Thanks for your comments, Andy. Very helpful. I would still like to know more about large diameter extrusion technology. A college saw a Popular Science (or similar) issue some time ago that touted the potential ( for economy, cost, strength, etc) in extrusion.
What are the comparitive benefits (strength, cost) of manufacturing a large diameter (10')tube versus a welded box shape for handling of liquids. Each ten foot diameter section would 30' plus in length.
What is the potential for extruding such a large diameter tube?