method of cleaning the inner surface of copper tubes to prevent corrosion caused by carbon film

摘要

1461961 Making copper tubing SOC ANON DES USINES A CUIVRE ET A ZINC DE LIEGE 5 July 1974 [6 July 1973] 29981/74 Heading B3A [Also in Division C7] A method of making copper tubes in coil form comprises drawing a copper tube, passing therethrough steam to which a degreasing substance has been added, whereby to remove a residual stretching lubricating film which would on reheating in manufacture be cracked and give rise to formation on the internal surfaces of the tubes of an undesirable carbonaceous film, and subsequently annealing the tube. The degreasing agent may be petrol, benzene, a surfactant, soda solution, or preferably trichlorethylene or perchlorethylene. A typical sequence after drawing is (1) inject degreasing agent, (2) inject steam, (3) inject further degreasing agent, (4) inject further steam, (5) blow with compressed air to evaporate residual water, (6) purge with gas to prevent oxidation during annealing and (7) introduce coil into annealing furnace.