The reason metal tubing is commonly used is because it provides a lot strength with less metal than solid bar. Large tubing,
Ping G15 Price, 2 4 inches in diameter is used to fabricate railings that are installed along highway bridges where a very strong railing is needed should a vehicle crash into it. Using tubing as opposedto solid bar translates to less weight and lower cost,
Titleist 913 Price, both desirable to the end user of metal fabrications.