Steel Pipe Anti-Corrosion Coating Process

Because steel pipes are susceptible to chemical or electrochemical reactions during the use and transportation of the environment and the transport medium, the use of steel pipe anti-corrosion
paint is a method to effectively prevent corrosion of the steel pipe.

1. Analysis of the current status of anti-corrosion coating technology for steel pipes. At present, there are four main types of factory-automatic coating processes for seamless steel pipes such as welded pipes and oil casing pipes commonly used at home and abroad:

Steel pipe anti-corrosion coating process 1: using the spray coating method, the front, the rear and the intermediate roller are directly conveyed to form a coating film. Then the fork is transferred,the hook-shaped chain is rolled and conveyed, and the steel pipe enters the steam oven horizontally and is heated and dried;

Steel pipe anti-corrosion coating process 2: using electrostatic coating method, before, after and during the application, the inclined roller conveyor is spirally conveyed to form a coating film.Then screw lift , transfer to the rack for cooling and natural drying;

Steel pipe anti-corrosion coating process 3: steel pipe straight conveying, using UV coating system, vacuum coating method, plus air flow scouring to form a coating film. Immediately after application,curing the film with UV radiation. It is characterized in that the formation and solidification of the coating film are completed between the two rollers;

Steel pipe anti-corrosion coating process 4: coating adopts heating airless spraying method, applying roller conveyor before coating, and applying segmented synchronous “V-shaped tooth” chain
conveying after coating to form coating film. After coating, the steel pipe is transferred from the stepper to the horizontal “V-shaped tooth” chain conveyor into the steam drying box and heated and dried.

2. Comparison of various painting processes
Steel pipe anti-corrosion coating process 1: Due to the use of the coating method, the coating film sag is serious. Due to the unreasonable design of the roller table and the chain, there are two
longitudinal and multiple annular abrasions on the coating film. This process is being phased out. The only merit of this process is that it is heated and dried after coating;

Steel pipe anti-corrosion coating process 2: the film has the quality defects of sag, whole body spiral abrasion and whitening. Particularly serious is that the coating thickness of the spiral abrasion is only one-fifth of the specified thickness, and the appearance is very poor. At the same time, there are hidden fires in the process of electrostatic ignition. In recent years, several fire accidents have occurred, posing a threat to safe production. The absence of a drying process is also an important drawback of the process. Because of the many contradictions that are difficult to overcome and mutually constrained in this process, it has become increasingly obsolete and can no longer meet the requirements of modern factory automatic coating, and will gradually withdraw from the field of steel pipe coating;

Steel pipe anti-corrosion coating process 3: It is a technologically advanced but not very mature process. Instantly complete spraying and curing between the two rolls, the advantages of which are
not mentioned. However, there are also weaknesses that are difficult to overcome. For example, the pretreatment requirements of the surface of the steel pipe are extremely strict, and the adhesion is significantly reduced. The UV coatings and equipment are expensive, the technical management requirements are high, the coating is brittle, and the transmission process is subject to Bump, easy to partially fall off, and difficult to apply. The promotion of this process is constrained by the existence of so many problems;

Steel pipe anti-corrosion coating process 4: It is a technologically advanced and relatively mature process developed in recent years. It overcomes the serious sag, scratches, whitening, fragility and
other defects of the coating film existing in other processes. The resulting coating film has strong adhesion, flexibility, good rust prevention effect, little sag, and beautiful appearance. The process also has the characteristics of simple operation, complete support, low technical management requirements and safety. Because the technology is perfect, it is called “the complete technology of steel pipe heating and airless spraying”.

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