the shaft 20 for rotation as well as seals 21 c and 21 d to minimize leakage from the case top case half 10 and bottom case half 50 form a clam shell configuration each case half generally being a mirror image of the other with exceptions as noted below top case half 10 and bottom case half 50 include top stiffening member 30 and bottom stiffening member 80 respectively in the preferred embodiment top stiffening member 30 comprises stiffeners 30 a 30 b and 30 c while bottom stiffening member 80 comprises stiffeners 80 a 80 b and 80 c the stiffeners and thus the respective stiffening members extend from exterior surfaces 10 b and 50 b on case halves 10 and 50 stiffeners 30 a and 80 a are positioned along the radial centerline of actuator 100 in the preferred embodiment the center lines of stiffeners 30 b and 30 c are positioned 11 u00b0 on either side of stiffener 30 a as measured centerline to centerline similarly in the preferred embodiment the center lines of stiffeners 80 b and 80 c are positioned 11 u00b0 on either side of stiffener 80 a as measured centerline to centerline while the preferred embodiment shows 3 stiffeners one or a plurality of stiffener s may be employed within the range noted above on either side of the centerline of actuator 100 one or more stiffeners may be positioned within the range between about 10 u00b0 and 20 u00b0 on either side of the centerline of actuator 100 for the purpose of minimizing deflection of the case when exposed to a working temperature range of u2212 50 f to 300 f and or a maximum working pressure of 150 psig and.