Processing process of large-diameter plastic-coated steel pipe

1. Surface treatment of steel pipe.
The inner and outer surfaces of the steel pipe are shot blasted by shot blasting equipment, and the treatment reaches the Sa2.5 level requirements stipulated in the GB8923-1998 standard. After shot blasting, the vacuum adsorption equipment is purged, the cleanliness reaches level A, and dust and oil are removed. The quality, cleanliness, and anchor pattern depth of the surface pre-treatment should be inspected. Plastic coating can only be carried out after passing the test.

2. Pipeline preheating.
Heat the pipes that have passed the shot blasting and rust removal treatment to the temperature range required by the process (200°-220°). The heating must be even and the inside and outside are heated once to prevent damage to the coating by secondary heating. layer. 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 on the inside and outside of the pipe.
Generally, the spray coating process is used for the outer wall of the pipe, and the roller coating process is used for the inner wall of the pipe. 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 assembly line. The coating thickness can be adjusted by adjusting the spray volume of the spray gun and the speed of the assembly line. The coating thickness is generally 150μm~600μm.

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

5. Check the packaging.
Inspect the plastic-coated steel pipes that come off the production line. The inspection methods mainly include: checking whether the appearance is smooth and free of burrs. Use a meter tool to check coating thickness. Check the adhesion, corrosion resistance, density, and other parameters of the pipeline. At the same time, the pipe walls that are difficult to be painted automatically are repainted with manual spray guns. Products that pass the inspection will be spray-labeled.

6. Packaging and shipping.
During transportation, the packaged coated steel 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.