Polyvinylidene fluoride corrosion resistance

PTFE is resistant to solvents, oxidizing acids, nonoxidizing acids, alkalis, and aqueous salt solutions. Other polyfluorocarbons, such as polyvinylidene fluoride (PVDF), are slightly less resistant to corrosives but are much more resistant than most other construction materials. 

Wet chlorine is extremely corrosive, attacking most common metals except Hastel-loy C, titanium, and tantalum. Surface oxide films protect these metals from attack by the acids formed in chlorine hydrolysis. Tantalum is an ideal construction material for service with wet and dry chlorine. However it is expensive and normally used only in instruments such as transmitters, diaphragms, transducers, and thermowells. FRP is used for wet chlorine. Rubber-lined steel is also suitable for wet chlorine gas up to about 100°C. At low pressures and low temperatures, PVC, CPVC, and reinforced polyester resins are also used. Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene-hexafluoropropylene (FEP) are resistant at high temperatures. Other materials stable to moist chlorine include graphite and glass. 

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