Abstract: A method and apparatus for sealing a hole in the inner wall of a double wall heat exchanger in which cover means is positioned in biased relationship to the hole and a frame positioned in the opening through which the cover means is inserted against the hole.

Abstract: A method and apparatus for sealing a hole in the inner wall of a double wall heat exchanger in which cover means is positioned in biased relationship to the hole and a frame positioned in the opening through which the cover means is inserted against the hole.

Abstract: A method of salvaging a heat exchange apparatus of the recuperator type is provided by which the inner tubular member can be withdrawn from a state of collapse and restrained in a position against further collapse. The heat exchange apparatus comprises a first tubular member having hookable means thereon; a second tubular member generally coaxial with said first member and disposed outwardly thereof so as to define a fluid flow zone therebetween, said second member having at least one passage therethrough in communication with said fluid flow zone and an outwardly disposed passage-circumscribing ring; a rod member extending inwardly through said passage and into said flow zone, means carried by the inward end of said rod in hooked relationship with said hookable means; and an apertured cap disposed coaxially about said rod outwardly of said second tubular member.

Abstract: Heat exchange apparatus of the recuperator type is provided with means by which the inner tubular member can be withdrawn from a state of collapse and restrained in a position against further collapse.