Abstract: The vane actuator according to the present invention is capable of operating effectively at a working pressure greater than 100 psig. The vane actuator comprises a vane shaft rotatably extending through a casing and a vane disposed within the casing defining a first pressure chamber and a second pressure chamber therein. The casing includes stiffening members for resisting deflection of and maintaining an internal seal within the casing when exposed to a pressure of 150 psig. The stiffening member may be located in the range of about 10° and 20° on either side of a casing centerline to minimize deflection of the casing when exposed to a pressure force.