An insurance policy against unforeseen plant downtime

By using the latest condition monitoring and automatic lubrication systems for bearings, process manufacturers can reduce the risk and costs associated with unforeseen breakdowns to critical production plant and machinery, says Kate Hartigan, Managing Director of Schaeffler (UK) Ltd.

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. Process manufacturers too, need to ensure that their 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.

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 plant, the cost of production downtime and any consequential losses as a result of a bearing failure, are often significant. 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 10-15% of total costs. Of course, every processing plant has a maintenance department to deal with such problems, 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.

There should be no excuses for this today. There are numerous technology safeguards available that, when compared to the cost of lost production, are relatively inexpensive. The more enlightened plants are using the latest condition monitoring and predictive maintenance systems, including bearing vibration monitoring, acoustic emissions monitoring and thermography, to protect their machinery. "Plant and maintenance managers need to justify expenditure on condition monitoring systems and services to their finance director or MD," says Hartigan. "I would suggest a risk management approach for this. Ask the question, '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!"

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. By holding more stock of a particular component such as a gearbox, bearing, pump, coupling or shaft, means that when a breakdown occurs a replacement 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 stock deteriorating over time or becoming obsolete. I would recommend reducing the risk of unexpected failures by installing condition monitoring systems on rotating plant and machinery. Don't think of this as capital outlay, but as insurance against the risk of 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 plant manager or maintainer picks up any problems early. During the next convenient downtime period, the maintenance team can remove and replace a bearing with minimum disruption costs and also avoid the risk of peripheral 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.She continues, "Most companies work in a breakdown culture which is reactive rather than proactive. "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 and this is where online monitoring equipment (for example, Schaeffler's own FAG ProCheck System) enables maintenance teams to monitor vibration levels and diagnose faults on critical rotating plant, including electric motors, drives, bearing arrangements, gearboxes, pumps, generators, ventilators and fans. Online systems can operate automatically to measure, record, analyse and issue alerts on vibration data from rotating plant. By continuously monitoring a machine or piece of rotating equipment changes in their behaviour can be detected early and maintenance personnel alerted to a potential problem before it actually occurs. Maintenance teams can therefore improve their planning and scheduling and production downtime is significantly reduced.

So how does such a system work?

Data recorded by sensors on rotating plant is subjected to initial assessment and if defined alarm limits are exceeded, alert warnings are automatically generated and sent to defined interfaces, where they undergo further assessment.  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 that, in the case of ProCheck, all the 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. 'Broadband parameter monitoring' is used to determine changes in the overall vibration behaviour of rotating plant, 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. As well as vibration, 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.
 
Coatings & Automatic Lubricators Cut Maintenance Costs at Pequiven

Based in Venezuela, Pequiven is a Government-owned company which specialises in the production of fertilisers and chemical products, as well as olefins and other synthetic resins, mainly for the domestic market.   At its phosphoric acid plant, 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 were regularly failing after just 15 days. As the plant was planning to increase its production capacity, it needed a bearing supplier who could solve the bearing problem and provide maintenance advice and guidance. Schaeffler Venezuela recommended the use of a coating material for the bearings, to improve the quality of the housing material.  The existing bearings were replaced with RASE40-N-FA125 housed bearing units, with the housings coated with Corrotect® - 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. Itis 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.
 
It was also noticed that manual greasing of the bearings was not always being carried out correctly. Therefore, along with the new coating materials for the bearings, it was recommended that the plant use automatic lubrication systems to ensure that lubrication of the bearings is controlled and that sufficient quantities of fresh grease is constantly supplied to the contact points inside the rolling bearings. An automatic lubrication system (in this case a FAG Motion Guard Champion) was installed. 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.
 
After supplying the 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, stainless steel bearings and a thermoplastic housing were finally specified. This further improved the running times and reduced maintenance costs significantly.