What are the main characteristics of large-diameter internally and externally coated steel pipes

Coated steel pipes, also known as plastic-coated pipes, steel-plastic composite pipes, or plastic-coated composite steel pipes, are steel-plastic composite pipes formed by fusing a layer of plastic anti-corrosion coating onto the inner and outer surfaces of a steel pipe through processes such as spraying, rolling, dipping, and suction.

The main characteristics of coated steel pipes are as follows:

1. Excellent corrosion resistance: Both the inner and outer walls of coated steel pipes undergo special anti-corrosion treatment, typically using high-molecular materials such as polyethylene (PE) and epoxy resin (EP) for coating. These coatings effectively isolate the steel pipe from contact with the external environment, preventing corrosion from moisture, oxygen, and corrosive substances in the soil, thus greatly extending the service life of the steel pipe.

2. Good mechanical properties: Coated steel pipes have high strength and rigidity, capable of withstanding significant pressure and tension. Simultaneously, they also possess good toughness and ductility, allowing them to adapt to a certain degree of deformation without cracking.

3. Hygienic and Non-toxic: The inner wall coating of plastic-coated steel pipes is smooth and flat, making it less prone to scaling and preventing the growth of bacteria and microorganisms, thus meeting national drinking water hygiene standards. Therefore, plastic-coated steel pipes are widely used in urban water supply and drinking water transportation.

4. Low Resistance and High Flow Rate: The smooth inner wall of plastic-coated steel pipes results in low fluid resistance, effectively improving transportation efficiency and reducing energy consumption. Compared to traditional steel and cast iron pipes, plastic-coated steel pipes can transport a larger flow rate under the same conditions.

5. Easy Installation: Plastic-coated steel pipes are lightweight and offer various connection methods, such as threaded connections, flange connections, and grooved connections, making installation convenient and quick, significantly shortening the construction cycle.

The production process of plastic-coated steel pipes mainly includes steel pipe pretreatment, plastic coating treatment, and curing. During production, strict control of various process parameters is necessary to ensure product quality. Meanwhile, plastic-coated steel pipes also need to undergo a series of performance tests, including adhesion test, bending test, flattening test, impact test, vacuum test, high temperature test, low temperature test, pressure cycle test, temperature cycle test, and warm water aging test, to verify whether their various performance indicators meet the standard requirements.