Archive | July, 2007

746

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July 1, 2007
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Oil Mist Systems In The Plant-Wide Lubrication Of General Purpose Machinery

Plant-wide oil mist systems have been in use in numerous reliability-minded refineries and petrochemical plants since the mid-1960s. The 8th (2000) and subsequent editions of the API-610 Standard for centrifugal pumps also have described advantageous application parameters for oil mist. In the United States, Canada, South America, the Middle East and Pacific Rim countries, oil mist lubrication has matured to the point where major design contractors now are specifying these types of plant-wide systems quite extensively.

0707_equipment_reliability_img2Oil mist is easily controlled & appliedModern plants use oil mist as the lube application of choice. Plant-wide pipe headers distribute the mist to a wide variety of users. Oil mist is easily produced in an oil mist generator console (Fig. 1) and its flow to bearings is not difficult to control. Flow, of course, is a function of orifice (“reclassifier”) size and piping (“header”) pressure. Unless plugged by an unsuitable (e.g., an elevated pour point) lubricant, reclassifiers have a fixed flow area that is selected based on bearing size criteria.

Depending on make and system provider, header pressures range from 20″-35″ (500-890 mm) of H2O. Modern units are provided with controls and instrumentation that will maintain these settings without difficulty. It should be noted, however, that mixing ratios—typically 160,000 to about 200,000 volumes of air per volume of oil—are frequently incorrect on oldstyle mist generators that incorporate gaskets and O-rings in the mixing head, unless these elastomers have been periodically replaced or properly serviced.

Comparing plants with non-optimized mist entry (Fig. 2) to equipment bearing housings with their modern optimized counterparts (Fig. 3), lubricant and air consumption are about 40% less for plants that have implemented the superior mist entry and vent locations of Fig. 3. This has been reported in the cited references and is implied in API-610 8th Edition (2000) and later standards.

Forward-looking plants have used the API method, i.e. Fig. 3, since the mid-1970s. These plants had recognized that mist entering at locations far from the bearings could have difficulty overcoming bearing windage effects. Windage is most often produced by the diagonally-oriented ball cages in angular contact bearings. If such windage were produced by the left row of the thrust bearing in Fig. 2, the mist would take the preferential path straight to the vent exit at the bottom of the bearing housing and insufficient amounts of oil mist would reach the bearing rolling elements.

A larger quantity of oil mist or specially designed “directional” reclassifiers will be needed with certain bearing types unless the API method is used. This latter method will overcome windage, the flow-induced action induced by the skewed cages.

Environmental & health concerns
For decades, environmental and health concerns related to oil mist have been addressed by using oil formulations that are neither toxic nor carcinogenic. Such formulations are available to responsible users. Appropriate lubricants also have been formulated for minimum stray mist emissions. These, too, are readily available to responsible users.

Stray mist emissions can be kept to very low values by installing suitable magnetically-closed dual-face bearing housing seals (Fig. 4, also Ref.1). Unlike old-style labyrinth or other housing seals that allow highly undesirable communication between housing interior and ambient air, face-type devices seal off this contamination route.

Closed oil mist systems also are available—and have been since first being applied in the Swiss textile industry in the late 1950s. Today, closed systems are in use at several U.S. petrochemical plants. They allow an estimated 99% of the lube oil to be recovered and reused. Closed systems emit no oil mist into the environment and are available to environmentally conscious users.

 

 

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Header temperature & size
Temperature never has been an issue for properly designed systems. Once a mist or aerosol of suitably low particle size has been produced—and particle size is influenced by the temperature constancy of both air and oil in the static mixing head—the oil mist will migrate to all points of application in non-insulated headers at low velocity.

Ambient temperature has little influence on mist quality and effectiveness. Mist temperatures in headers have ranged from well below freezing in North America to over 122 F (50 C) in the Middle East. Regardless of geographic location, conscientiously engineered systems will incorporate both oil and air heaters, since these are needed to maintain constant and optimized air/oil mixing ratios. The heaters must have low-watt density (low power input per square inch of surface area) in order to prevent overheating of the oil. Users that try to save money by omitting heaters or using undersized headers will not be able to realize the greatest life cycle cost benefits from their assets.

Using undersized headers may increase the flow velocity to the point where the small oil globules suspended in the carrier air experience too many collisions. They may thus agglomerate into droplets large enough to fall out of suspension, causing excessively lean mist to arrive at the point to be lubricated.

Wet sump (“purge mist”) vs. dry sump (“pure mist”)
In the wet sump method, a liquid oil level is maintained and the mist fills the housing space above the liquid oil. Wet sump (also called “purge” mist) is essentially “old technology”— and primarily used with sleeve bearing-equipped pumps and blowers(Figs. 5 and 6).

Dry sump oil mist describes the application method whereby no liquid oil level is maintained in the bearing housing. (This principle was illustrated earlier in Figs. 2 and 3.) Pumps lubricated in dry-sump fashion are depicted in Figs. 7 and 8. Here, lubrication is provided entirely by oil mist migrating through the bearing.

The application of dry sump oil mist is advantageous for a number of reasons. Among these, we find lower bearing temperatures, the presence of nothing but uncontaminated oil mist and the exclusion of external contaminants. However, one important, but often overlooked, reason involves oil rings (Fig. 9)—or rather the fact that no oil rings are used with this application method.

0707_equipment_reliability_img4Oil rings often represent outdated 18th century technology as they were developed for slow-speed machinery during the Industrial Revolution. Elimination of oil rings is one of the many keys to improved reliability of virtually any type or style of bearing. Oil rings are known to have journal surface velocity limitations, sometimes as low as 2000 fpm, or 10 m/s. So as not to “run downhill,” which might cause the rings to make frictional contact and slow down, ring-lubricated shaft systems would have to be installed with near-perfect horizontal orientation.

Furthermore, frictional contact often results in abrasive wear and the wear products certainly contaminate the oil. Oil rings will malfunction unless they are machined concentric within close tolerances. They suffer from limitations in allowable depth of immersion and, to operate as intended, need narrowly defined and controlled oil viscosity.

Experience with modern oil mist systems
Actual statistics from a world-scale facility convey an accurate picture of the value of properly applied oil mist technology. This petrochemical plant went on-stream in 1978 with 17 oil mist systems providing dry sump oil mist to virtually every one of the many hundreds of pumps and electric motors in the facility. As stated previously, with the dry sump (“pure”) method per current API recommendation, the oil mist is introduced at a location that guarantees its flow through the bearings and to an appropriate vent location. There are neither oil rings nor any other provisions for the introduction of liquid oil on pumps and motors with rolling element bearings at the plant.

Over a period of 14 years, one qualified contract worker serviced these systems by visiting the plant one day each month. In this 14-year time period, there was only one single malfunction; it involved a defective float switch in one of the 17 systems. The incident caused a string of pumps to operate (and operate without inducing even one bearing failure!) for eight hours. In 1992, the combined availability and reliability of oil mist systems at this U.S. Gulf Coast plant was calculated to be 99.99962%.

Concluding comments 
Being aware of the relative unreliability of conventional lubricant application methods involving oil rings and certain constant level lubricators (Fig. 10), knowledgeable reliability professionals can attest to the utility and overall advantages of properly engineered dry sump oil mist systems. Certainly, the known advantages of properly engineered oil mist systems far outweigh the actual or perceived disadvantages. It is unfortunate that much information to the contrary is either anecdotal or pertains to systems that were not correctly designed, installed, maintained and/or upgraded as new technology became available.

Only dry-sump applications will lubricate, preserve and protect both operating and stand-by rolling element bearings. At all times, only fresh oil will reach the bearings. In many instances, bearing operating temperatures with dry sump oil mist lubrication are 10 or even 20 F degrees (6 or 12 C degrees) lower than with wet sump lubrication.

Industry experience with dry-sump oil mist systems is well documented [Refs. 1, 2 & 3] and its superiority over both conventionally applied liquid oil and wet sump oil mist lube applications has been solidly established.

Regrettably, there are still entire plants that try to get by on wet sump oil mist. Wet sump lubrication makes economic sense on sleeve bearings only. Here, its only function is the exclusion of atmospheric contaminants. It does so by existing at a pressure slightly above that of the surrounding ambient air. Often, the wet sump oil level is expected to be maintained by an externally mounted constant level lubricator. However, due to the slight pressurization, and on bearing housings equipped with traditional open-to-atmosphere constant level lubricators [Ref. 2], the oil level in the bearing housing will now be below the oil level in the lubricator. Keep in mind that fully pressure-balanced constant level lubricators will be more reliable than many other wet sump lubrication alternatives available today.

References:

  1. Bloch, H.P., and Shammim, A.; Oil Mist Lubrication, Practical Applications, 1998, The Fairmont Press, Inc., Lilburn, GA, ISBN 0-88173-256-7
  2. Bloch, H.P., “Case Study in Reliability Implementation,” Hydrocarbon Processing, August, 2002
  3. Bloch, Heinz P. and Alan Budris, Pump User’s Handbook: Life Extension, 2006, The Fairmont Press, Inc., Lilburn, GA, ISBN 0-88173-517-5

Contributing editor Heinz Bloch is the author of 17 comprehensive textbooks and over 340 other publications on machinery reliability and lubrication. He can be contacted directly at: hpbloch@mchsi.com

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143

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July 1, 2007
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Introduction To Synthetic Lubricants & Their Applications

All synthetics are not alike. Selection should be based on the optimum base stock type for the application. The additive system, which also is very important, imparts unique properties to the finished synthetic lubricant. As a result, there can be major differences in performance for the same synthetic type from different suppliers. Case histories and actual field tests are the best way to select a particular synthetic fluid. There are many applications where mineral oils, because of their cost and performance, are perfectly acceptable. Synthetics are problem solvers to be used in applications where their unique properties are cost-justified under the following conditions:

  • Temperature Extremes—Since synthetics contain no wax they are used at very low temperature conditions. ISO 32 PAO and ISO 32 diesters have pour points > -50 F. They also are effective at temperatures well above 200 F, whereas mineral oils should be limited to a maximum of 200 F and synthetics should be considered at temperatures as low as 180 F.
  • Lower Wear—In general, synthetics provide much higher film strength and lubricity than mineral oils, especially in a high-sliding environment that occurs in worm and hypoid gears.
  • Energy Savings—Some synthetics have low coefficients of friction because of their uniform molecular structure, resulting in significant energy savings in many applications.

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Properties & applications of synthetics 

Table I illustrates the most common synthetics and their major applications.

Polyalphaolefins (PAO)… 
If only one synthetic could be selected in a plant, it would be a PAO. These are the most versatile and most widely used synthetics. They operate over a very wide temperature range, can be produced in a wide viscosity range without changing their basic properties and are compatible with most other lubricant types. Because of their nonpolarity, they have poor additive solubility and cause slight seal shrinkage. Consequently, they must be blended with a polar synthetic such as an ester, which swells seals and gives good additive solubility.

Some of the more common uses for PAOs include:

  • Hot and heavily loaded gear boxes: an EP PAO is used for helical and herringbone gears, while a non-EP ISO 460 is commonly used for worm gears.
  • Rotary screw air compressors: PAOs and polyalkylene glycols (PAGs) are the two most commonly used air compressor oils for extended life service.
  • ISO 68 PAO is used in oil mist lubrication of rolling element pump and motor bearings.
  • PAOs have H1 approval in food plants and are used in a wide range of applications.
  • PAOs are not recommended for high-temperature reciprocating compressors because they can form hard deposits on exhaust valves, thus not allowing them to seat properly.

Diesters…
Diesters are one of the oldest synthetic types—and they are limited in the viscosity ranges produced. The most common ISO VGs are 32, 46, 68, 100 and 150. The viscosity indexes are only high for the ISO 32 while the others are in the 70- 100 range, depending on the alcohol and acid used in their manufacture.

The major performance strength for diesters is their excellent solvency minimizing deposit formation. They also have good low-temperature properties and high thermal stability and flash point.

Diesters have a low aniline number and a tendency to swell elastomeric seals. Therefore, resistant seals, such as DuPont Viton, need to be used. Diesters also can hydrolyze in a hot, high-moisture environment—something that
occurs in rotary screw air compressors.

Uses for diesters include:

  • Major application in severe duty reciprocating air and hydrocarbon compressors: diesters’ high thermal stability and excellent solvency will prevent carbon buildup on exhaust valves.
  • The synthetic of choice in air compressors many years ago: diesters are still used, but to a limited extent because of their potential for hydrolyzation. They are blended with mineral oils to form partial synthetics used in air compression and with PAGs for air compression.
  • Diesters are used extensively both in the ISO 68 and 100 viscosity grades for oil mist lubrication of rolling element pump and motor bearings.

Polyol Esters (POE)… 
POEs have very high thermal stability allowing them to be used in a very high temperature environment. They also are fire resistant with high flash- and fire-point temperatures. Because they are readily biodegradable, they can be used as hydraulic fluids in environmentally sensitive areas.

The major disadvantage of POEs is their cost. They are 50% more expensive than PAOs, PAGs and diesters. Although they have a tendency to hydrolyze at hightemperature and high-moisture conditions, POEs are more stable than diesters.

Primary uses for POEs include:

  • Aviation and industrial gas turbine applications where the effective operating range is -40 F to 400+ F, with primary viscosity ~27cSt.
  • Extended life fluid for air compressors: rated >12,000 hours and stable at temperatures of 240 F, which is higher than the maximum temperature allowable in a rotary screw air compressor.
  • Fire-resistant hydraulic fluid for underground mining, steel mills and foundries: Factory Mutual approved and MSHA certified; flash point for ISO VG 46 > 510 F and fire point >680 F.
  • Environmentally friendly hydraulic fluids that are readily biodegradable and contain ashless antiwear additives.

Polyalkylene glycols (PAG)…
As discussed in the first article in this series, PAGs are quite versatile. They can be designed to produce a wide variation in water solubility by adjusting the ratio of ethylene and propylene oxide during manufacturing. They have very high viscosity indexes exceeding 250, as well as excellent polarity for metal surfaces that gives them good lubricity. PAGS don’t produce deposits and can be designed to minimize hydrocarbon gas solubility. Their major weakness is compatibility with hydrocarbon lubricants like mineral oils and PAOs. They also shrink many elastomeric seals and attack certain paint types.

Some primary uses for PAGs include:

  • Rotary screw and centrifugal air compressors
  • Enclosed gear boxes in particular worm gears
  • Fire-resistant hydraulic fluids
  • Food grade products ISO VG 150 and higher needing H1 approval
  • Hydrocarbon-flooded rotary screw compressors
  • High-pressure ethylene compressors in HDPE production

Applications 
This following list highlights several applications where synthetics provide major cost justifications. Many more applications could have been presented:

  • Air Compressors
    • Rotary Screw
    • Reciprocating
  • Hydrocarbon Compressors
    • Rotary Screw
    • Reciprocating
  • Enclosed Gear Boxes
    • Helical, Herringbone, and Spiral Bevel
    • Worm

0707_formulations_img1Air compression
Rotary screw compressors…
 
Most of today’s industrial air compressors are rotary screws like that shown in Fig. 1.

 

In a rotary screw compressor, air is compressed, high temperatures are generated and, along with the moisture that is present, a severe oxidative environment is present for oil. The lubricant in this equipment performs four major functions: cooling, lubricating (bearings, gears and screws), sealing and corrosion prevention. This requires an oxidatively stable lubricant with high VI and good lubricity. Many OEMs have their own fluids—which are mainly synthetics. As shown in Table II, the different lubricants used can be classified based on fluid life.

The expected hours shown in Table II are OEM recommendations on expected life. Depending on the conditions, synthetics may exceed these numbers if the temperature and moisture are lower than normal.

 

0707_formulations_img3

The most common fluids used for air compressors for extended service are ISO VG 46 PAO and PAG/Ester. The esters most commonly used with PAGs are diesters and POEs that swell seals to counteract shrinkage caused by PAG.

POE gives the longest life extension for the fluid and is being used for extendedwarranty applications. Some POEs on the RPVOT test, which is a measure of the oxidative stability of a fluid, give results in excess of 3000 minutes—that’s nearly double the results obtained with PAOs and PAGs. POEs can be used at temperatures up to 240+ F, which is above the shutdown temperature of an air compressor. PAO can handle temperatures up to 220 F and PAGs are lower at 200 F. PAGs have the added advantage of very high viscosity indexes that gives a thicker film at high temperatures which minimizes wear. Furthermore, they don’t form deposits at high temperatures when they oxidize.

Two major cost justification areas for the use of synthetics is in fluid life extension and energy savings. Consider the following case study.

An evaluation was performed on a 300 hp compressor with a 60-gal. sump capacity operating at 180 F. Running mineral oil required change-out every 1000 hours, while a PAO greatly exceeded the OEM recommendation of an 8000-hour change by running 15,000 hours. This resulted in a 67% savings—or more than $1700—in lubricant costs in one year. (Data courtesy of Dr. Ken Hope, Chevron Phillips.)

Energy savings can be significant with air compressors. A number of studies have shown savings between 3-5% with rotary screw compressors. Combining energy savings and longer fluid life, along with less wear and better operation, synthetics make sense for air compression applications.

Reciprocating… 
While reciprocating compressors (Fig. 2) are not used much in air compression today, there are still many old compressors working in the industry.

Because of high temperatures, the cylinder region in a reciprocating compressor is the most difficult area to lubricate. One major problem associated with the use of mineral oils for this application is that they form hard deposits when they oxidize and coat the exhaust valves, thus keeping the valves from seating properly. As a result, hot gas is drawn back into the cylinder to be recompressed. This dangerous condition can lead to high heat generation and a possible fire.

The lubricant of choice for reciprocating compressor applications is an ISO 100 or 150 diester with excellent solvency. Fig. 3 shows two actual exhaust valves. The valve on the left had been running for six months on diester. The valve on the right had been running four months on mineral oil. The valve on diester continued to run with no coking, saving over $10,000 in valve replacement costs.

0707_formulations_img4Hydrocarbon compression Rotary screw compressors…
Non-flooded rotary screw compressors running at temperatures below 180 F can use mineral oils without major problems. Users, however, may want to turn to a synthetic like a diester or a PAO for their energy-saving potential. Flooded screw compressors with hydrocarbon gas will quickly lose their viscosity with most mineral oils and synthetics because the gas dissolves in the lubricant, thus lowering the viscosity.

PAGs are the most resistant lubricant to hydrocarbon gas dilution and are recommended for flooded screw compressors. More resistant to dilution than mineral oils, PAGs will, however, be diluted to an extent with hydrocarbon gases, a fact that must be taken into consideration in selecting the initial viscosity to arrive at the correct viscosity at the operating temperature. PAGs have the added advantage of having very high VIs.

Ethylene high-pressure reciprocating compressors…
PAGs are the lubricant of choice for high-pressure ethylene compressors because of their minimal dilution by hydrocarbon gas. The typical viscosity of PAGs used in this application is 270 cSt. The film integrity at a reasonable viscosity is maintained at very high pressures, leading to low lubricant consumption and very low wear rates.

Low-pressure hydrocarbon compressors…
Mineral oils at ISO VG at moderate temperatures have been used successfully. As conditions become more severe, though, synthetics need to be considered. Both PAGs and diesters are good alternatives. PAOs, however, are not recommended because of their tendency to form hard deposits when they oxidize.

Enclosed gearboxes Helical, herringbone and spiral bevel…
0707_formulations_img5Gearboxes experience EHL lubrication through sliding and rolling motion. A key criterion in lubricating gear teeth is to have thick enough film for the high sliding and shock loads. In many cases, EP additives are effective as anti-scuffing agents and are used in many loaded gear reducers. Parallel and right angle shaft gears such as helical, herringbone and spiral bevel are lubricated normally with an ISO VG 220 with EP. Under abnormal conditions, such as high temperatures and high shock loads, an ISO VG PAO with EP is used. Although PAGs can be used, because of their incompatibility problems, PAOs are preferred. Energy savings are more diffi- cult to attain with high-efficiency gears like helicals, herringbones and spiral bevels. Normally, synthetics have shown efficiency improvements of 3% or less. Therefore, the use of synthetics for these gears is not justified by energy savings alone. A better way to justify in these applications is to take into account how dramatically gear performance is improved under difficult load or temperature conditions when synthetics are used.

0707_formulations_img6Worm… 
Worm gears (Fig. 4) are highly inefficient. They also are good candidates for synthetics. A worm gear is a right-angle gear with non-intersecting shafts. These units consist of a steel worm and a sacrificial bronze wheel. There is very little rolling motion. Most motion is sliding—which causes the high wear and high heat. Worm gears typically can run 90 F degrees or higher than ambient temperatures. Since EP additives can attack bronze, very few EP gear oils had been used in the past. The only alternative had been to use a compounded high-viscosity mineral gear oil—such as ISO 460—containing animal fat for lubricity to protect the teeth during boundary lubrication. These types of lubricants oxidized quickly at high temperatures and didn’t provide a high level of wear protection.

The two most popular synthetics used in worm applications today are ISO VG 460 PAO and PAG. Each will perform very well. Neither of these synthetics contain EP and they both provide a high film strength and score very high on the FZG test that measures scuffing of gear teeth at different load stages. Mobil SHC 634, which is an ISO 460 PAO with no EP, exceeds 13 stages, the highest level on the test. This results in very low wear rates and energy savings.

Efficiency savings in excess of 7% have been documented. Because of their lower traction coefficient (which is the internal friction in the lubricant) PAGs often provide higher efficiency savings—but PAOs do very well. Temperature drops with a synthetic can be 20-30 F degrees. While PAGs are more common in gearboxes in Europe, more are being used in the United States. A PAG, because of its greater energy efficiency, is a good choice for new gears and can be used on other gears only with the proper flushing procedures. Moreover, PAGs attack some paints. A safer choice to convert a worm gear from mineral to synthetic is to use a PAO.

The following is a case history of the conversion from mineral oil to PAO:

A major can manufacturer used double-enveloping worm gears with an average reduction ratio of 60:1. The company was using a compounded ISO 460 mineral oil. On average, the company was experiencing four gear failures per year, each costing an average of $12,500 to repair. Temperatures typically were 200 F—and in some cases got as high as 215 F. The mineral oil was replaced with an ISO 460 PAO and the failures were eliminated. In fact, to date, 18 months later, there still have been no failures in this equipment. In addition, the average temperature dropped across the worm gears by more than 20 F degrees.

Conclusion
Synthetics are real problem solvers. While they can work well and be cost justified, there are many applications where mineral oils will do just as well. Three applications where synthetics can improve equipment operation and provide major cost savings are air compressors, high-pressure and hot reciprocating compressors and worm gears.

Deciding which synthetic to use is very important. Each candidate will have advantages and disadvantages that need to be considered before a final decision is made.

Keep in mind that the same synthetic type from different manufacturers can give different results. Even though the base stocks may be similar, the additive package may impart different properties from one supplier to another. Make comparisons between the data sheets, but let your final decision rest on field performance. Look at case histories and, if possible, run a carefully controlled plant test where meaningful data can be collected. Even though this will not be possible in some cases, definite equipment improvements can still be observed without rigorous testing and data collection. Be sure to document this data. Since synthetics are more expensive than mineral-based oils, you will want to be very accurate in your cost justifications.

Acknowledgements
The author wishes to thank Tim Taylor of Summit and Dr. Martin Greaves of Dow Chemical for their assistance in the preparation of this article.

Contributing editor Ray Thibault is based in Cypress (Houston), TX. An STLE-Certified Lubrication Specialist and Oil Monitoring Analyst, he conducts extensive training in a number of industries. E-mail: rlthibault@msn.com; or telephone: (281) 257-1526.

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86

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July 1, 2007
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Lubrication Management & Technology News

DECKER TO HEAD TYCO FLOW CONTROL
Patrick Decker has been named president of Tyco Flow Control, a business segment of Tyco International and one of the world’s largest providers of fl ow control products. Decker joined Tyco in May 2003 as the CFO of its Plastics & Adhesives business. In his most recent role with the corporation, he had been serving as CFO for the Tyco Engineered Products and Services (TEPS) segment since January 2005. He also collaborated with Tyco Flow Control’s leadership in the development of the Evolution to Excellence strategic initiative and related imperatives.

MULLER RECEIVES ASHRAE’S DISTINGUISHED SERVICE AWARD
Purafi l’s technical director, Chris Muller, has been honored with the ASHRAE Distinguished Service Award. A 12-year ASHRAE member, Muller serves as a Distinguished Lecturer for the organization and as chair of its Standard Committee 145P, which was charged with the task of engineering the ASHRAE Standard 62.1. He remains thoroughly involved within the organization as a voting member of several committees and as a co-author of the ASHRAE Standard 62.1-2004 User’s Manual.

GE MOVING SOME GAS TURBINE OPS TO HUNGARY
In response to growing international demand, GE Energy has announced the decision to add capacity for its 50-Hertz LM6000 aeroderivative gas turbines to a GE manufacturing facility located in Veresegyhaz, Hungary.

“We are shipping more and more LM6000 units to customers throughout Europe, Asia and the Middle East. By utilizing the Hungary facility, we can provide our international customers with more localized service and support,” said Charles (Chip) Blankenship, general manager of GE Energy’s aeroderivative division. According to Blankenship, this move will free up resources at the company’s Houston, TX, facility to better accommodate increasing demand for the LMS100.

The operations in Hungary, located approximately 20 kilometers outside of Budapest, have been in operation since 2001 supporting the build and repair of the corporation’s heavy-duty gas turbines. Packaging and testing for both the SAC and DLE models of the 50-Hertz LM6000 can now be completed there. GE Energy’s aeroderivative division is the world’s largest service provider for this type of gas turbine technology.

ASSOCIATION NEWS

PUMP SYSTEMS MATTER ANNOUNCES 4 NEW SPONSORS
Pump Systems Matter™ (PSM), a North American educational organization aimed at lowering energy needs by optimizing pump system performance, has announced four new sponsor organizations: Hydro Inc., Engineered Software, Inc., Manitoba Hydro and Xcel Energy. PSM was launched to help assist pump users gain a more competitive business advantage through strategic, broad-based energy management and pump system performance optimization. Its initial development was led by the Hydraulic Institute (HI). Incorporated as a new 501(c) 3 educational organization in 2006, PSM currently is seeking sponsors and board members that can actively contribute to its growth. Membership is open to utilities, market transformation organizations, government agencies, pump users, contractors, consultants, engineering fi rms, trade and professional associations, as well as North American pump manufacturers and suppliers of motors, drives, seals, couplings, bearings, housings, instrumentation and control systems and pump specifi c software. For more information, contact Joananne Bachmann at (973) 267-9700 x 22 or via JBachmann@pumps.org.

NEW EXECUTIVE DIRECTOR NAMED FOR PTDA FOUNDATION
The Power Transmission Distributors Association (PTDA) Foundation has announced the appointment of Phyllis Russell to executive director. In her new role, Russell will be responsible for all aspects of the Foundation’s management. Charged with implementing the Foundation’s missions, goals and objectives, she will oversee fundraising and relationship development in support of the organization’s major workforce development initiative, the Industrial Careers Pathway® (ICP).

SMRP OPENS LOUISVILLE CONFERENCE REGISTRATION
This year’s SMRP Fall Classic conference takes place October 7-10, 2007 in Louisville, KY, and registration is now open. To take advantage of the Early Bird Registration Fee of $825, you’ll need to register by August 26. For more information, visit www.SMRP.org. Remember, to register online, SMRP members must use their membership ID number. Plan now. Don’t miss this opportunity for “Building Your All-Star Team with the SMRP Body of Knowledge.”

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165

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July 1, 2007
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An Independent State Of Mind

ken_bannister

Ken Bannister, Contributing Editor

As this July 4th rolled around, my thoughts drifted back to 1776 and the excitement that must have surrounded America’s independence from British rule. Yet, as the British lamented their loss of the Americas, they too were on the cusp of celebrating a unique revolution of their own—the Industrial Revolution.

Seven years earlier, James Watt had successfully delivered the world’s fi rst viable steam engine capable of powering an entire factory of machines. Improving on the crude design of the original Savery-Newcomen engine used primarily to draw water, Watt’s design converted reciprocating motion into rotary motion. The rotary motion of the driven shaft could now be slaved into driving multiple line shafts simultaneously. Fourteen years later, in 1783, North England inventor James Arkwright was credited as the fi rst industrialist to use a Watt steam engine to power his entire textile mill.

The rotary motion of crank bearings and leatherbelt- driven line shafts introduced a constant need for lubrication. Petroleum-based lubricating oils as we know them today would not be discovered for another 70+ years, requiring the use of animal/ vegetable based lubricants such as olive oil for the rotary bearings and tallow (animal grease derived from cattle and sheep) for the drive belts.

The drawback with animal/vegetable oils is their lack of chemical inertness that results in acid formation after short periods of use, requiring constant cleaning and reapplication of lubricant. This important job became the responsibility of children. Because of their small stature and dexterity, they were able to scurry around quickly on all fours, on severely height-restricted fabricated gantries above the line shafts, applying lubricant as and when required.

Countless youngsters worked 18-20 hours per day in appalling conditions—and many of them were maimed and killed in the lubrication process. These little children, scampering across the gantries in a stooped manner, were said to resemble monkeys, which is how the term “grease monkey” is thought to have originated.

While children no longer take care of the lubrication in our facilties, have times really changed? Today, as I work with companies to implement engineered lubrication management programs, I am constantly amazed by the number of organizations that still treat lubrication as a “necessary evil,” and their lubrication personnel as second-class citizens, referring to them as “grease monkeys,” “grease jockeys” and “oilers.” Many have low expectations for their lubrication personnel, providing little or no training for the job, using the position as preretirement staging positions, etc. Sound familiar?

I submit that it’s time to lead an independent charge of our own to elevate the status of lubrication in the minds of all industrial personnel!

Although we may not be able to strike a unilateral declaration of independence, we all can work toward seriously legitimizing the science of lubrication in the minds of our co-workers. This can be achieved by taking responsibility for reducing machine downtime and reducing energy costs through the use of improved lubricants and lubrication practices. We also need to implement defi ned roles and responsibilities for all lubrication personnel, insist on quality training and accreditation for them and strongly support their being recognized as an integral part of an equipment reliability program/initiative/approach/team.

Are you and your company ready to take on this challenge? Good Luck!

Ken Bannister is lead partner & principal consultant for Engtech Industries, Inc. Phone: (519) 469-9173; e-mail: kbannister@engtechindustries.com

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Communications: The Maintenance/Engineering Partnership

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Ken Bannister, Contributing Editor

Whenever the cost of a repair is calculated, it typically is broken down into two specific components—parts and labor. The stocking of maintenance, repair and overhaul (MRO) parts in preparation for a planned or unplanned maintenance event typically necessitates ongoing partnerships with multiple vendors. The set-up and continued management of these types of ongoing partnerships will have a tremendous impact on equipment availability, reliability and cost of maintenance.

 

Deadly sins
“Machine down, waiting for parts.” If this is a familiar statement found on your returned work orders or daily maintenance schedule, you are likely working in a highly reactive maintenance environment.

0707_communications1Unfortunately, when equipment downtime is being experienced as a result of the part(s) unavailability, the tendency is to pay premium prices for both parts and delivery. For example, have you ever been in a situation in which a crucial part is not available locally, forcing you to air-freight and taxi a non-discounted part into the plant? In a proactive Maintenance department, this scenario is viewed as a deadly sin, since a part purchased in such a manner significantly compounds the maintenance repair cost.

A second “deadly sin” is associated with Maintenance developing the tendency to overstock low-turnover items. Purchased in multiples, these items often are stored in non-controlled, cached inventories (sometimes called “squirrel stocks”), in places like tradesmen toolboxes, equipment cabinets, etc. With annual carrying costs as high as 35 cents on the dollar and prohibitive access to “squirreled” parts, inventory costs easily skyrocket with poor or no return to the Maintenance department.

Working to eliminate out-of-stock, overstock and guaranteed delivery of non-stock items (without penalty) requires a defined Maintenance/ MRO vendor partnership in which each partner understands his/her role in ensuring that parts are “ready to go” at any time.

Establishing vendor partnerships
One of the hallmarks of a successful business is a trust-driven relationship between the company and its supplier/vendor base that views those purveyors of goods and services as a natural extension of the company itself.

A basic MRO inventory consists of three major spare part categories:

  • Original Equipment Manufacturer (OEM) items—These are proprietary items available only from the machine builder, usually with longer lead purchase times.
  • Insurance Spares—The items are inventoried for purposes of due diligence, and required by the corporate underwriter for equipment that could pose high-risk consequences when in a prolonged failed state.
  • Industrial Supply Items—These are available “off the shelf” from many different vendors.

Vendor relationships can vary significantly. They depend not only on the willingness of vendors to work with Maintenance, but also on the relationship and partnership already established between Maintenance and Purchasing, which acts as the corporate agent with the vendor. (See the March 2007 installment of this column in Maintenance Technology for a description of the Maintenance/Purchasing partnership.)

There are basically four types of partnership agreements in which a Maintenance department and parts vendor can engage:

  • The Lowest Bidder—This is a common relationship in which the Maintenance department, often driven by a strong Purchasing department mandate, follows a path of least-resistance and acquiesces to the purchase of supplies from the lowest-priced vendor. This method is especially time-consuming in that every item must be individually “shopped,” requiring extensive use of the purchasing system. This type of relationship is reactive in nature, not built on trust. Furthermore, it is not conducive to building long-term relationships with vendors.0707_communications2
  • The Preferred Vendor—When a vendor has established a good, trustworthy service record and a history of fair pricing, it can be considered an excellent candidate for “preferred vendor” status. Such an agreement generally means the vendor receives exclusive selling rights for listed inventory items, for an agreed price, delivery and specified time period. In return for this agreement, the vendor agrees to keep a minimum stock ready for immediate delivery (often from the vendor’s premises) at no additional cost to the Maintenance department. This partnership agreement promotes consistency of purchasing and supply; allows free exchange through a single blanket purchase order; and reduces or eliminates the carrying costs associated with carrying and managing maintenance inventory.
  • The Consignment—This type of partnership allows the inventory vendor to set up its own shelving and stock items on the company’s premises, again at no additional cost to the company. The Maintenance department then simply uses the “free-issue” items as its own, while the vendor accounts for items used on a daily, weekly or monthly time basis, and bills the company for the parts used after the fact. The advantage of this type of partnership is having managed inventory immediately available—for zero capital outlay at a previously agreed upon pricing structure. In return, the vendor receives a term-based, exclusive right-to-sell agreement. Already popular on the basis of free issue style items that include gloves, rags, nuts and bolts, etc., these partnerships rapidly are gaining more ground by offering higher-priced, highuse items such as bearings, electrical and power transmission supplies.
  • The Hub Vendor—Such a partnership is a radical shift from those listed previously, in that it reflects a performance-based service arrangement in which the vendor operates and controls the entire MRO inventory on behalf of the Maintenance department. A single-source vendor acts as an outsource agency and takes responsibility for purchasing, stocking and staging of all MRO inventory. The vendor is rewarded for parts availability and turnaround time—and paid on a monthly basis. The inventory may or may not reside on the plant floor, and could possibly have consignment inventory as part of its make-up.

Get smart
Whatever type you choose, remember that you want it to be a “smart” one. That’s because smart Maintenance/MRO vendor partnerships help the Maintenance department run smoothly, while reducing carrying costs and working capital expenditure.

Ken Bannister is lead partner and principal consultant for Engtech Industries, Inc. Telephone: (519) 469-9173; e-mail: kbannister@engtechindustries.com

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Factors For Success In Lean Maintenance

With management support and implementation of the right amount of the right technology in the right areas, improving maintenance performance doesn’t have to be an uphill battle.

One of the most popular buzzwords in business today is “lean.” This term conveys the idea of fat reduction. In industry, fat reduction includes the elimination of enterprise waste, the streamlining of processes to increase productivity and the more efficient use of capital assets and valued personnel in the pursuit of continuously improving the bottom line. There is, of course, nothing new in this concept.

0707_leanmaint1Most of the literature available on lean, however, woefully neglects the importance of the maintenance processes that are relied upon to keep enterprises running consistently, reliably and profitably. The typical lean expert groups maintenance in a bundle with “other processes.” Rarely does he/she offer tools that address lean methodologies specific to maintenance efforts.

This attitude mirrors the view of maintenance held by corporate management in general. Although asset downtime disrupts production and drives up both process and per-unit operating costs, executives often lose sight of this because they focus on output—not on the assets used to create it. As one CFO put it, “Companies care about how many widgets they make, not the widget-making machine.” The irony is that companies can use lean maintenance techniques not only to make more widgets, but to make each widget more profitably.

When discussing ways to improve maintenance practices, inevitably the discussion splits into compartmentalized topics. The dominant topics typically focus on parts inventory, preventive maintenance scheduling, trade and skill management, tool costs and breakdown management. Yet, the heart and soul of contemporary lean management—be it maintenance or any other endeavor—is the totality of the coverage. Top-down, bottom-up, sideways, the maintenance process requires more than a single approach.

An effective enterprise recognizes the interdependent issues that impact maintenance efficiency and ultimate success. These are addressed by a broad spectrum of solutions. Additionally, effective lean maintenance—like all other areas of the enterprise—requires continuous review, improvement and evaluation.

Gathering ideas
The first step a company must take to accomplish the goal of “getting lean” is to gather all stakeholders together in an open dialogue and evaluation process that covers all aspects of maintenance. This includes bringing in the “customers” of the maintenance process—assemblers, parts storeroom managers, shipping foremen, even product designers and engineers. Each of these individuals sees a different aspect of the maintenance picture and can provide pertinent input.

The overriding aim is to identify problems and suggest solutions. Management participation is essential. Without that buy-in, the effort of organizing for leanness is doomed to failure.

0707_leanmaint_q1A recent Aberdeen Group study found that more than 70% of survey respondents report that their Maintenance departments function on a stand-alone basis. At the same time, 87% of respondents agree that asset maintenance is very or extremely important to their organization’s overall financial performance, but only 7% are completely satisfied with their maintenance performance. [Ref. 1] Without energetic management participation in the “leaning” of maintenance processes, improvement becomes an uphill battle.

Successful meetings will reveal weaknesses in processes, as well as viable remedies and other required improvements. The results of these meetings can be developed into an overarching improvement plan and published to all stakeholders. In addition to setting direction for the team, such publication serves to recognize and reinforce team members’ valuable contributions to the improvement process.

Areas most affected
There is no concrete list of typical improvements to revamp a business, since there is no such thing as a “typical” business. Specific areas within the maintenance arena do, though, lend themselves to generally similar examinations.

  • Spare Parts Inventory Management: Most parts storerooms contain a substantial number of excess or obsolete parts. Often these parts add up to a six- or seven-figure investment that languishes within the maintenance budget. An enterprise must optimize its parts inventory so that parts are available for preventive and corrective maintenance without worthlessly gathering dust on shelves. Such optimization requires communications between storeroom managers, purchasers and maintenance personnel. Discussions center on parts usage, maintenance routines, anticipated demands and historical usage data. In a multi-site enterprise, the discussion needs to focus on options to centralize expensive, critical and seldom-used items. Stakeholders must be open to suggestions for altering maintenance operations scheduling to permit more control (and less waste) in the parts inventory management regimen.
  • Preventive Maintenance Management: A quality preventive maintenance (PM) campaign is the cornerstone of a quality maintenance program. The budget benchmark is generally 90% for PM activities and 10% for corrective/ breakdown maintenance. Anything less indicates an urgent need for improvement, as larger spending on corrective maintenance means more unplanned equipment shutdowns, greater wear and a reduction in the useful life of equipment. In today’s competitive business world, preventive maintenance must be further refined to examine predictive maintenance, reliability-centered maintenance and risk-based inspection management. Companies are now able to tailor PM activities for critical assets based on historical maintenance and breakdown data. It also is critical for enterprises to facilitate communication between line maintenance personnel and PM planners and managers. This generates a flexible preventive maintenance program that can use any opportunity to accomplish upcoming PM activities. Such “opportunities” include equipment breakdowns and equipment changeovers. By taking advantage of an unplanned shutdown, PM managers can “save” a planned shutdown, thus improving overall productivity.
  • Cross-Training Personnel: To be effective, lean maintenance can’t be the responsibility of just one domain. This means that maintenance personnel must become more flexible in their skills. It does not mean that a plumber must qualify as an electrician. It does, however, mean that the plumber learns about important switchboards, conduits and power supplies while the electrician learns about important valves, piping, pumps and reservoirs. The result is a savvier workforce that is better prepared to recognize potential problems before they impact operations.
  • Continuous Improvement Throughout The Maintenance Spectrum: Once lean methodology is initiated, all stakeholders must buy-in and contribute as a part of an ongoing daily routine, emphasizing the need for cross-training personnel and enabling continued reduction in wasted time, effort, material and production capacity. Each member of the maintenance team must be encouraged and empowered to initiate improvements.

Technology’s role
According to Defense Acquisition University, “The lean model stresses an evolutionary process of change and adaptation, not an idealized technology- driven end state.” [Ref. 2]

Keep in mind that lean maintenance is not the same thing as the acquisition of more technology. This is a conceptual error committed by many businesses that make large investments in new equipment, software and hard ware—all in the belief that these purchases will solve their problems. Such a path is counterproductive to the lean model.

Technology does play an important role in the progress toward greater leanness in the maintenance process. It is critical in lean activities such as tracking parts usage and cost trends; automated/tailored parts purchasing; evaluating effectiveness of preventive maintenance and the associated trends in breakdown occurrence; recording of personnel cross-training results; and, especially, the ongoing tracking of lean efforts to document progress, identify areas for improvement and monitor past efforts.

Nearly all successful business enterprises employ enterprise asset management (EAM) software applications. Primarily, these applications manage work assignment through various methods.

0707_leanmaint_q2Quality EAM offerings provide integration between the maintenance effort and spare parts inventory management. Excellent offerings include a variety of data requirements associated with maintenance activities so that each activity provides building-block information leading to trend and event analysis. The best EAM products integrate storeroom, repair, preventive maintenance planning and purchasing functions with additional lean-oriented technologies, including mobile connectivity, bar codes, radio frequency identification (RFID) and automated communications features such as e-mail, pager and operating screen notifications to key personnel.

The inclusion of key performance measurements within the EAM offering is a must to ensure that leanness goals are met. Businesses also should look for a separate analytical capability that is incorporated within the EAM umbrella. These capabilities clearly contribute both to the streamlining of the maintenance work process and to the gathering of critical performance, cost and productivity information.

Empowerment
With enhanced, business-specific technology and software applications, companies are able to reap the significant benefits of making lean maintenance an integral part of their overall lean business practices. As a result, they aren’t just turning out more widgets, they’re doing it profitably.

In the end, lean maintenance is really about people, their functions and their contributions to the business processes that make up the associated enterprise. Everyone in the business is a stakeholder. Strong, insightful business leaders will see the benefit of ensuring that every stakeholder is empowered to accomplish lean maintenance goals.

References

  1. Aberdeen Group, Collaborative Asset Maintenance Strategies, December 2006
  2. Tom Shields, “What is Lean,” TEACHING NOTE, Senior Research Associate, Massachusetts Institute of Technology, January 1999

Marty Osborn is Infor’s senior director of Enterprise Asset Management. Telephone: (864) 422-5001; e-mail: Marty.osborn@infor.com

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July 1, 2007
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Careful Planning, Hard Work And Luck

The successful and speedy Comanche Peak steam generator replacement was marked by real teamwork from the get-go.

Shattering a world record…

Careful Planning, Hard Work And Luck

On April 20, 2007, TXU closed Comanche Peak Unit 1’s breaker and ramped up in power, completing a combined steam generator and reactor head replacement outage that began on February 24, just 55 days earlier. That’s right, just 55 days. While steam generator replacement projects have been performed in the U.S. and around the world many times over the past two decades, short outage durations have come to be known as the measurement of success—and competition for “who” is the best is measured in days and hours of outage durations. Interestingly, until Comanche Peak was completed, the world record stood at 63 days, 13 hours. That was until a TXU-Bechtel team of highly motivated, experienced personnel shattered that record by more than a week at the Comanche project. (Bechtel was TXU’s prime contractor for the replacement of the steam generators.) Here’s how the team did it.

0707_outagestrat_img1The site
Comanche Peak is a two-unit nuclear generating station located about 60 miles southwest of Dallas. Each unit generates 1150 MWe, and the pressurized water reactor design includes four steam generators per unit, with each steam generator weighing about 400 tons, nominally 15 feet in diameter and about 70 feet long.

During original construction, the containment structure around the nuclear steam supply system was completed after the steam generators were installed. Consequently, there was no existing access to remove and replace the steam generators. The replacement methodology would dictate an opening through the containment wall. This containment access opening had to be located approximately 100 feet above the ground elevation outside, directly above the containment building’s only equipment hatch. The logistics associated with creating and closing an opening above the equipment hatch without impacting the normal flow of tools and equipment to support the outage through the hatch took years of planning and coordination. Furthermore, the existing crane in the containment building did not have adequate capacity to lift the old or new steam generators, so an alternate lifting system would be installed.

After the project was awarded in 2004, TXU challenged Bechtel to work with it to match or beat previous steam generator replacement (SGR) outage durations, focusing on 65 days as an aggressive but attainable schedule. In addition to the replacement of four steam generators, the scope of the project included the replacement of the reactor head, along with installation of new cabling, new cable trays and a new air-handling unit with all new ductwork. The upgraded design of the new steam generators included the installation of new, rerouted main feed water piping, as well as new hangers, snubbers and whip restraints.

The rerouted feed water piping interfered with existing containment building ventilation ductwork, so the ductwork required rerouting, along with new hangers. The new steam generators’ instrument tap locations required removing the old and installing new instrument tubing, again with all new seismicallydesigned hangers. For planning purposes, the scope of work to be performed during the Comanche Peak outage was considerably greater than that of comparable projects. In fact, by the time planning was completed, there were over 5000 measurable activities in the replacement’s schedule.

The four new steam generators were built in Spain and arrived on site December 9, 2006. Their journey began on an oceangoing vessel from Spain to Houston, and continued by train to the site, using an upgraded train track that hadn’t been used since the power plant’s original construction in the 1980s. The new reactor head, also fabricated in Spain, was outfitted with new control rod drives in Pennsylvania and transported by barge to Houston, then trucked to the site.

0707_outagestrat_quote1Application of technologies
During the replacement planning process at Comanche Peak, significant consideration was given to the use of both proven technologies and new technologies. Over the years, TXU and Bechtel had developed strong working relationships with specialty contractors who had been able to demonstrate high-performance capabilities. Integrating these specialty contractors and their technologies with the project team proved crucial to the project’s success.

Every aspect of the Comanche Peak project was reviewed and scrutinized to determine if the current technology was the best available, or if something new might be worth pursuing. This approach to technology use was applied to rigging, concrete removal, templating, decontamination, welding, non-destructive examinations and other activities within the project.

Rigging…
To handle the large components through an opening in the building, a lifting system would be needed. Prior to the outage start, erection of the Outside Lift System, or OLS, was completed. The Comanche Peak OLS was by far the tallest that had ever been used for replacing steam generators. Because of the OLS height and the presence of certain underground safety-related commodities in the vicinity, the OLS header beam was tied back to the containment building.

Large Kevlar slings, six on each side, running from the header beam to the baseplates on the containment wall, were installed in the unlikely event that a tornado would strike. If the OLS were to take a direct “hit” from a tornado, the slings would keep the header from falling away from containment and potentially damage important underground commodities.

0707_outagestrat_img2The height of the OLS and the amount of work to be performed from the work platform required installation of an elevator as well as a stair tower. During hydrodemolition, rebar removal, liner plate work and reinstallation of these commodities, a break area was installed on the runway. This area offered workers a place to eat without having to make the trek from the OLS to the ground and back.

Another interesting feature of the OLS was the use of a strand jack system in lieu of a chain jack system. Chain jack systems are very reliable and have been used on all Bechtel steam generator replacements to date. However, given the height of the Comanche Peak Unit 1 alternate access, the travel time from the opening height to the ground or vice versa was going to be almost six hours each way if the traditional chain jack system was used. The strand jack system, in comparison, was not only reliable, it traversed the same vertical distance in less than two hours, reducing steam generator lifting/ lowering time by two-thirds. This improved the project’s overall schedule while also limiting the time that the loads were on the OLS and potentially exposed to changes in the weather, such as high winds.

After OLS erection, the lifting system was load tested. The weights for the load test were large concrete blocks placed on a large frame. The load test weight requirements were 110% of the heaviest load to be lifted—which was a new steam generator. For Comanche Peak, the load test weight was 500 tons.

Concrete removal…
Hydrodemolition (the use of high-pressure water to demolish or remove concrete) was used on the containment building to create the Containment Alternate Access (CAA). Since the size and location of the containment’s equipment hatch was not sufficient to remove steam generators or a reactor head, an alternate access was needed to remove and install the old and new components. The access was located more than 100 feet above the ground, directly above the existing equipment hatch. The hydrodemolition equipment was mounted on a work platform at this elevation.

Tanker trucks brought about one and a half million gallons of water needed for hydrodemolition, preserving Comanche Peak’s supply of lake water. Twelve dieselpowered 475 hp pumps delivered water via high-pressure hoses to the two robots on the work platform. The water, at a pressure of 20,000 psi and a flow rate of 300 gpm, was directed at the containment through four rotating nozzles, each with a delivery opening of 3/8”. In simple terms, the process pushed 5500 horsepower through four small holes! This process also was extremely noisy, and hearing protection was an operational requirement.

During the concrete removal, as several layers of rebar were exposed, the hydrodemolition process was temporarily interrupted so that the rebar could be match-marked, cut and removed. A single bar weighed over 400 pounds, so each one was handled with ropes and pulleys until it was safely placed on the work platform. While the components were being moved in and out of the containment, each removed rebar was inspected, replaced if necessary and reinstalled later in the project using the cadwelding process.

Laser templating…
The project selected laser templating to measure and determine where to machine the new steam generators, cut/machine the existing reactor coolant piping, and to ensure fit-up for welding when the new steam generators were installed. Using laser technology (i.e., laser templating), technicians measured the size of the reactor coolant piping and recorded the piping’s location with respect to the steam generator support system. A threedimensional database was created with this information. This process was done for all four steam generators.

When the new steam generators arrived on site in December, they were stored in the new steam generator storage facility (NSGSF). Technicians used laser templating to record the locations of the new primary nozzles in relationship to the steam generator tube sheet extension, which is the steam generator’s lower support system. Similar to what was done for the existing steam generator/reactor coolant piping geometry, a three-dimensional database was created for each new steam generator.

The two databases were then merged for the existing RCS piping and its corresponding new steam generator. Through model comparison and data reduction, where to cut and machine the new primary nozzles was determined. Laser templating was then used to position the cutting and weld preparation machines on the new steam generators. All of this work was completed before the outage started in February. During the outage and after the old steam generators were removed from containment, laser templating was used inside containment to position the weld preparation machines on the existing RCS piping. The weld preparations and non-destructive examinations (NDE) were then completed.

Pipe-end decontamination…
While it’s called pipe-end decontamination, this activity is really the decontamination efforts applied to the remaining stainless steel hot leg elbow and the remaining stainless steel cross-over leg elbow for each steam generator. During the outage, this process was applied a total of eight times, to four hot leg elbows and four crossover leg elbows.

After an old steam generator was lifted out of its respective cubicle, the open-ended elbows created a very high dose rate in the general area where templating, machining and welding subsequently took place. This required the highly contaminated oxide layer inside the elbows to be removed. Pipe-end decontamination equipment was placed in the cubicle. The equipment consisted of a seal dam that was inserted down into the elbow. Another piece of equipment, called the blast head, was attached to the end of the elbow and an air-tight seal was created. Grit-impregnated sponge media was delivered through a rotating arm with a nozzle on its end, all of which was mounted inside the blast head. High-pressure air delivered the media and the overall effect was to blast the oxide layer off of the inside of the elbow. The computer-controlled rotating arm moved into and out of the elbow, effectively covering 100% of the inside surface of the elbow. The spent media was recovered through a vacuum system and emptied into shielded spent media drums. The drums were located in shielded carts for subsequent handling and disposal.

Narrow groove welding…
After installation, the new steam generators were re-attached to the reactor coolant piping by way of “narrow groove” welding. While the new steam generators were stored in the NSGSF, a narrow groove weld preparation was machined on the new primary nozzles. After machining, the weld preparations were buffed and NDE was performed to assure that no machining marks were present to provide false indications of defects in subsequent weld examinations.

Once the steam generators were removed from containment, the existing pipe ends (actually the RCS stainless steel elbows) were machined to a narrow groove weld preparation. After the new steam generator was rigged into containment, upended, lowered into place, and final fit up was achieved, the narrow groove welding process began. The track and weld head were mounted onto the nozzle-elbow configuration. Weld wire was fed into the groove, and the actual welding was monitored and/or adjusted by welding operators observing the welding through the use of cameras and monitors. As the weld progressed and suffi- cient weld material was deposited, another welding machine was mounted inside the nozzle-elbow configuration so welding could take place both inside and outside of the piping simultaneously.

Narrow groove welding provided the project with a number of benefits compared to conventional grooves. The amount of weld volume to be deposited was 70% less, reducing time and radiation exposure, as well as saving money. Production rates were improved due to automation and weld shrinkage was greatly reduced, which helped to prevent movement of the existing piping systems. This, in turn, reduced work for resetting clearances on critical components as part of restoration.

All of the narrow groove welding equipment was designed for remote operation. Therefore, during the outage, all of the RCS welding operators were stationed in a central location in containment, in a lowdose area. From this location, three, four or even five RCS welds were occurring simultaneously. Upon completion, the welds were thoroughly inspected, including with xray. Weld quality on these eight, large-bore stainless steel welds was first-time, with no defects recorded and no repairs needed.

Computed radiography…
When welding of the piping for the reactor coolant, feed water, auxiliary feed water and main steam systems was completed, the code of record required that each finished weld product be radiographically examined. The project elected to use Computed Radiography, or digital radiography, for this NDE, primarily because this technology would minimize the effects on adjacent/near work activities during the actual radiography process. Low-curie sources were used throughout the project for shooting the welds. Boundaries were established in a similar fashion, as with all types of radiography, but the low-curie sources allowed the boundaries around the weld to be radiographed to be much closer to the source, allowing adjacent work activities to continue.

On-site concrete batch plant…
Restoration of the CAA required the concrete to be replaced with material equal to or better than what was removed. Upon restoration, the concrete was tested and after the new concrete reached its designed strength, the containment building was pressurized to demonstrate its acceptability for use. The new concrete was “batched” on site using a portable batch plant. (The decision to use a portable batch plant in lieu of a local concrete company had been made by the project many months prior. Although several local companies had been given an opportunity to provide the concrete for the project, for various reasons, including logistical ones, they had chosen not to participate.)

There were a number of important considerations associated with the use of the portable batch plant. For example, the potential for dust during batching operations required submitting an application for a state air-quality permit.

Another concern involved the moving of freshly-batched concrete from the portable plant to the containment opening. Concrete trucks and drivers were rented and used for the opening, ensuring the project that the resources would be there when needed. To get the concrete from the trucks up to the opening, a pumper truck was rented and used. And, as normally planned, a second pumper truck was available on site in the event that a malfunction on the first pumper jeopardized placement activities. During placement, a seal on the delivery piping did blow out, but the seal replacement took a shorter amount of time than moving the existing pumper and replacing it. Again, luck was on the project’s side.

Staffing
As planning for the project neared completion, over 1300 additional people were needed at Comanche Peak to carry the steam generator replacement. Of this number, about 400 were made up of TXU personnel, radiation protection contractor personnel, security personnel and Bechtel Field Non-Manual personnel. The remaining 900 were craftsmen from direct hire and specialty subcontractors. Of the 900 craftsmen, Bechtel typically subcontracts work scopes that require about 250 subcontract supervision and craftsmen. Typical subcontract scopes that include craftsmen were:

  • Reactor Coolant Pipe Cutting, Machining and Welding
  • Liner Plate Cutting and Welding
  • Insulation Installation

0707_outagestrat_quote2Attracting and retaining qualified craftsmen in the numbers required for the project—about 650 in total—was a challenge. Early on, the project realized that recruiting adequate numbers of personnel would require some special things.

To effectively recruit in a tight and specialized job market, creative methods were developed to attract and retain the quantities of qualified craftsmen needed to complete the project. In parallel, contingency plans were made by the project in the likely event that shortages of craftsmen became a reality. Various project work scopes were identified and packaged. Then, subcontractors capable of performing to the project’s expectations were identified and retained. In reality, approximately one-third of the work scope originally planned to be performed by direct-hire personnel was performed by subcontractors, either through packaged work scopes or by augmenting the direct hire contingent of personnel.

Execution
A week before the outage started, the entire project moved to two 12-hour shifts, with working hours from 0530 until 1800, and 1730 until 0600. Working 12-hour shifts for several days prior to the outage start provided ample opportunities for everyone’s minds and body clocks to acclimate. Similarly, any issues with traffic backups, how long it took to enter the protected area, etc. were sorted out, prior to (and without affecting) the outage.

Even though the project worked 24/7, each and every Bechtel individual, including Field Non-Manual personnel, direct-hire craft and all Bechtel subcontractors, were assigned a day off. Once they were assigned that day, it was their day off for the duration of the outage. The project hired additional personnel to ensure that, when someone had his/ her day off, work continued.

Prior to the start of each shift, the project had its Plan of the Day (POD) meeting. Chaired by the Bechtel shift outage manager, the main focus of the POD was to present, in written form, what was planned to be performed in the next 24 hours. The POD covered project safety, project quality and the project’s schedule progress. These shift meetings lasted no more than 10 minutes. This same information was shared with the all of Bechtel’s Field Non-Manual personnel, its craft personnel and its subcontractors at the start of each shift.

The replacement outage started on Saturday, February 24, 2007 when TXU took Comanche Peak Unit 1 offline at 12:00 PM. At this time, hydrodemolition of the concrete on the outside of containment was set to commence with equipment that was positioned 100+ feet off the ground on the work platform. Unfortunately, that same day, north central Texas experienced its worst dust storm in over 20 years. Sustained winds in excess of 50 mph with gusts of over 70 mph were recorded. As a result, almost all of the project’s equipment, including cranes and man lifts, had to be secured for the day. Almost all of it. Interestingly, the only pieces of equipment qualified to operate in this tough first-day environment were, luckily enough, the work platform and the hydrodemolition robots.

Teamwork
TXU and Bechtel worked closely together, performing concurrent activities during plant defueling as well as during reactor core reloading, system fill and post-outage testing, such as containment pressure testing. Project engineering kept pace with the accelerated schedule, ensuring that system conditions met all of the plant’s technical requirements for the plant’s configuration.

Differing work groups pitched in and helped when requested by outage management. In lieu of reducing the work force when certain work activities were completed and turned over for testing, the work force was redirected to complete future work activities or to assist other work groups. As was the case for Comanche Peak, when all of the project’s critical path work activities and its near-critical path work activities were over 10 days ahead of schedule, opportunities for work activity completion were everywhere, furthering the project’s momentum.

World record results
The successful completion of this 55- day outage is truly one for the record books. The following results of the project speak for themselves:

  • Over 1,000,000 job hours without a Lost Time Accident
  • 21 of 21 (100%) large-bore piping first time quality RT welds
  • 52 of 63 (83%) feedwater & auxiliary feedwater first time quality RT welds
  • Completed Project with Code- Compliant 100% Computed Radiography
  • Multiple ( i.e., 5 ) crane operation in containment with no mishaps
  • Sustained cadweld production of over 50 per day ( plan was 32 per day)
  • Never exceeded the 72-hour per week per employee rule
  • ALARA Dose Goal: Plan 156 REM Actual 123.9 REM
  • Breaker-to-Breaker: Plan: 65 Days Actual: 55 days (a world record by over a week).

Richard L. Miller is senior project director with Bechtel Power Corporation. Telephone: (301) 228-6215; e-mail: rmiller@bechtel.com

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6:00 am
July 1, 2007
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Publishers Notes: Strategic Partnering

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Bill Kiesel, Vice President/Publisher

At a time of great challenge and opportunity in the global business environment, tremendous forces are reshaping today’s marketplace. How manufacturing responds to this is critical. The Maintenance and Reliability function of your plants and facilities is crucial to staying competitive. Market intelligence and evidence-based recommendations enable businesses to make better decisions and deliver new ideas that are essential to advancing Maintenance and Reliability solutions.

At Maintenance Technology, it is our unique point of view that makes us such a vital strategic partner. Our publication applies quality, in-depth information and proven methodologies to deliver insights that demonstrate the solution, outcome and economic value of Maintenance and Reliability practices. What makes us unique is not only the richness and relevance of our editorial content—it is the way it is leveraged by you, our readers.

As I stated in an earlier editorial: “We know that you and your operations are constantly being challenged by a changing world and economy.” But we are ideally positioned to deliver value and solutions to the issues and challenges you face every day.

Looking ahead, our goal is to build on the foundation and strengths we have established over the past 20 years to become even more valuable to you. Across all of our properties, we will keep adding to the quality and benefi ts we consistently deliver.

That being said, this month’s issue of Maintenance Technology is wrapped in a renewal notice for those subscriptions about to expire. Please take a few moments and complete this form to ensure your continued receipt of our publication. If you’re not receiving the wrapcover I still urge you to renew today. By doing so, you’ll continue to gain valuable knowledge from industry professionals. However, we want to hear from you, too, and we encourage you to help others learn from your own experiences. So please, don’t only fi ll in the renewal notice, but also send us your ideas, opinions and successes.

Thank you to all our loyal readers! MT

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