When selecting tubing for a product, choices are numerous and can sometimes become overwhelming. These choices are mainly down to the characteristics of the tubing, which include material selection, dimensions, tolerance, and what process is used to manufacture the tubing. The three methods used in tube fabrication are called seamless, welded, and drawn. Each of these methods has advantages and disadvantages respectively.
Seamless tubing is fabricated by drawing the material through a die. This produces a seamless tube, which does not have the variants usually found in welded products. There are two potential problems caused by this process. However, due to the limited use of various materials, the diameter of the tube is smaller, which means that there is the risk of the lubricant used in the drawing process not being fully removed from the inside of the tube, thus leaving impurities.
In terms of the requirements needed for a quality tubing, the three methods have strengths in various fields, such as:
Burst strength – seamless provides the strongest burst strength for the same material type and tube dimensions.
Roundness – welded tubing can have a problem with roundness, which is eliminated in both seamless and drawn tubing.
Consistency of wall thickness – plug drawn tubing provides the most consistent wall thickness, while seamless provides the least.
Corrosion resistance – seamless tubing has the greatest corrosion resistance, as the tube is made of all the same material without any weld seam.
Cost – seamless is the most expensive option and welded is the least expensive.