Patent ID: 7192656

Claim:
A zinc galvanizing method for a single surface of a metal tube, said method comprising: a first step of material preparing: preparing seamed or seamless metal tubes; a second step of zinc galvanizing: placing said metal tubes in a zinc solution and carrying out galvanizing a zinc layer on both the inner surface and the outer surface of said metal tubes; a third step of washing with acid: washing and removing either of said zinc layer galvanized on the inner and the outer surface of said metal tubes finishing the second step, by using a strong acid solution; a fourth step of washing with water: placing said metal tubes with only the inner or the outer surface galvanized with zinc finishing the third step and washing off miscellaneous matter remained on said metal tubes; and, a fifth step of drying: drying said metal tube finishing the fourth step for wrapping, wherein if only the inner surface of said metal tube is to be galvanized, with the outer surface not to be galvanized, said metal tube with both the inner and the outer surface already galvanized have the two end openings sealed with stoppers of acid resistant substance, and then is washed and removed the zinc layer galvanized on said outer surface with strong acid.