Making pods predictable

Since The Motor Ship reported on the first cruise ship installation of MetalSCAN on the Voyager of the Seas last year, things have come a long way.

Barry Taylor, GasTOPS? marketing manager says: “We have had great success from our first installation in November 2000, to more than 100 installations now.” The company?s latest success is winning the contract to supply four MetalSCAN systems for installation and evaluation on each of the Rolls-Royce Mermaid propulsion pods to be fitted on the Queen Mary 2. The MetalSCAN systems are also being considered as a potential core component for integration into Rolls-Royce?s pod monitoring program.

MetalSCAN will be installed on the return oil lubrication line of each pod to monitor bearing health. The MetalSCAN system is a real-time, on-line full flow oil debris monitoring system, which detects metallic particles, both ferrous and non-ferrous, that pass through the sensor.

It is designed to detect and quantify metallic particles carried within the oil system, which are tell-tale signs of hidden damage. Reportedly, MetalSCAN has proved effective in triggering maintenance alerts long before component failure.

Queen Mary 2 is the fifth ship installation on Mermaid propulsion pods. Royal Caribbean International and Carnival have also made a decision to install oil debris monitors on all of their propulsion pod bearings. In addition, the cruise ship operator is correlating this information with data received from new vibration monitoring instrumentation as part of its condition based maintenance program.

Proactive

In order to eliminate the lost revenue costs associated with an unexpected or emergency dry-docking; the ship must be proactive in detecting bearing wear on its propulsion pods.

Modern condition-based maintenance tools permit the ship to be proactive in monitoring bearing performance. The correlation of oil debris monitoring data with such things as boroscope and vibration monitoring data can provide the ship with a good opportunity to manage bearing wear effectively until the next planned dry-docking.

MetalSCAN provides a very early warning of bearing damage by counting metal particles in the lube oil system; recent experience has provided more than nine months notice on a bearing failure. MetalSCAN also provides an easily understandable approach to monitoring the total damage to the bearing, and the rate at which the damage is occurring.

It is this early warning and damage management that allows the cruise ship operator to plan the dry-docking required to replace the failing bearing. This proactive strategy that results in a planned maintenance action is substantially less expensive than a reactive or breakdown maintenance action, as shown in the accompanying cost comparison figure.

Clearly, there is a significant bottom line advantage in using a proactive approach to planning an outage or a dry-docking, without risking the possibility of expensive secondary damage to the machine.

Sensors such as MetalSCAN do not require the constant cleaning and recalibration associated with chip detectors, nor do they require an expert to interpret the data such as is required with vibration analysis.

It provides early wear detection and a clear graphical indication of the degree of damage, along with an intuitive view of the remaining useful life of the bearing. Oil debris monitoring has dispelled the traditional views that bearings fail over short periods of time, or that they continuously shed particles when they are damaged.

The ability to count metal particles in real-time provides the operator with a true picture of the condition of the bearing, thus a planned action can be taken to change the bearing during a convenient work period.

By utilizing modern technology, it is possible to become proactive in the management of bearing damage. The key is to be able to measure the number and size of the wear particles being shed by the bearing.

This provides the possibility of a prediction on how long the bearing can be safely operated. The benefits from using the proactive stance of predictive maintenance are significant when compared to the costs of reactive maintenance.

In any industry that is operating expensive, mission critical machinery, a predictive app-roach to bearing management will undoubtedly provide tangible dividends.