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  1. #1
    Join Date
    Apr 2004
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    MN
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    21 foot sections?

    Can anyone tell me why black iron pipe comes in 21 foot lengths? Seems like such an odd number. It's not like you have to account for saw kerf or anything.
    A Veteran is a person, who at some point in their life, wrote a blank check payable to the United States of America for payment up to and including their life.
    Gene Castagnetti-Director of the National Memorial Cemetery of the Pacific in Hawaii

  2. #2
    Join Date
    Feb 2007
    Location
    Helena, Montana
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    2,155
    Misconceptions
    One common misconception is that the standard length of 21 feet is the result of a metric conversion, while another suggests that it is to conform to the average length of a flat-bed truck. Neither of these theories is generally accepted.

    History
    For much of its existence, steel pipe was produced using some variation of the bell and tong method, which utilized a heated strip of steel that was pulled through a cone-shaped hole to curve it into a tube. As it turned out, 21 feet was the length at which the steel could both hold a quality weld along the seam, and exhibit the necessary yield for forming the tube.

    I had looked this up before, but had to go look it up again on ehow to find the answer! I knew it had to do with production.
    Don't worry zombies are looking for brains, you're safe...

  3. #3
    Join Date
    Apr 2004
    Location
    MN
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    1,829
    Still seems odd that they would not cut it back to 20 feet. Thanks for the reply though.
    A Veteran is a person, who at some point in their life, wrote a blank check payable to the United States of America for payment up to and including their life.
    Gene Castagnetti-Director of the National Memorial Cemetery of the Pacific in Hawaii

  4. #4
    Join Date
    Feb 2005
    Location
    Barrie, Ontario
    Posts
    4,622
    Funny... As soon as I saw 21 foot sections, I knew what this was about :P
    Is this a Fabreze moment? C.Y.D. I'm voting white elephant. 2’.
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  5. #5
    Join Date
    Apr 2004
    Location
    MN
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    1,829
    I guess what is still bothering me about this is the fact that nowadays, they are pulling hundreds of feet of pipe at a time using mass production equipment that is much more efficient at heating/forming/welding than they were decades ago. So why not make the change and standardize with all the other pipe on the market at 20 feet? I suppose about the time they do something like that, I will need a 21 foot section on a job and would have to use a coupling and 12" nipple to extend the 20 foot pipe I'm currently asking for.
    A Veteran is a person, who at some point in their life, wrote a blank check payable to the United States of America for payment up to and including their life.
    Gene Castagnetti-Director of the National Memorial Cemetery of the Pacific in Hawaii

  6. #6
    Join Date
    Jan 2007
    Location
    Mn the state where absolutey nothing is allowed
    Posts
    1,375
    steel gas mains used these with double nut compression fittings ( normacks). about 50-60 years ago. if you see patches every 20 or 40 0r 60 feet in the street thats where the repairs on the normacks have taken place
    my boss thinks its possible to repeal the laws of physics

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