Condition monitoring is insurance against unforeseen downtime

Paul Boughton
Condition monitoring systems and automatic lubrication systems for bearings can reduce the risk and costs associated with unforeseen breakdowns to critical processing.

When it comes to owning and managing a high cost item such as a car or home, most of us are comfortable with paying insurance premiums, to help safeguard us against unforeseen accidents or breakdowns. The policy we take out is a type of risk management policy that invariably helps us to sleep better at night.

So, as process manufacturers, surely we too need to ensure that our high value capital goods, such as production machinery and other critical plant equipment are adequately insured against the cost of unforeseen breakdowns? In the downstream oil and gas sector, 'lost' production time can equate to hundreds of thousands of pounds per day - until the problem is rectified.

Although the cost of a machine component such as a bearing, pump or electric motor is very small compared to the total cost of the machinery, the cost of production downtime and any consequential losses as a result of the bearing failure, are often significant.

For example, take a petrochemical processing plant. The typical cost of production downtime can be anything from £100 000 to £500 000 per day. Total maintenance costs for a typical oil and gas processing plant are around 10 to 15 per cent of total costs.

Of course, every processing plant has a maintenance department to deal with problems like these, but often, because of time and resource constraints, the maintenance team becomes reactive, fire fighting problems around the plant as they occur, with no predictive maintenance systems, little preventive maintenance and often with no maintenance strategy at all.

But there should be no excuses for this today. There are numerous technology safeguards out there that, when compared to the cost of lost production, are relatively inexpensive. Using the latest condition monitoring and predictive maintenance systems, including bearing vibration monitoring, acoustic emissions monitoring and thermography to protect plant and machines, is what the more enlightened plants are doing. But many more companies need to pay heed.

"Plant managers and maintenance managers need to justify any expenditure on condition monitoring systems and services, to their finance director or MD," says Kate Hartigan, Managing Director of precision bearings and automotive components manufacturer Schaeffler (UK) Ltd. "We would suggest using a risk management approach for this. Ask the question of your finance director: 'What will it cost the company in lost production if I lose that critical pump or motor for five hours?' Or "What would you be prepared to pay as an insurance premium, to secure the running of the plant and toprotect it against unforeseen breakdowns?' You may get some very positive reposnes."

Of course, companies can protect their plant without using condition monitoring or predictive maintenance systems, for example, by holding more stock of a particular component such as a gearbox, bearing, pump, coupling or shaft. This means when a breakdown occurs in the plant, the component that caused the breakdown is available to hand, ready for the maintenance team to fix the problem.

In order to help companies monitor vibration levels on critical rotating plant or machinery, including electric motors, drives, bearing arrangements, gearboxes, pumps, generators, ventilators and fans, Schaeffler (UK) Ltd has developed the 'FAG ProCheck' online monitoring system. This system enables maintenance teams to monitor vibration levels and diagnose faults on critical rotating plant, preventing machine breakdowns and eliminating problems before they occur.

Omce set up the sytem can operate automatically without further intervention from the user, to measure, record, analyse and issue alerts on vibration data from rotating plant. By continuously monitoring a machine or piece of rotating equipment, FAG ProCheck can detect changes in their behaviour early and alert maintenance personnel to a potential problem before it actually occurs. Maintenance teams can therefore improve their planning and scheduling and production downtime is significantly reduced.

The FAG ProCheck system can be expanded and customised through a new expansion slot system and digital filter algorithms.

So how does it work?

The data recorded by sensors on rotating plant is subjected to initial assessment by FAG ProCheck and if defined alarm limits are exceeded, alert warnings are automatically generated and sent to defined interfaces, where they undergo further assessment. The system can be configured and adapted either by the end user customer or by Schaeffler's maintenance and asset management service division, FAG Industrial Services (F'IS).

The stored algorithms process the data to extract the necessary information on the condition of the machine. This initial check is independent of connection to a server PC, which holds the configuration and analysis software. This means all FAG ProCheck systems in a network can operate independently of a server connection and store their data on a permanent memory medium.

Depending on system configuration, the data can be held locally for up to several weeks.

The system can accommodate up to 16 sensor channels plus additional analogue and digital inputs and outputs, and so can be expanded from monitoring an individual machine, right up to monitoring complete production plant systems. Multiple FAG ProCheck units can be connected to a network and managed using the same database.

FAG ProCheck uses 'broadband parameter monitoring' to determine changes in the overall vibration behaviour of rotating plant at an early stage, in combination with 'selective frequency monitoring'. This is used to detect changes in the behaviour of individual components and therefore enables precise analysis of component damage.

Monitoring parameters include time and frequency domains, measuring velocity, acceleration and envelope signals, both broadband and frequency selective.

As well as vibration, further parameters such as temperature, pressure, load, speed, torque, oil status and oil quality can be recorded and correlated with the vibration data.

For communication with high-level plant operating data systems, various inputs and outputs are available. Extra signals can be received via digital or analogue inputs and used for triggering or validation of messages. They can therefore be used as 'command' variables for dependent signal analysis such as alarm threshold control. These signals can also be used to initiate time-controlled or event-controlled measurement tasks, for example, to control automatic data logging for specific applications. Communication with FAG ProCheck can be carried out via network (TCP/IP), serial or modem links.

Schaeffler also supplied its 'FAG Motion Guard Champion' automatic lubrication system. This is a robust, electromechanically driven unit that operates on replaceable batteries. The device is electronically controlled and has a back-geared motor that enables the unit to discharge lubricant at adjustable intervals of one, three, six or 12 months. A lubricant canister is screwed to the drive unit, holding 60, 120 or 250cm3 of lubricating grease. Automatic pressure control at 5 bar is provided and the unit operates in temperatures from -10°C up to 50°C. The device is also protected against dust and splash water and is immune to electromagnetic interference

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