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2021

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03

How to deal with the rust of stainless steel reactor

Author:


Weihai Huixin Chemical Machinery Co., Ltd. produces all kinds of stainless steel reactors, magnetic reactors, laboratory stainless steel reactors, etc. We found in the production that stainless steel will rust under certain conditions.

Weihai Huixin Chemical Machinery Co., Ltd. produces all kinds of stainless steel reactors, magnetic reactors, laboratory stainless steel reactors, etc. We found in the production that stainless steel will rust under certain conditions.

Stainless steel has the ability to resist atmospheric oxidation-that is, rust resistance, but also has the ability to resist corrosion in media containing acid, alkali, and salt-that is, corrosion resistance.

The size of its anti-corrosion ability is changed with the chemical composition of the steel itself, the state of mutual addition, the conditions of use and the type of environmental media. For example, 304 steel pipe has excellent anti-corrosion ability in a clean and dry atmosphere, but it will quickly rust in sea fog with a lot of salt in coastal areas; while 316 steel pipe performs well. Therefore, not any kind of stainless steel is corrosion-resistant and does not rust in any environment.

Stainless steel relies on a very thin, strong, dense and stable chromium-rich oxide film (protective film) formed on its surface to prevent oxygen atoms from continuing to penetrate and continue to oxidize, thereby obtaining the ability to resist rust. Once this film is continuously destroyed for some reason, oxygen atoms in the air or liquid will continue to infiltrate or iron atoms in the metal will continue to separate out, forming loose iron oxide, and the metal surface will continue to be rusted.

There are many forms of damage to this surface film, and the following are more common in daily life:

1. The surface of stainless steel has accumulated dust containing other metal elements or attachments of foreign metal particles. In humid air, the condensation between the attachments and stainless steel connects the two into a micro battery, which initiates an electrochemical reaction. , The protective film is damaged, which is called electrochemical corrosion.

2. The surface of stainless steel adheres to the organic juice (such as melon, vegetable, noodle soup, sputum, etc.), which forms organic acid in the presence of water and oxygen, and the organic acid will corrode the metal surface for a long time.

3. The surface of stainless steel adheres to containing acid, alkali, and salt substances (such as alkaline water and lime water splashing on the decoration wall), causing local corrosion.

4. In polluted air (such as the atmosphere containing a large amount of sulfide, carbon oxide, and nitrogen oxide), it will form sulfuric acid, nitric acid, and acetic acid liquid spots when encountering condensed water, causing chemical corrosion.

The above conditions can cause damage to the protective film on the stainless steel surface and cause rust. Therefore, in order to ensure that the metal surface is permanently bright and not corroded, Weihai Huixin has summarized several prevention methods in production:

1. The surface of decorative stainless steel must be cleaned and scrubbed frequently to remove attachments and eliminate external factors that cause modification.

2. 316 stainless steel should be used in coastal areas, which can resist seawater corrosion.

3. The chemical composition of some stainless steel pipes on the market cannot meet the corresponding national standards and cannot meet the 304 material requirements. As a result, rust will also be caused. This requires careful selection of products from reputable manufacturers and at the same time allow them to provide credible quality inspection reports to ensure the quality and safety of stainless steel reactor equipment.

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