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Re: [TowerTalk] tubing vs. pipe-- and a question

To: Jim Jarvis <>,,
Subject: Re: [TowerTalk] tubing vs. pipe-- and a question
From: Jim Lux <>
Date: Fri, 01 Jun 2007 06:22:15 -0700
List-post: <>
At 05:56 AM 6/1/2007, Jim Jarvis wrote:

>The first difference is that pipe is rated by its ability
>to carry a fluid. (gas, water, etc.)  As a result, it is
>first specified by cross sectional area... inner diameter.
>So, 2" pipe has a 2" i.d., in order that you can use flow
>tables to calculate both volume and pressure in systems.

Except for plumbing.. 1" PVC Sch 40 pipe has no dimension that's 
1".  It does have an od that's the same as some iron or lead pipe 
that DOES have a 1" id.

>There may be something I've missed, here, but I think I captured
>most of it.  Does anyone know why there is a 24'length limit on the
>normally available product?   I've always wondered, and never
>remember to ask the vendor!

Not sure, but I'll speculate that it has to do with the length of a 
truck trailer in a double trailer rig and/or the length of a flatbed 
truck for delivery.  Or maybe it's because it's twice a dozen 
feet.  (As my daughter said when doing the whole fractions thing in 
school.. Curse those Babylonians for their Base 60 number 
system).  Or maybe it's the biggest machine you could make/fit in 
some standard location back in the 1900s. (kind of like the spurious 
story about railroad gauge being related to the width of a roman 
ass). Or maybe it's to match lumber?

For extruded shapes there is a practical limit because you can only 
ram so much material through the die at one time and you have to have 
room for the extruded product.

An interesting question..


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