On-line automatic pretreatment process for steel pipe hot-dip galvanizing

Abstract

The invention relates to an on-line automatic pretreatment process for steel pipe hot-dip galvanizing. The process includes following steps performed on line in order: degreasing, rinsing, washing with an acid to remove rust, rinsing, performing plating assistant treatment and drying. The step of degreasing and the step of washing with the acid to remove the rust are performed at a condition lower than 40 DEG C, thus reducing energy consumption and significantly reducing discharge of acid mist and alkali mist. By adoption of the process, under the conditions of not adding a rare earth plating assistant and not adding rare earth into a zinc bath, hot-dip galvanizing of zinc-aluminum alloys can be achieved, the plating thickness of the zinc-aluminum alloy is uniform, and defects such as skip plating are avoided.

Description

technical field [0001] The invention relates to the technical field of hot-dip galvanizing, and more specifically, the invention relates to an online automatic pretreatment process for hot-dip galvanizing of steel pipes. Background technique [0002] Corrosion of steel materials occurs all the time. According to statistics, about 10% of steel products cannot be recycled each year due to corrosion. In order to prevent corrosion and reduce the huge loss caused by corrosion of steel materials, various anti-corrosion methods must be adopted. Hot-dip galvanizing treatment on steel surfaces, such as steel pipe surfaces, is a commonly used treatment method. Hot-dip galvanized steel pipe has strong corrosion resistance and strength, and can be widely used in gas, heating and water pipelines. However, even if the thickness of the single zinc coating is increased, its corrosion resistance and service life are difficult to meet the requirements of practical applications, and hot-dip ...

AI Technical Summary

Problems solved by technology

However, even if the thickness of the single zinc coating is increased, its corrosion resistance and service life are difficult to meet the requirements of practical applications, and hot-dip galvanized aluminum alloys are not easy to achieve the ideal process conditions, even if a small amount of rare earth alloys are added. The defect of missed plating; and in the prior art, the alkali washing and degreasing and pickling and rust removal processes carried out on the steel pipe are all carried out under the condition of heating, which not only consumes a lot of heat, but also produces a large amount of acid mist and alkali mist. It also needs to consume a lot of electric energy for fog collection, and a large amount of acid mist or alkali mist overflow will also affect the environment of the construction site and the health of the staff