On Fri, 31 May 2002, Lee Jones wrote:

>>> Whatever, a pipe will certainly be easier to bend than solid stock.
>
>> For a given cross section of metal, the above is certainly FALSE.
>> It is the whole reason structural tubing is structural _tubing_.
>
>Agreed.  But people usually compare solid round stock to tubing
>of the same outside diameter, not cross sectional area.  Given a
>fixed outside diameter, the cross sectional area will be much
>smaller for structural tubing; specific ratio depends on radius
>and wall thickness of the tubing.

Unless it's an electrical conductor in which case the cross section
inmetal counts. This thread is/was about electrical conductors.

>For equivalent weight per length, the tubing will be _much_ larger
>diameter than the solid stock.  For example, given a cross sectional
>area of 1 square inch...
>
>solid stock:
>
>    area = pi * r^2 ; outside diameter is 2 * sqrt( area / pi )
>
>solid round stock 1.128" in diameter has a 1 sq in cross section
>
>
>structural tubing (r is outside radius, wt is wall thickness):
>
>    area = (pi * r^2) - (pi * (r - wt)^2)
>         = (pi * r^2) - (pi * (r^2 -2*r*wt + wt^2)
>         = (pi * r^2) - (pi * r^2) + (2 * pi * r * wt) - (pi * wt^2)
>         = (2 * pi * wt * r) - (pi * wt^2)
>
>solving for radius r...
>
>    r = (area / (2 * pi * wt) ) + (wt / 2)
>
>or  [monospaced font needed]
>
>            area           wt
>    r = -------------  +  ----
>        (2 * pi * wt)       2
>
>
>with 0.060" wall thickness, it takes 5.365" outside diameter
>structural tubing to get 1 sq in of cross sectional area.
>
>with 0.125" (1/8") wall thickness, it takes 2.671" outside
>diameter tubing to get 1 sq in of cross sectional area.
>
>
>Not sure if anyone cares, but I needed the mental exercise.
>
>                                                Lee Jones
>
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>
>

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