determine the differentials.Threshold values are then set against these calculated differentials and exceptions used to trigger maintenance.This means … no exception then no maintenance, no cleaning, no excessive use of spares and NO leaks.

Results

The Cruise Line Company calculated it saved them over 250,000 labour hours over 11 ships over the first two years of introducing Mimic Heat Exchanger monitoring. An obviously significant number but the real benefit has to be with the labour force. There is little that demoralises engineers more than conducting unnecessary maintenance.

This approach to heat exchanger management is not limited to plate type heat exchangers. The same strategy can be used for any design and type, whether large or small, air cooled or liquid cooled all can benefit from monitoring the right operational effectiveness indicators and intervening only when required.

Like many ship owners and operators today, the cruise line company traditionally carried out maintenance according to fixed periodic scheduling of maintenance tasks and elapsed running hours. In partnership with Lloyds Register, the cruise line company wanted to move to condition based maintenance to maximise the contribution of each asset over its lifetime.