SMC is leader in aluminum tubing, structural aluminum tubing, and standard and custom aluminum extrusions. We are capable of 

producing some of the largest OD sizes and highest precision tolerances in the industry for virtually any type of application, from 

high pressure and mechanical to architectural and framing.

Extruded tube is brought to final dimensions by the hot extrusion process and can be seamless or non-seamless. Although you 

cannot visually tell the difference between seamless and structural pipe and tube, they are different, and choosing the right one will 

depend on your application.Extruded aluminium tubes are produced essentially by the following two methods:

Extrusion through porthole dies (Fig. 1)
(s. standard EN 755-1, -2, -8) 
The essential features (including round tubes as drawing stock, hollow profiles and multiport extrusion (MPE) are: 
longitudinal pressure welds (generated in the porthole die)  
close concentric tolerances (compared to seamless tubes)
Extrusion by mandrel (Fig. 2)
(s. standard EN 755-1, -2, -7)
The essential features are
seamless tube wall (no pressure welds, homogeneous microstructure)
larger concentric tolerances compared to porthole die extrusion  
shapes limited to concentric cross-sections