The production process of epoxy resin coated steel pipes inside and outside

For steel pipes coated with epoxy resin inside and outside, first pre-treat the base pipe - grind the steel pipe (Advantages: Automatic spraying makes the coating on the inner and outer walls of the base material uniform and has good leveling properties. It meets CJ/T120-2008 standards and GB/ T5135.20---2010 standard---Put the polished steel pipe into the electric oven for preheating. When the temperature reaches 230°~250° (generally preheating for about one and a half hours)--it is good for preheating Coating the pipe - after coating, put it into the curing box for curing (keep it for 15 minutes when the temperature reaches 200 degrees) - the finished product. After spraying, the heating equipment is preheated to 180 degrees to solidify the sprayed substrate. Advantages: When spraying, the epoxy resin powder has not yet been completely fused to the inner and outer walls of the substrate. After 30 minutes of preheating and solidification, the epoxy resin The curing agent in the resin is fully cured, resulting in stronger coating adhesion to the inner and outer walls.

In my country, the earliest internal and external epoxy resin coated steel pipe base pipes were galvanized steel pipes. Later, it was found that the galvanized layer on the inner wall was not beneficial to improving the adhesion of the inner coating, but had an impact. At the same time, it increased the cost of the galvanizing process. To improve the inner coating, Due to the adhesion of the coating, a dezincification process is required for the inner galvanizing of galvanized steel pipes, which again increases the cost and causes a waste of energy. Therefore, welded steel pipes are also directly coated. The steel pipe base pipe coated with epoxy resin inside and outside should be sandblasted before plastic coating to remove rust, oil stains, and galvanized layer on the metal surface, which is generally called surface pretreatment. The construction industry has no quantitative index requirements for surface pretreatment, while the petroleum industry has relatively specific requirements.