A plate heat exchanger including a plurality of heat exchanger plates joined to each other. Each plate has a heat transfer area, a first porthole area, a second porthole area, a third porthole area and a fourth porthole area. Each porthole area surrounds a porthole having a porthole edge. Each porthole area comprises an annular flat area, a set of inner portions on the annular flat area along the porthole edge, and a set of outer portions along the annular flat area at a distance from the inner portions. The outer portions of the first porthole area have a first relative peripheral position with respect to the inner portions. The outer portions of the fourth porthole area have a second relative peripheral position with respect to the inner portions. The first relative peripheral position includes a peripheral displacement in relation to the second relative peripheral position.