Why is the life of flanged butterfly valves so long

Why is the life of the flange butterfly valve so long-the sealing structure of the flange butterfly valve uses PTFE and synthetic rubber to form a composite valve seat, which is characterized in that the elasticity of the valve is still provided by synthetic rubber and the friction coefficient of PTFE is low, Not easy to wear, not easy to age and other characteristics, so that the life of the butterfly valve can be improved.