Stainless and acid-resistant steel and control cabinets
Control cabinets made of sheet steel are used in various industries. In most of them, the environment is neutral and the use of traditional materials without additional protection is sufficient. However, in certain industries and specific production departments, control cabinets made of stainless steel or acid-resistant steel must be used. What is the difference between these two materials, where should they be used and how should they be maintained? Below you can find the answers to these questions along with a comprehensive characteristics of these materials.
What are control cabinets?
Control cabinets are used as housings and electrical switchgear. They are designed to separate electrical switches, switchgear and control systems from space. They are used practically everywhere because in no circumstances, such equipment should be located in a commonly accessible place. Control cabinets provide protection for the above systems against adverse effects of the environment and unauthorized access. Control cabinets can be made of different materials. Usually the choice of material is determined by the conditions in which the cabinet will be used. The materials used include carbon steel, aluminium steel, stainless steel and acid-resistant steel. All elements in the control cabinet structure are usually tight welded. The cabinets are fitted with electrical, electronic, electromechanical, pneumatic and programmable equipment, i.e. all equipment that requires a high level of protection. All control cabinets available on the market should meet the requirements for tightness, corrosivity and other aspects having a huge impact on safety.
Stainless steel in the production of control cabinets
Accordingly, stainless steel control cabinets are manufactured most often. An example of steel used in the manufacture of control cabinets is 1.4301 (AISI 304) stainless steel. It belongs to a group of austenitic stainless steel and is very common in the industry. Its composition includes 18% chromium and 8.0 – 10.5% nickel. It is resistant to corrosion and, in accordance with a popular division, belongs to the group of stainless steel. This grade of steel has one more basic advantage. Namely, in case of contact with oxygen said steel passivates, i.e. generates a protective coating. It is created on the surface of steel in the form of oxides that protect the steel from corrosion. This is possible because of the chromium in the alloy, which has passivating properties that transfer onto alloys with other elements. But be aware that in situations where the atmosphere is detrimental due to high temperature, humidity or aggressive pollution, then it may be necessary to use acid-resistant steel, which have a much higher resistance to these negative factors.
Where is 1.4301 (AISI 304) stainless steel used?
As already mentioned, this type of stainless steel is very widely used. However, in the context of control panels, it is most commonly used where exposure to corrosion is moderately high. It can be used as well as wherever it can have contact with water, e.g. on wharfs, swimming pools. In addition, it is also used in urban and industrial areas where exposure to corrosive agent is small or moderate. Such steel is also used in seaports, quays, chemical plants and other places where chemical reactions causing increased corrosion can occur. It is used also in the food industry, chemical industry and in the production of hospital equipment. Its wide application in such sensitive industries can be attributed to the fact that it shows chemical inertia in contact with food, traditional chemicals, etc.
Acid-resistant steel in the production of control cabinets
Unfortunately sometimes the resistance of traditional stainless steel is too small in relation to the conditions prevailing in a given environment. It may be necessary to use acid-resistant steel. An example of such material may be e.g. 1.4404 (AISI 316L) acid-resistant steel. Owing to its composition, it is called austenitic chromium‐nickel‐molybdenum steel. It contains also a small quantity of carbon. AISI 316L steel owes its high resistance to corrosion to molybdenum content ranging from 2 – 2.5%. In comparison with the previously discussed steel and its equivalents, it is far more resistant to corrosion. Its high quality results from less carbon content. Stainless steel is resistant to intercrystalline corrosion and is also resistant to sea water. The weldability of this material is very good, although its machinability is average. The material can be polished and it is worth adding that when polished, it has improved anti-corrosion properties.
Where is 1.4404 (AISI 316L) acid-resistant steel used?
As already mentioned, acid-resistant steel has a better anti-corrosion properties. It can be used wherever regular stainless steel is not sufficient. Acid-resistant steel works well in marine, industrial, rural and urban atmospheres. It also tolerates well atmospheres associated with distilled water, mine water, mineral drinking water and river water. It is Ideal as an enclosure in sea water conditions. Very intense industrial atmospheres may cause corrosion of said steel. The steel is resistant also to oxidising processes, saline solutions and some organic acids. Its enormous resistance is however limited in the case of pitting and aggressive industrial water. Nevertheless, it is used on a large scale in the following industries:
– chemical and petrochemical,
– pulp and paper,
– synthetic fibres.
Maintenance of control cabinets
The maintenance of stainless and acid-resistant steel cabinets should be carried out mainly using non-aggressive detergents. This will allow the cabinets to serve longer and maintain their characteristics. Cleaning should be carried out regularly so that harmful conditions and substances have the least possible effect on the steel. Regular cleaning will also help to maintain the systems housed in the cabinets in proper working condition. The mobility of hinges, guides, etc. should also be ensured. These are just general guidelines and one must not forget that actual maintenance should be based on the detailed recommendations for a specific product.