On Jul 29, 2:04*pm, "Jim Wilkins" wrote:

Marks' Standard Handbook shows nothing. Machinery's Handbook 23 has a
couple of pages on thin- and thick-walled pressure vessel design. For
you thin means tubing, thick means drilled from solid stock.

jsw

There is also Hollow Bar. As the name suggests it is bar stock that
has a hole thru it.
There is a Seattle metalheads yahoo group. You might be ablo to
persuade someone in the Seattle area to check the specialty steel
distributor just north of where Boeing Surplus used to be. They had
remnants of hollow bar. Do not know what the situation is now.

Dan