I need to know the torsional strength (in lbs/ft) of 1" and 1.25"
square tubing in ASTM A500 Grade B and ASTM A513 carbon steel.  Wall
thickness is .065"

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Request for Question Clarification by redhoss-ga on 02 Sep 2006 06:41 PDT

I can answer your question for ASTM A500 Grade B using published
numbers for yield strength (46,000 psi). However, ASTM A513 refers
only to method of manufacture: Electric-Resistance-Welded Carbon and
Alloy Steel Mechanical Tubing. If you have specific yield strength, we
can use that number. I am assuming that you want to use yield and not
ultimate (tensile) strength. Also, torsional moment is expressed in
ft-lbs not lbs/ft.

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Clarification of Question by twisterman-ga on 03 Sep 2006 06:09 PDT

In regards to the ASTM A513 question, the material grade would be
1010.  Also, to my knowledge, lbs/ft and ft/lbs are commonly
interchanged.

lbs/ft means pounds per foot, obviously not the same thing as feet per
pound.  if you're talking torsion, you mean pounds times feet,
commonly written ft-lbs or lbs-ft.  probably would be better to use
ft*lbs, but nobody does.

there are some people who try, ad nauseum, to force you to
differentiate between ft-lbs and lbs-ft (one being torsion and one
being energy; i forget which is supposed to be which), but these
people are nitpicking and best ignored by normal humans.

-cab