2017-8-24 Why and how to protect the rusty stainless steel tube
Most of us have a misconception about stainless steel that it won’t rust or rust is not stainless steel. In fact, stainless steel will be rusty in certain conditions.
Stainless steel has the ability to resist atmospheric oxidation-stainless. In the mean while, it also has the ability to resist corrosion in the medium of acid, alkali and salt-corrosion resistance. But its corrosion resistance is changed by its chemical composition, mutual state, conditions of use and the type of environmental media. For example, there is absolute good anti-rust inhibitors when the SUS304 in a dry, clean atmosphere. But it will soon become rusty if it is in the waterfront area and with a large number of salt sea fog, while 316 steel pipe the performance is good. Therefore, it is not any kind of stainless steel, in any environment can resist corrosion, not rust.
Stainless steel depends on its surface form a layer of very thin and sturdy finely stability of rich Chrome Oxide Film (protective film), to prevent the continued infiltration oxygen atoms, continue to oxidation and access to anti-rust. Once there is some reason, this film has been continuously undermined, air or liquid oxygen atom will continue to infiltrate or metal iron atoms constantly resolve the formation of unconsolidated iron oxide, metal surfaces will be continuously corroded. Such damage to surface film took many forms, the daily lives. There are several:
1/ Deposited on the surface of the stainless steel contain other metal elements of attachments, or heterogeneous metal particles are managed using of dust in the humid air, attachments and the condensed steel, stainless water between the both together as a micro battery, triggers the electrochemical reaction, protective film is damaged, to call the electrochemical corrosion.
2/ The surface of stainless steel adheres to organic juice (such as vegetables, soup, process, etc.), forming organic acids (in the presence of water oxygen, and the corrosion of organic acids (on the metal surface for a long time.
3/ The surface of stainless steel adheres to contain acid, alkali, salt material (such as the alkaline water, lime water spatter), cause local corrosion.
4/ In the polluted air (such as the atmosphere with a large amount of carbon and nitrous sulphide, oxidized oxide), it can be used to form sulfuric acid, nitric acid and acetic acid, causing chemical corrosion.
The above conditions can cause corrosion of stainless steel surface protection film.Therefore, to ensure that the metal surface is permanently bright and not corroded, we recommend as below,
It is necessary to clean and scrub the surface of the stainless steel regularly to remove the attachment and remove the external factors that cause modification.
The beach area shall use 316 material stainless steel, and 316 materials can resist seawater corrosion.