Passivation of small diameter stainless steel tubes, e.g. hypotubes comprises arranging them upright in holder, flooding them with electrolyte, applying suction, draining electrolyte, flooding with water and draining

摘要

Passivation of stainless steel tubes (5), e.g. hypotubes, with an internal diameter of 150mu m and a length of 150 cm comprises: (A) arranging the tubes upright in a holder surrounded by a larger diameter tube (1); (B) flooding them with an electrolyte; (C) applying suction to them; (D) draining the electrolyte; (E) flooding them with water; and (F) draining the water. An independent claim is included for apparatus for carrying out the method comprising a large diameter tube with a base (6) with a liquid inlet and outlet (9) and a cap (7) with a vacuum connection (8). A sieve (2) is mounted above the base and a tube holder made up of uprights (3) and horizontal grids (4) stands on this.