How Tube and Hollow Bar Differ

Hollow metal tubes and bar are used for various structural applications. Metal tubes and hollow bar are cheaper and weigh less than a solid metal bar, while still providing the strength of a solid metal bar. Though they look similar, the two have a variety of differences. In this article, we will see the main differences between tube and hollow bar.

Manufacturing Process

Tubing is formed by running slit coils of metal through a tube mill to create a round, rectangular, or square tubular shape. The edges are then welded together using a process such as electric resistance welding or high-frequency welding. The method used depends on the type and thickness of the metal, as well as the preferences of the manufacturers. The tube is then refined with an annealing process to create the final product.

Hollow bar is not welded together. Instead, hollow bar is created using one of two processes. The first, called drilling, involves sending a drill through a solid bar stock. The second, called centrifugal casting, is when molten metal is poured into a cast as it undergoes high-speed rotation. The high-speed rotation forces the metal to the outside of the frame, where it hardens as it cools to create a dense, uniform final product. Hollow bar typically only come in bronze and stainless steel.


The difference in manufacturing makes for a big difference in quality. Hollow bar can be created to be flexible and fit into tight dimensions in a way that tube can’t. Tubing can also result in a lower quality product when the manufacturer is unskilled.

Avoid a reduction in quality by removing the excess weld metal and heat-treating, or annealing, the tube after welding. Otherwise, crystalline structures may affect the strength and structure of the metal that develop.


Most materials can be formed into tube using the welding process. This process is appropriate for any material that conducts electricity. While hollow bars can also be made out of most materials, it can be challenging to extrude strong and hard materials.

The choice between hollow bar or tube is ultimately up to you. Take into consideration what type of project you’re doing, your desired material, budget, and your project’s final application.

Regardless of what you choose, be sure that your materials and compounds are of the highest quality by choosing Avion Alloys. We procure prime metals exclusively from United States Mills, and we are a NASA approved vendor. For a free quote, contact us at (866) 610-1660.

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