Structural Tubing is a hollow section most commonly constructed from hot rolled metal coils.  The coils are slit to the proper width for the section being manufactured and then formed into the final shape needed.  Once the size is formed and the seams are welded together the tube is cut to the desired length to make a single piece of tubing.  Structural tubing is offered in round, rectangular and square shapes.
Structural tubing is relatively low in cost, has a high strength-to-weight ratio and is easily welded, formed, punched, and drilled.  Its hollow shape protects and conceals wires, pipes, moving parts and it can be left exposed.  Additionally it can offer a lightweight alternative to solid steel products such as I-Beams and Wide Flange.  Triad Metals International offers many different sizes, lengths and specifications for Structural Tubing.
ASTM – 500 – Standard specification for cold-formed welded and seamless carbon steel structural tubing in rounds and shapes .  This specification covers cold-formed steel round, square, rectangular, or special shape structural tubing for welded, riveted, or bolted construction of bridges and buildings, and for general structural purposes.  Four grades are produced each having a different chemistry and tensile requirement.
Grades B and C, being the most common stock available, can be subjected to most of the usual fabricating operations.  Ductility is good.  Bends well, flattens, cuts, punches, flares, flanges and welds easily.