Processing process of large-diameter plastic-coated steel pipe for water supply

1. Surface treatment of steel pipe:
The inner and outer surfaces of the steel pipe are shot-blasted by shot-blasting equipment. After treatment, they meet the Sa2.5 requirements in the GB8923-1998 standard. After shot blasting, the vacuum adsorption equipment is purged to achieve Class A cleanliness and remove dust and oil. Check the quality, cleanliness, and fixation depth of the surface preparation, and use plastic only after it is qualified.

2. Preheat pipe:
The pipes that have been shot blasted and trusted are heated to the temperature range required for the process (200°-220°), and they need to be heated evenly, both inside and outside at one time, to avoid damaging the coating by secondary heating.

3. Plastic coating inside and outside the pipe:
A common tool for spraying the inner walls of pipes is a compressed air spray gun, which is used to spray the inner and outer walls of preheated pipes. The coating thickness depends on the spraying amount and linear speed of the spray gun. The coating thickness can be adjusted by adjusting the spraying amount and linear speed of the spray gun. The coating thickness is generally 150μm~600μm.

4. Solidify and cool:
The solidified plastic-coated steel pipe is cooled and placed in the stockyard for inspection.

5. Check the packaging:
To inspect offline plastic-coated steel pipes, the inspection methods mainly include: checking whether the appearance is smooth and burr-free, using instruments and tools to check the coating thickness, and testing the pipe’s adhesion, corrosion resistance, density, and other parameters. At the same time, the pipe walls that are difficult to spray automatically are re-sprayed with a manual spray gun to mark qualified products.

6. Packaging and transportation of large-diameter plastic-coated steel pipes for water supply:
When transporting packaged coated composite pipes, severe impact, throwing, and sun exposure should be avoided. It is strictly forbidden to drag or scratch with sharp hard objects. Nylon straps should be used to lift when loading and unloading. Small-diameter plastic-coated steel pipes should also be packed to prevent the plastic-coated steel pipes from slipping during transportation.

Application fields of large-diameter plastic-coated steel pipes for water supply:
1. Urban large-diameter and small-diameter water pipes, direct drinking water transportation, and food pipelines.
2. Pipelines used in pharmaceutical, chemical, printing and dyeing, and other industries;
3. Pipes, cables, and communication cables used in marine and offshore engineering;
4. Chemical water treatment systems, roads, and river projects;
5. Oil and gas pipelines, oil field anti-corrosion pipes, fire protection pipelines, highway pipelines, etc. are all application fields of internal and external plastic-coated steel pipes.