There is no change of the seat when sealing it so, the contact surface between disk and seat is greatly reduced.
Because of precision machining contact surface is uniform and because of the semi-circular machining of the disk end seating torque is reduced.
With improved seat and disk design it keeps seating torque and high pressure of fluid and it ensures the long life and prevents the damage to the seat.
With the insertion of phenol back up ring it keeps support and stability and the seat twisting and torque can be reduced.