First, pre-treat the base pipe of epoxy resin coated steel pipe inside and outside—-grind the steel pipe (Advantages: Automatic spraying makes the coating of the inner and outer walls of the substrate uniform and has good leveling. Meet CJ/T120-2008 standard and GB/T5135.20—2010 standard—Put the polished steel pipe into the electric oven for preheating. When the temperature reaches 230°~250° (generally preheat for about one and a half hours))—-Paint the preheated pipe—-After coating, put it into the curing box for curing (when the temperature reaches 200 degrees, keep it for 15 minutes)—-Finished product. After spraying, the heating equipment is preheated to 180 degrees to cure the sprayed substrate. Advantages: When spraying, the epoxy resin powder has not been completely fused to the inner and outer walls of the substrate. After 30 minutes of preheating and curing, the curing agent in the epoxy resin is completely cured, making the coating adhesion of the inner and outer walls stronger.
In my country, the earliest steel pipes coated with epoxy resin inside and outside were all galvanized steel pipes. Later, it was found that the galvanized layer on the inner wall had no benefit in improving the adhesion of the inner coating, but had an impact, and at the same time increased the cost of the galvanizing process. To improve the adhesion of the inner coating, the inner galvanizing of the galvanized steel pipe must also be de-galvanized, which again increases the cost and causes energy waste. Therefore, there are also welded steel pipes that are 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 layers 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 is relatively specific.
Post time: Sep-09-2024