Abstract: The field of this invention is fluid flow control through large conduits. In particular, this invention is contemplated for use in a combined cycle power plant wherein gas turbine exhaust gas is either sent through a heat recovery steam generator (HRSG) or diverted to the atmosphere. The invention is a damper and frame assembly believed to be well suited to the purpose of channeling the hot exhaust gas within the context of a combined cycle power plant either as an isolation damper to the HRSG or a bypass damper to the exhaust stack. One key consideration is the thermal relationship between the damper blade and its adjacent frame and provision is made to provide a damper blade that will not warp and a frame wherein thermal growth and distortion are limited.