What is the structure of triple -offset butterfly valve?

Offest 1: The shaft is offest behind the seat axis to allow complete sealing contact around the entire seat.
Offest 2: The shaft center line is offset from the pipe and valve which provides interference free opening and closing of the valve.
Offest 3: The seat cone axis is offset from the shaft center line to eliminate friction during closing and opening and to achieve uniform compressive sealing around the entire seat.