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Basics

PTFE PFA/FEP Fluoropolymers Resin

Properties of fluoropolymers are unequalled. They are practically unaffected by nearly all Chemicals, Acids, Alkalis and Petrochemicals. Certain of them also have very low co efficient of friction. After wet ice to wet ice, PTFE has the least co efficient of friction, that is known to the mankind.

General

As far as the ASTM standard specification D3418 is concerned, PTFE / PFA is a perfluoroalkoxy resin that matches this standard. The combination of PTFE / PFA is to make the processing easy of conventional thermoplastics with properties same as those of PTFE (Poly Tetra Fluoro Ethylene). They have high melt power, stability at excessive processing temperatures and can resist excessive service temperature.

PTFE / PFA resin gives the higher ranking properties, typical of the fluoropolymers, retention of properties after service at 260*C (500*F) and chemical inertness to all most all industrial chemicals and solvents. The factors of Dielectric constant and dissipation factors are reasonably low. End products of PTFE / PFA are highly suitable for chemical lining for valves, pipes and fittings.

The ASTM Standard Specifications for FEP Fluorocarbon Molding and Extrusion Materials under ASTM Designation D 2116-95a are met by PTFE / FEP fluorinated ethylene propylene resin. Coating, Melt Extrusion, Impregnating etc. are the applications of resins.

PTFE FEP’s end products are known about their superb chemical resistance, high precision electrical properties and high level service temperatures of up to 200*C (400*F). To add to this PTFE / FEP gives excellent low temperature toughness and a peculiar flame resistance.

Processing

Properties of fluoropolymers are unequalled. They are practically unaffected by nearly all Chemicals, Acids, Alkalis and Petrochemicals. Certain of them also have very low co efficient of friction. After wet ice to wet ice, PTFE has the least co efficient of friction, that is known to the mankind.

The excessive melt strength and draw-down feature makes it easy the use of big dies and draw-down tooling to rise production rates. The equipment should be made of corrosion-resistant metals, which is in contact with liquid resin.

To give reasonable occupancy time at excessive production rates to melt these high temperature polymers bigger length-over-diameter extruder barrels are to be used.

Installation and Maintenance for “4MATIC” Lined Valves
  • Only trained personnel should undertake the Installation and Maintenance procedure of “4MATIC” lined valves.
  • Flange covers should be removed only when flanges are ready to be bolted into positions or else lined flange face may get damaged or distorted. If it is necessary to remove the covers for inspection purpose, then they should be properly replaced instantly afterwards.
  • Gaskets are required only when the valves/ pipes/ fittings are connected to a flange face of another material, like carbon, reinforced plastic, ceramic, glass etc., otherwise there is no need of gaskets.
  • Bolts should be rightly tightened through proper bolt torques.
  • Threads should be clean and thoroughly lubricated and to make sure of correct torque, washer should be utilized. Tightening of the bolts should be done alternatively.
  • If there is a leakage in the flange and bolts of the leakage side are duly torqued, then they should not be further tightened any more or else it may result into permanent damage to the sealing face. In such a case the opposite side bolts should be loosened by half a turn at a time and then the leakage side bolt should be tightened by the same amount. If the leakage still persists, then it is required to remove the bolts and then the sealing faces should be examined to check whether there are any scratches or dents which are less than 10% of the lining thickness can be removed by hand polishing by abrasive cloth or paper.
  • If leakage takes place after the system has been cycled to a high temperature and back to ambient temperature, then after the cool down period bolts must be re-torqued. No more tightening is required.
  • The process such as brazing, welding, flame cutting, soldering etc. should not be done near the metal housing, as it may result into permanent damage to the lining material. It is necessary to take precautions to stop them from being exposed to high volume of heat.
  • Safety vent holes, meant for releasing gases, that may be generated at high level temperature and trapped between lining and housing, should not be plugged through cement, paint or filler etc. These vent holes are also necessary as they give signal of alert of any accidental damage to lining area before leakage increases to dangerous levels.