Pulp and Paper Kynar Pipes and Vessels

8/13/2019 Pulp and Paper Kynar Pipes and Vessels

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KYNAR Spotlight Vol 17 No 1

SPECIAL ISSUE PULP & PAPER

Features:

LONG WIRE LIFE TO BECOME EVEN LONGER AFTER CHRESTBROOK

OPTIMIZATION PROGRAM.HIGH-TECHNOLOGY ALABAMA RIVER MILL STANDARDIZES FACE WIRES MADE

FROM KYNARPVDF.GROWING AFFAIR WITH COMPONENTS MADE FROM KYNAR PVDF IN BLEACHPLANT AT FINCH, PRUYN MILL.ST. REGIS REDUCES DOWNTIME WITH SWITCH TO FACE WIRE AND PIPING MADEFROM KYNAR PVDF.KYNAR FLUOROPLASTIC: THE SOLUTION FOR CORROSION AT JAMES RIVERMILL.FIFTEEN YEARS IN A SWEDISH PAPERMILL NOT A LONG TIME FOR LINED PIPEMADE FROM KYNAR PVDF.STEADILY EXPANDING ROLE FOR KYNAR PVDF AT BOISE CASCADE'S PAPER

PLANT IN RUMFORD, MAINE.

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LONG WIRE LIFE TO BECOME EVEN LONGER AFTER CRESTBROOK OPTIMIZATION

PROGRAM

A major $20 million optimization program, now underway at the Skookumchuck Pulp Division ofCrestbrook Forest Industries Ltd., will reduce operating costs significantly through reductions inconsumption of energy, chemicals, and other materials while increasing fiber utilization andimproving product quality and cleanliness.

The capacity of the plant, located 35 miles above Cranbrook in British Columbia, will also be

increased 15% to the level of 560 air-dried tons a day of bleached kraft pulp.

One side benefit of the program will likely be an extension of the already exceptionally longservice life Crestbrook Forest Industries (CFI) is getting from its bleach washer drum covers made

from KYNARPVDF.

The Skookumchuck mill has been using wire made from KYNAR resin on all its bleach washerdrums since the present 5-stage bleach line went into operation in 1977 and has converted frompolypropylene to KYNAR PVDF on its brown and bleach deckers for complete standardization.They're supplied by the Barrday Division of Wheelabrator Corp. of Canada Ltd.

Al Manjak, production superintendent, says he has been getting up to three years of life fromKYNAR PVDF on the chlorination stage and up to five years or more on the chlorine dioxide

drums. In August of 1985, for example, the covers (made from KYNAR PVDF) on the twodioxide stages had been in place for approximately 5 years each; and the second extraction wirehad been running since it was put on in 1977.

Ironically, this good service comes under less than ideal operating conditions, according toManjak. The existing wire-cleaning shower system no longer provides adequate pressure to clearthe buildup of pitch, talc, and stock which can blind the wires on these vacuum-filter drums. Theresulting loss of drainage capacity can shorten wire life as well as boost chemical costs through

Technical Polymers: CPI Spotlight http://www.arkema-inc.com/literature/cpi-spotlight-17-1

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reduced washing efficiency.

To remedy this, a new high-pressure, oscillating-head shower system for cleaning bleach plantwires is being installed at a cost of $115,000 as part of the optimization program. "It shouldsubstantially increase the very good wire life we're now getting," according to Manjak.

The drums on Skookumchuck's bleach washers are not designed for D-wire or winding wire.When the bleach plant started up in 1977, this resulted in too much fabric movement and the

cutting of fabric. To overcome this, Barrday designed a 10-mesh backing fabric - face wire madefrom KYNAR resin - that is shrunk onto the drum before the facing fabric is installed.

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HIGH-TECHNOLOGY ALABAMA RIVER MILL STANDARDIZES ON FACE WIRES MADE

FROM KYNAR

PVDF

The Alabama River Pulp Company in Clairbore, Alabama, was designed to serve the internationalmarkets of Western Europe, Japan, and U.S. specialty paper mills. The latest technologies andsuperior processing equipment were specified to ensure a high level of cleanliness and brightnessfor the bleached kraft pulp.

The 5-stage bleach plant (D/C-E-D-E-D) exposes an average 1,100 tons a day of brown stock toa series of chemical treatments that transform the natural brown fibers into a high brightness pulp.

Face wire made from KYNAR PVDF has been used for the cylinder covers on all five stagesever since the bleach plant went into full operation at the beginning of 1979. This face wire wasalready industry state-of-the-art when the plant was built; everybody was using it by that time,explains Tom Tippy, mill manager.

"We already had favorable experience with covers made from KYNAR PVDF in our plant in NewBrunswick, Canada," he adds. "And it's since proven to be the best material for the job here."

Despite a pH range of 2 to 10.8 on the bleach line, the mill is getting up to one year's life out of

the PVDF wire supplied by National Wire Fabric Corporation, Star City, Arkansas. "When we dolose a wire," says Jim Calloway, pulp mill superintendent, "it's usually the result of something else,and a strip patch remedies the situation. We've hardly ever been shut down because of KYNARPVDF material failure."

In addition to longer service life in these highly corrosive conditions, the face wires are muchlighter and easier to install than stainless steel covers. The mill can change a cover in 4 hourscompared to the 8 to 10 hours it takes to change the stainless steel wire on its brown stockwasher, the one drum in the mill not using wire made from KYNAR PVDF.

Today, National Wire supplies the covers made from KYNAR PVDF not only to the 5-stagebleach washer line but also for the brown decker and two bleach deckers. All are 30' wide by 13'diameter drums of split design. Two 15' wires made from KYNAR PVDF are used to cover each

cylinder. Alabama River has standardized on KYNAR fluoropolymer for all these reasons: (1) tosimplify inventory, (2) to prevent accidental error in wire selection, and (3) because its use ofrecycled filtrate calls for higher corrosion resistance even on the extraction stages of the bleachline.

PIPING LINED WITH KYNAR PVDF FOR ClO2WET Cl2

Lined piping has been at work here since startup of operations. Approximately 1000' of carbonsteel pipe (lined with KYNAR PVDF) supplied by Dow Chemical - most of it 3" to 6" in diameter -


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moves 20 to 30 tons a day of chlorine dioxide from the chemical prep area to the bleach plant.

Piping lined with KYNAR PVDF is also employed in the ClO2generating plant and in the mill'swet chlorine lines.

"We find that KYNAR fluoropolymers work better on a cost-performance basis in theseapplications than stainless steel, in lined FRP, or CPVC (SARAN)-lined systems," says DonAckerman, maintenance manager.

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GROWING AFFAIR WITH COMPONENTS MADE FROM KYNAR

PVDF IN BLEACH PLANT

AT FINCH, PRUYN MILL

Over the past five years, Finch, Pruyn & Co., Inc., in Glens Falls, N.Y., has had increasingexperience with a variety of different fluid handling system components made from KYNARfluoropolymers.

This includes both solid and lined piping, vessel linings, filter covers and winding wire, and mostrecently the complete resurfacing of a worn bleach washer drum.

The net result has been a steadily increasing reliance on ATOFINA's polyvinylidene fluoridematerial throughout the bleach plant.

In the Hypochlorite System

The sodium hypochlorite generating plant is a good example.Finch, Pruyn produces NaOCI by combining dry chlorine gas witha mixture of caustic in water. From this point on, just about all ofthe hypochlorite fluid handling system is protected with KYNARPVDF resin.

Pipe lined with KYNAR resin was first introduced into thehypochlorite system around 1977 as a replacement for CPVC when Finch, Pruyn initiated its longrange program of upgrading and expanding capacity. Today, hundreds of feet of Resistoflex steelpiping lined with KYNAR PVDF resin - in diameter sizes from 1 !" to 4" - now carry thiscorrosive bleaching agent all the way from point of production up to the bleaching floor. Theresolid 2" piping made from KYNAR PVDF takes over, including a 16' long perforated shower linethat sprays the NaOCI into the pulp on the discharge side of the preceding caustic stage.

The sodium hypochlorite is at a concentration of 30 g/l of Cl 2at 100F and has a pH of 12.Evidence of its corrosiveness is the fact that the three centrifugal pumps in the system (forrecirculation and delivery, plus a backup) are all made of titanium.

The hypochlorite facility also includes three vessels lined with KYNAR fluoropolymer. Two900-gallon FRP tanks supplied by Ceilcote - each 5' in diameter by 8 !' high - are lined with 1/4"

thick glassbacked laminate made from KYNAR PVDF. One serves as the recirculating ormake-up tank in the system, the other as the NaOCI delivery tank.

These vessels had been lined with a variety of materials in the past, most recently withpolypropylene. The polypro on average gave about 10 months of service, according to SteveEliot, project engineer in charge of the new hypo plant. He expects four times that life from thelining, which is made from KYNAR PVDF and which has already been in service for 16 monthswithout any signs of deterioration.


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The third lined vessel supplied by Bee Fiberglass is an instrument pot that serves as an end-pointcontroller for chlorine flow by monitoring the residual Cl2in the system.

In the Chlorine Supply System

The earliest use of piping made from KYNAR PVDF at the Glens Falls plant was probably in thechlorine supply system where it replaced polypropylene lines.

Finch, Pruyn pumps dry chlorine under pressure from tank cars and moves it through thick-walledsteel piping until the point where the Cl2is vaporized with steam. From that point on steel pipelined with KYNAR fluoropolymer takes over in handling the corrosive Cl2gas. The Cl2is injectedthough a perforated nozzle (also made from KYNAR PVDF) into a static mixer for combinationwith the brown stock pulp.

On Bleach and Brown Stock Washer Drums

Finch, Pruyn produces an ammonium sulfite-based pulp suitable for the production of its fineprinting papers in the adjacent paper mill. Present bleached pulp capacity is 350 tons a day andgrowing. A three-stage bleaching process is used: chlorine, caustic (NaOH), and hypochlorite.There are two bleach washers in the final hypo stage. The process bleaches to an 84 brightness(GE standard).

Face wires and winding wires (made from KYNARPVDF) supplied by Barrday are now the firstchoice on all three stages (four washer drums) as well as on the thickener stage and two brownstock washers that precede the bleaching phase.

The first cylinder cover made from KYNAR PVDF was introduced about 5-6 years ago on thechlorine (first) bleaching stage. It replaced polypropylene and gave a full three years or more ofservice in the severe 140-150F wet chlorine (pH 2) environment. Face wires made fromKYNAR resin have since been put on the two hypo stage washer drums and will now also beused on the caustic (NaOH) stage once Finch, Pruyn has used up the stainless steel wires still ininventory.

Innovative Washer Drum Restoration

Latest role here for ATOFINA's versatile polyvinylidene fluoride has been as the protectiveoutercoat for a completely resurfaced chlorine stage bleach washer drum. The heavily pitted andcorroded stainless steel cylinder - measuring 8' in diameter by 16' long - was completelyrenovated in a new procedure developed by the Impco Division of Ingersoll-Rand in conjunctionwith El-Chem Construction Company, Ltd., Canada.

The process involves restoration of the mechanical integrity of the drum, and then virtualencapsulation of all exposed surfaces in polyvinylidene fluoride. Three different forms of KYNARfluoropolymers are involved: dispersion coating, wet of dry laminate, and solid extrusions forcapping of the cylinder grids.

The restored drum cost Finch, Pruyn several hundred thousand dollars less than the purchase ofa brand new unit, yet should last almost as long. It's on standby now, waiting to replace the nextcylinder that has to be pulled.

The bleach plant previously had several other drums resurfaced with fiberglass-reinforced plastic.These have given good service, according to Dick Dingman, maintenance coordinator. Reportsfrom other mills of failures due to peeling off of the FRP, however, prompted Finch, Pruyn toswitch to the KYNAR PVDF system.


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"The drum lined with KYNAR PVDF can be used on any stage in the plant - either in bleachingor brown stack washing," says Dingman, "and temperature won't bother it."

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ST. REGIS REDUCES DOWNTIME WITH SWITCH TO FACE WIRE AND PIPING MADE FROM

KYNAR

PVDF

The Pensacola, Florida, mill of St. Regis Paper Company, the largestcomplex of the 136 operated by the company in 10 countries, took a chanceon KYNAR polyvinylidene fluoride five years ago. Today, thisfluoropolymer is used extensively in the firm's bleach plant and chemicalrecovery operation.

The 800-acre St. Regis Kraft Center, located 15 miles north of Pensacola, isa sprawling complex where 1,800 employers produce 900 tons of kraftpaper and a million multi-wall bags each day.

The kraft paper is used for shipping sacks, linerboard, drinking cups, cartonand sanitary food wraps, and pulp for disposable diapers. This production requires an extensive

and corrosive bleaching operation, and it was into this bleaching operation that KYNAR PVDFwas first introduced in 1974.

While officials at St. Regis now consider KYNAR PVDF valuable in their operations, it tookspecial circumstances for the highly corrosion-resistant material to get a foothold in the bleachplant.

In the late fall of 1974, St. Regis was completely replacing a washer drum - the chlorine stage andfirst washer in the C-E-H-D-E-H bleaching sequence.

While the chlorine washer was down, St. Regis officials had a choice of putting the usual 317stainless steel face wire and backing wire on the drum or replacing it with wire made fromKYNAR PVDF, which had never been used at St. Regis. In the words of St. Regis Pulp Mill

Superintendent Fred Bond, the company decided to "take a fling" with KYNAR fluoropolymer.

"It was strictly a case of taking a calculated risk because it was the first time any of the St. Regisplants had used KYNAR PVDF," Bond reports. The main reason officials opted for the KYNARresin, Bond recalls, was its reputation for quick installation.

It usually took almost a full day to replace the stainless steel face wireand tacking wire on a washer drum, but the time was considerablyshortened by using KYNAR PVDF.

"The maintenance men were ready to put the KYNAR PVDF on about 9p.m., and they were cleaned up and out of the area by shortly aftermidnight. It saved us almost a full day's time," Bond says.

The original wire made from KYNAR resin, installed in the fall of 1974,was not replaced until March of 1977. Its replacement lasted until July1978 and was replaced then only because of another malfunction in thewasher and not due to corrosion. The third generation of face and backing wire made fromKYNAR fluoropolymer on that particular washer is still in service.

Wire coated with KYNAR PVDF was installed on a second washer (chlorine dioxide) in June1975. It lasted until May 1978, and its replacement is still on the washer. This performance was


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extremely impressive to St. Regis officials since the face wire had lasted almost three yearsdespite subjection to a ClO2solution with a pH level of 2 and temperatures of 150 F.

KYNAR PVDF was installed on a third washer (the first sodium hypochlorite stage) in April 1978and that wire is still in operation. It was also installed on a fourth washer drum (the secondhypochlorite stage) later on.

While wires made from KYNAR PVDF have served the bleach plant operation well, solid and

lined PVDF pipes have also been used at St. Regis with good success.

There are several hundred feet of pipe lined with KYNAR PVDF, supplied by Dow Plastic LinedPiping Products, which carry chlorine throughout the bleach plant. The mill had previously usedPVC piping, but KYNAR resin has proved to be tougher in resisting the chlorine which has a pHof 3.5 .

There is also some 60 to 80 feet of solid pipe made from KYNAR PVDF in the by-products plantat St. Regis. The tall oil plant takes black liquor soap, a by-product of the kraft cooking process,and produces a liquid known as "tall oil." The "tall oil" is sold as a basic ingredient for perfume andsoap.

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KYNAR

FLUOROPLASTIC: THE SOLUTION FOR CORROSION AT JAMES RIVER MILL

The chlorine dioxide spent acid line is no longer a problem line at the Naheola Pulp Mill of JamesRiver Corporation. Eight years ago, however, high temperatures in the sulfuric acid streamcontaining chlorine and chlorine dioxide traces necessitated frequent replacement of failedsections of the CPVC-lined steel piping.

Normal operating temperature of the highly corrosive (pH=1) spent acid was 43C. The problemwas further complicated with the addition of insulation and steam heat tracing to preventfreeze-ups during the especially severe winters of the early 70s.

The original CPVC lining material in these 2-inch diameter lines just couldn't take the high and lowtemperature extremes.

Beginning in 1974, plant maintenance started replacing failed sections with steel pipe lined withKYNAR PVDF, which was supplied by Dow Chemical USA, and soon converted the entire600-foot system. In the intervening eight years, according to William Irby, mill technicalsuperintendent, "We only had to replace one or two small pieces of the entire 600-foot run."

Situated on the west bank of the Tombigee River, near Pennington, Alabama, the 1000 ton-a-dayNeheola Mill (until 1982 a part of American Can) produces pulp, paper, paperboard, and a widevariety of finished paper products. The latter includes a broad range of nationally known qualityhousehold and service paper towels, tissues, and napkins.

The favorable introduction of ATOFINA's fluoropolymer soon led to a similar conversion of the wetsection of the plant's chlorine gas lines with similar success.

KYNAR fluoropolymer has since also established itself as the face wire of first choice on thebleach washer drums of both the hardwood and pine bleaching lines. These filter cylinder coversare woven of monofilament (made from KYNAR PVDF) by the National Wire Company of LittleRock, Arkansas, and give up to double the life of the stainless steel face wires they replaced.

The superior performance is most notable on the chlorine and chlorine dioxide stages where the


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face wire is consistently providing 2-3 years of trouble-free service. The stainless filter coverslasted about 1-1 !years before in this service, according to Oscar Spencer, pulp mill areasupervisor.

There's another significant benefit to face wire made from KYNAR PVDF, according to Spencer.It can be applied in about half the time it took to install the stainless steel wires. "It takes about 8hours for the sleeves, compared to about 16 hours for stainless," says Spencer. "Anytime we caneliminate eight hours of downtime in this high productivity mill, we're mighty happy," he added.

Today, components made from KYNAR PVDF are being used at the Naheola Mill everywherethere's an appropriate application. As process engineer Dale Smith claims, "Initially, we only usedthe lined piping on the pineline, but we recently switched over on the hardwood line too."

"ATOFINA's fluoropolymer has played a welcome role in helping keep this facility operating fulltime," adds Smith. "Over 30 railroad carloads of consumer products are scheduled to leave hereevery day. At this end of the line our responsibility is to keep bleached pulp moving to ourmanufacturing plant, and components made from KYNAR PVDF are making a constantcontribution to that effort.

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FIFTEEN YEARS IN A SWEDISH PAPERMILL NOT A LONG TIME FOR PIPE LINED WITH

KYNAR

PVDF

Jan berg, of BTR Industries AB in Sweden, has an interestingpaperweight on his desk at the company offices in Halmstad. It's a ninety-degree elbow in two-inch pipe lined with KYNAR PVDF, and it camefrom the first installation of such pipe sold in Sweden.

The pipe came from a papermill operated by AB lggesunds Bruk atStrmsbruk where it carried the chlorine used in the bleaching process forcellulose. Between the time that Jan berg sold the pipe and the time itcame back to rest on his desk, it was carrying a high-corrosive chlorine and water mixture at 35C

- 24 hours a day, seven days a week - for 15 years with no downtime for repairs throughout theperiod.

When piping made from KYNAR fluoropolymer first became available in Sweden in 1967, one ofthe first applications to be considered was for bleaching plants. Using normal materials, evenexotic alloys, bleaching plant pipework had a life expectancy which was measured in months orweeks rather than years. The corrosion-resistance of the KYNAR PVDF promised much betterperformance, but papermill engineers were skeptical.

The first test of this lined pipe in a bleaching plant was on an experimental basis a the MorrumsBruk plant of Sodra Skogsagarna AB, Sweden's second largest forestry company. With theexperiment successful, the first sale of pipe was to AB Iggesunds Bruk for its cellulose factory atStrmsbruk.

Walter Tegenfelder of the Strmsbruk engineering and safety department was skeptical about thequality of pipe made from KYNAR resin and made provision in the designs for a secondduplicate steel pipeline to run alongside the new line. He was worried that there was a longsection of the line which ran in an exposed position outside the building; and with nighttimetemperatures which can drop to well below -20C, he anticipated problems.

He was even more worried when he found that the length of pipe required would need no less


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than eight joints along its length, each of which would have no extra gaskets or seals and wouldrely on butt-joints between the flanges (also made from KYNAR PVDF) of each section held inplace by bolts tightened to pre-set torque limits. "I was sure it wouldn't work," he says now, "and Iwas convinced we would need that duplicate pipeline."

That was at the end of 1967. In 1982, Iggesunds Bruk undertook a reorganization. Its celluloseplant, which has specialized in the production of raw material for photographic paper, was to betransferred to another location; and the bleaching plant was taken out of commission. Thechlorine pipeline lined with KYNAR PVDF was still there and so was the reserve steel line.

The reserve, however had never been used. In almost fifteen years of continuous use, the linedinstallation had never had to be closed down apart from normal maintenance. When the two lineswere cut by the demolition gangs, the interior of the unused steel duplicate pipeline was in worsecondition than its KYNAR PVDF-lined neighbor which had spent its lifetime carrying the chlorineand water mixture! There was no evidence whatsoever of the chlorine permeating the liner madefrom KYNAR PVDF and attacking the steel casing.

In anticipation of the leaks which he was sure would come, Walter Tegenfelder also laid in aselection of spare lengths of pipe lined with KYNAR PVDF for replacement purposes. Fifteenyears later, the pipes still lie in the engineering stores, unused. In all the time that the plant was

operating, no replacements were made at all!Since the first sale of pipe for the bleaching plant, pipe lined with KYNAR PVDF has found aready acceptance on the Swedish market. Chlorine is one of the most dangerous substances ingeneral industrial use. The need for secure systems for carrying the chlorine is obvious, and thefact that piping made from KYNAR fluoropolymer has received approval from the Swedish safetystandards authorities has made its use even more acceptable.

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STEADILY EXPANDING ROLE FOR KYNAR

PVDF AT BOISE CASCADE'S PAPER PLANT IN

RUMFORD, MAINE

Seventeen years of uninterrupted service with PVDF-lined pipe carryingwet chlorine gas have proven the durability and toughness of KYNARPVDF and led many other corrosion-resistant applications at BoiseCascade's Rumford paper plant.

Since its first cook of soda pulp on November 9, 1901, Boise Cascade'sRumford, Maine, plant, long known as the Oxford Paper Company, hasgrown to the point where today it produces 1,650 tons per day at its siteon a bend in the Androscoggin River.

Boise Cascade acquired the plant in 1976. Today, the mill produces coated and uncoated stockfor book publishers as well as magazines such as NATIONAL GEOGRAPHIC, VOGUE,COSMOPOLITAN, and TV GUIDE.

Many different factors are responsible for the success of the Boise Cascade plant, and one ofthem is due to KYNARpolyvinylidene fluoride.

Use of KYNAR PVDF began at the Rumford plant in 1963, then under the ownership of OxfordPaper Company. Plant officials, impressed with similar KYNAR PVDF applications, ordered 200feet of two-inch piping lined with KYNAR resin and installed it to transport wet chlorine gas. "Thepipes have been in place for nearly 17 years and have not required any significant repairs,"


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reports Mel Aylward, plant superintendent. Aylward recalls that the polyvinylidene chloride pipesused prior to 1963 had to be replaced on the average of every six to eight months.

Since that time, the use of KYNAR fluoropolymer has been multiplied many times. Today, pipelined with KYNAR PVDF is used extensively throughout the bleach plant; and face wire alsomade from KYNAR PVDF is in service on all eight washer drums in the bleach plant.

There are more than 900 feet of two-inch pipe lined with KYNAR resin carrying chlorine dioxide

at temperatures of 100F and higher throughout the bleach plant.

This lined pipe (in 4-inch, 2-inch, and 1-inch diameters) also carries several different corrosivesolutions, including 60% sulfuric acid, 46% sodium chlorate solutions, and pure methanol. Thispiping has been in place on these applications since 1976 without the need for repairs.

This lined pipe is also used in the new chlorine unloading system at Rumford. Less than a yearafter the system went on line, sections of FRP-lined pipe exposed to wet chlorine failed. Now, pipelined with KYNAR PVDF is installed whenever wet chlorine may be present.

Boise Cascade obtains more than 95% of its pipe lined with KYNAR fluoropolymer fromResistoflex Corporation and Dow Chemical Company.

Piping is not the only application where KYNAR PVDF has paid dividends at this plant. One ofthe most interesting uses of PVDF at Boise Cascade was as packing in sodium hypochloritemanufacturing tower. Several types of packing were tried; but KYNAR resin was the onlysubstance that stood up to the sodium hypchlorite solution, which averaged 40 grams per liter at100F.

In fact, KYNAR PVDF was also used to coat the tower walls because the FRP lining repeatedlyfailed after only approximately six months of service. Ceilkote, Inc., which supplied the towerpacking, laminated sheets made from KYNAR PVDF to the tower walls. This constructionperformed without problems for 18 months until the process was discontinued.

"It's too bad we don't know what to do with the KYNAR PVDF in the old tower," says Aylward,"It's as good as the day we put it in."

KYNAR PVDF is also taking over a greater responsibility for corrosion control in the bleachingsystem at Boise Cascade. The first face wires made from KYNAR fluoropolymer were installedon two washer drums six years ago. The initial face wire installed on the sodium hypochloritedrum at that time is still in service.

Now, all eight washers in the bleach plant (chlorine, sodium hypochlorite, chlorine dioxide, andcaustic extractions with temperatures to 158F) have face wires made from KYNAR PVDFsupplied by Barrday. Each wire lasts an average of four years, according to the plantsuperintendent. This is two to four times as long as the 317 stainless steel wires which were usedpreviously.

The wires made from KYNAR PVDF are also much easier to install. "It takes only about a

quarter of the time to replace these face wires, and less downtime means more money in thebank," Aylward says. At Boise Cascade, face wires made from KYNAR resin can be replaced inas little as four hours. Stainless steel wires had taken as long as 16 to 20 hours to change.

Given the wide range of successes at Boise Cascade, it is no wonder plant officials have come torely on KYNAR polyvinylidene fluoride for many of their corrosion problems.

"We're big KYNAR PVDF fans up here," says Aylwar, "because it works."


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