Pickling Steel Tubes Using Multi-Tank and Single-Tank Methods

In the multi-tank method of pickling steel tubes, the tubes are first pre-pickled in a tank with a relatively low acid concentration but high iron salt content. At this stage, the temperature of the acid solution can be raised higher, offering several benefits. Firstly, it helps remove minor oil contamination and other impurities remaining on the surface of the steel tubes. Secondly, in the high-temperature acid pickling solution, the dissolution rate of thick mill scale accelerates, facilitating the diffusion of hydrogen atoms into the steel substrate and subsequently forming hydrogen gas. As the hydrogen gas escapes, it causes the mill scale to peel off. Thirdly, since a large amount of mill scale and other dirt are retained in the pre-pickling tank, this ensures the cleanliness of the pickling solution in the final pickling tank.