On Sep 5, 2004, at 5:05 PM, Pete's Mail wrote:
> you will find the bores are also not exactly 1/2" or 1" but have an
> odd exact dimesion
For cultural value, the reason the actual pipe ID is larger than the
nominal is to provide an allowance for fouling and scale. The reason
that 2x4 lumber is called 2x4 is that the finished lengths are made
from sections that actually are 2 inches by 4 inches. And the US sheet
steel gage numbers denominate unit weight rather than thickness. 3 gage
plate weighs 10.00 lb/ft2, with the nominal thickness based on a
density of 0.2904 lb/in^3, which in turn derives from taking the weight
of a steel plate 1 inch thick as exactly 41.82 lb. This isn't strictly
correct, but the nominal thicknesses got into common use before anyone
knew better. The best advice these days is to order by thickness and
don't bother about gage numbers.
Christopher Wright P.E. |"They couldn't hit an elephant at chrisw@skypoint.com | this distance" (last words of Gen.
...................................| John Sedgwick, Spotsylvania 1864)http://www.skypoint.com/~chrisw Received on Sun Sep 05 20:30:00 2004
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