The formation process of large-diameter 3PE anti-corrosion steel pipes is generally as follows:
1. Pre-treatment of large-diameter steel pipes: Large-diameter steel pipes are inspected, and those with obvious defects are discarded. Then, shot blasting or sandblasting is used to remove oil, rust, dust, and other impurities from the surface of the large-diameter steel pipe, ensuring the surface reaches the specified cleanliness and roughness, generally SA2.5 level, to enhance the adhesion of subsequent coatings.
2. Heating of large-diameter steel pipes: The pre-treated large-diameter steel pipes are heated to a suitable temperature using medium-frequency heating equipment, generally to 180-220 degrees Celsius, so that the epoxy powder can better fuse to the surface of the large-diameter steel pipe.
3. Spraying epoxy powder: Using electrostatic spraying equipment, epoxy powder is evenly sprayed onto the surface of the heated large-diameter steel pipe. Epoxy powder melts rapidly at high temperatures and bonds tightly to the surface of large-diameter steel pipes, forming a continuous and uniform anti-corrosion coating, typically greater than 100 micrometers thick. This coating provides excellent corrosion resistance, directly protecting the surface of the large-diameter steel pipe from chemical corrosion.
4. Adhesive Wrapping: Before the epoxy powder coating cools and cures, an adhesive layer is wrapped around the epoxy powder coating using an extruder. The thickness is generally 170-250 micrometers. Its function is to firmly bond the epoxy powder layer and the outer polyethylene layer together, preventing coating peeling and cracking.
5. Polyethylene Wrapping: Following this, a high-density polyethylene layer is wrapped around the adhesive layer using an extruder. The polyethylene layer thickness is generally 1.8-3.7 mm. This layer has good corrosion resistance, wear resistance, and impact resistance, effectively isolating the surface of the large-diameter steel pipe from contact with the external medium.
6. Cooling and Shaping: After the three-layer coating is applied, the large-diameter steel pipe is cooled by spraying water to quickly solidify and shape the coating, ensuring that the three layers are tightly bonded together to form a stable anti-corrosion structure.
7. End Treatment: The ends of the cooled large-diameter 3PE anti-corrosion steel pipe are treated. A beveling machine is typically used to bevel both ends of the large-diameter steel pipe, creating a weld joint of a certain length (e.g., 15 cm) to facilitate welding during pipe installation.
8. Quality Inspection: A comprehensive inspection of the large-diameter anti-corrosion steel pipe is conducted using equipment such as an electric spark leak detector to check for defects such as leaks and pinholes in the coating. The coating thickness and adhesion are also tested to ensure that all indicators meet relevant standards and requirements.
9. Packaging and Warehousing: The inspected and qualified large-diameter 3PE anti-corrosion steel pipes are packaged according to customer requirements, typically using methods such as bunding and adding protective sleeves, and then stored in the warehouse or shipped to the construction site.
Post time: Mar-05-2026