This is the first time in my life that I have heard of such term: shipping tube. So I did what I think was right, ask Google.
I found that mailing tubes are long cardboard tubes designed for mailing large papers like posters, house plans or other documents. (How come I have not seen one in my Uncle’s office, who is an architect?)
Anyway, that is another term I learned. The things you discover exist just by browsing online, amazing!