In the early 1990s, Southern Company adopted a predictive maintenance program in conjunction with a time-based preventive maintenance program. In 1994, predictive maintenance guidelines were issued for Southern Company plants. This program was improved upon in 1998 when the plant reliability optimization (PRO) program and streamlined reliability centered maintenance (SRCM) was introduced. Thanks to the Southern Company Services, Routine Maintenance Group, under the leadership of Randy Lee and Randy Jones, all Southern Company plants began focusing on the new maintenance strategy.
It was during this time that the management and employees at Plant Branch, a Southern Company coal-fired generation power plant operated by Georgia Power, embraced the company’s new maintenance philosophy and began focusing heavily on a maintenance strategy toward maximum reliability at the lowest cost. By incorporating oil analysis, vibration analysis, infrared thermography, ultrasonics and acoustic monitoring into a condition-based maintenance (CBM) program, the 1,600 megawatt, four-unit facility has saved hundreds of thousands of dollars in maintenance costs and improved the overall performance of its estimated 10,000 pieces of equipment.
Plant Branch’s CBM team was formed as a part of the PRO program. The team was made up of three CBM specialists: Joe Hughes, vibration and ultrasonics specialist; Butch Knight, thermography and motor signature specialist; and Danny White, oil analysis and lube oil program specialist. These three men were instrumental in bringing Plant Branch’s maintenance program to world-class status. They understand the importance of sharing information among all team members so equipment anomalies can be detected before failure occurs.
The Oil Analysis and Lubrication Component
Danny White, Plant Branch’s oil analysis and lube oil program specialist, is credited with developing and implementing the site’s thorough and carefully designed oil analysis and lubrication program. This program was key to the maintenance successes at Plant Branch. White was able to determine and optimize the appropriate balance of corrective, preventive, predictive and proactive maintenance techniques. He also knew that the decision-making process had to integrate all diagnostic, maintenance, financial and process data. Through careful brainstorming, White came up with several ideas to make a world-class lube oil program at Plant Branch. In fact, the Plant Branch oil analysis program and White were recognized at Noria’s Lubrication Excellence 2004 conference when White received the International Council for Machinery Lubrication 2003 Gill Award. The award recognizes organizations that have exhibited excellence in the application of used oil analysis in machine and lubricant condition monitoring.
Early in the development stage, White looked at the plant equipment’s condition and found that failures were occurring on the rotating equipment that could not be explained. He recognized that the equipment was basically being poisoned. Maintenance personnel were using open containers such as plastic soda bottles to dispense oil and replenish oil levels on rotating equipment. These containers were not only open to the harsh environment of a fossil utility plant, but the type of oil in those containers was often unknown. This was contributing heavily to unacceptable amounts of waste oil.
White put together a presentation for management that explained the existing oil program at Plant Branch and discussed steps needed to achieve a world-class lubrication program. The management team highly approved and gave its full support on implementing this new process. This process included selecting the critical equipment to be sampled, selecting the proper sample locations, determining the sampling frequency, setting cleanliness targets and alarm limits, enhancing lubrication procedures, purchasing new labeled oil-safe containers and new oil safety cabinets, installing desiccant breathers, installing new types of sight glasses that allowed better viewing, performing turbine oil quality test, consolidating lubrication, installing new filtration systems for critical equipment, and training all personnel. This new program was designed to meet the plant’s reliability objective by extending the mean time between failures and predicting failures before they occurred.
White knew that for this process to be successful, he had to have support from all employees. Maintenance personnel were trained on oil contamination and its damaging effects on the plant’s equipment. White gave them a road map that, if followed, would allow the plant to become world-class in machinery lubrication. He listened to their ideas and included them when making major decisions in the process. The hurdle of changing the way things had been done for 30 years was conquered one step at a time.
Impact of Oil Analysis
Incorporating oil analysis into the lubrication program was an important item on the road to a world-class lubrication program. An on-site laboratory consisting of the CSI 5200 oil analyzer, a viscometer and a lab microscope was set up for the CBM team. Team members use the on-site lab to analyze chemistry, wear debris, contamination and viscosity on used oils. They also perform lubrication analysis on new bulk oils.
In addition to the on-site laboratory, a contract was established with an off-site lab that could work with and support the team. When selecting the lab, White looked at several key factors including the off-site lab’s quality assurance procedures, the tests the off-site lab was capable of performing and the lab technicians’ qualifications.
The oil analysis program, which includes scheduled routes, daily occurrences and continuous monitoring of unhealthy equipment, has been successful in alerting team members to machine faults and abnormal wear conditions. The CBM team now has the ability to plan, track and trend the plant’s maintenance strategy with a predictive maintenance and CMMS database. All fan and motor bearings were once inspected annually which took a lot of time, money and human resources. Oil changes and bearing inspections are now based on the oil analysis reports as well as analysis results obtained through the other CBM technologies - vibration analysis, ultrasonics, infrared thermography and acoustics.
Before the on-site lab was established and oil analysis became routine, maintenance personnel did not know how well the filtration systems were working nor did they know the cleanliness levels of the turbine oils or electrohydraulic control (EHC) system oils. A set of cleanliness specifications for both has now been established. Filters are continuously being upgrading to reach cleanliness targets and performance measurements are being tracked through a cost benefit analysis.
Several major achievements have been noted since the oil analysis program was established. The cleanliness level in the Unit No. 3 and 4 pulverizers went from an ISO level of 22/19 to 16/13 with a two-and-a-half times life extension; Unit No. 3 boiler feed pump turbine bearings went from ISO 19/16 to 15/12 with more than two times life extension; the EHC systems went from ISO 16/13 to 13/10 with two times life extension; and the forced draft fan bearings from ISO 21/18 to 14/11 with more than four times life extension. An oil flush and change out of turbine oil on all four units were also completed.
The oil analysis program has also allowed the plant to avoid some major equipment failures. One example is the Unit No. 1 pulverizer, Pulverizer 1B. In early November of 2002, the first abnormal oil sample from the pulverizer’s gear box was analyzed. Particles in the 20 to 40 micron range were abnormally high, indicating signs of rolling element bearing failure. Upon learning of the high particle count, the CBM team began sampling the gearbox once a week and within four weeks more particles were appearing, some as large as 100 microns. The particles indicated severe rolling element bearing and sliding gear wear. They were flat ferrous particles with striations. Additional inspection of the pulverizer gearbox revealed that the low-speed cartridge had dropped out of place due to broken head cap screws.
Had oil analysis not been a part of the condition-based maintenance program, it is likely the pulverizer would have been run to failure. With no spare gearbox on-site, shipping time for a new gearbox estimated at 48 hours, and an estimated 260 hours of labor to actually replace the gearbox, a failure would have been costly (Table 1).
Table 1. Cost Benefit Analysis for 1B Pulverizer
Another example of the benefits of the oil analysis program was seen on the Unit No. 1 forced draft fan, 1A FDF. Shortly after the fan’s bearings were replaced during the spring 2003 outage, oil analysis indicated abnormal ferrous wear in the inboard bearing. Further investigation of the fan revealed that the thrust collar was spinning on the shaft and thus producing ferrous wear particles. The ferrous wear was causing premature bearing failure and severe shaft wear.
Again, had oil analysis not been implemented at the site, it is likely that the fan would have been run to failure. However, oil analysis tipped off the CMB staff and they were able to replace the inboard bearing and thrust assembly before the fan failed. They also had to shim the thrust collar to the shaft due to shaft wear. Table 2 shows the cost benefit analysis for this fan.
Table 2. Cost Benefit Analysis on 1A FD Fan
Impact of Lubricant Storage and Handling
Consolidation of grease lubricants was another big issue that had to be dealt with on the road to world-class status. Prior to the implementation of the lubrication program, it seemed that staff took the advice of a supplier or vendor and added its grease to the plant’s inventory. After looking into the compatibility of each lubricant, a decision was made to consolidate. The lubricant inventory went from 19 greases to only five. The plant also adopted a color code for each type of grease and labeled the grease guns accordingly.
New greasing procedures were implemented and all personnel were trained on this new grease program. In addition, sealed and labeled oil-safe containers are now in use and new oil safety cabinets were installed throughout the plant. As an additional improvement, White is working with Southern Company and its vendors to achieve cleanliness specifications for new bulk oil deliveries.
Plant Branch is committed to constant improvement of its lubrication program by fitting the best type and quality of lubricants to the reliability needs of its equipment. With time and research, White and the CBM team consolidated and developed a lubrication program that optimized equipment reliability and lowered inventory. If new equipment is added, White is notified so that he can recommend the correct lubricant. If any new lubricants are to be added to the inventory, the addition must first be approved by White and then receive final approval from the plant review board.
After achieving success and a complete culture change at Plant Branch, the CBM team was asked to share its lubrication program techniques with other plants, EPRI, and at CBM User Group meetings. The maintenance strategy has become a best practice throughout Southern Company.