My error. Tubing is measured OD though, right?
----- Original Message -----
From: "Rick Karlquist" <email@example.com>
To: "Tower and HF antenna construction topics." <firstname.lastname@example.org>
Sent: Wednesday, March 17, 2010 7:21 PM
Subject: Re: [TowerTalk] 2" O.D. Pipe???
> Richard M. Gillingham wrote:
>> Pipe is measured ID.. TUBING is measured OD. Try tubing..
>> Good luck.
>> Gil, W1RG
> No, pipe is measured by OD, but specified by "trade size".
> Trade size "1 1/2 inch" pipe has an OD of 1.900 inches.
> The ID varies with wall thickness. Schedule 40 has an
> ID that is slightly larger than 1.5 inches and schedule
> 80 has an ID that is slightly smaller than 1.5 inches.
> The ID can also vary depending on what material the pipe
> is made from. Thin wall sprinkler pipe has an ID that is
> considerably bigger than 1.5 inches.
> Trade size "2 inch" pipe has an OD of 2.375 inches.
> Again the ID varies above and below 2 inches.
> This is actually good because you know that anything with
> 1.9 or 2.375 OD is almost certainly water pipe, which
> you probably don't want to use for antenna support.
> The reason why the OD of pipe is invariant vs wall thickness
> is so that they only need one threading system for all
> schedules/wall thicknesses, and so that fittings are
> interchangeable between schedule 40 and schedule 80 (also
> other schedules in PVC). Also, the OD is held to a very
> close tolerance so the fittings fit, whereas the ID has
> very loose tolerances and I have found when buying actual
> pipe that it indeed varies all over the place and is sometimes
> out of tolerance, even though the tolerance is loose. I have
> probably annoyed a number of pipe salesmen by taking a pair of
> calipers to their pipes to check ID before buying.
> Rick N6RK
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