What are the principles and advantages of anti-corrosion steel pipes, and what are their coating requirements?
Release time:
2022-11-07
With the increasing development of national pipeline transportation infrastructure, pipelines have found widespread application. Coating is one of the fundamental methods for preventing corrosion of steel pipes. After removing rust from metal pipelines, the paint should be applied evenly and firmly to effectively isolate the pipe from various corrosive media. Let’s now take a closer look at the principles behind anti-corrosion steel pipes.
With the increasing construction of national pipeline transportation systems, pipelines have become widely used. Coating is one of the fundamental methods for preventing corrosion of steel pipes. After removing rust from metal pipelines, the paint should be applied evenly and firmly to effectively isolate the pipe from various corrosive media. Let’s take a look below. Anti-corrosion steel pipe The principle.
An increasing number of composite materials or composites are being used for anti-corrosion coatings on steel pipes. These materials and structures should exhibit excellent dielectric, physical, chemical properties, as well as broad temperature adaptability. Polyethylene is odorless and non-toxic, has a wax-like appearance, and is resistant to low temperatures (with a minimum operating temperature as low as 7–100°C). It boasts good chemical stability and is resistant to most acids and bases (except for non-oxidizing acids). At room temperature, it has a low water absorption rate; however, due to its linear molecular structure, it can be utilized in certain organic compounds.
Anti-corrosion steel pipe insulation layer: To reduce heat loss from soil around small- and medium-diameter thermal oil or crude oil pipelines, an additional composite insulation and anti-corrosion layer is applied to the pipeline. The commonly used insulation material is rigid polyurethane foam with a temperature range of -185°C to -95°C, characterized by its soft texture. To enhance its strength and prevent groundwater from seeping into the insulation layer, a layer of HDPE is coated on top of the insulation, forming a composite structure.
Advantages of anti-corrosion steel pipes:
1. Combines mechanical strength with the corrosion resistance of polyethylene; with an exterior coating thickness exceeding 2.5 mm, it is resistant to scratches and impacts.
2. The friction coefficient of the inner wall of the anti-corrosion steel pipe is low, fundamentally reducing frictional losses; the inner-wall anti-corrosion coating complies with recognized standards.
Main requirements for coatings:
Excellent corrosion resistance: Under the influence of corrosive media such as acids, alkalis, salts, industrial wastewater, and chemically aggressive atmospheres, the coating formed by this material remains highly stable and is not dissolved by corrosive agents. It also exhibits excellent impermeability: when the coating comes into contact with highly permeable liquids or gases, it effectively prevents these substances from penetrating and corroding the pipe surface! Good adhesion and flexibility: The coating will not peel off even if the pipeline experiences vibrations or minor deformations!
What are the applications of anti-corrosion steel pipes in daily life? There are many uses for anti-corrosion 3PE steel pipes in residential areas—such as municipal water supply and sewage disposal—but most of these pipes are buried underground. The outer wall is coated with a three-layer anti-corrosion system formed by the hot-melt wrapping process (consisting of an inner layer of epoxy resin, an intermediate layer of adhesive, and an outer layer of polyethylene), which integrates the layers into a single, robust structure. The inner wall is protected by a hot-sprayed epoxy powder coating: the powder is heated to a high temperature, melted, and evenly applied onto the pipe surface, significantly enhancing the coating’s adhesion and thickness, as well as its resistance to impacts and corrosion. Moreover, this coating process is simple to implement; both the inner and outer surfaces of the pipe can be coated and cured simultaneously, forming a continuous film in one step. As a result, this coating system is widely applicable to various anti-corrosion projects.
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