Huayang Steel Pipe, a renowned figure in the pipeline equipment manufacturing industry, is set to revolutionize the pipeline anti-corrosion sector with its upcoming anti-corrosion workshop, scheduled to commence production in June. This state-of-the-art facility is equipped with a meticulously designed process flow that combines cutting-edge technology and strict quality control measures, promising to deliver top-notch anti-corrosion solutions.
1. Pipe Inlet: Seamless Transportation to the Production Line
The process kicks off with the pipe inlet stage. Here, an innovative "tumbler" mechanism is employed to transport steel pipes to the end of the platform. Subsequently, a pipe transporter smoothly shifts the pipes from the tumbler rack onto the shot blasting transmission line. This seamless operation efficiently moves the steel pipes from the outdoor pipe rack to the shot blasting line, setting the stage for the subsequent processes.
2. Surface Preheating: Ensuring Optimal Conditions for Rust Removal
To enhance the effectiveness of shot blasting and eliminate surface moisture, the steel pipes undergo surface preheating. This is achieved through medium-frequency heating, which raises the temperature of the pipes to the required level. By doing so, not only is the surface moisture removed, but the shot blasting process that follows can achieve a more thorough rust removal and create an ideal surface condition for subsequent coatings.
3. Outer Wall Shot Blasting for Rust Removal: Precision and Quality Assurance
Two shot blasting machines are arranged in series to carry out the outer wall shot blasting process. This step serves a dual purpose: removing surface rust to achieve a cleanliness level of Sa2.5 as defined by GB/T 8923, and creating an appropriate roughness with an anchor pattern depth of 50 - 90µm. This roughness significantly increases the contact area with the FBE coating, promoting better adhesion. The series arrangement of the shot blasting machines ensures a comprehensive and high-quality rust removal process.
4. Rust Removal Inspection: Stringent Quality Control
After shot blasting, a strict rust removal inspection is carried out on the inner and outer surfaces of the steel pipes. Qualified pipes proceed to the next workstation, while those that do not meet the standards are subject to repair. Defective pipes are clearly marked and moved to a designated area. This inspection step is crucial in maintaining the overall quality of the anti-corrosion products.
5. Outer Anti-Corrosion Pipe Loading: Smooth Transition to Coating
Steel pipes that have passed the rust removal inspection are transferred from the pipe platform to the coating fast - forward transmission line using a pipe transporter. Once in place, the fast - forward roller control is activated to initiate the transportation of the pipes, preparing them for the coating processes.
6. Dust Removal: Preparing for Coating Application
Before powder spraying, the steel pipes are likely to accumulate dust during storage and transportation. To address this, a rotating brush is used to clean the surface dust, and an external common bag dust collection device is employed to remove the loosened particles. This ensures a clean surface for the subsequent coating application, which is essential for the quality of the final product.
7. Medium-Frequency Heating for Coating: Melting and Bonding
The spiral transmission line moves the steel pipes to the heating station. To enable the epoxy powder to melt and gel on the steel pipe surface, the pipes need to reach a specific temperature. Medium - frequency heating is used, where the steel pipes passing through the medium - frequency coil generate induced current eddy currents on their surfaces, heating the steel. Typically, the inner surface of the steel pipes is heated to 180℃ - 220℃.
8. Epoxy Powder Spraying: Forming the Protective FBE Coating
The heated steel pipes are then sprayed with epoxy powder. The epoxy powder melts, gels, and cures on the hot steel pipe surface, forming a FBE coating with a thickness that meets relevant standard requirements. This coating provides an initial layer of protection against corrosion.
9. Adhesive Extrusion Winding: Creating the Bonding Layer
The adhesive layer is applied using the extrusion hot - winding method. A dedicated extruder melts and plasticizes the base adhesive, which is then extruded as a ribbon - shaped film through a flat - mouth die and continuously wrapped around the rotating and advancing steel pipe surface. This forms an intermediate bonding layer with a thickness of 170 - 250μm, ensuring a strong bond between the FBE coating and the outer protective layer.
10. Polyethylene Extrusion Winding: Adding the Outer Protection
Similar to the adhesive extrusion winding, high - density polyethylene is melted and plasticized by a dedicated extruder and extruded as a ribbon - shaped film through a flat - mouth die. This film is then continuously wrapped around the rotating and advancing steel pipe surface, forming the outer protective layer. This layer provides enhanced protection against external factors such as moisture and mechanical damage.
11. Water Cooling: Tempering the Coated Pipes
After the coating and wrapping processes, the steel pipes and their coatings are at a high temperature and require immediate water cooling. Sufficient cooling is necessary to bring the temperature below 60℃ before the pipes can be removed from the production line. Additionally, rapid water cooling has a "quenching" effect on HDPE. As a highly crystalline polymer material, HDPE's grain structure is refined through quenching, enhancing its toughness.
12. Coating Inspection: Multiple Checks for Quality
The coating inspection process involves both visual inspection and instrument - based inspection. Visual inspection focuses on the surface quality of the coating, while instrument inspection includes spark - testing for leaks and thickness measurement using a thickness gauge. Only anti - corrosion pipes that pass these inspections can move on to the end - cleaning workstation.
13. Pipe End Coating Grinding: Precise Finishing
The anti - corrosion pipes are placed on a beveling machine using a transporter. The end - beveling power brush is moved to grind the bevel, with the bevel angle controlled below 30°. The length of the reserved part at the pipe end is adjusted according to the pipe diameter, ranging from 110 - 150mm. This step ensures proper connections and seals when the pipes are installed.
14. Marking and Packaging: Ready for Shipment
Finally, the inner and outer surfaces of the pipes are marked according to standards, and they are wrapped with straw ropes before being shipped. This marking and packaging process ensures that the products can be easily identified and safely transported to their destinations.
With this comprehensive and advanced process flow, Huayang Steel Pipe's new anti - corrosion workshop is well - positioned to offer high - quality anti - corrosion products, further strengthening its position in the global pipeline equipment market.
