when making the pipe it was hot rolled. then run through a die to size and straigten.Along with lettering the pipe. I worked with the rail road back in the early 70's to late 90's. The youngstown sheet and tube was a 7 mile long mill. . Even had a coke mill. It is all gone. It was a awsome place to work around. A lot of people say the unions caused the sheet and tube to close. BUt in reality it was the EPA that nailed to coffen shut. Close to 8000 jobs lost plus the ripple down . There is a couple small mills still going but nothing like back in the day.
Collector of Farmall cubs and cub cadets.Injoy helping people keep their cubs running. Years of experipnce.