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Post subject:Round pipe seams
 Posted: May 11, 2006 - 07:45 PM #4835
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Joined: Jan 23, 2006
Posts: 1
Location: Illinois
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| Before it came from a box like it does now, was light gauge, round duct pipe field fabricated? I'm wondering how to make snap lock seams. Or what kind of seams did they used to use? Thanks. |
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Post subject:RE: Round pipe seams
Posted: May 11, 2006 - 09:36 PM #4837
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Pro Tinner
Joined: Dec 14, 2004
Posts: 201
Location: Illinois
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I bet the pittsburgh seam predates the snaplock seam.
I doubt round pipe in lengths above 2 feet was made on site. The size of the rollers needed to form the metal becomes an issue.
Every single old home with forced air heat that I have worked in has had all rectangular duct. Some of that duct was made with a groove lock seam. Lots of time involved in putting that together.
That's why the round pipe is used now. Faster to install, and easier to change directions with a couple of adjustable machine made elbows instead of retangular fittings. |
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Post subject:RE: Round pipe seams
Posted: Apr 20, 2007 - 06:59 PM #6284
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Joined: Apr 17, 2007
Posts: 9
Location: Goiania
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groove seam pre grooving machine days allowance 3 times groove allowance +3 x thickness material ie, 1/4" seam = 3/4" x 3 x thickness material + circumference of required diameter ie 7"dia duct manufactured with 20g = cut size of dia. of pipe = 2215/16" approx, 1/4" to be folded both sides 135% approx. opposite (ie turning the sheet over 180% in the folders), sheet then rolled and slid over suitable mandral, bar, the 2 1/4" edges inserted into each other knocked flat with hide mallet then finished with hammer and hand grooving tool of 5/16", back in the bad old days when TV was in black and white
it is nice to be nice |
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Post subject:RE: Round pipe seams
Posted: Apr 27, 2007 - 01:16 PM #6322
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Pro Tinner
Joined: Sep 03, 2003
Posts: 179
Location: edinburgh
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| Hate to admit it ,i dont do much duct nowadays but any i have to do is still hand grooved ,for any square or rectangular i hand form pitsburg joints on the folder ,some times the old black and white telly was best. aw ra best Marky |
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