Face to Face Vol. 15, No. 2

PIPELINE POSSIBILITIES

Seals with laser machined wavy SiCfaces support uninterrupted flow of

crude oil and natural gas liquids

Vol. 15 No. 2

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

FaceToFace4.qxp 5/26/04 12:49 PM

Natural gas liquids (NGLs)and crude oil are pumpedin batch mode, so seal pres-

sure varies over a wide range andthe pumps are subjected to vigor-ous start/stop operation. The pres-ence of abrasive pipe rouge (ironfines) is a further complication.Mechanical seals were developedto perform in such demandingpipeline applications.

Flowserve engineers used state-of-the art technology to design sealsfor this difficult application, andverify seal performance in labora-tory tests. Mechanical seals incorpo-rating laser machined wavy siliconcarbide (SiC) faces have been run-ning in the field since September2000, with great success.

Pipeline pump stations arespaced about 30 to 40 miles apart.Each station uses three or fourpumps in series. One to fourpumps are active at the same time.The third or fourth pump experi-ences a wide range in suction(seal) pressure. To determine sealoperating conditions, the fourthpump at one station was moni-tored using instrumentation hard-wired to a computer in the stationcontrol room.

A modem was used to accessperformance in real time anddownload data. This information

PIPELINE POSSIBILITIES

Cover story

2 www.flowserve.com Face to Face

Mechanical seals equipped with wavy silicon carbidefaces make possible uninterrupted pipeline flow for

crude oil and natural gas liquids.


revealed that seal chamber pressure var-ied from about 150 psi to more than 1,300psi. In addition, the data showed seal pres-sure spikes of 350 psi (up or down) whena pump 1, 2 or 3 was turned on or off.

The dual mechanical seal arrange-ment consists of an HDHW primary sealthat handles full system pressure dropand a dry running GSL containment seal(see Figure 1). The primary seal isdesigned to handle NGL and crude oil atpressures as high as 1,500 psig. The con-tainment seal minimizes product releaseto the environment in the event of a pri-mary seal failure; it features a bi-direc-tional wavy lift-off face for long life andlow wear. This tandem seal arrangementwith a dry running secondary seal is easyto maintain, as it doesn’t require a liquidbuffer fluid support system.

Special analysis software was used todesign seal faces to handle the range ofoperating conditions. Seal faces distort(cone) as a result of pressure and thermalloading. To ensure long life and low leakrate, net face deflection coning must beless than about 1/400 the thickness of asheet of paper. The final seal design was

Face to Face www.flowserve.com 3

A mechanical seal incorporating laser machinedwavy silicon carbide faces can perform successfullyin demanding NGL/crude oil pipeline applications.

Laser Machining SolvesPipeline Problems Fast

The Flowserve-designed laser micro-machiningprocess has been used to solve other pipeline appli-cation problems.

Laser technology produces very uniform patterns,improves surface finish and allows more complexpatterns to be made and tested more quickly. “Thetime needed to move from pattern concept to proto-type is much shorter,” says Lionel Young, specializedtechnology manager at Flowserve’s Temecula, Calif.,facility. “Before, the process could take weeks. Nowwe can make new patterns within minutes.”

In a Canadian pipeline application that runs acrude oil/ethane batch, the seals endured abrasiveconditions and pressures ranging from 400 to 1,000psi. A special problem, however, was the specificgravity, which ranged widely from 0.85 to 0.44.“Ethane is hard to seal because it tends to go into agaseous form between the faces,” says Young.“When this happens, the pumped fluid no longerprovided lubricity.”

Laser machined waves on the stationary face ofthe Flowserve HDHW 5500 seal (which features sili-con carbide against silicon carbide) coupled with aGSL 5250 backup provided the solution. “Afterpulling out one set of seals after 5,000 hours ofoperation, the faces [were] in excellent condition,”says Young.

Multiphase pumping applications in Venezuela are a good example of where laser machined wavyfaces have helped solve a tough sealing condition.These applications pump crude oil directly from theground. The process temperature on the twin screwpump – 90 to 125 degrees F – wasn’t that bad, and the shaft speed was a low 900 rpm. But theproblem was the pressure, particularly the 750 psistart up pressure, compared to the steady-statepressure of 90 psi. The crude oil also is extremelyviscous, and it contains gas, water and sand, whichmakes it hard to pump and hard to seal. Lasermachined wavy faces solved the problem.

‘The time needed to move frompattern concept to prototype is

much shorter…. Now we can makenew patterns within minutes.’

Fig. 1 The dual mechanical seal arrangementconsists of an HDHW primary seal that handlesfull system pressure drop and a dry runningGSL containment seal.


computed to distort less than half that amountwhen operating on propane (NGL) at 1,200 psi.

Laboratory tests were conducted with theseals running on propane. Seals that per-formed well on the test stand were installed inthe field. Initial seals used conventional facematerials: a carbon face running against a sili-con carbide face. The original seals tended tohave limited life, particularly in the higherpressure pumps.

Improved lubricity and abrasion-resistantfaces were required. Using SiC against SiCfaces virtually eliminated wear from piperouge. Furthermore, SiC is about 15 timesstiffer than carbon and, thus, much less sensi-tive to pressure-induced distortions. Lasermicro-machining, a Flowserve innovation, wasused to manufacture a smooth wave pattern inone SiC face (see Figure 2).

The laser process allows complete control ofwaviness amplitude, seal dam location andnumber of waves. The wave pattern enhanceslubricity. Wave amplitude is small, on theorder of 2.5 to 10 microns, depending onoperating conditions. The radial taper aspectof the wave valley provides load support underany operating condition, while circumferen-tial waviness provides hydrodynamic load sup-port during shaft rotation. The seal dam resists

leakage and the wave pattern is resistant tocontamination. Other advantages to this wavyshape include bi-directionality, high fluid filmstiffness, long life and high reliability.

Laboratory tests on propane proved thatwavy SiC face seals could handle pressurespikes in excess of 400 psi and operating pres-sure to 1,300 psi. There was no measurableface wear in tests running as long as 140 hours.

The first two wavy SiC seals were installed inSeptember 2000. As of December 2003, wavyface SiC seals have been installed in 67 pumps(134 seals). Only four NGL primary sealsfailed with high leakage. Three had faces inexcellent condition (1,037, 2,149 and 4,276operating hours). The fourth failure had heav-ily damaged SiC faces (1,697 hours). Figure 2shows the excellent condition of the wavy facethat ran 4,276 hours. The cause of these fail-ures is undetermined.

Extensive analysis, laboratory testing andfield experience has shown that a mechanicalseal incorporating laser machined wavy siliconcarbide faces can perform successfully indemanding NGL/crude oil pipeline applica-tions. The wavy SiC seals are achieving signifi-cantly longer life compared to conventionalseals using non-featured faces of carbonagainst silicon carbide. r


The wavy SiC seals are achieving significantlylonger life compared to conventional seals using

non-featured faces of carbon against silicon carbide.

Fig. 2 Laser micro-machining, a Flowserveinnovation, was used to manufacture a smoothwave pattern in one silicon carbide face.

Cover story


Like the “embedded journalists” interested in get-ting the best possible story from the warfront,embedded engineers from Flowserve Flow

Solutions Division get up close and personal with cus-tomer pump systems in order to improve equipmentreliability. These on-site Application Engineers (AEs)are Flowserve employees who work exclusively for aspecific customer, such as Marathon AshlandPetroleum (MAP).

Flowserve did not have to look far to find an AE forthe MAP refinery in Robinson, Ill. Ted Stone knowsthe Robinson plant better than just about anyone--because he was a MAP employee for 32 years. Stonehad already been part of the MAP-Robinson SealImprovement Team and, after he retired, he joinedup with Flowserve.

MAP is a member of Flowserve’s Alliance Program,in which the two companies work toward a commongoal of reducing pump failures and improving equip-ment reliability at MAP refineries. MAP-Robinsonsigned its first five-year agreement with Flowserve inSeptember 1998, and another just last year.

“We’re like one of their employees,” explainsFlowserve District Sales Manager Brian Bradley. “It’sa team. We’re all part of the same team.”

Although all seven MAP refineries participate infixed-fee contracts, the arrangement works particu-larly well at the Robinson facility, which is far fromany major highway or Flowserve QRC facility.

The centerpiece of the alliance is the embeddedon-site AE. They are tasked with executing theAlliance and managing the overall program on adaily basis. This includes performing a review of allfailed equipment and suggesting solutions that helpimprove overall reliability. Rather than MAP havingto call for services every time something breaks down,the on-site application engineer can make equip-ment upgrades quickly. This helps keep the costsfor such maintenance consistent – no budget sur-prises, and no delays for funding to be approved.

“With the agreement, we are not concerned asmuch about trying to justify upgrades as they comealong,” says Kent Paschen, who has worked closelywith Flowserve as a member of MAP-Robinson’sReliability Department since 2000. Paschen says the

agreement eliminates the need for MAP to spendtime on assessment each time an engineer requestsan equipment upgrade.

The Alliance Program also facilitates continuousquality improvement through regular monitoring ofequipment performance. “It’s a continuing, ongoingproject,” Stone says. “You look at every aspect of thepump and try to make it work better.” In addition toStone, the MAP-Robinson Seal Improvement Teamconsists of the plant’s craft supervisor, reliabilitysupervisor, machine shop foreman, a rotating equip-ment engineer and someone from the purchasingside of the business. The group meets monthly to dis-cuss the concerns of each department and shareadvice on improving plant operations.

Flowserve’s equipment database, Flowstar.net, isalso used by MAP-Robinson. Flowstar.net keeps an

inventory of all pumps in the program and a recordof past equipment failures so engineers can avoid thesame problems in the future.

Stone raves about the operator training coursedeveloped by the Seal Improvement Team — includ-ing an online version created by Paschen. The courseshows MAP technicians the proper ways to operateand maintain equipment.

At MAP-Robinson, the teamwork that arises fromthe Alliance program has led to an improvement inMTBF from 24 to 70 months in five years. This resultsin an annual savings of over $1.4 million dollars toMAP-Robinson. While all customers may not achievesuch tremendous results so quickly or enjoy suchextensive, site-specific experience from a Flowserveon-site engineer like Stone, they can expect the samelevel of attention, cost-savings and continuousimprovement from every Flowserve AE as part ofFlowserve’s Alliance program. r


The Benefits of theEMBEDDED ENGINEERFlowserve’s Alliance Program supports the MarathonAshland Petroleum refinery to reduce pump failures andimprove equipment reliability.

Services

‘You look at every aspect of the pump and try to make it work better.’ – Ted Stone


Every two years in Dortmund, Germany,Flowserve's Flow Solutions Division customers attend a Technical Forum

to learn about the latest technical advances. In Spring 2004, the Technical Forum coincidedwith the re-opening of the FSD test lab, whichadded additional compressor seal test capability.

Key European customers toured the facility inwhich offices were moved to create a customermonitoring area. Test data streamed live ontoLCD monitors in a quiet room away from thetesters that kept customers safe from test pres-sures up to 450 bar (6,500 psi).

Flowserve FSD President Andy Beall, who wasin Dortmund for the grand re-opening, said,"This state-of-the-art test facility in Dortmund isyet another example of our commitment to pro-viding our customers with excellent capabilityand service."

During the forum presentations, the CircpacLO was introduced. As the newest solution forreducing nitrogen consumption as a separationseal in compressors, this carbon ring seal is in

contact with the shaft during static conditions,but lifts once the shaft starts to rotate. Thisallows for low leakage rates both statically anddynamically, and eliminates carbon wear andcontamination from the rings. r

A correctly specified seal support system contributes significantly tothe durability and correct function

of pumping systems. Seal support systemsprovide fluid at the right temperature and pressure to keep the mechanical sealproperly lubricated. This helps achievemaximum safety and maximum useful lifewith minimum leakage.

Flowserve Flow Solutions has standardAPI plan 52 or plan 53A reservoirs in stockand ready for fast delivery. These reservoirssatisfy the API 682 guidelines and aredesigned to ASME VIII div 1 standards, inaccordance with the Pressure EquipmentDirective (P.E.D.).

GRAND RE-OPENING OF

News

GERMAN TEST LAB

FAST DELIVERY FORSTANDARDRESERVOIRS


European customers recently attended presentations at Flowserve FSD's biennual

Technical Forum in Dortmund, Germany,(above right), and toured the test lab (above),

which added additional compressor seal test capability.


Both the first and second edition of API 682contain clear design guidelines for reservoirsthat are to be used for API plan 52 or 53A configurations. API plan 52 calls for the use ofbuffer fluids for “dual unpressurized seals.” Inthis design, an unpressurized buffer fluid inthe reservoir acts as a receptacle for primaryseal leakage. For volatile liquids, any leakageevaporates and is vented through an orifice ina controlled fashion. For non volatile liquids,the primary seal leakage is dissolved into the buffer fluid, which needs to be replacedperiodically.

API plan 53A calls for “dual pressurizedseals,” in which a pressurized barrier fluid fillsthe cavity between the two seals. Because thepressure in the barrier system is higher thanthe seal chamber pressure, pump product is prevented from leaking to the atmosphere.

Connections are present on the FlowserveFlow Solutions reservoirs for the most commonly used components, such as levelswitches, pressure switches and pressuregauges. Both Flowserve standard componentsand customer-specific components can besupplied. The standard specification includesa cooling water element, so an extra cooler isnot normally required. r

F lowserve BV, Flow Solutions Division,has signed an agreement to distributein Europe high-quality thermoplastic

pump components from Greene, Tweed &Co. The five-year agreement covers GreeneTweed’s WR® and AR™ materials.

The WR material, which consists of long-carbon-fiber-reinforced thermoplastic com-posite, is intended for use in rings, bushings,

seals and wear plates in a variety of pumpsused in the refining, chemical and petro-chemical industries. It is an alternative formetal, carbon and graphite pump elements.

WR material has very high resistance towear and good self-lubricating propertiesunder almost all circumstances. It also has alow coefficient of expansion, so that it is pos-sible to work with much smaller tolerances. It reduces internal leakages losses, whichresults in increased pump efficiency andreduced vibrations.

The AR material is a composite speciallydeveloped for bushings, bearings and wearrings in pumps moving abrasive and erosivesubstances. The material is also highly resist-ant to thermal shock and very impact-resist-ant. This makes it a good alternative to traditional rubber and bronze material.

Ben van Eyndhoven, director of EMA salesfor Flowserve Flow Solutions, says, “We haveextensively tested the WR and AR materialsfrom Greene Tweed and these tests con-firmed what we believed. Pumps run moreefficiently when these high-quality compositepump elements are used. This is good news for our clients in the chemical andpetrochemical industries."

Says Robert van de Velde, general managerof Greene, Tweed & Co. HoldingsInternational BV, “We are very pleased withthe deal with Flowserve. Worldwide, the company has a great reputation in the field ofproducing and maintaining mechanical sealsfor pumps in the process industry. Our WRand AR materials fit well with the high qualityproducts and service offered by Flowserve.”

Greene, Tweed & Co. Benelux BV, based inHalsteren, in the Netherlands, is a subsidiaryof Greene, Tweed & Co., Kulpsville, Pa. r


WR, AR MATERIALSDISTRIBUTIONAGREEMENT

API Plan 52 and Plan53A ReservoirsDesign pressure: dependent on temperature, from58 to 77 Barg (840 to 1117 psig)Total volume: 27 liters / 7 gallonsNormal working volume:6.4 liters / 1.7 gallonsMaterial: stainless steel AISI 316LConnections: 3/4" 600# flangesMore information: www.flowserve.com/seals

Wear on the bushings is negligible whenusing WR300 material.

FaceToFace4.qxp 6/3/04 9:04 AM

The Flowserve

Piping Plan Flip Book

Get yours FREE by visiting

www.fl owserve.com/seals/fl ipbook

a durable, compact reference book provides concise summaries of the essential piping plans used successfully in today’s process plants

Piping Plan Flip Book

Get yours FREE by visiting

www.fl owserve.com/seals/fl ipbook

a durable, compact reference book provides concise summaries of the essential piping plans used successfully in today’s process plants

For each piping plan identified in API Standard 682 2nd editio

n and recommended by

Flowserve, each page set of this book shows:

Seal End View

Piping Plan Layout

What, Why, a

nd Where

Pump Cross-section

Mechanical Seal

outlet

inlet

pressure source,

normally openpressure gage

pressure switch

level switch (high)

level switch (low)

cooling incooling coils

drain,

normally closed

level gage

cooling out

reservoirliquid fill,

normally closed

Flow Solutions Division

What

• Pressurized barrier flu

id circulation through reservoir.

• Fluid is circulated by a pumping ring in the dual seal assembly.

Why

• Isolate process fluid.

• Zero process emissions.

Where

• Used with dual pressurized seals (Arrangement 3 or “d

ouble”).

• High vapor pressure fluids, lig

ht hydrocarbons.

• Hazardous/toxic fluids.

• Heat transfer flu

ids.

• Dirty/abrasive or polymerizing flu

ids.

• Mixers/agitators and vacuum service.

Presventative Maintenance - Reference Appendix A

• Piping loop must self-vent to

reservoir locate at highest elevation.

• Reservoir must be pressurized at all tim

es - typically gas charge up to 200 psi (1

4bar).

• Barrier flu

id must be compatible with process.

• Reservoir level gage indicates both inboard and outboard seal le

akage.

Plan

53A

Plan

53A

seal

end view

Preventative Maintenance

• Viewed from drive end

• Shows preferred gland

connection orientation

• Illustrated schematic

of auxiliary components

• Describes piping plans,

their purpose, and

typical applications

• Simplified centrifu

gal

pump shown for all

plans

• Shows typical seal

arrangements

• Provides general tips to

improve reliability and for

troubleshooting

Argentina, Buenos AiresPhone 54-11-4709-6800

Australia, Marayong, NSWPhone 61-2-8822-7100

Austria, SieghartskirchenPhone (43) 2274-6991

Belgium, AntwerpenPhone (32) 3-5460450

Brazil, Sao PauloPhone 55-11-4231-6300

Canada, Edmonton, ALPhone 780-464-1188

Denmark, AllerødPhone (45) 48 176500

Flowserve Flow Solutions Primary ContactsFrance, CourtaboeufPhone (33) 1-69592400

Germany, DortmundPhone (49) 231-6964-0

Italy, Cormano (Milano)Phone (39) 02-61558.1

Japan, OsakaPhone 81-72-885-5571

The Netherlands, RoosendaalPhone (31) 165-581400

Mexico, TlaxcalaPhone 52-2-461-6791

Poland, WarszawaPhone (48) 22-844-7108

Russia, MoscowPhone (7) 095-777 717

Saudi Arabia, Al KhobarPhone (966) 3-857-3150

SingaporePhone 65-6-8465100

Spain, TarragonaPhone (34) 977-544400

Switzerland, OensingenPhone (41) 62-3883088

United Arab Emirates, Abu DhabiPhone (971) 2-317141

United Kingdom, ManchesterPhone (44) 161-8691200

United States, Kalamazoo, MIPhone 269-226-3927

The best little reference guide in the business

© 2004 Flowserve Corporation

Face to Face Vol. 15, No. 2

Documents

Transcript of Face to Face Vol. 15, No. 2