Rectangular structural tubing (RHS) is produced from coils that are run through several different types of dies. These hollow structural tubes are welded from the inside to form their shape. These types of tubes are generally used for maintenance and structural purposes. Such as for storage systems, guardrails, construction of structures, support columns and truck frames.
Seam welding or Electric Resistance Welding (ERW) is a type of welding process where rectangular metal tubing is produced by welding the prepared edges of steel strips that are unwound from coils and side-trimmed. These strips then pass through a series of contoured rollers which cold-form the material into a rectangular shape. The edges are forced together under pressure and then welded by heating the material to temperatures above 1100° Celsius or 2000° Fahrenheit. The flash weld that has formed is then removed from the outside diameter of the tube. Once the weld has been properly tested, the tube then passes through a series of sizing rolls to attain its exact size, after which the tube is straightened and cut to specification.
There are two types of processes from which one can attain these rectangular hollow tubes: hot and cold rolling. Hot rolling is the process of creating metal sheets by passing the metal through rollers which is well above its recrystallization temperature. The metal passes multiple times through the rollers in order to produce the final dimensions.
Cold rolling is when metal is rolled at room temperature, which is well below its recrystallization temperature. This process yields metal that has increased strength and hardness. In addition to improvement of mechanical properties, cold rolling results in more control over the dimensions of the end product. Furthermore, it has improved surface finish and a stronger tolerance compared to its hot rolled variant.
When acquiring RHS (Rectangular Hollow Section) or Rectangle ERW tubes or pipes from QSIF you receive: