Abstract: A filtering apparatus for separating particulates from high temperature, high pressure gas streams has a vessel divided into upper and lower chambers by a tubesheet, the tubesheet having a flexible support means with the rim thereof resting in a groove in outwardly extending flange portions securing together upper and lower sections of the vessel wall. The flexible support means for the tubesheet has a cylindrical wall depending from a support plate and a conical wall depending from the rim, the two walls secured together, with insulation between and about the walls. The vessel is insulated and preferably has a steam coil cooling device in the lower section thereof. A backflush system includes vertically spaced rows of pipes having tubes depending therefrom directed to the open tops of the filter elements, with the spaced rows connected together by pivotal links, and alignment means provided to align the open ends of the tubes with the open tops of the filter elements.