... PTFE Coated3.Stem: SS4.Seat: PTFEOur PTFE lined butterfly valve adopting the PTFE butterfly board to sealed spherical surface, being ... on the rotry base between the butterfly board and valve seat, therefore, the impact and beautiful outlook,reasonable ... corrosion,such as sulfuric acid, rofluoric acid, phosphoric acid,chlorine, strong alkaline, aquaregia, etc.Type of connection: counter connection ...