Black steel pipes are made of steel that has not been coated with a substrate such as zinc or paint. Since it has a dark color surface that is forms by iron oxide during the manufacturing process, it is called black steel pipe.
Seamless black steel pipes
Seamless pipes are manufactured by extruding the metal to the desired length. Thus, they do not have any joint in its cross-section throughout its length.
Manufacturing process of seamless black steel pipes
How are black steel pipes different from carbon steel pipes?
In general, black steel pipes and carbon steel pipes have almost the same procedures for welding. That is in the case of general welding, but not of some specific application like very cold temperatures. Black steel pipe is not really a specification but rather a generic term used primarily by plumbers to distinguish regular steel pipe from galvanized steel pipe.
Black steel pipes are cast from several grades of ductile or malleable iron, whereas carbon steel pipes are generally welded or seamless. Black steel pipes are used for underground or submerged applications as well as for mainstream pipes and branches subjected to acids. It is also common to use cast iron pipes and fittings for municipal cold-water lines 4″ diameter and above. Commercial die casting is unsuitable for lines subjected to expansion strains, contractions, and vibration unless the pipe is very heavy. It is not suitable for superheated steam or for temperatures above 575 degrees F. Cast iron pipes in underground applications (such as sewer lines) usually have bell and spigot ends whereas exposed pipes usually have flanged ends.
Application of Seamless black steel pipe
1. Low and middle pressure fluid pipeline
2. Casing Tube
3. Boiler Pipe
4. Petroleum and natural gas industry
5. Chemistry industry
6. Electric industry