A valve seat structure for an automotive thermostatic fluid control valve device is disclosed, which comprises a rigid fluid flow control member (20) which includes a cylindrical wall (24) which forms a fluid flow passage and an annular base (28) which encompasses the cylindrical wall. An elastomeric sealing or engagement member (30) resiliently encompasses the cylindrical wall and is clamped between two portions (90, 92) of a fluid conduit to position the valve seat structure within the fluid conduit. The elastomeric sealing member (30) is also engageable by a movable valve member (80) to control fluid flow through the fluid flow passage. The cylindrical wall (24) extends beyond the elastomeric sealing member (30) and protects the elastomeric sealing member (30) against the forces of fluid flow.