Pipes/piping fluoropolymers

Grafting of functional monomers onto fluoropolymers produced a wide variety of permselective membranes. Grafting of styrene (with the following sulfonation), (meth)acrylic acids, 4-vinylpyridine, A/-vinylpyrrolidone onto PIPE films gave membranes for reverse omosis, ion-exchange membrane, membranes for separating water from organic solvents by pervaporation, as well as other kinds of valuable membranes. 

FIGURE 4.15 Extruded pipes from FEP. (Courtesy of DuPont Fluoropolymers.)... 

In telecommunications similar requirements are placed on insulation materials in addition to low dielectric losses. Thus, even here fluoropolymers are capable of meeting them. Typical applications are insulations and jackets for wires and cables, tubing, piping, and films. 

PVDF is the third most widely used fluoropolymer, after polytetrafluoroethylene (PTFE) and fluorinated ethylene-propylene (FEP). The worldwide consumption of PVDF was approximately 15,000 metric tons in 2001 and is growing at an annual rate of 6-8%. PVDF applications have been expanded over the past 40 years because of its unique physical properties, and have over 30 years of proven and field performance data on thermal, chemical, radiation, and weathering applications. PVDF applications include, but are not limited to, chemical processing of pipes and components, semiconductor, architectural finishes and coatings, electrical plenum, cable jacketing. 

In the chemical processing industry, for example, fluoropolymers are selected for their resistance to chemical attack. They serve as linings for carbon steel vessels, and for piping and other fluid handling components. They provide durable, low maintenance, and economical alternatives to exotic metal alloys. In these applications, fluoropolymers also offer thermal stability for use at high temperatures. And because they do not react with process streams, they help prevent contamination of products. 

Some parts might need to have a coating thickness less than what other lining processes can provide. These might include valves, tubes, pipes, and impellers. These parts may still need to be protected by a fluoropolymer coating. One of the best references is published by the Powder Coating Institute although other sources are also available. 

Dual Laminate - FRP (fiberglass reinforced polyester) piping lined with fluoropolymer is manufactured by forming FRP over a fluoropolymer tube. The resulting stmcture is called adual laminate. 

Fluoropolymers are a family of polymers containing C-F bonds. Polytetrafluoro-ethylene (PIPE) has the following structure ... 

Certain polymers are used largely, if not exclusively, for corrosion control purposes. The significant markets for corrosion control by polymers are composites (primarily glass-reinforced thermosetting resins) PVC pipe, polyethylene pipe, and fluoropolymers. 

PVDF exhibits the excellent resistance to harsh environments, characteristic of fluoropolymers. It is widely used in the chemical processing industry, in piping systems, vales, tanks (both molded and lined), and other areas where its combination of excellent mechanical properties and superb resistance to most chemicals make it an ideal material for fluid handling equipment. Increasingly important is use of PVDF as the base resin for long-life, exterior coatings on aluminum, steel, masonry, wood, and plastics. 

Butterfly valves can provide tight shut-off when soft seats are used, and their major application in chlorine service is in the larger pipe sizes. The usual design features standard adjustable packing, a wetted shaft/disc arrangement, and a one-piece soft-hp seal. Fully lined butterfly valves have lower pressure ratings and are suited only for gas applications. Fluoropolymer resin liners cover all internal surfaces. Back-up liners, not exposed to the chlorine, provide seats. Butterfly valves can provide tight shut-off with quarter-turn operation. Like the other types of valve, they should have blowout-proof stems. 

Arkema supplies fluoropolymers for the polyolefins used in film, pipe and cable sheathing. Its products include Kynar 761 and Kynar Flex 2801 and 2821, which are designed to reduce die pressure and eliminate melt fracture. Kynar Flex 2500 has a melting point 25 C lower than usual so as to facilitate dispersion. 

Fluoropolymers possess excellent thermal stability and are nearly completely inert to chemical attack. Polytetrafluoroethylene (FIFE), discovered in 1938 by Roy Plunkett at I.E. du Pont de Nemours and Company, is the world s most used fluoropolymer. PIPE accounts for 59% of the fluoropolymers market and its production amounted to some 79,000 metric tons in 2004 [1], Applications exploiting the extraordinary properties of the material are wide-ranging and include gaskets, thread-seal tape, pipe liners, bearings, gears, slide plates, filter bags, medical prosthetics, and architectural material [2,3]. 

Where unfavorable combinations of chemical, mechanical, and physical environments may preclude the use of other materials, PVF has been successfully used, as for valve and pump parts, heavy wall pipe fittings, gears, cams, bearings, coatings, and electrical insulation. Its limitations include lower service temperatures than the highly fluorinated fluoropolymers, not having antistick qualities, and the fact that it produces toxic products upon thermal decomposition. 

Engineered thermoplastic and fluoropolymer materials used in specialty pipe, tubing, and fittings applications include the following ... 

Fluoropolymers, including polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PIPE), and perfluoroalkoxy (PFA)... 

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