Patent ID: 6886629

Claim:
A plate heat exchanger block comprising: an aluminum or aluminum alloy housing, at least partly within said housing a plurality of aluminum or aluminum alloy sheets ( 2 ) of at least partially corrugated metal arranged parallel to one another and forming a plurality of heat-exchange passages, at least one steel header ( 3 ) in communication with at least some of the heat-exchange passages, wherein at least two parts ( 1 , 2 , 3 ) of the plate heat exchanger block consist essentially of aluminum metallic materials that cannot be welded to one another, and wherein the plate heat exchanger block includes an intermediate piece ( 5 ) between the header ( 3 ) and the heat exchange passages ( 2 ) containing the plurality of sheets, the intermediate member having a steel part facing the header and an aluminum part facing the housing, the parts being explosively bonded together wherein the intermediate piece is welded, aluminum-to-aluminum or aluminum alloy, to at least one of (a) the housing and (b) the corrugated sheets and is also welded steel-to-steel with the steel header.