Spray Winding Production Line

Product parameters: Steel pipe Φ630-Φ1620

• Spraying and wrapping insulation pipe working principle

1. Rust removal + preheating: Shot blasting is used to clean the surface of the original steel pipe, ensuring that the surface is clean and free of rust, oil stains, and other impurities. The derusted steel pipe is preheated by medium frequency to reach the required temperature, so that the polyurethane foam can better adhere to the surface of the steel pipe during subsequent foaming.

2. Spraying section: The heated steel pipe enters the spraying chamber through a spiral conveyor line for spraying. According to the set polyurethane thickness, the spray gun adjusts the pressure of the spraying machine to spray the steel pipe surface evenly. The sprayed polyurethane material foams rapidly on the surface of the steel pipe, forming an insulation layer.

3. Wrapping section: When the foamed and solidified pipe moves spirally to the PE extrusion die, the polyethylene sheet extruded from the die is evenly wrapped around the surface of the pipe insulation layer, compacted by a pressing device, and the pipe enters the spray cooling chamber for cooling and shaping to ensure that the outer protective layer and the insulation layer are tightly combined, forming a stable "three-in-one" structure.

4. Cutting and trimming: The continuously produced finished pipes are cut by a cutting saw, separating the two pipes, facilitating subsequent transportation and trimming. The trimming machine cuts the ends of the finished pipe, leaving a certain length of the original steel pipe for subsequent installation and connection.

• Spraying and wrapping insulation pipe process characteristics

The surface of the insulation layer formed by polyurethane spraying is rough, which allows the molten polyethylene outer protective layer to be pressed into the tiny recesses on the surface of the insulation layer, increasing the bonding force between the insulation layer and the outer protective layer, ensuring that the three main materials of the pipe—steel pipe, polyurethane, and polyethylene—form a strong and tight "three-in-one" structure. 
The prefabricated buried insulation pipe produced by the spraying and wrapping process allows the thickness of the polyurethane insulation layer and the polyethylene outer protective layer to be adjusted according to user needs. The production process does not require additional mold tooling investment, making it flexible, convenient, and easy to operate. Since the spraying and wrapping process does not produce expansion stress on the polyethylene outer protective layer during foaming, the polyethylene outer protective layer can be made relatively thin, saving production costs.

• Spraying and wrapping insulation pipe product characteristics

1. The density, thermal conductivity, and compressive strength of the polyurethane protective layer are uniform and consistent, resulting in good overall product performance. 
2. The polyurethane protective layer is formed by free foaming, and the direction of the bubble initiation is perpendicular to the pipe axis, improving the compressive strength of the insulation pipe. 
3. The polyurethane insulation layer is formed by spraying. The raw materials are sprayed onto the surface of the steel pipe in liquid form and then initiated. Due to the high reactivity of the sprayed polyurethane raw materials, its adhesion is superior to other processes. 
4. The surface of the polyurethane foam is rough, which is conducive to the bonding between the insulation layer and the outer protective layer. 
5. The thickness of the polyurethane insulation layer can be sprayed according to the engineering or design requirements, with a minimum thickness of 15-20mm. 
6. The thickness of the polyethylene outer protective layer can be reduced to save costs while ensuring its common functions. 
7. The polyethylene outer protective layer is formed by circumferential wrapping. Affected by the process stretching, its circumferential elongation and tensile strength are significantly improved.

• Application prospects of spraying and wrapping insulation pipes

The spraying and wrapping process technology has changed the traditional production process of insulation pipes and achieved a major breakthrough in insulation pipe manufacturing technology. The biggest advantage of spraying and wrapping insulation pipes over traditional insulation pipes is cost. The spraying and wrapping process can determine a reasonable and economical insulation layer thickness according to the temperature of the medium transported by each project, reducing unnecessary excess quality. Under the condition of low internal stress, the thickness of the outer protective layer only considers the thickness required for corrosion protection, protection, transportation, and installation. This thickness can be significantly reduced compared to the outer protective pipe wall thickness of the pipe-in-pipe process, saving costs. The spraying and wrapping production line has a compact structure and fewer links, which can reduce production costs. With the vigorous promotion of national environmental protection and energy-saving policies, the advantages of spraying and wrapping buried insulation pipes will be highlighted, and it has high promotion value.