Large Diameter Plastic Coated Steel Pipe Process Flow

About raw materials:
1. Steel pipe manufacturing and acceptance conform to the steel pipe pressure requirements and pipeline industry standards required by the project.
2. The coating material meets the technical requirements of the project, and its performance complies with the provisions of the CJ/T120-2016 standard for plastic-coated composite steel pipes for water supply.

Processing process
1. Steel pipe surface treatment.
The inner and outer surfaces of the steel pipe are shot-blasted by shot-blasting equipment. After treatment, they meet the Sa2.5 level requirements specified in the GB8923-1998 standard. After shot blasting, they are purged with vacuum adsorption equipment to achieve level A cleanliness and remove dust and oil. Inspect the quality, cleanliness, and depth of the anchor pattern of the surface pretreatment. Plastic coating can only be carried out after passing the test.

2. Pipeline preheating.
The pipes that have passed the shot blasting and de-rusting treatment are heated to the temperature range required by the process (200°-220°), and the heating must be even, and the inside and outside are heated at one time to avoid damaging the coating by secondary heating. If the temperature is too high or the temperature is too low, it will cause insufficient coating adhesion and affect the service life of the plastic-coated steel pipe.

3. Plastic coating processing inside and outside the pipe.
Generally, the outer wall of the pipeline adopts the spray coating process, and the inner wall of the pipeline adopts the roller coating process. A common tool for spraying the inner wall of a pipeline is a compressed air spray gun, which is used to spray the inner and outer walls of the preheated pipeline. The coating thickness depends on the spray volume of the spray gun and the speed of the line. The thickness of the coating can be adjusted by adjusting the spray volume of the spray gun and the speed of the line. The coating thickness is generally 150μm~600μm.

4. Solidify and cool.
The solidified plastic-coated steel pipes are cooled and placed in the inventory yard to await inspection.

5. Inspect the packaging.
Inspection of plastic-coated steel pipes coming off the production line mainly includes:
Check whether the appearance is smooth and burr-free, use instrument tools to check the coating thickness and check the pipe's adhesion, corrosion resistance, density, and other parameters. At the same time, the pipe walls that are difficult to paint automatically are re-coated with manual spray guns. Products that pass the inspection will be spray-labeled.

6. Packaging and transportation.
During transportation, the packaged coated composite pipes should be protected from violent impact, throwing, and exposure to the sun. Dragging and scratching with sharp and hard objects are strictly prohibited. Nylon straps should be used for lifting when loading and unloading. Small-diameter plastic-coated steel pipes must also be packed to prevent them from rolling off during transportation.