Hot dip galvanized pipe is causes the molten metal and alloy layerandiron substrate reaction and attack so that the substrate andcoatingcombination of both. Is hot dip galvanized steel pipes topickling, inorder to remove iron oxide on the surface of the steel tubeafter acidpickling, ammonium chloride or zinc chloride or ammoniumchloride andzinc chloride mixed aqueous solution to clean in the tank,and thensent to the hot dip plating tank. Hot dip galvanized withuniformcoating, strong adhesion, long life and other interests. Withmoltensolution attack messy physical, chemical reaction, to form thestructuretight a zinc alloy corrosion resistant layer. Pure zinc alloylayer andlayer and steel substrate. So the corrosion resistant ability.