Fluoropolymers lining

Non-Metallic Materials Numerous engineering thermoplastics have been commercialised including materials such as polyetherether ketone (PEEK) and polyether sulphate (PES) with much improved thermal/chemical resistance. The usage of FRP equipment has increased, and fluoropolymer lining technology/applications have come of age. Of particular interest is the development of stoved, fluoropolymer coating systems for process industry equipment. 

Jinks, P., and Marsden, S. (1999),The development and performance of a fluoropolymer lined can for suspension metered dose inhaler product, in Fradley, G., Ed., Proceedings of Drug Delivery to the Lungsa X, The Aerosol Society, Portshead, United Kingdom, pp. 177-180. 

Table 4.22. Comparison of Fluoropolymer Lining Technologies for Vessels and Columns... 

Dual Laminate (Fluoropolymer-lined FRP) Same as Adhesive-bonded Fabricate liner first on a mandrel (hand and machine welding) and build FRP laminate over the liner. Use carbon cloth for spark testing Shop and Field Pressure OK (RTP-1 Dual lam) Vacuum OK for FRP/fluoropolymer bond. Design FRP for vacuum 33 dia max Visual Spark AE CRBBD Possible Testing recommended... 

The principle of dual laminate construction is to line an FRP vessel or column with a fluoropolymer lining. However, the sequence of construction is to first make the liner out of fabric-backed sheets the same as in the adhesively bonded construction. The FRP structure is then laminated on the liner to pro-... 

The most commonly used valves in the chemical processing industries (CPI) are available with fluoropolymer lining. These are ... 

Unlike metals, which respond to various techniques, there are no methods of determining conditions of the fluoropolymer lining from the outside. This remains a major limitation in the use of fluo-ropolymers to replace metals. Initiatives are under way to address this gap at the research and development level. 

Table 9.1. Type and Frequency of Inspection of Fluoropolymer Lined Systems...

Welding and Flame-Cutting Fluoropolymer-Lined Metals... 

The next level of containment is probably the fluoropolymer-lined digestion bomb. These autoclaves are sold by a number of vendors and are inexpensive (ca. 300 each), easy to handle, and require no special auxiliary equipment [31]. They are the vessels of choice for a number of workers doing some remarkable chemistry [32]. They also have the important advantage that they are inert to aqueous base and fluorides, making them a workhorse for the zeolite industry. However, they have the limitation that the fluoropolymer liner will deform and weaken above about 240 °C. Also, the autoclaves have simple screw top seats meaning they can rarely contain pressures exceeding 140 bar. Thus they cannot contain true supercritical aqueous fluids. Nonetheless their convenience makes them the vessel of choice for the large amount of hydro-thermal work done at 200 °C and below. 

Several cautions apply to ratings of valves. The user should discuss this situation with the manufacturer. Nickel valves may have pressure ratings that are low for then-nominal design class. The pressure rating of diaphragm valves depends on size and material of construction. Fluoropolymer-lined plug valves are satisfactory only under certain conditions. 

Fluoropolymer linings are installed using adhesive bonded fabric-backed sheets, sprayed dispersions, rotolining, electrostatic sprayed powders and by mechanically attaching loose sheet linings. 

Partially fluorinated materials are ECTFE, ETFE, and PVDF. These materials have higher mechanical properties but lower temperature (<300°F/150°C) and chemical resistance. Fluoropolymer linings can cost 5-20 times more than thermoset linings so they are typically restricted to elevated temperature environment. 

Holds worth GS, Dalgleish A. Plasma Advancement Expands Applications of Fluoropolymer Linings and Coatings in the Battle Against Corrosion. COMPOSITES 2001 Convention and Trade Show Composites Fabricators Association. October 3—6, 2001 Tampa, FL. 

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