Marine Grade Black Steel Pipe

The time of issue:2014-9-9 9:45:50       Author:

The majority of black steel pipe contains nickel and more elements might be added for a number of reasons. However, in most cases, it is done particularly to change the crystal structure of black steel pipe from ferrite to austenite. To be more specific, austenitic black steel pipe is ductile, tough and, most importantly, easy to form and weld. The steel materials are not magnetic in the annealed condition but they are widely used in the world. The lower carbon version is also popular on the black welded pipe since black steel pipe is always preferred in more corrosive environments where welding is involved. There are numerous applications for different black steel pipe grades, ranging from domestic kitchen sinks to commercial food processing equipment and to chemical plant piping.

In some cases, molybdenum is added to black steel pipe to increase their corrosion resistance, particularly in marine and acidic environments. It will also increase the pitting and crevice corrosion resistance of black steel pipe since corrosion might be caused by the highly aggressive chloride ion. It is present in salts, such as sea salt and table salt and they are sometimes referred to as the marine grades of black steel pipe. For instance, black welded pipe is widely used for items such as boat fittings and they are also known as the acid resistant grades since they have better corrosion resistance in some acids. But their range of black steel pipe applications is wide, and we may use black steel pipe in aggressive atmospheres and in onboard chemical tankers. For most corrosion resistant applications, black steel pipe strength is not a key issue. There are exceptions, such as pressure vessels since high strength of duplex grades can make black welded pipe more attractive.

A characteristic of black steel pipe is that they harden easily and their strength increases rapidly when they are formed at ambient temperatures. This is especially true in rolling or wire drawing operations. And this characteristic is valuable in items like bolts and springs that are made from black steel pipe. Two important physical properties of black welded pipe are thermal conductivity and thermal expansion rate. In the case of common austenitic stainless steels, some black steel pipe has lower thermal conductivity than other steel pipes. And this is useful in applications such as thermos flasks since their rate of thermal expansion is also greater than ordinary steel pipes. Therefore, care must be taken in using black welded pipe during welding so as to ensure that the recommended jigging and tacking procedures are followed closely. Uniform corrosion might take place on the entire surface of the steel pipe except in special environments such as strong acids.

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