Plate heat exchanger and method for manufacturing a plate heat exchanger

Method for manufacturing a plate heat exchanger comprising a stack of heat transfer plates, comprising the steps of:

• arranging heat transfer plates in a stack, each heat transfer plate extending in a general plane and comprising four edge parts,
• providing first flow channels and second flow channels between the heat transfer plates, with every first flow channel for a through-flow of a first fluid and every second flow channel for a through-flow of a second fluid,
• forming cells by pairs of heat transfer plates, and by arranging inner spacing elements between the heat transfer plates of a cell, the inner spacing elements extending along the four edge parts of the heat transfer plates leaving open a first inlet opening and a first outlet opening for the one of the fluids, and further by providing outer spacing elements and welding the outer spacing elements to at least one of the heat transfer plates on at least one of the sides of the heat transfer plates facing away from each other, along at least two of the edge parts;
• stacking the cells against each other and joining the cells by welding the outer spacing elements;
• providing cover plates and covering sides of the stack of heat transfer plates, thereby covering first two sides of the stack of heat transfer plates with interruption for an inlet port section formed by the first inlet openings and for an outlet port section formed by the first outlet openings,
• welding together the heat transfer plates and the inner spacing elements on second two sides of the cell not comprising the first inlet opening or first outlet opening, and
• providing leakage passageways between the heat transfer plates in the first two sides of the cell for the one of the fluids in addition to the passages of the first inlet opening and the first outlet opening by not welding together the heat transfer plates and the inner spacing elements on the first two sides of the cell comprising the first inlet opening or first outlet opening.