Circular hollow section steel pipe

Circular hollow section is a hollow structural section that is a type of metal profile with a hollow tubular cross section. The common type of circular hollow section in the steel pipe market is round steel pipe. The transformation of steel strip into circular hollow sections is the result of a series of operations including forming, welding and sizing. Electric resistance welding technology is one of the commonly used processing in the steel pipe manufacturing. In the tube mill, flat steel strip is formed continuously around its longitudinal axis to produce circular hollow sections.

Seamless steel pipe and welded steel pipe are the two common type of circular section in use today. Nowadays, welded circular hollow sections with a longitudinal weld are mainly made employing either electrical resistance welding processes or induction welding processes. Circular hollow sections have the most effective cross section for resisting torsional moments, because the material is uniformly distributed about the polar axis. Large circular hollow sections are generally made by rolling plates to the required shape in a mill. And the longitudinal weld is made by a submerged arc welding process. Besides, another process for large tubes is to use a continuous wide strip, which is fed into a forming machine at an angle to form a spirally formed circular cylinder. And then the edges of the strip are welded together by a submerged arc welding process to produce a spiral steel tube.

As one of the common structural steel pipes in the steel pipe industry, circular hollow sections after galvanization in a mill offer advantages of corrosion protection in applications. Some hollow sections have rounded corners resulting in a better protection than that with sharp corners. This is especially true for the joints in circular hollow sections where there is a smooth transition from one section to another. Meanwhile, this better protection increases the protection period of coatings against corrosion. In the current steel pipe market, besides circular hollow sections, square and rectangular hollow sections and some other shapes are also available for certain applications in life. Today, some China steel tube manufacturers are committed to customized shapes as per the specific requirements of clients in the world. For example, the elliptical hollow sections have become more popular for architectural designs. Of course, you can often find that some other shapes of hollow structural sections have been used in a variety of infrastructure construction around us.