Manufacturing method of environmentally-friendly type hot galvanized steel pipe

Abstract

The invention discloses a manufacturing method of an environmentally-friendly type hot galvanized steel pipe. The manufacturing method comprises the following steps: at first, carrying out pretreatment and hot galvanizing on the steel pipe, then, adopting a spraying manner to spray chromate-free passivation agent on the outer surface of the hot galvanized steel pipe, soon afterwards, adopting an air knife to blow off redundant passivation agent effusion on the surface of the steel pipe, and finally drying the galvanized steel pipe. The water-based chromate-free passivation agent comprises thefollowing components: A, anion acrylate modified epoxy resin, B, nanoscale modified alkaline silicasol, C, molybdate and D, alkaline zircon salt. The hot galvanized steel pipe manufactured through themanufacturing method is environmentally-friendly, has high corrosion resistance, heat and humidity resistance and weather fastness, can replace a traditional chromium-containing galvanized steel pipein the hot galvanized steel pipe industry, is expected to be widely applied in the hot galvanized steel pipe enterprise and has extremely high industrial value and social value.

Description

technical field [0001] The invention belongs to the technical field of hot-dip plating technology and metal corrosion protection, and in particular relates to a method for manufacturing an environment-friendly hot-dip galvanized steel pipe whose surface does not contain chromium. technical background [0002] Hot-dip galvanizing technology is one of the most basic and extensive methods of steel corrosion protection in the world. Hot-dip galvanizing technology has been widely used in various fields of national economy such as metallurgy, building materials, electric power, transportation, and agriculture. Among them, the hot-dip galvanizing of steel pipes is to dip the processed steel pipes with a clean surface into the zinc solution for hot-dip galvanizing to obtain metal pipe fittings with excellent surface properties. Hot-dip galvanized steel pipes have been applied to all aspects of the national economy. The leading industries include fire-fighting pipes, construction pip...

AI Technical Summary

Problems solved by technology

[0003] However, during the storage of hot-dip galvanized steel pipes, especially in the high-temperature and humid environment in summer, the galvanized layer is prone to corrosion, which makes the surface form white corrosion products or become dark, which affects the appearance quality and quality of galvanized steel pipes. Corrosion resistance of coating

In order to prevent corrosion of the zinc layer, passivation treatment is usually performed on the galvanized layer. The traditional passivation treatment process uses hexavalent chromium chromate for passivation treatment. The hexavalent chromium passivation film has excellent anti-white rust performance. , but the resistance to heat and humidity is unsatisfactory. Hexavalent chromium passivated steel pipes tend to darken or produce black spots after high temperature and high humidity, and hexavalent chromium is extremely harmful to the environment and the human body.

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