A plate heat exchanger comprises a plurality of heat exchanger plates joined to each other. Each plate (1) has a heat transfer area (20), a first porthole area (21), a second porthole area (22), a third porthole area (23) and a fourth porthole area (24). Each porthole area surrounds a porthole having a porthole edge (25). Each porthole area comprises an annular flat area (31), a set of inner portions (32) on the annular flat area along the porthole edge (25), and a set of outer portions (33) along the annular flat area (31) 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.