DN1700 hinged expansion joints with 904L (1.4539) bellows were manufactured from 3 x 0.6mm layers for low spring rates. Addition of copper to 904L gives it corrosion resistant properties superior to the conventional chrome nickel stainless steels, in particular to sulphuric, phosphoric, and acetic acids. This grade is non-magnetic in all conditions and has excellent formability and weldability. Main field of application are offshore, seawater technology, chemical industry, good stability against reducing acids of medium strength like sulphuric acid and phosphoric acid and various chloric media, refinery, pulp and paper industry.