Method for carrying out outer anticorrosion on DN3600 buried steel tube by adopting molten epoxy powder

Abstract

The invention relates to a method for carrying out outer anticorrosion on a DN3600 buried steel tube by adopting molten epoxy powder, and belongs to the field of anticorrosion of tube materials. A coating process comprises material loading, preheating of the outer surface of the steel tube, deep shot blasting and derusting, superlarge power medium-frequency heating, powder spraying and coating and water cooling. Aiming at the characteristics of large diameter and extremely-small rate of the wall thickness to the diameter of a large-diameter buried steel tube with DN3600 millimeter and more than DN3600 millimeter, the method optimizes the whole machining process, controls the velocity of temperature rising, heating and cooling through the control of a moving speed of the steel tube, ensures the coating environment and the coating effect of the steel tube and the adhesion effect of a coating layer and ensures that the quality of an outer anticorrosive coating layer of the large-diameterburied steel tube meets the relevant quality acceptance standards of the state.

Description

technical field [0001] The invention belongs to the field of anticorrosion of pipe materials, and in particular relates to an external anticorrosion method for large-diameter buried steel pipes. Background technique [0002] In order to prevent buried steel pipes from being corroded and oxidized by underground moisture and various chemical substances, and prolong the service life of steel pipes, a protective layer should be added to the outside of the steel pipes to isolate or shield the corrosive environment. Among them, protective methods such as coating asphalt anti-corrosion layer, spraying the outer surface of steel pipe with epoxy powder, and adopting three-PE anti-corrosion are widely used. [0003] The epoxy powder anti-corrosion method is to dry and solidify the epoxy resin with additives and curing agents, and then crush it into powder, then spray it at a temperature above 150 degrees, and cure it on the steel pipe after shot blasting and derusting, forming a 350 t...

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Problems solved by technology

[0008] However, most of the above-mentioned technical solutions can only be applied to medium and small diameter steel pipes below DN2000 mm, and for large diameter steel pipes exceeding DN2000 mm (for example, large-diameter push-off steel pipes above DN3600 mm used in a water supply project in a certain city) , due to its large diameter, the wall thickness / diameter ratio of the steel pipe is extremely small, which brings a series of problems in heating, powder coating, heat preservation, cooling, etc. If the external anticorrosion is carried out according to the above method, it will be difficult to implement. There are many difficulties, which will eventually lead to quality problems in the adhesion, thickness, and uniformity of the external anti-corrosion coating, and it is impossible to produce products that meet the specifications.

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