Permanently joined plate heat exchanger

Plate heat exchanger comprising a package of heat exchange plates, each having a peripheral portion and within this a heat exchange portion and several port portions with throughflow ports, the heat exchange plates being permanently joined to adjacent heat exchange plates of the package both along their peripheral portions and at a variety of places in their heat exchange portions in such manner that they leave flow passages between adjacent heat exchange plates, the ports of the plates being aligned and forming first inlet and outlet channels through the package for a first heat exchange medium, which communicate with every other flow passage between the heat exchange plates, and second inlet and outlet channels through the package for a second heat exchange medium, which communicate with remaining flow passages between the heat exchange plates, and along each of the inlet and outlet channels the port portions of adjacent heat exchange plates which form a flow passage separated from the inlet and outlet channel, respectively., being permanently joined around the inlet and outlet channel, respectively, between an outer line and an inner line, located closer to the inlet and outlet channel, respectively, characterized by means arranged to keep the port portions of the heat exchange plates together along the inlet and outlet channels, said means being placed along each of the inlet and outlet channels in the plate interspaces communicating with said inlet and outlet channels, respectively, and in each such plate interspace being permanently connected to both of the heat exchange plates delimiting the plate interspace in question in an area around the inlet and outlet channel, respectively., located between said inner line and the inlet or outlet channel, itself.