1. Surface treatment of coated steel pipe: The inner and outer surfaces of the coated steel pipe are shot blasted by shot blasting equipment. After treatment, it meets 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 fixing depth of the surface pretreatment, and the plastic can be used only after it is qualified.
2. Preheating coated steel pipe: The coated steel pipe that has been shot blasted and rust-removed is heated to the temperature range required for the process (200°-220°), and it needs to be heated evenly, heating the inside and outside at one time to avoid secondary heating to damage the coating.
3. Plastic coating inside and outside the coated steel pipe: The common tool for spraying the inner wall of the coated steel pipe is a compressed air spray gun, which is used to spray the inner and outer walls of the preheated steel pipe. The coating thickness depends on the spraying amount and line speed of the spray gun. The coating thickness can be adjusted by adjusting the spraying amount and line speed of the spray gun. The coating thickness is generally 150μm~600μm.
4. Curing and cooling: Cool the cured plastic-coated steel pipe and put it into the yard for inspection.
5. Inspection and packaging: Check the offline plastic-coated steel pipe. The inspection methods mainly include: checking whether the appearance is smooth and burr-free, using instrument tools to check the coating thickness, and testing the adhesion, corrosion resistance, density, and other parameters of the coated steel pipe. At the same time, the coated steel pipe wall that is difficult to spray automatically is re-sprayed with a manual spray gun, and qualified products are marked.
6. Packaging and transportation of large-caliber plastic-coated steel pipes for water supply: When transporting packaged-coated composite pipes, violent impact, throwing, and sun exposure should be avoided. It is strictly forbidden to drag and scratch with sharp hard objects. Nylon belts should be used to lift during loading and unloading. Small-caliber plastic-coated steel pipes should also be packaged to prevent plastic-coated steel pipes from slipping during transportation.
7. Application fields of large-diameter plastic-coated steel pipes for water supply:
(1) Large-diameter and small-diameter urban water supply steel pipes, direct drinking water transportation, and food steel pipes.
(2) Steel pipes used in the pharmaceutical, chemical, printing and dyeing industries;
(3) Steel pipes, cables, and communication cables used in marine and offshore engineering;
(4) Chemical water treatment systems, roads, and river projects;
(5) Oil and gas steel pipes, oilfield anti-corrosion steel pipes, fire protection steel pipes, highway steel pipes, etc. are all application fields of internal and external plastic-coated steel pipes.
Post time: Jun-09-2025