Equipment reliability, availability and operational efficiency are vital areas for all plants. Capital expenditures and operating costs are viewed as controllable expenses in these facilities. A focus on “Technology that improves capital efficiency” while improving equipment availability can significantly improve operational efficiency. In the key areas of equipment condition management and monitoring and corrosion management, expertise and technology are available that enable plant operators to meet these challenges with confidence. Through unique advanced-technology solutions, the ability to predict and influence asset availability is provided. Through a comprehensive understanding of equipment health, operational intelligence can be utilized so that profitability is increased and equipment reliability is enhanced.

Powerful systems have been developed that facilitate the integration and analysis of data and have been proven to improve equipment reliability, identify potential problems/failures and reduce the total cost of plant operations. These systems are at the forefront of new technology and have numerous advanced features including: remote viewing capability; networking; open architecture; intelligent data analysis.

The integration of corrosion data with condition monitoring data within a single platform provides truly comprehensive machinery and plant health management. This information, coupled with data interfaces from DCS and SCADA systems provides Asset Managers with a complete real time picture of the status of their plant.

In today’s operating environment, where pricing and deregulation pressures require Managers to think fast, this combination of on-line condition and corrosion data with process information provides the operational intelligence that allows optimal decision-making. Integration of plant systems in this way can have a direct impact on equipment reliability, reducing total cost of operation and improving plant performance.

This paper describes both the technology, and real-life examples of where significant value opportunities have been realized. Specific reference is made to proven applications within sour gas operations, offshore oil production, chemical processing and paper manufacturing industries.

Advanced-technology equipment reliability solutions have assisted plant operators in significantly improving business profitability by applying more efficient equipment and process management strategies. The approach is based upon the application of corrosion management and condition monitoring expertise and technology, and has resulted in outstanding value delivery in the following terms:

• Canadian Gas Processor - savings in excess of $12M Canadian in a four year period
• US Petrochemicals Plant - saved US$1.4M by avoiding heat exchanger failure
• UK Chemical Processor - early failure identification saved £1.1M in the first year
• Offshore North Sea Operator - maintenance cost down to 40% compared with equivalent operators

Operational Excellence

Achieving operational excellence today means generating sustained profitable revenue and minimizing safety and environmental risks. Sustaining operational excellence necessitates an in-depth understanding of plant operation so sound business decisions can be made - every dollar invested by the plant is invested directly toward this goal.

The question is - how is operational excellence achieved today and what innovative tools are available to reach this goal ?

Achieving operational excellence requires a balance between Maintenance and Operations, cost and opportunity. As a result, operational excellence necessitates an understanding of the equipment reliability in a facility.

EQUIPMENT RELIABILITY SOLUTIONS: PHILOSOPHY

Meeting the Maintenance Challenge

Refiners and processors must reduce maintenance expenses and optimize practices. The maintenance process should integrate seamlessly with reliability principles, risk analysis, continual process improvement and operational needs. Focusing on realistic objectives for improvement makes it possible to increase the availability of capacity-limited systems and reduce the risk of environmental incidents.

Operations - The Opportunity Cost Compromise

Optimized plant operation is about achieving the fine balance between lowest operational cost and maximum return from profitable high production. An example of this is where the price of crude oil has a direct impact on profit for refining and petrochemical operations. Heavy, high-sulfur crudes provide good cost opportunity, while increasing the risk of early equipment failure and unplanned maintenance outage. In addition, market prices often dictate processing of a dynamic range of highly variable feedstocks. This results in production processes that are increasingly episodic in nature. The decreased quality, higher gravity and greater impurity levels leave operators blind as to the effect of the feedstocks upon plant processing capability and reliability. The processing of these crudes can also result in greater operational expenditure through higher equipment, energy and labor cost.

Performance Means Profitability

Achieving greater equipment performance means opportunity for higher profitability. Value is gained through reducing equipment and maintenance cost and implementing intelligent process monitoring that enables rapid detection and mitigation of the circumstances leading to failure. Advanced-technology Corrosion Management and Condition Monitoring Solutions can be successfully utilized, applying consulting expertise to implement appropriate technologies at strategic locations on the plant, and providing intelligent information to Operations personnel through Key Performance Indicators for individual applications. For the first time, a plant can be operated with full knowledge of the impact of process changes upon equipment reliability.

EQUIPMENT RELIABILITY SOLUTIONS: TECHNOLOGY & SYSTEMS INTEGRATION

Corrosion Management – Monitoring plus Operational Correlation

A critical factor in the failure of plant machinery and infrastructure is corrosion. Corrosion affects many aspects of the operation of a facility; not only the availability of plant but also the throughput and overall ROI (return on investment) of an asset through the reduction of corrosion costs. Major operators have reported that as much as 60% of the cost of plant breakdown is directly related to corrosion. Although some facilities are more advanced, current practice at many plants is to wait until components fail due to corrosion or mechanical failure rather than undertaking preventative maintenance. Corrosion is “accounted for” rather than measured on-line and in real time, consequently there is a great deal of inspection required and correlation to process parameters is virtually impossible. Real-time technology enables plants to adopt a proactive approach to corrosion control by seeing where, when and what type of corrosion is happening on-line and in real time.

On-line, real-time corrosion management systems give the operator the ability to monitor the condition of static plant (pipes, vessels, manifolds, etc.) in much the same way as vibration monitoring on pumps and turbines. Utilizing a systems integration approach, the rate and mode of attack can be correlated with process parameters downloaded from installed process control systems (PCS).

Advanced corrosion management systems adopt a multi-technique approach to corrosion monitoring, that incorporates real-time corrosion measurement technology along with conventional monitoring. The combined approach maximizes the breadth of information gathering and increases confidence in the data.

By utilizing Electrochemical Noise (EN), for example, a system has the significant advantage of being able to identify localized as well as general corrosion, in real time. EN technology works in condensing and multi-phased systems, in aqueous and hydrocarbon environments and helps to increase understanding of the corrosion mechanism whilst providing a rapid and continual assessment of corrosion rate.

Condition Monitoring & Management – Intelligent Decisions from Integrated Information

Advanced plant condition monitoring technology combines on-line and off-line data from turbines, motors, pumps, reciprocating equipment, battery systems and generators. State-of-the-art on-line Condition Monitoring systems have sophisticated analysis capability that allows problems to be isolated – such as identifying an impending failure of a specific bearing. The ability to detect this type of failure mode at its earliest stages is critical, thereby minimizing or avoiding entirely the excessive costs that may arise from unit replacement, repair, downtime and production losses, not forgetting the safety and environmental issues.

Through a systems integration approach, any parameter, including vibration, speed, load, pressure, temperature and flow, can be acquired from existing sensors and protection monitors. The system should be able to integrate easily with other hardware and software including PCS platforms.

Data are typically presented as on-line graphs, trends, vibration spectra, waterfalls, orbit plots, etc. and Users may define scan and storage rates and apply overall and band alarms to the data. These systems are easy to use and customize.

Diagnostics can be performed on-line via the use of Fuzzy Clips technology, configured to contain rules for the most common rotating machinery faults. In its most appropriate configuration, this type of technology does not depend on absolutes and can deal with a degree of uncertainty. It can also incorporate data from different locations in the decision tree, and is able to be tailored to non-standard faults, or site specific indicators. This is then enhanced by the system having an advisory pane that suggests a course of action to the operator.

An Integrated Approach to Total Equipment Reliability

The combination of corrosion management and condition monitoring information, coupled with data interfaces from PCS and SCADA systems, provides Asset Managers with a complete real time picture of the status of their plant (Figure 1).

Figure 1: On-line Integrated Equipment Reliability System

In today’s operating environment, where pricing and deregulation pressures require Managers to think fast, this combination of on-line condition and corrosion data with process information provides the operational intelligence that allows optimal decision-making. Integration of plant systems in this way can have a direct impact on equipment reliability, reducing total cost of operation and an improvement of plant performance.

EQUIPMENT RELIABILITY SOLUTIONS: REAL-LIFE EXAMPLES

To illustrate the value of implementing advanced-technology equipment reliability solutions, four specific industry examples are described:

Case Study 1: Sour Gas Operations

A Canadian sour gas processor achieves optimal equipment reliability and availability across multiple remote fields by utilizing an integrated approach to corrosion, condition and plant process monitoring. Major areas of plant and equipment that have been proven to benefit from this approach include:

An oilfield development, located in the UK Continental Shelf region of the North Sea in 85 metres of water, was one of the first in the North Sea to be specifically designed with minimal manning and a condition based maintenance philosophy. As part of this strategy, the designers included a comprehensive condition monitoring system as a feature of the topsides specification.

The facility undertakes continuous oil production at the rate of 135,000 BPD. "Critical" equipment is required to operate at 100% availability, as follows:

• RB 211 Gas Turbine Driving Three-Stage Compressor (Coopers)
• Five Gas Turbine Generator Sets
• Three Main Oil Line Pumps
• Three Booster Pumps
• Two Seawater Injection Pumps
• Seawater Lift Pumps
• Emergency Generator Set

On-line condition monitoring of this critical equipment is provided by 1,700 on-line sensors. The condition monitoring system also integrates 2,500 off-line data points monitoring other critical items including several hundred additional parameters on ancillary plants, which are routinely measured with portable data collectors.

The entire dataset is analyzed and displayed in the same format as the on-line data. The system provides users with the ability to quickly and easily identify and react to problems.

Parameters include vibration, temperature, pressure, flow, power factor, motor current, exhaust gas temperature spread, battery levels, etc.. The information is made available to engineers and technicians on the platform, also to rotating equipment specialists and diagnostic engineers onshore. This configuration puts the information in a clear and direct form into the hands of the specialists and enables informed decisions to be made on maintenance and operational activities.

Shortly after commissioning, the system identified a shaft bearing fault on one of the Platform’s five main generator sets.

This sub-synchronous fault was not detected by the generators’ protection system and could have led to catastrophic damage to the set.

The value of the generators was placed at £650,000. Further investigation using the system revealed that the problem was an inherent design fault that existed on all five generator sets on the Platform.

The fault was remedied at no cost to the Operator. The rapid fault identification also enabled the Operator to avoid excessive downtime and subsequent production losses.

Plant and equipment health are determined by the system and this is the basis of ongoing platform maintenance activities. As a result of the cost reductions arising from the comprehensive approach to condition monitoring, this platform is widely recognized as a low cost producer with operations & maintenance costs 40% lower than comparable platforms.

A UK chemicals production facility had been acquired and subsequently modified to produce hydrogen gas. Of concern, was a carbon steel transmission pipeline that was required to transport wet gas.

The Customer’s concern at this new plant surrounded the decision of whether to operate the carbon steel pipeline alongside an intensive inspection program, or to replace

the pipeline with a more expensive, higher metallurgy specification.

The carbon steel pipeline in question had been incorporated into the facility as part of the modifications, to transport a wet gas mixture prior to the separation of hydrogen. The gas mixture consisted of predominantly hydrogen, carbon dioxide and methane, with nitrogen, carbon monoxide and water present in trace quantities.

A corrosion assessment program was implemented that would evaluate the corrosion resistance of the carbon steel piping under real service conditions. Of particular interest was the performance of the pipeline on exposure to wet carbon dioxide, and the corrosion behavior in the pipeline following the installation of a gas boost heat exchanger. The heat exchanger had been installed to raise the gas temperature in an effort to reduce condensation and hence corrosion in the pipeline.

It was of particular concern that the presence of the wet carbon dioxide could result in unacceptable levels of internal corrosion in the carbon steel transfer line at locations where an aqueous phase would preferentially collect. Furthermore, bends were also considered to be at risk from erosion-corrosion by droplets of condensate swept along at high velocity by the gas stream.

A Corrosion Management system was utilized to acquire on-line corrosion data from a number of multi-technique (electrochemical noise and linear polarization resistance) corrosion sensors installed at selected key locations on the plant.

The system enabled short-term variations in plant operation and ambient weather conditions to be correlated with corrosion rate and mechanism information, across the spectrum of established plant operating conditions.

The knowledge gained allowed modification of plant operation in order to mitigate both CO₂ induced corrosion and localized flow-induced effects resulting from the high gas velocities.

The corrosion assessment program was able to eradicate the need for frequent costly inspection and, ultimately, the early replacement of the carbon steel wet gas transfer line with a more expensive corrosion-resistant alloy was eliminated.

As part of a major plant refurbishment, a UK Chemical Company reviewed its maintenance strategy and commissioned a scoping study to identify those items of equipment critical to its production processes that would benefit from condition monitoring.

The study identified a wide range of plant and equipment that had historically experienced unexpected breakdown which resulted in serious disruption to production and high repair costs. Much of the equipment was capable of being monitored using advanced condition monitoring techniques to provide early indication of component deterioration.

A criticality assessment and failure mode analysis identified the following equipment as being most likely to produce significant return from investment utilizing on-line condition monitoring:

Five atmospheric centrifuges
Five pressure centrifuges
Five high pressure dissolver feed pumps
Seven agitators
Two dryers
One main air compressor

Other items rated slightly lower in the criticality assessment were suitable for weekly routine monitoring using a portable data collector (pumps, motors, gearboxes, conveyors, etc.).

The monitoring techniques recommended in the scoping study required parameters such as acceleration, velocity and displacement to be measured, trended and correlated with data from the plant DCS, e.g. temperatures, pressures and motor current, to provide corroborative evidence of deterioration.

Potential savings determined from the scoping study indicated a payback on investment in the condition monitoring solution in less than one year. The economic justification was based largely on the Customer’s historical records of failure modes and costs.

The condition monitoring solution included accelerometers (intrinsically safe for hazardous areas), data acquisition units for low and high-speed equipment, an operator workstation and a suite of Condition Management software (on- and off-line modules).

The total measured parameters were in excess of 1,000 points.

Based on the early detection of a fault with one of the seven agitators during the first year of system operation, an interesting case history is provided which resulted in major cost savings.

The agitators are equipped with two accelerometers. One is mounted on the gearbox casing between the drive motor and the output shaft, whilst the other is mounted on the Hitachi cartridge seal which prevents leakage between the vertical rotating shaft and the vessel wall. This seal is a critical component, which in the event of failure, would result in severe production losses. Other parameters, such as temperature and glycerine level, are also incorporated via an interface to the plant Distributed Control System (DCS).

Within a few months of installing the condition monitoring, an alarm condition report was generated on one of the agitators and, utilizing the system diagnostic tools, a cause-and-effect determination was established which resulted in the identification of early intermediate shaft damage.

The Customer realized total savings, in terms of replacement parts, labor and lost production as a result of early detection and intervention, of £1.11M.

A producer of carbonless copy paper manufactures 70,000 tonnes per annum, on a single paper machine running at 710m/minute with a paper width of 5m. Production is a 24 hour, 365 days a year continuous process, with planned machine maintenance stoppages of 20 hours per month.

The paper making process is dependent on the continuous running of the rollers and bearings, which support the felts carrying the paper from the wet end through to the reeler at the finishing (dry) end.

A Condition Monitoring system was commissioned at the facility in 1991. During only the first year of operation the system provided early warning of deterioration of six bearings in the dryer section of the paper machine, thus enabling continuous production and minimizing repair costs.

Shortly after installation, the system alerted Operators to rapid deterioriation of a roller element bearing in the dryer section of the paper machine. A physical examination of the bearing housing revealed higher than expected temperature, caused by a blockage in the lubrication system. This could not be remedied on-line and, as the Mill was in full production with a firm delivery deadline to meet, there was reluctance to stop the machine.

To reduce the rate of deterioration of the dry bearing, manual lubrication was applied. The system confirmed significant reduction in rate of deterioration, thus enabling the bearing to continue to function beyond the end of the current production run.

The benefits of early warning from the system were therefore threefold:

• The production run was completed without interruption
• There was no consequential damage due to unexpected failure of the bearing
• The bearing was changed out in a planned and efficient manner at the end of the production run

Ignoring the effect of any consequential damage, it is estimated that a saving in production and maintenance activities of around £16,000 is attributed to this one incident. Had consequential damage occurred, the losses could have been in six figures.

Savings of this level have been repeated on a regular basis. Benefits of the condition monitoring system are:

• Unplanned downtime reduced from 2.25% to 1.30% per year
• Greatly improved understanding of the effect of tensioning dryer felts upon machine dynamics
• Payback of the initial investment in less than one year

The application of equipment reliability solutions has been reviewed through real life examples on gas processing, offshore oil production, chemical processing, and paper manufacturing plant.

In the majority of instances, value is realized in monetary terms through savings in maintenance costs and equipment replacement. Whilst such tangible benefits are obvious, often the more valuable benefit is derived from the confidence that plant and processes can be operated in an optimal fashion. In this way, cost opportunity can be exploited to ensure that the plant produces at its maximum capacity at the lowest cost. The ability to confidently run plant at its threshold can provide the producer with the competitive edge needed to succeed in today's demanding market. Ensuring equipment availability through reliability means that there can be few equipment breakdown "surprises" so production can be assured - this can help in leveraging the power of the producer as regards pricing control.

In conclusion then, the following points are to be noted:

• Integration of corrosion and condition monitoring information within a single platform can provide a comprehensive view of plant equipment and process reliability
• The ability to view corrosion and condition monitoring information against plant operational data can provide early identification of plant episodes which may be detrimental to equipment reliability
• An equipment reliability solution which provides a real-time picture of plant process and equipment interactivity provides the operator with the opportunity to mitigate incipient problems well in advance of any equipment failure
• The benefits achievable through the implementation of equipment reliability solutions are proven through a variety of industries, and have been realized in terms of both improved profitability and increased confidence in operations

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2. Teevens, P.J., "Pressure Equipment Life Extension Through Advanced Corrosion Surveillance Methods", Paper 3, Session 8, Maintec, Birmingham, United Kingdom, March 1996.
3. Balleau, D., Eden, D.A., and Eden, D.C., Troubleshooting Critical Process Problems in Oil & Gas Production and Refining Using Real-Time Monitoring Methods, GTF Environmental Conference, Brussels, Belgium, April 2000.
4. Integriti Solutions, Internal Project Reference Library, 1995-2000.