Condition monitoring: An insurance policy against unforeseen plant downtime
26 August 2010
By using the latest condition monitoring systems and automatic lubrication systems for bearings, oil and gas processing companies can reduce the risk and costs associated with unforeseen breakdowns to critical production plant and machinery.
Condition monitoring: An insurance policy against unforeseen plant downtime
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% 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 to protect it against unforeseen breakdowns?’ You may get some very positive responses.”
One of the finance director’s responsibilities is to ensure that the company’s assets are protected. Risk assessments should be carried out regularly to see what effect breakdowns would have on critical machinery and equipment. The severity and likelihood of breakdowns on particular machinery are assessed and given a corresponding risk value. Those with the highest risk scores are given priority by the maintenance team and should certainly be protected with some sort of condition monitoring device.
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. However, as Hartigan points out: “As well as the obvious increase in stock holding costs, the company also runs the risk of the stock deteriorating or becoming obsolete over time. We would recommend that customers reduce the risk of unexpected failures, by implementing suitable condition monitoring systems on rotating plant and machinery. Don’t think of this as capital outlay, but as insurance against the risk of possible lost production.”
So what is the true cost of a bearing failure in each of your key production areas?
Hartigan continues: “By installing a predictive maintenance system, the customer picks up any problems early. During the next convenient downtime period, the maintenance team can then remove and replace a bearing with minimum disruption costs and also avoid the risk of breakdown damage to the equipment.”
Condition monitoring also prevents maintenance teams replacing components unnecessarily and introducing possible new and unrelated problems. Manufacturing maintenance staff should be using CM systems to predict when failures are likely to occur and plan replacement during production shutdowns. “In too many companies, parts are changed on a time basis rather than on a condition basis because the maintenance team considers this to be the safest option. However, this introduces a further risk, because whenever there’s human intervention, problems can occur,” explains Hartigan.
“Most companies work in a breakdown culture which is reactive rather than proactive,” she continues. “Rather than boasting about how rapidly they can repair or replace components and get machinery or pumps back into production, maintenance teams need to be asking themselves ‘How can we prevent the problems occurring in the first place?’ CM is the most effective solution.”
If a process plant plans to achieve very high production efficiencies, predictive maintenance is critical. Unforeseen plant breakdowns simply cannot be tolerated.
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 has developed the ‘FAG ProCheck’ online monitoring system.
This system enables maintenance teams to monitor vibration levels and diagnose faults on critical rotating plant, therefore preventing costly machine breakdowns and eliminating problems before they occur.
What really differentiates ProCheck from other condition monitoring systems is its inherent flexibility due to its modular design. This means the system can be easily integrated into a customer’s existing control and automation environment.
FAG ProCheck is intelligent, easy to set up and is both robust and reliable. The system is ATEX-certified and so can be used in hazardous or explosive environments and the system has a range of communications interfaces so that it can be easily integrated with a company’s existing plant management or production control and maintenance systems.
Once set up, the system 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 easily expanded and customised through a new expansion slot system and digital filter algorithms. The unit is therefore easy to integrate into a company’s existing production data management system, statistical process control (SPC) system or PLC network.
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.
The FAG ProCheck hardware was developed in collaboration with National Instruments, a leading supplier of instrumentation and measurement software and hardware.
Coatings and Automatic Lubricators Cut Maintenance Costs at Pequiven
As well as condition monitoring systems, Schaeffler also provides a range of corrosion-resistant coatings for bearings and automatic lubrication systems, both of which can help reduce maintenance time and costs.
Based in Venezuela, Pequiven is a Government-owned company founded 30 years ago. The company produces petrochemical products, mainly for the domestic market. The company specialises in the production of fertilisers and chemical products, as well as olefins and other synthetic resins.
At its phosphoric acid plant, which has a production capacity of around 250 tonnes of P2O5 per day, Pequiven wanted to improve the running time of a critical conveyor system that separates the solids from the phosphoric acid mixture.
The bearings on the conveyor system were regularly failing after just 15 days. As the plant was planning to increase its production capacity, it needed a bearing supplier that was able to provide an integral solution to the bearing problem, including maintenance advice and guidance.
Schaeffler Venezuela recommended that Pequiven use a coating material for the bearings, to improve the quality of the housing material. Also, Schaeffler engineers noticed that manual grease lubrication of the bearings was not always being carried out correctly at the plant. Therefore, along with new coating materials for the bearings, Schaeffler recommended that the plant use automatic lubrication systems to ensure that relubrication of the bearings is controlled and that sufficient quantities of fresh grease is constantly supplied to the contact points inside the rolling bearings.
Schaeffler replaced the existing bearings with its RASE40-N-FA125 housed bearing units, with the housings coated with Corrotect. Corrotect is a relatively low cost, 0.5 to 5µm thick zinc alloy coating with cathodic protection, which is effective against condensation, rainwater, contaminated water and weak alkaline and weak acidic cleaning agents. Under load, the coating is compacted into the surface roughness profile and is partly worn away. The chromate coating and the passivation increase anti-corrosion protection and contribute to the optical appearance of the component.
Corrotect is ideal for small bearings and bearing mating parts that need to have a greater resistance to corrosion, for example drawn cup needle roller bearings with open ends and thin-walled components in large numbers.
Schaeffler also supplied its ‘FAG Motion Guard Champion’ automatic lubrication system. FAG Motion Guard CHAMPION 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 from surrounding equipment.
By using Motion Guard Select Manager software, the user can select the discharge interval for the application, determine replenishment quantities and select preferred lubricating greases.
FAG Motion Guard Champion and Compact lubricators can be used on all types of plant, including pumps, compressors, fans, conveyors and vehicles.
After supplying the Corrotect coated bearings and automatic lubricators, the running time of the conveyor system was improved as the bearings were now lasting more than twice the time of the original bearings – but this still wasn’t long enough for Pequiven. Because of the very harsh corrosive environment in which the bearings had to operate, Schaeffler then recommended using stainless steel bearings and a thermoplastic housing.
After installing the new bearings, Pequiven is now satisfied with the running times of the conveyor system and maintenance cost has been reduced significantly. Schaeffler now takes full responsibility of bearing maintenance and has helped the customer develop a special maintenance programme.
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