Abstract: The heat exchanger of the welded plate type is characterized in that it comprises and receives an assembly of a plurality of modules (M) comprised of two plates (5 and 6), said plates being interconnected by connection zones obtained by laser welding and shaped by hydroforming, said plates having their transversal extremities folded and defining between each other an internal longitudinal cavity forming a first fluid circulation conduit, said modules being associated with each other by connection of the folded extremities of the plates facing each other thereby defining, in a transversal plane, a second fluid air circuit (B).

Abstract: An industrial gas operated liquid heater is provided comprising a tubular hearth or furnace a front end face of which is provided with a gas burner and a heat exchanger in which the liquid to be heated and the combustion fumes flow concurrently, the exchanger forming with said tubular hearth a unitary monobloc assembly so designed that the liquid to be heated forms, a first liquid sheet enclosing substantially the whole of the tubular hearth, except for said front end face receiving the gas burner and, in the exchanger, a plurality of second liquid sheets extending substantially parallel to the longitudinal direction of the tubular hearth and adjacent, in said exchanger, to chambers through which flow the combustion fumes issuing from the tubular hearth.

Abstract: Plate exchanger of the type comprising a plurality of juxtaposed metallic plates defining spaces between them, every other of which spaces receives a flow of a first fluid whereas the other spaces receive a flow of a second fluid, substantially parallel to the first, each plate being joined in tight manner, by its periphery to the two adjacent plates, while inlet or outlet orifices are provided for the fluids, the plates being paired up by straight seam welding in two opposite end parts of the plates of each pair of plates, characterized in that one plate at least from each pair comprises a flange, at least in one of the end parts and close to said welding, which flange is bent substantially at right angle and joined by straight welding of its free bordering part to a plate facing the next pair.