Abstract: A rotary coke drum un-heading valve adapted for engagement to an extremity of a coke drum having an orifice therein. The rotary coke drum un-heading valve includes a valve body, having a passage which extends therethrough along a mass flow axis and at least two valve seats that circumscribe the passage. The passage is aligned for mass flow communication with the orifice. A rotatable flow obstructing member defines a bore therein and is rotatable within the valve body between an open position, wherein the bore is in communication with the passage permitting mass flow through the un-heading valve, and a closed position, wherein mass flow through the un-heading valve is prevented by the flow obstructing member. In one embodiment, the flow obstructing member is a gate pivotable in a plane perpendicular to the mass flow axis by a valve stem rotatable about its central axis which intersects the plane.