METHOD FOR INSIDE SURFACE BLOWING OF GALVANIZED PIPE

摘要

PURPOSE:To easily develop the beautiful metallic gloss of the inside surface of a galvanized pipe by blowing a prescribed concn. of a boric acid soln. to the inside surface of the pipe right after galvanizing by using the steam mixed with said soln. at a specific ratio per unit inside surface area of the pipe. CONSTITUTION:A chuck 3 is actuated by driving of an air cylinder 4 to clamp the pipe from above and below when the pipe 1 pulled from a zinc bath tank is conveyed by a conveyor 11. The steam kept under 3-5kg/cm<2> pressure is then instantaneously fed through a steam pipe 8 to a blow bell 5 and the boric acid soln. is released into the pipe 8 by opening a solenoid valve 17 of a boric aid soln. supply pipe 15 at the same timing as said feeding and is thereby blown to the inside surface of the pipe 1. The boric acid soln. in this case is prepd. to 0.5-3.5% concn. and the steam mixed with said soln. at 6-10cc ratio per 1m<2> of the inside surface of the pipe 1 is used. No interference colors are developed and the perfect zinc gloss is obtd. even if the steam is used according to this invention.