PTFE Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that finds numerous applications. The most well known brand name of PTFE is Teflon by DuPont Co.
PTFE is inert to virtually all chemicals and solvents when used in thick sections. Service temperatures rated up to 160°C.
It is not a true melt processable Fluoroplastic. It is usually used as a loose liner to line columns and pipes of simple design.
HISTORY PTFE was accidentally invented by Roy Plunkett of Kinetic Chemicals in New Jersey in 1938. While Plunkett was attempting to make a new CFC refrigerant, the tetrafluoroethylene gas in its pressure bottle stopped flowing before the bottle's weight had dropped to the point signaling "empty." Since Plunkett was measuring the amount of gas used by weighing the bottle, he became curious as to the source of the weight, and finally resorted to sawing the bottle apart. Inside, he found it coated with a waxy white material which was oddly slippery. Analysis of the material showed that it was polymerized perfluoroethylene, with the iron from the inside of the container having acted as a catalyst at high pressure. Kinetic Chemicals patented the new fluorinated plastic (analogous to known polyethylene) in 1941 and registered the Teflon trademark in 1945. An early advanced use was in the Manhattan Project as a material to coat valves and seals in the pipes holding highly reactive uranium hexafluoride at the vast K-25 uranium enrichment plant at Oak Ridge, Tennessee. DuPont, which founded Kinetic Chemicals in partnership with General Motors, was producing over two million pounds (900 tons) of Teflon brand PTFE per year in Parkersburg, West Virginia, by 1948. In 1954, French engineer Marc Grégoire created the first pan coated with Teflon non-stick resin under the brand name of Tefal after his wife urged him to try the material he had been using on fishing tackle on her cooking pans. In the United States, Kansas City, Missouri resident Marion A. Trozzolo, who had been using the substance on scientific utensils, marketed the first US-made Teflon coated frying pan, "The Happy Pan," in 1961.
APPLICATION AND USES
Powdered PTFE is used in pyrotechnic compositions as oxidizers together with powdered metals such as aluminum and magnesium. Upon ignition, these mixtures form carbonaceous soot and the corresponding metal fluoride, and release large amounts of heat. Hence they are used as infrared decoy flares and igniters for solid-fuel rocket propellants.
Case History :
50 NB MS spool pipe & fittings internally lined with PTFE supplied in 2006 3 mm PTFE + FRP Chlorination column having 0.4 m Diam x 4 m ht
3 mm TFM or PTFE lined Mild steel agitator used in a 50 KL reaction vessel used by a surfactant industry based in Egypt.
M-PTFE lined agitator has been a replacement to Duplex steel. All critical parts on the agitator are appropriately lined with PTFE.
PTFE has been made wieldable by years of research by various companies. It is a boon to the chemical industry which faces extreme corrosion.
Appropriate mask & gear has to be used by welders doing PTFE welding as fluorine fumes are emitted during welding.
2 mm FEP lining on Mild steel equipment of 150 KL. The size of the equipment is 4200 mm Diameter x 11,200 mm height. Other equipments were of 3000 mm Diameter x 6266 mm height.
The equipment is used by a fluorine handling company based in Abu Dhabi. It has given satisfactory performance installed since 2002. Total FEP consumed is more than 1000 m2. It has been the single largest order for 2 mm FEP fabric backed sheets for the FEP sheet manufacturer.
3 mm PTFE/TFM /M-PTFE with FRP REACTION VESSEL of 20 KL with double mechanical seal. This is used by a chemical company to carry out various reaction. They wanted a universal material of construction which can sustain all chemicals upto 100 Degree Centigrade. PTFE was our first choice of solution. It has worked well for client, it is installed since 2006.