The invention relates to a spiral heat exchanger (1) including a spiral body (2) formed by at least onespiral sheet wounded to form the spiral body (2) forming at least a first spiral-shaped flow channel for a first medium and a second spiral-shaped flow channel for a second medium, wherein the spiral body (2) is enclosed by a substantially cylindrical shell (4)being providedwith connecting elements (8a, 8b, 9a, 9b) communicating with the first flow channel and the secondflow channel, where the shell (4) comprises at least two shell parts (4a, 4b), and that the spiral body (2) is provided with at least one fixedly attached flange (3) on its outer peripheral surface, whereupon the at least two shell parts (4a, 4b) are flexibly attached.