The process of galvanizing is pickling, cleaning, washing, dipping solvent, drying. The welded pipe is lifted from the truck to the pickling tank for pickling (about 2 tons per lift). About 26% of hydrochloric acid solution was pickling. In order to prevent excessive pickling and volatilization of acid mist, 0.5~1.0g/L corrosion inhibitor and fog-suppressor were added into the pickling solution, and pickling was carried out at room temperature. Pickling time was generally 30~60 minutes. To improve the effect of pickling. When the acid concentration drops to 100g/L, it should be supplemented or replaced, and the iron content reaches 220~260g/L as waste acid discharge. After pickling, the steel pipe is lifted by the truck to the cleaning tank for cleaning to remove residual acid and ferric salt accumulated on the surface of the steel pipe after pickling. Then, it is lifted to the washing bench and washed with 0.7~0.8Mpa clean water. After the water drops dry, the steel pipe is lifted to the solvent tank for dipping and dipping for about one minute. 600~650g/L zinc chloride, 80~100g/L ammonium chloride and 1~2g/L OP-10 surfactants were used as solvents. In order to improve the pre-plating effect in the solvent of the steel pipe, the solvent always maintains a weak alkaline, and then the truck is lifted to the drying stove rack into the drying furnace drying, drying temperature of 100~130 degrees, the time is generally 6~10 minutes.
The biggest advantage of sulfate galvanized pipe is that the current efficiency is up to 100% and the deposition rate is fast, which is unmatched by other galvanized processes.