"engsol" wrote in message
...
On Mon, 03 Jan 2005 11:53:24 GMT, "Roger Long"
wrote:
bit snipped for brevity
One more point....a 1 1/2 inch "pipe" on a thru-hull is indeed 1 1/2
inches, but that's the ID.
The wall thickness is the "schedule", and I noticed that the old
thru-hulls have
a greater wall thickness, but not so much as the proclude screwing on a
modern
seacock.

Regards, Norm B

Just to explain this further to prevent any misunderstanding:

While it is true pipe is measured by it's inside diameter, the size stated
is a nominal size. The outside diameter of a pipe does not change as the
pipe's schedule changes. The actual inside diameter does. For example a 1
1/2 inch pipe has an outside diameter of 1.90 inches weather it is schedule
40 or 80. The inside diameter does vary with schedule 40 1 1/2" pipe having
an ID (inside diameter) of 1.61 inches and schedule 80 1 1/2" pipe an ID of
1.50 inches.

This constant outside diameter allows plumbers to use one set of cutters and
the same setup to cut threads onto the outside of any schedule pipe of the
same nominal dimension. And any threaded pipe of a certain nominal size (of
any schedule) will thread into any fitting of the same size (assuming they
both have tapered (NPT) threads or both have straight (NPS) threads). Clear
as mud?

For further info go to http://www.mts.net/~william5/library/pipe.htm and
scroll down to the QUICK REFERENCE CHART.

Happy New Year all!
--
Ken Heaton & Anne Tobin
Cape Breton Island, Canada
kenheaton AT ess wye dee DOT eastlink DOT ca