Triple offset butterfly valves have the same component as a concentric butterfly valve. A triple offset butterfly valve is usually metal to metal seat configuration valve. With this design the valve can achieve zero-leakage. Typically a triple offset butterfly valve has no cavity to allow build-up.
The design of a triple offset butterfly valve consists of three separate “offset”. First offset is applied to the centreline of the bore in the shaft. The second offset is applied to the centreline of the disc sealing surface. The third offset is the design of the axis of the seat cone angle that is inclined to the centreline of the valve bore. This will minimise the rubbing of seat contact during operation. The seal will come in contact with the seat when the valve is completely close.
Generally triple offset butterfly valve is used in bi-directional tight shut-off application in oil and gas industry.