Plastic-coated Steel Pipes

Tianjin Lefin Industrial Co., Ltd is one of the most experienced manufacturers and suppliers of plastic-coated steel pipes in China. Please feel free to buy high quality plastic-coated steel pipes from our factory. Good service and reasonable price are available.

The full name of plastic-coated steel pipe is plastic-coated composite steel pipe. It is made by using steel pipes (such as straight seam welded pipes, seamless steel pipes, spiral welded pipes, etc.) as the base material.

Through processes such as electrostatic spraying, hot immersion plastic coating, and melt adsorption, a uniform plastic coating layer is evenly applied to the inner and outer walls or the inner and outer surfaces of the steel pipes. After high-temperature curing, it forms a steel-plastic composite pipe material. The core is to integrate the mechanical strength of the steel pipe with the protective characteristics of the plastic.

The mainstream coating materials can be classified into two categories, and the choice between single-layer or composite structure can be made based on the working conditions:

• Epoxy Resin (EP, fused epoxy powder): Mostly food-grade epoxy powder, with strong adhesion, dense coating, excellent thermal resistance (able to withstand 80-100℃ for a long time), and meeting hygiene standards. It is the preferred material for internal coatings in drinking water, hot water, and chemical pipelines.
• Polyethylene (PE): Outstanding in impact resistance, weather resistance, and chemical corrosion resistance. It can adapt to pH 2-12 acidic and alkaline media. It is more suitable for use as an external coating for buried pipelines or an internal coating for the transportation of sewage and highly corrosive media.
• Composite Coating Structure: Common combinations include "inner epoxy + outer polyethylene". The inner wall ensures transportation efficiency and hygiene, while the outer wall enhances the anti-corrosion ability for burial and the resistance to mechanical damage; there is also a low-cost solution of external galvanization and internal plastic coating, which combines the cathodic protection of the galvanization layer with the protection of the coating.

The essence of the coated plastics process is to upgrade the performance of ordinary steel pipes. Its core value lies in:

• Solving the problems of easy corrosion, easy scaling, and short service life of steel pipes at their root by creating a dense coating that isolates water, soil, and corrosive media from contacting the steel pipe base;
• Retaining the advantages of high strength, high pressure-bearing capacity, and resistance to deformation of steel pipes, while endowing plastic with the characteristics of corrosion resistance, low resistance, and hygiene, achieving complementary advantages in material performance;
• Significantly reducing the operation and maintenance costs throughout the entire life cycle of the pipeline, minimizing the costs of repairs and replacements due to corrosion leakage and scaling blockage, and achieving much higher comprehensive benefits in buried and highly corrosive environments compared to ordinary steel pipes.

Coated steel pipes are widely used in various fields including municipal, industrial, and energy sectors:

• Municipal Water Supply and Drainage: For the transportation of drinking water and municipal sewage/recycled water, they are the mainstream upgraded and alternative products to traditional galvanized steel pipes and cast iron pipes.
• Fire Protection Engineering: For fire sprinkler systems and main water supply pipes for fire protection, they are resistant to corrosion and scaling, ensuring long-term non-clogging and reliability of fire water supply.
• Chemical Corrosion Prevention Field: For the transportation of chemical acid, alkali, and salt solutions, as well as corrosive fluids, and for seawater desalination and coastal infrastructure projects.
• Energy and Mining: For oil and gas field gathering pipelines, mine pulp/tailings transportation, and power plant circulating cooling water systems.
• Other Scenarios: For power cable protective conduits, heating and ventilation air circulation water pipes, and clean fluid transportation pipes in the food and pharmaceutical industries.

• High mechanical strength and strong pressure-bearing capacity: The base material is steel pipe, which has much higher resistance to impact, tension, and geological settlement deformation than pure plastic pipes. It can adapt to complex construction and geological conditions.
• Excellent corrosion resistance and long service life: The coating is dense without pinholes, which can resist various corrosive environments such as soil, seawater, acids, alkalis, and salts. Under normal conditions, the service life can reach 30-50 years, which is 3-5 times longer than that of ordinary steel pipes.
• High transportation efficiency and low operation and maintenance costs: The inner wall is smooth, with a friction coefficient of only about 1/3 of that of ordinary steel pipes. It is not prone to scaling or waxing, and the transportation resistance does not increase significantly over a long period of operation. The energy consumption and maintenance costs for cleaning and repair are low.
• Hygienic and safe, suitable for a wide range of working conditions: The food-grade epoxy coating complies with drinking water hygiene standards and does not release heavy metals. Different coating formulas can adapt to temperature ranges of -30°C to 100°C, covering various working conditions such as cold water, hot water, and corrosive media.
• Strong installation compatibility: It can be connected by various methods such as grooved connection, flange connection, and welding (welding joints need on-site repair), and is fully compatible with traditional steel pipe construction techniques. No additional replacement of construction tools is required.