Square Steel Tube – Manufacture and Usage

A stainless steel tube is a closed structure designed to perform a specific function. Such tubing is found commonly in round, square, and rectangular shapes. Other unique shapes like oval, flat oval, or hexagon also can be found from time to time to cater to specific needs. Tubes are generally measured by their outer diameter; unlike pipes, which are measured by their inner diameter. This is because the exteriors of the tube play an important role in their application, as opposed to pipes whose insides are used for fluid flow.

Making of stainless steel tubes

There exist two types of stainless steel tubing – welded and seamless. The two differ in their manufacturing techniques. Here is how they are made.

• Welded tubing

Stainless steel tubes of this kind begin as flat rolls. These hot-rolled or cold-rolled structures are then delivered to the tubing manufacturers in coils. These are sometimes processed to remove scale and residue, improve finish, or in order to achieve a specific end feature. The coils, after such processing, are run through grooved rollers until the desired shape has been formed. At this stage the coils also have free edges that are correctly spaced for welding. Post this stage, the edges of the tube are welded together, typically using electrical resistance welding. The residue that forms on the outside and inside are removed. At this stage, the tube may still be oversized, which is why it is then passed through two semicircular rollers that smooth it to its final outside dimension.

• Seamless tubes

Seamless tubing begins in a melting furnace or an electric arc furnace where the steel gets cast as an ingot or continuously as a bloom. This is then rolled into a billet, and subsequently into a tube by being drawn over a piercing tool. This tool contains two external rollers set at an angle to each other, which helps move the billet. This results in the formation of a rough tube. Post this process, the crudely formed tube is passed through an elongator. In this process, three rollers and an internal mandrel shape the tube, creating a product close to its final outside diameter and wall thickness. After this process, the tube goes through a reducing mill and sizer, which improve the final finish and bring the tube to its exact outer dimensions.

Welded and seamless square steel tubing can also be manufactured by cold drawing. In this method, the tube is drawn over a mandrel to form it into its necessary shape. Cold drawing results in tubes with better physical properties and surface finish.

Welded tubing was initially thought to be weaker than seamless ones, as welded joints became weak spots that could deform easily. However, with advanced technology, it is possible to manufacture welded tubing with the same strength and resistance as that of seamless tubing.

Uses for square steel tubing

Square shaped stainless-steel tubing finds many applications. This is because square sections enhance the reliability of structure. Some advantages of tubing of this kind include good resistance to torsion, high impact strength, better tensile strength, dimensional accuracy, and good weldability. The primary use of square steel tubing lies in the construction industry where it is used for load bearing purposes. Such tubing can be seen as columns in residential or commercial buildings under construction. In interiors, they can be found on railing handles, and often as exhaust pipes, or other structures exposed deliberately for a chic industrial feel. Square tubes are also used for support applications in the automotive industry, transmission tower plants, storage systems, machinery industry, and many others. They also play an integral role in the medical industry – as protective railings, in procedural equipment etc.

The reason that square steel tube finds such extensive application is because the metal that makes it is extremely strong, durable, and highly resistant to corrosion, fire etc. Additionally, the square shape gives such tubes the advantage of better dimensional accuracy for use in structural applications.

Pin It on Pinterest