when the inner and outer cylinders of a cyclone separator are operated at different temperatures such as in a cyclone separator having walls formed by water steam cooled tubes this causes differential thermal expansion and contraction circumferentially and radially across a roof extending between such inner and outer cylinders the cyclone separator roof of the present invention includes a corrugated annular upper seal plate having expansion joints which enable the roof to accommodate differential circumferential and radial thermal expansion and contraction the corrugations in the plate extend radially from the center of the plate and accommodate differential circumferential thermal expansion and contraction across the roof the expansion joints are disposed in the plate and are aligned coaxially with the inner and outer circumferences of the plate to accommodate differential radial thermal expansion and contraction across the roof application_number US 67392091 A description referring to fig1 of the drawings the reference numeral 10 refers in general to a cyclone separator which includes a lower ring header 12 and an upper ring header 14 the lower ring header 12 extends immediately above and is connected to a conical hopper 16 disposed at the lower portion of the separator 10 a group of vertically extending spaced parallel tubes 20 are connected at their lower ends to the header 12 and extend vertically for the greater parts of their lengths to form a right circular outer cylinder 22 the tubes 20 are connected by means of continuous fins not shown disposed at diametrically opposed portions of the tubes and connected thereto in a conventional manner to.