Kynar® Polyvinylidene Fluoride (PVDF) A History of Performance
Kynar® Fluoropolymer for Chemical Processing
Kynar® PVDF Linings Impervious to neat Bromine After a Decade of Use at Boots in England
At the Boots Company Limited in Nottingham, England, Kynar®-lined and solid Kynar® PVDF piping has been used successfully for 10 years to handle bromine, one of the most corrosive and unpleasant substances known.
Boots is a household name in the United Kingdom. In 1980, the group achieved worldwide sales of $2.7 billion. It is best known as a pharmaceutical manufacturer and retailer, with a large chain of chemist's shops (drug stores) throughout the country. But it also has an industrial division making pesticides, fungicides and other agrochemicals.
Bromine is used as a compound in some fungicides, but it can also be used as a building block in the synthesis of certain pharmaceutical products. Being highly reactive, bromine can be added to the molecule and then removed later to make way for another element.
It is used in this way in the manufacture of an anti-rheumatic drug, called Froben, Boots' latest pharmaceutical product recently launched in over 37 countries. Froben follows on from a line of highly-successful anti-rheumatic drugs developed by Boots. These, when they were introduced about ten years ago, were considered something of a breakthrough in the field.
Handling bromine is a problem due to its toxicity and corrosive nature. According to B.K. (Jack) Robinon, senior project engineer at Boots, before suitable plastic materials became available, lead-lined pipes and tanks were common. These, however, were expensive.
"We were always looking for another material," he notes. "We still use lead-lined tanks for main storage and we started off in the early-'70s using solid Kynar® PVDF ipes in conjunction with these. By the mid-'70s, we had switched to Kynar-lined pipes."
In all, some 30 meters of 1-in. diameter Kynar-lined pipe supplied by BTR Silvertown is in use at Nottingham and performance has been trouble-free.
10-Year-Old Kynar® Pipe Performs for Company that Drawas Bromine Salts from Lowest Point on Earth
More that 2 miles of PVDF-lined and solid-Kynar® PVDF pipe keep operations running smoothly near Beer-Sheva, Israel, at the plant of Bromine Compounds Ltd., a subsidiary of Dead Sea Bromine Company, Ltd. The PVDF piping, some in continuous service for as long as 10 years, handles pure bromine in the plant's unloading section, and various bromine compounds in some of the processing operations. Kynar® PVDF initially replaced lead that provided corrosion-resistance to bromine but tended to leak at joints, due to excessive expansion and contraction caused by extremes in desert temperature.
The Dead Sea Bromine Company is a leading worldwide supplier of elemental liquid bromine. Part is exported for processing abroad, and the remainder is processed in Sedom or at the Beer-Sheva plants to produce a wide range of bromine compounds.
Dead Sea Bromine draws its raw material from the lowest point on earth, the Dead Sea, which holds an estimated one billion tons of bromine salts. Its Sedom plant extracts elemental bromine from these high-concentration brines. A nearby chlorine production facility provides the company with an assured supply of the principal raw material used in bromine extraction.
Solid Kynar® PVDF and lined pipe and other components are at work in all locations in Israel.
Solid Kynar® PVDF Pumps Lift "Witch's Brew" From Depths of Bolivia s Metal Mines
A hardy band of centrifugal pumps, made of solid Kynar® PVDF, has been reliably toiling away since 1974 in the depths of Bolivia's mine country, pumping out a highly corrosive ground water that had quickly crippled every other pumping device that the mine operators had tried.
The mines in question are run by Corporacion Minero de Bolivia (COMIBOL), a state-controlled mining operation. They produce tin, silver and related minerals from one of the richest metal lodes in South America.
At the deeper levels of these mines, which go down 300 meters or more, miners encountered a large volume of extremely corrosive ground water. It had to be removed if operations were to continue.
The very acidic water, laden with corrosive metallic chlorides, quickly attacked underground equipment, including even the stainless steel pumps that COMIBOL first used in the application. The "witch's brew" is so reactive that the mine shaft elevators are made entirely of wood - except for the cable which have to be replaced every few weeks.
COMIBOL finally solved this problem with a staged pumping network of Stan-Cor® centrifugal pumps made by TRW Mission Manufacturing Company. These all-Kynar® PVDF pumping units provide a high degree of resistance - both inside and out - to a broad range of chemicals, including chlorides and strong acids. The original Stan-Cor pumps installed in 1974 are still in operation, and dozens more are now at work in at least four other COMIBOL mines performing the same function.
The system at the Oruru mine, 500 kilometers south of LaPaz, is typical. A total of five pumps handles the ground water — each raising the corrosive fluid approximately 60 meters to the level above. Dam-like holding basins formed out of the natural rock at each stage receive the ground water coming up from the level below.
Ball check valves in the system, supplied by Peabody Dore Corporation, are also line with Kynar® PVDF.
The Bolivian mine pumps are all 3 x 4 Stan-Cor units powered by 40-hp motors. Pump housing and suction covers are made of carbon-filled Kynar® 320 PVDF. The carbon-filled resin has less thermal growth than the unfilled PVDF, providing a higher degree of control in maintaining clearances.
Corrosive material do not come in contact with any metal parts of the Stan-Cor units. (The name "Stan-Cor" stands for "standard pumps for corrosion resistance"). In fact the solid Kynar® PVDF construction gives COMIBOL a pump which is just as corrosion-resistant on the outside as the inside — a critically essential feature in Bolivian mine country.
Kynar® PVDF Helps Maintain Product Purity, Minimize Maintenance At Ashland Chemical
The Specialty Chemicals plant of Ashland Chemical Company in Eaton, Pa., produces a broad range of etchants, cleaners and related chemicals for the electronics industry.
The high-purity reagents are for the most part highly reactive, and include the various mineral acids, aqueous hydrofluoric, ammonium fluoride, and a family of nitricacetic-hydrofluoric acid etchants.
To maintain the requisite high-purity standards, which in some cases range down to one half part per million, while safely handling this mix of chemicals, the plant has come to rely on Kynar® PVDF components in many applications.
Arkema's polyvinylidene fluoride is at work here as solid piping, valves and fittings in diameters up to two inches, as vessel lining and agitator coatings, as the wetted surfaces of numerous centrifugal pumps and, recently, as the material for the filling nozzles of Ashland's high-speed automatic filling machines.
Production Manager Walter Zieger, an old hand in managing reactive chemicals, first introduced Kynar® PVDF at Easton eight years ago in piping for the mineral acids plant. Ashland had been using solid glass in this operation which produces high-strength nitric, hydrochloric and sulfuric acids.
The Kynar® PVDF pipe and fittings proved much easier to work with, while performing every bit as well as the glass in this demanding service. Zieger has since been replacing the glass with PVDF as the need or opportunity arose. Kynar® PVDF valves and lined pumps have also been introduced at one time or another in the mineral acids system.
Because of its superior physical properties, as well as its broad-spectrum resistance to a wide range of chemicals, the Easton plant has extended the use of Kynar® PVDF components to the hydrofluoric plant, where anhydrous HF is converted to a highly active 50% aqueous solution, and to the acid etchants operation, where nitric, acetic and hydrofluoric acids are combined in various compositions.
Most recently, Ashland used Kynar® PVDF to coat the agitators in a new system of three large blending tanks in the production of acid etchants. Mixtures in nitric, acetic and hydrofluoric are fed to these vessels through a common header made of solid Kynar® PVDF and then mixed to various compositions as proprietary Ashland products.
Two years ago, Ashland installed an automatic filling line for mineral acids. Both the external and internal parts of the four automatic nozzles were specified in Kynar® PVDF - for chemical resistance and for superior mechanical properties. The PVDF has performed trouble-free in this demanding service.
A similar automatic filling line was installed this year for bottling hydrogen peroxide. Though this is much less demanding chemically, Ashland specified that the inner sleeves of the filling heads still be made of PVDF, to take advantage of the fluoroplastic's physical strength and resiliency. The inner sleeve is the part of the nozzle that contacts the bottle as it is being filled, and this is subject to varying mechanical stress.
For most pumping operations, Ashland relies on one of the series of Vanton Chem-Gard* horizontal centrifugal pumps. Since no metallic contamination of any sort can be tolerated in these extreme purity chemicals for the electronics field, pump wetted parts must be nonmetallic and inert to the corrosive substances. For the more critical applications here, including the mineral acid filling line, the wetted parts of the Chem-Gard CG-KY-200 unit are made of solid molded Kynar® PVDF.
Kynar® PVDF components will be found in some applications where a lesser polymer might provide adequate chemical resistance. This is a reflection of Walt Zieger's desire to standardize; whenever economically feasible, on a high performance material that will provide insurance against the contamination of the plant's high-purity products and also provide an extra margin of performance in both mechanical and elevated temperature properties. Normal plant process temperatures range up to 150°F, well within Kynar® PVDF capabilities.
*Registered trademark of Vanton Pump & Equipment Corp.
Kynar® Fluoropolymer Resists Stress Cracking Across Broad Temperature Range At Akzo Plant
A significant part of the chlorine produced at Akzo Zout Chemie (Akzo Salt Chemical) in Delfzijl, Holland is used in their company's own chlorinated solvents plant. This began operation in 1970 when PTFE-lined steel pipes were installed. At this particular plant a mixture of carbon tetrachloride, perchlorethylene and hydrogen chloride is formed from chlorine and propylene. The hydrogen chloride is dissolved in water and distributed as 30% hydrochloric acid while carbon tetrachloride and perchlorethylene are brought to their required purity by distillation, washing and drying.
In 1973 Akzo Zout Chemie began having serious problems at the chlorinated solvents plant. The PTFE-lined steel pipes that carried the corrosive chemicals were blistering from the inside and cracking on the outside, because of the permeation of the end products: sulfuric acid, carbon tetrachloride and perchlorethylene.
According to Bart Goede, Akzo project engineer, some of the PTFE-lined pipes began having problems only six months after initial installation. "Replacing the pipes was costing Akzo valuable downtime and money," says Goede. Finally, after three years of continuous plant shut downs for repairs and replacements, Akzo turned to Kynar® PVDF for help.
This fluoropolymer, also known as polyvinylidene fluoride, was already widely used as a medium for lining steel pipes where its very high chemical and temperature resistance withstands attack from the corrosive mixtures used in chemical manufacturing. It also protects steel pipe because of its excellent diffusion characteristics and great mechanical strength.
Help arrived via Peabody in the United States, when they shipped Akzo 200 meters of Kynar-lined 1-inch, 2-inch, 3-inch, 4-inch and 6-inch steel pipe. Ten years later all the Kynar-lined pipe up to 3-inches was still in place at Akzo, in excellent condition and handling the extreme temperature ranges has saved Akzo hundreds of hours in
"Kynar® proved to be more economical than PTFE-lined pipes," says Goede.
Rheind Koens, Akzo's chief of maintenance, shuts down the chlorinated solvents plant once a year for routine maintenance and cleaning. He claims he has rarely had to dismantle or replace a Kynar-lined pipe up to 3 inches in the 10 years since they were installed.
The chlorinated solvents plant produces about 30,000 metric tons of chlorinated hydrocarbons annually. The carbon tetrachloride produced is used as raw material for the production of (chlorofluorocarbon) types 11,12 and 13. It is also used as a solvent for oils, fats, waxes, rubber and some resins. The perchlorethylene produced by Akzo is mainly for finishing processes and degreasing of light and thin metal products.
Akzo Zout Chemie in Delfzijl produces a total of some 2,980,000 metric tons of chemicals annually, mostly for industry in Europe. It is the largest chemical facility in northern Holland, containing 15 plants that produce 32 different chemical products.
Akzo is just one of many facilities around the world that require broad temperature ranges for the manufacturing of chlorinated hydrocarbons. Given the opportunity, Kynar® PVDF proved to Akzo that it could easily meet the challenge of the 100° C range.
Nine Years Later Kynar® PVDF Tower Packing Still Going Strong In Muriatic Acid Unit
Nine years ago Standard Chlorine of Delaware replaced the ceramic tower packing in its hydrochloric acid absorber with saddles made of Kynar® PVDF. The No.2 Norton Super INTALOX® saddles are still going strong, even though the original absorption tower isn't.
The operation is part of Standard Chlorine's acid manufacturing unit, at its Delaware City, Delaware plant. There by-product HCI gas is converted into commercially strong 20° Beaume muriatic solution at temperatures up to 212°F. The ceramic tower packing was coping with the harsh chemical conditions, but was breaking up due to surge conditions in the feed. Particularly at start-up, the initial flow tended to bounce the ceramics and chip off pieces. These pieces were collecting at the bottom of the tower and causing manufacturing flow problems.
The absorber was repacked with PVDF saddles in 1972. The tough saddles, made of Kynar® PVDF, have survived both the highly acid, elevated temperature condition and the periodic physical abuse. The absorber column has since been replaced by another — filled with the original Kynar® PVDF saddles.
It's the kind of performance that Tom Pierson, production superintendent, has since come to expect from Kynar® PVDF. The Delaware City plant is the principal production facility for parent company, Standard Chlorine Chemical Co., Inc., one of the world's major producers of chlorinated benzenes and largest domestic marketer of these products.
Success in the acid manufacturing area led to an application for solid PVDF piping in the organic absorber system, where benzene and chlorinated benzenes are removed from the HCI gas stream. Steel pipe carrying the organics to holding tanks was being attacked by the reactive wet HCI. This was replaced in 1975 with 1-in. diameter solid Kynar® PVDF, which has been performing well ever since.
Today, more than 300 feet of solid PVDF piping — from 1 to 2 inches in diameter — has since been added to plant operations here, either as replacement or as additions in new plant processes. A typical example is the piping in the neutralizing section, where the chlorinated benzenes are washed with water and 2% caustic to neutralize the HCI. Solid PVDF pipe up to 2 inches in diameter has been handling this flow for the past four years.
In 1977, when Standard Chlorine installed a solvent recovery system as part of its wastewater treatment program, tower packing of Kynar® PVDF was specified for the stripper column. Collected wastewater, treated to a pH of 4-5 and containing dissolved organics and ½-1% HCI, is fed into this 2-ft. diameter by 28 ½ -ft. high tower. There, the organics are steamstripped from the collected wastewater at a temperature of approximately 212°F. The stripper, packed with No.1 Super INTALOX® saddles made of Kynar® PVDF operates at a 30-35 gpm flow rate with 100 lbs. of steam and the shell side of the unit.
Pierson reports no problems with the PVDF material in the more than nine years experience with the material — whether in handling the wet hydrochloric, or in moving the chlorinated benzenes and other organics, some of which had a tendency before to soften other plastics, such as PVC.
Kynar® PVDF Solves Piping Problems In Two Generations Of Insecticide Plants
In 1972, after extensive testing, FMC Corporation designers selected Kynar® PVDF- lined pipe for many corrosive areas of its new insecticide intermediate plant. Five years later, when expansion became necessary, no testing was needed. Kynar® PVDF had proven its chemical and mechanical capabilities.
The performance of FMC's organic insecticide intermediate plant in Baltimore, Maryland has come a long way since it began operations back in 1967.
The original plant was plagued by a continuous stream of piping problems causing extensive downtime. The solid phenolic pipe and resinous pipe could not withstand the severely corrosive chemicals they were called upon to carry. The piping was also mechanically weak.
"It was one thing after another," says Frank J. Peterson, plant engineer. "A workman would be sent out to repair a section of pipe. He'd step on another section and that would break. The original pipe had no structural strength or chemical resistance. It was a nightmare."
The experience with the original plant led FMC to search for a substitute pipe when, because of rapidly growing sales, the company had to build a new plant with triple the capacity.
Foremost in the minds of FMC officials during the search for new piping was the need for a significant reduction in downtime. The pipe chosen had to resist the harshest chemicals, be mechanically tough and be replaced quickly and easily should a failure occur.
The new plant opened in 1972 with thousands of feet of Kynar-lined steel pipe concentrated in the four most demanding parts of the production sequence.
FMC officials had done their homework well. Downtime was significantly reduced in the ensuing years, and shutdowns due to pipe malfunctions became a rarity.
So much so, that when FMC built a virtually identical plant in 1977 as part of an incremental expansion of the insecticide intermediate operation, Kynar-lined pipe was readily specified.
Now, both facilities, sitting side-by-side on Curtis Bay in Baltimore harbor, rely on thousands of feet of Kynar-lined pipe supplied by Peabody-Dore Corporation and Dow Chemical, U.S.A., in sizes ranging up to 10 inches to carry corrosive chemicals throughout the system.
The first area in both plants where Kynar® PVDF plays a prominent role is in the section known as the "MAC" plant where a vital raw material — methallyl chloride — is manufactured. This is a chlorinated hydrocarbon with hydrochloric acid as a by-product.
This system includes a huge three-column distillation train for purifying the methallyl chloride. Virtually every foot of piping in this section of the plant is Kynar-lined.
Kynar® PVDF also plays an important role in the first stages of insecticide intermediate processing - the manufacture of high molecular weight ether in a glass-lined tank. A complex installation of Kynar-lined pipe, in diameter sizes up to 10 inches, runs through the entire system here.
Piping in this section must exhibit resistance to abrasion as well as corrosion. The reaction producing the ether takes place in an aqueous slurry containing sodium chloride at relatively low temperatures. This usually tough combination at a relatively high pH creates an extremely abrasive environment, but plant officials report Kynar® PVDF has performed well.
The fourth stage of processing also puts Kynar® PVDF to a stern test. Here, an organic salt is produced in a highly acidic mixture.
The toughest task for Kynar® PVDF lies at the end of the production process. In the plant's waste treatment system all of the various mixtures from the entire processing operation are brought together, but thousands of feet of Kynar-lined steel pipe routinely carry the highly acidic, salty solution with a high concentration of chlorinated organics.
Since 1972, Kynar® PVDF has allowed FMC officials to concentrate on producing insecticide intermediates to be shipped to its Middleport, New York plant where they are used in the manufacture of an insecticide used on corn and alfalfa crops.
The constant fear of pipe failures and ruptures is a thing of the past.
"Kynar® has made a world of difference," says Don Jennings, a manufacturing engineer at FMC. "It is rare the plant, or any part of it, has to be shut down due to pipe failure. In fact, much of the original pipe installed in 1972 is still in operation."