On Tue, 05 Mar 2013 13:22:02 -0500, wrote:

On Tue, 5 Mar 2013 11:18:31 -0500, "Jim Wilkins"
wrote:

"Joe Gwinn" wrote in message
.. .
In article
,
Pilgrim
wrote:

Can any one tell me what the difference between rigid conduit and
iron
pipe? inner finish threads on the pipe and in the fittings and any
other
significant differences.

It's not a good idea to use iron water pipe for rigid conduit, even
though the sizes are similar, because water pipe usually has a rough
and sharp longitudinal welded seam that will cut through the wire
insulation during pulling. Conduit, being intended for wire, has a
smooth-walled bore.

Joe Gwinn

Is either better for structural uses?
jsw

Yes and no -depends. Black Iron water/gas pipe today is pretty much
an unknown, quality-wise. Cheap rough Chinese crap in many cases - in
which case Rigid conduit MAY be stronger/more predictable.

ASTM A53 is the standard that covers common steel plumbing pipe in the
US. Even Home Depot and Lowes cite that spec for the black pipe they
sell, so I don't think it's fair to say that the quality of black pipe
is an unknown. It may not be exactly what one might want for a
particular purpose, but it is qualified for its intended use.

The steel dealers around here stock uncoated A53 pipe, which is much
better looking than the black stuff, and preferable if you're welding
or painting it.

--
Ned Simmons