After the square tube is heated, a layer of black oxide skin will appear, which will affect the appearance. Next, we will explain in detail how to remove the oxide skin on the large-diameter square tube.
Solvent and emulsion are used to clean the surface of large-diameter square pipe to remove oil, grease, dust, lubricant and similar organic matters. However, it can not remove rust, oxide scale and flux on the surface of large-diameter square pipe, so it is only used as an auxiliary means in anti-corrosion operation.
Generally, chemical and electrolytic methods are used for pickling treatment. Only chemical pickling is used for pipeline anticorrosion, which can remove oxide scale, rust and old coating. Sometimes, it can be used as the reprocessing after sand blasting. Although chemical cleaning can make the surface reach a certain degree of cleanliness and roughness, its anchor pattern is shallow and easy to cause pollution to the surrounding environment. Large diameter square pipes shall be submitted for acceptance in batches, and the batch rules shall comply with the provisions of the corresponding product standards.
The inspection items, sampling quantities, sampling positions and test methods of large-diameter square pipes shall be in accordance with the provisions of the corresponding product standards. With the consent of the demander, the hot-rolled large-diameter square tubes can be sampled in batches according to the rolled root groups.
If the test results of large-diameter square tubes fail to meet the requirements of the product standards, the unqualified ones shall be picked out, and double number of samples shall be taken from the same batch of large-diameter square tubes for re inspection of the unqualified items. If the re inspection result (including any index required by the project test) is unqualified, the batch of large-diameter square pipes shall not be delivered. If the following inspection items fail to pass the initial inspection, re inspection is not allowed: a There are white spots in the macroploid tissue; b. Microstructure.
Post time: Aug-22-2022
