When steel pipes are coated with a solvent-water solution and then dried, if they are not heated to the required drying temperature for hot-dip galvanizing and contain excess moisture, they are considered not to be thoroughly dried. The consequences of inadequate drying can lead to the following problems:
(1) It fails to adequately expel the hydrogen gas generated during the pickling process within the steel pipe's metal substrate, affecting the quality of the galvanized layer.
(2) It causes unnecessary corrosion of the steel pipe's metal substrate, producing iron chloride, which increases zinc consumption and results in a rough galvanized layer.
(3) The aluminum component in the zinc bath undergoes intense oxidation due to moisture, generating a significant amount of aluminum oxide (Al₂O₃), which not only wastes aluminum but also accelerates solvent aging.
(4) When moisture encounters hot zinc liquid, it rapidly turns into water vapor, hydrogen, and oxygen, causing the zinc liquid inside the steel pipe to eject violently from exposed holes, posing a danger, wasting zinc, and resulting in missed galvanizing spots.
(5) The water vapor produced when moisture encounters zinc liquid can intensely oxidize zinc at 350°C. Given that the zinc liquid itself operates within a temperature range of 470-500°C, the oxidation becomes even more intense, leading to increased zinc consumption and inferior galvanized layer quality.
