brief introduction
Principle of pickling passivation: The corrosion resistance of stainless steel is mainly due to the fact that the surface is covered with a very thin (about 1nm) dense passivation film, which mainly causes iron and iron oxides to dissolve preferentially over chromium and chromium oxides. The chromium-depleted layer is removed, resulting in the enrichment of chromium on the stainless steel surface. There are various pickling and passivation technologies for stainless steel, and enterprises adopt different methods according to different product types and on-site operating conditions. Now combined with the Daqing Oilfield Chemical Group's first phase project storage tank area 3 5000m3, 2 1000m3, 2 600m3, 3 100m3, a total of 10 stainless steel storage tank inner wall on-site overall pickling passivation treatment, talk about our experience.
Determination of pickling passivation process for stainless steel storage tanks
The main process of pickling passivation is: pre-treatment (purification surface) → pickling passivation and rinsing → post-treatment (finished product protection). The main content of pre-treatment is to purify the surface of pickling and passivation parts, and to remove all kinds of grease, welding spatter, welding scar, oxide skin, etc. on the surface. Pickling and passivation can be processed separately, or they can be combined into one and processed simultaneously. When the pickling and passivation are treated separately, the whole workpiece is immersed in the pickling passivation solution, which is suitable for small parts or pipelines and linear equipment with internal liquid circulation. When the pickling and passivation are combined into one treatment, the liquid immersion method can be used (the suitable range is the same as above), or the paste can be used for smearing. Because the paste is easy to apply, it can be kept for a long time in different positions without loss and wetting. Therefore, it ensures the necessary time for pickling and passivation, and is widely used in on-site pickling and passivation treatment of large equipment. The stainless steel storage tank has a large volume, so it is impossible to realize the pickling passivation in the overall soaking method, and it is impossible to realize the recycling of the pickling passivation solution in the tank. For this reason, pickling passivation can only be carried out by applying pickling passivation paste. The two processes of pickling and passivation are combined into one for processing, which saves the process and facilitates construction, and the paste can maintain a wet state for a long time, which is beneficial to ensure the effective time of pickling and passivation and ensure that a dense oxide film can be formed. . For this reason, the overall process of pickling and passivation of stainless steel storage tanks is as follows: erection of scaffolding → cleaning of plate surface → smearing of pickling passivation paste → washing with clean water (desalted water, i.e. Cl- content less than or equal to 25ppm) → neutral detection (pH value) → pickling passivation quality inspection → drying, sealing finished product protection.
Stainless steel surface pickling passivation, stainless steel surface treatment, stainless steel surface polishing and bright. Hongchang stainless steel surface treatment material research and development and production, stainless steel pickling passivation paste, stainless steel passivation solution, stainless steel electrolytic polishing solution, copper pickling solution, stainless steel pickling passivation solution, stainless steel pickling passivation agent, Tel: 0550- 7093728 Mobile: 18175233777 Contact: 18175233777.
