Abstract: A plate heat exchanger is provided which includes a plurality of plates mounted in abutting face-to-face relation. Interposed adjacent plates is a sealing gasket. The plates are held in assembled relation by an adjustable press. Each plate is provided with an extruded first section having second sections secured to opposite peripheral segments thereof. Each section is provided with broad opposed exterior surfaces. The first section has a plurality of internal passages formed therein defining first flow-paths for a first heat exchange medium. The opposed broad exterior surfaces of adjacent plates coact with the sealing gasket to define second flow-paths for a second heat exchange medium. The pressure exerted on the plates by the press to maintain same in abutting relation is determined by the maximum pressure generated by the second heat exchange medium within the second flow-paths during operation of the plate heat exchanger.