VOL. 12, NO. 3

T H E S E A L I N G T E C H N O L O G Y M A G A Z I N E

COVER STORY 2

EVOLUTION 4

INNOVATIONS 5

CONNECTIONS 6

Flow Solutions DivisionBW SealsDurametallic SealsPacific Wietz SealsPac-Seal

We need more power! This yell isbeing heard around the world asthe electronic revolution contin-ues. To help the power genera-

tion industry squeeze more efficiency out ofexisting systems and improve relia-

bility of rotating equipment,Flowserve Seals is making

waves...faces, that is.Boiler circulating

pumps are criticalequipment in steampower generationplants, as they circu-late boiler water atpressures approach-ing 3,000 psi andtemperatures of 600

to 700° F. Under theseextremes, the pumps

can be a source of costlydowntime and frequent

maintenance requirements.They also represent one of the

greatest areas for efficiency improve-ments within the steam-electricity generationcycle.

History reveals that advances in generationefficiency and equipment reliability havedirectly translated into life cycle cost savings. Italso explains why applying the latest technol-ogy available today—wave face mechanicalseals—is important.

A costly propositionBoiler feed pumps commonly discharge waterat 350° F. Each gallon carries a heat content—enthalpy—of 2,240 BTU. Traditionally, feedwater also cools braided packing and mechan-ical seals used in boiler circulating pumps.Simply put, each gpm of feed water used forcooling can represent a waste of 2,240BTU/min. (0.039374 MWe) that can’t be usedto make electricity. While that doesn’t soundlike much, a single gpm represents 1.2 trillionBTU per year (21,000 MWe) of wasted energy.

It’s equivalent to 3.21 railroad cars of coal or9,748 gallons of gasoline wasted annually.

PackingIn the 1960s and 1970s, braided packingsealed most rotating pump shafts. A series ofclose-clearance floating rings and leak offports were used to reduce the discharge pres-sure down to an acceptable level needed in thepacking box of a vertical boiler circulatingpump. This allows valuable steam energy toescape the system and not be used for electric-ity generation. Between 100 and 200 gpm of350° F boiler feed water must be injected toprevent steam flashing as the boiler circulatingwater pressure drops from discharge to thatcreated in the packing box. A single boiler cir-culating pump can represent the equivalent of642 railroad cars of coal, 2 million gallons ofgasoline or more than 4 million MWe ofwasted energy annually.

Additionally, costly purified, deaeratedmake-up water must be added to account forwater losses. Rotational wear, fouling by oxidesand hydraulic system upsets can require con-stant adjustment and frequent packingreplacement. This obviously adds to mainte-nance costs, but most importantly, it reducesgeneration capacity as equipment is taken off-line for repair.

Single mechanical sealsIn the late 1970s and early 1980s, singlemechanical end-face seals gained popularityover braided packing as a way to reduce main-tenance costs and improve uptime. Close-clearance carbon graphite bushings reducethe circulating pump discharge pressure to300 psi in the seal chamber. As with packing,boiler feed water injection is still needed toprevent flashing, often at a rate of 25 to 50gpm. This flow represents 160 coal cars, 0.5million gallons of gasoline or more than 1 mil-lion MWe of wasted electricity in a year.

Payback periods easily justify using singlemechanical seals instead of braided packing.

2 www.flowserve.com Face to Face

Making waves for thepower industryThey improve efficiency and reliability of boiler service

coverstory

Figure 2. Waves still visible on a primary rotor after verification testing attests to minimal face contact forces.

Seals are more efficient because they operateat higher pressures, which minimizes lost heatand make-up water costs. But, boiler feedwater pumps or separate dedicated boosterpumps used to provide the needed coolingwater injection must be brought online firstand remain operational when the circulationpumps operate.

It is common for the single Flowserve D sealfitted with API Piping Plan 23 to achieve threeyears or more of continuous service in boilercirculation pumps. This reliability and uptimeis several orders of magnitude better than forbraided packing.

Pressure-staged multisealsPressure-staged multiple mechanical seals canfurther reduce energy loss and water make-upif boiler feed water is the seal cooling media.Multiple face mechanical seals, such as theFlowserve HS series mechanical seal, have two,three or four sets of faces, or “stages.” Eachstage takes a fraction of the pressure drop toprevent flashing at any set of faces. The last setcan act as a safety back-up. Staged pressureseal technology eliminates the need for injec-tion cooling and associated system make-upwater, but it also requires a complicated sealdesign and a reliable seal support system tofunction properly. Typically, each stage uses itsown dedicated API Plan 23 setup.

The ultimateWave face technology makes it possible to seala 3,000-psi discharge pressure in boiler serviceusing only one set of faces, without pressurestaging or injection cooling. These custom-designed seals can feature either a singlearrangement or a dual, non-pressurized tan-dem arrangement in which the secondary setof faces can act as a full safety back-up seal.

Laboratory testing at actual seal chamberoperating conditions using API Plan 23 veri-fies the suitability of the DHTW mechanicalseal for a given application. Critical functionalparameters are verified against design criteriausing a full complement of flowmeters, pres-sure transducers and thermocouples.

The designEach seal rotor has an undulating face that wasdesigned using computer code that combinessophisticated fluid mechanics and finite ele-ment analysis and then manufactured withprecise laser technology incorporating pro-prietary computer modeling.

To reduce face contact and wear, algorithmsdetermine the amplitude, tilt and number ofwaves needed to optimize full-surface liquidlubrication down to the sealing dam area (seeFigure 1). The wave face design reduces facecontact to the point that the shaft can berotated by hand, even at full system pressure.

Figure 2 shows a primary rotor after a series ofrotating verification tests. Its pristine condi-tion shows waves still visible to the naked eye,which attests to its minimal face contact forces.

Wave face technology translates to improvedreliability in rotating equipment because theseal support systems are less complicated com-pared with pressure-staged seal designs. DHTWseals maximize the efficiency of steam electric-ity generation because no boiler feed water isneeded as a cooling fluid. As a result, utilitieshave the potential to save in excess of half a mil-lion dollars simply by upgrading conventionalsingle mechanical seals. The limited contact inwave face seals helps to optimize the generatingunit uptime and system output. As far as thesteam electricity power generation industry isconcerned, making waves is a good thing.

Technical detailsThe DHTW seal is a balanced, stationarymulti-spring configuration in a stainless steelcartridge design. The standard unit uses a sili-con-carbide rotating face working against acarbon or silicon-carbide stationary face.Other custom combinations are available. Thegaskets are made of high-performance elas-tomers, such as nitrile, fluoroelastomer, per-fluoroelastomer or ethylene-propylene. Apumping ring eliminates any need for theinjection of cooling water during operation,with stable temperatures maintainablethrough thermosiphon even in hot stand-byconditions.

The Flowserve DTHW seal is rated to handlepressures to 3,000 psi, temperatures to elas-tomer limits and speeds to 15,000 feet perminute. It is available to fit shafts from 2.00 to11.00 in. and can be fitted to most existing sealchamber bores. ●

(Based on an article by John Marta, Manager ProductMarketing, Flowserve Corp.)

Face to Face www.flowserve.com 3

Tilt

WavinessAmplitude

Seal Dam

Figure 1. Computers determine the amplitude, tilt and number of waves needed for full-surface

lubrication down to the sealing dam area.

More than half the power generated in the U.S.comes from coal-burning power plants. Abyproduct of coal combustion is sulfur diox-

ide, which combines with moisture found in air to formacid rain. Removing sulfur dioxide before it reachesatmosphere is called flue gas desulfurization, or FGD.Eric Adolfsen, who manages the FGD process atConectiv’s B.L. England Generating Station in southernNew Jersey, explains the process. Flue gases are divertedto an absorber vessel, a tank eight stories tall by 33 ft.across. It contains 300,000 gallons of limestone slurry inits base that is circulated through spray headers.

As the flue gas passes through the spray levels, theslurry absorbs sulfur dioxide gas. In the process, the

SO2 reacts with the calciumfrom the limestone to form

calcium sulfate. Oncethe sulfur dioxide isremoved, the remain-ing gases pass ontothe stack.

Adolfsen’s plant usesfive 17,000-gpm Hazelton

pumps (heritage product ofthe Weir Slurry Group) to

recirculate the limestone slurry—which is like “pump-ing out a residential swimming pool every minute.”

The limestone slurry also collects additional abra-sives from combustion—fly ash consisting of aluminumoxide and silicon dioxide. “You’ve got gas tempera-tures above 200 degrees. You’ve got chlorides in thecoal that end up in solution, so the pH is acidic. It canbe a hostile environment for a no-flush mechanicalend face seal if you don’t know what you’re doing,” saysBarry Hart, Flowserve senior sales engineer for theConectiv plant.

Flowserve originally designed its RIS (Rubber-In-Shear) seals in the early 1980’s specifically for mineraland ore type slurries, like those found with all wetFGD applications. These component seals look simi-lar to and are set manually like a packing gland. Metalcomponents are milled from corrosion and abrasion-resistant alloys and use silicon carbide seal face rings.The faces are lapped to a flatness of one to two light-bands, or 11 to 22 millionths of an inch. That leaves afluid film gap of approximately three microns—small

enough to filter or strain out larger abrasive particlesthat can wear out the seal faces in a process known asthree-body abrasion.

Adolfsen, whose FGD system uses the largest diame-ter Flowserve RIS 9500 size seals, says, “I don’t believewe ever took a pump apart because of a Flowservemechanical seal. Sometimes we’ve had to flush andreset them, but I don’t remember any seal failures.

New on the horizonFlowserve has taken things one-step further and intro-duced the new SLM series cartridge seal to minimizethe effects that equipment assembly tolerances, sealinstallation setting variances, and impeller adjust-ments can introduce. “The SLM seals are designedusing proven flat face criteria and manufactured tosurvive the same slurry equipment tolerances as theRIS units, but are offered in a cartridge design,”explains John Marta, Flowserve’s manager of productmarketing in Littleton, Colo. “We use power plant flyash to make a 20-percent slurry at our test facility

located in Temecula, Calif. to verify our no-flushslurry seal designs.”

According to Marta, Flowserve isn’t necessarilyemphasizing the repair market for the SLM line. Manypower plants have gotten five to 10 years’ service out oftheir RIS seals, and most plants have spares in inven-tory. The SLM may better suit the new generation ofFGD systems. “It’s a good fit with modern slurry equip-ment,” Marta says. “It’s precision-set at the factory. It’sverified using the same parameters we used in our pre-vious no-flush slurry seal designs, and it uses the sameflat face design criteria that we’ve always had.”

The new SLM seal also has an expanded pres-sure/temperature capacity to meet any future needsof an evolving FGD industry. This coincidentallyexpands the scope of the SLM to be able to be appliedin other demanding slurry applications like foundwith the new millennium of mineral and ore processesas compared with those from just 20 years ago. TheSLM seal has a higher capability than its predecessor.

“Flowserve will support its installed base of RISseals,” Marta says, “and continues to stock parts forthem. But if you’re looking at a new FGD installation,why not use the latest and greatest sealing technologyavailable today?” ●

4 www.flowserve.com Face to Face

evolution

Don’t flush your slurry sealsThe power industry discovered you don’t need to do that

The Conectiv B.L. England GeneratingStation in Beesleys Point, N.J., provideselectrical power to the grid serving a

part of New England. It operates two 155-megawatt generators (one coal, one oil) andone 129-MW coal-fired generator for a peakcapacity of 439 megawatts.

A dedicated 1,800-psi boiler serves each tur-bine. Each boiler uses twin feed pumps oper-ating at about 1,480 gpm at 2,750 psi. Theseten-stage barrel pumps feed 326° F water tothe boilers.

When one boiler feed pump is down, thebest its twin can do is provide feed water foronly about 60 percent of the turbine’s capac-ity. Any downtime is a graphic demonstrationof “time is money.”

Eliminating maintenanceSealing high-pressure pumps can be problem-atic. For years, Conectiv’s B.L. England stationused braided plastic/lead packing to seal itsboiler feed pumps. And for years, the stationtolerated a continuous maintenance programwith these pumps. After a while, the packingswould leak. A few turns of a wrench wouldtighten the gland enough to stop the leak. Butsooner or later, they would leak again. Thisregimen carried the risk of over-tighteningand scoring the pump shaft/sleeve, whichwould require taking the pump offline. Therealso came a time when continued tighteningwas simply impossible. As a result, the pumphad to be taken offline to be repacked com-pletely. This happened about four times a year.

Seeking better optionsIn 1994, the station gave Flowserve Corp. anopportunity to improve this situation.Flowserve’s solution was to replace the pack-ing with the D seal—a single mechanical sealdesigned for high-temperature, high-pressureboiler feed pumps. The installation relied onAPI Plan 23 piping to cool the seal.

The bulk of the changeover was painless.“The retrofit required no modifications to thestuffing box on Unit 2 boiler feed pumps,” saysCharles Ash, project engineer at the Conectivfacility. “Flowserve made a new shaft sleevebecause the original cross section would notallow installation of a cartridge seal.”

According to Barry Hart, Flowserve seniorsales engineer, “The design of one of thepumps prevented an easy retrofit. It requiredreworking the stuffing box so the D seal wouldfit.” This project was handled at Flowserve’sBridgeport N.J. Quick Response Center.

Normally, the oil-fired unit is the last to comeonline. It handles forecasted peak loads andprovides electricity when the spot prices justifythe sales. The multi-stage boiler feedpumps on this

unit had adifferent problem.Although the graphite-laminated packing at the low-pressure, inboard end functioned well, the highpressures developed at the outboard end had atendency to blow out the packing. Besidesbeing a maintenance headache, failed packingallowed water to contaminate the lube oil.

Conectiv asked Flowserve to address thisproblem. The solution required retrofittingonly the outboard end with a D seal. This het-erogeneous sealing scheme has worked well.

“Not every pump has been equipped with theD seal yet,” says Ash. “We have been making theretrofits kind of piecemeal. When a pumpneeds rebuilding, we replace the packing withseals. The payback for converting from packingto seals is typically achieved in about 1 year.”

When asked about stocking spare seals on-site, Ash says “We don’t stock any. If I needone, I can call Flowserve and they’ll be here inno time. I don’t need a seal onsite because theturnaround is so good.” ●

Face to Face www.flowserve.com 5

Simple, but effectiveA single seal takes abuse and solves problems

innovations

re nagging maintenance problems inone of your plant’s pumping sys-

tems causing costly failures and wreakinghavoc on your organization’s profits? What ifyou could tear apart an identical system—with-out affecting your plant’s uptime—and effec-tively diagnose the problem? Or, perhaps youhave an idea about how you might be able toimprove the functionality and efficiency ofyour facility’s fluid management system, butrealize it would be financially impractical totake your system offline and foolhardy toexperiment with the system’s components.

Created to provide plant professionals withreal solutions to these critical issues,Flowserve’s Learning Resource Center (LRC)in the Dallas suburb of Irving provides an edu-cation-based program that gives students ahands-on opportunity to test their knowledge.The end result is tangible benefit to theiremployers by improving their organization’sproductivity.

Flowserve provides users with the knowledgeand skills they need to improve the perform-ance and maintenance records of their ownorganization, allowing companies to get fullvalue from their equipment.

Putting instruction and theory into action,students move from the facility’s classroom toits state-of-the-art labs where they can test, dis-assemble and reassemble more than 100 staticpumps and 28 operating pumps that simulateactual working conditions.

Unique learning modelBut while it may be commonpractice to learn through lecture and hands-on meth-ods, the LRC provides anuncommon third educational experience—experimentation.By testing their theories, par-ticipants validate past learn-ing and discover what can’tbe taught in a classroomalone. The LRC’s uniquethree-tiered adult learningmodel of instruction, imple-mentation and discovery isimplemented in three dis-tinct facility areas: the class-

rooms, the Static Lab, and the Power Lab.First, students find out the “why” through

classroom instruction that introduces theoryand references needed to get the most fromfuture hands-on experience. Next, studentsmove to the implementation phase of theirlearning by working in the LRC’s Static Lab. Inthe 2,300-square-foot Static Lab, students workon current equipment from around the world,including a wide range of pumps, valves andseals that give students the chance to workwith the equipment they encounter in theireveryday work environment.

In the LRC’s four 900-square-foot Power Labs,students work with innovative see-through train-ing aids such as glass flowmeters, transparentplastic suction lines, extensive gauges, thermo-couples, vibration monitoring equipment andunique clear acrylic pumps that allow students alook into the working mechanisms of the equip-ment. In the Power Lab, pumping systems oper-ate as they do in plants around the world, butmany of these pumps have been modified toallow students to compare maintenance meth-ods, and some have been altered to simulatereal life failures for the purpose of diagnosis.

What really closes the loop to complete thislearning experience is the experimental or dis-covery phase. These hands-on experiments giveparticipants the answers to “what if” scenarios.During discovery, students recognize they havethe skills to solve the very same problems backhome. The opportunity to experiment and

6 www.flowserve.com Face to Face

connections

Learning solutionsHow hands-on education at Flowserve’s Learning ResourceCenter can improve your plant’s competitive edge

change the flow characteristics of these pumpingapplications allows students to see what will hap-pen if they put their solution ideas into action.Previous to the development of this innovativeapproach, maintenance engineers could onlytalk about what might happen. Flowserve pro-vides the opportunity to be creative in the learn-ing and problem solving process.

Companies that have sent employees throughthe program remark at how extraordinaryFlowserve’s LRC is. Said Shawn Bassiri, ProcessArea Specialist at DuPont’s La Porte, Texas facil-ity: “It’s great because the programs provide anoverview of the principles of pumps andhydraulics, and show participants how seals reallywork. They start at the basics and then go intomore advanced applications. It’s the combina-tion of classroom instruction and hands on labexperience that makes Flowserve so unique.”

This learning philosophy is best reflected inthe LRC, where clear epoxy casings on pumpsallow students to see exactly what happenswhen they experiment with seals. For example,they are able to see the immediate effects fromtemperature changes on pumps and the effecton the resultant life of the seals.

Interactive trainingFlowserve also takes training to the next levelthrough its Educational Services CertifiedTraining program, an interactive competence-based equipment-intensive certification pro-gram for pump, mechanical seal, and systemsengineers and specialists. Students are certifiedon the standards required by OSHA that meeta specified body of knowledge in areas such aspump assembly and disassembly, propermechanical seal installation, calibration andrepair and control valve position.

The program’s goal is to provide participantswith two primary, yet essential tools: knowledgeand skill. Certification includes complete doc-umentation of a student’s skill level, allowingorganizations to see the tangible differenceFlowserve has made

One phase of the training is preparing an“On The Job Checklist” that includes research-ing and documenting the critical reliabilitymeasures and issues used in their organization.Students return home to their plant, examinetheir equipment, evaluate their procedures,develop an improvement strategy, and preparea reliability self-audit.

While many of the students are maintenanceengineers or operators who have dealt with theproduct, they often are not involved in theproduct’s original selection. Upon returning totheir organizations, students are now betterequipped to understand the installed base bygoing through the questions and becomingfamiliar with their own situation. In terms ofreliability, they can look at worst performanceover time, perform a case study, identify com-

monalities of failure, and make correctionsthat improve their system’s reliability.

Flowserve seeks to establish long-term learn-ing alliances with companies so that skillimprovement doesn’t end once a student com-pletes the program. As in any profession, main-taining and upgrading skills are essential toremaining relevant, and profitable.

Positive return on investmentFlowserve looks at learning from a customer’sperspective, which is why students always comeaway with the skills needed to increase their com-pany’s competitive position. When an employeeis empowered to identify a glitch in his systemback at home, and implement a response to cor-rect the problem, the return on investment isnothing but positive. The LRC’s competency-based training includes instruction, implementa-tion and experimentation, ensuring thatstudents return to their organizations equippedto increase uptime, decrease equipment failures,and realize real dollar savings. The result isincreased earnings for the organization.

And because pump seals are a major portionof a plant’s maintenance budget, the potentialfor savings is significant. Avoiding seal prob-lems frees up labor, improves uptime, andeliminates contamination on the path, whichcan have costly environmental ramifications.

But for most companies, the real payoffcomes through a more focused eye on thefuture. Eliminating seal problems frees humanresources to address long-term strategies andmoves the organization away from working ina reactionary mode.

It’s all fostered by Flowserve’s belief that inorder to leap forward you first need to bestanding on solid ground.

For more information about the programs atFlowserve’s Learning Resource Center, pleasesend an E-mail inquiry to ESG@flowserve.com or through the company’s Web site at www.flowserve.com. Flowserve’s Educational ServicesGroup also can be reached at (800) 446-0401. ●

Face to Face www.flowserve.com 7

Lab equipment features a full array of instrumentation.