how much margin do I have in pipe threads?

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  #1  
Old 06-10-19, 01:00 PM
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how much margin do I have in pipe threads?

I need to change out a submersible pump, the current pump has an outlet which is 1.5mm higher than the new pump, can I reuse the first segment of pipe between the disconnect and the pump. The current segment is pretty well screwed in to both the union and the pump housing?

Could i get the 1.5mm in extra length and still have the pipe make a seal? Pipe is 2Ē galvanized.
 
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Old 06-10-19, 02:36 PM
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1.5 mm is about 1/16 of an inch. Can't the pump or connecting pipe be moved this much?
 
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Old 06-10-19, 03:25 PM
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There is no predicting the length a NPT joint will be when tightened. They are tapered threads and even the same fitting can vary in dimension as the manufacturer's tooling wears with use.
 
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Old 06-10-19, 03:36 PM
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1.5 mm is about 1/16 of an inch. Can't the pump or connecting pipe be moved this much
this is a vertical segment and I have the pipe union at the exact height above the bottom of the pit where when itís screwed together the union itself seals with the cover. If itís a little lower Iíll have to re invent the whole cover situation

I remember really cranking down when I made these connections and Iím was hoping I could add a few extra wraps of Teflon or hemp and graphite (would that be better?) and get a seal at an earlier point in the taper.
 
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Old 06-10-19, 03:59 PM
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A picture would help. Adding or subtracting 1.5 mm to the cover seems like an easier task. What king of seal does the cover provide?
 
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Old 06-10-19, 04:34 PM
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No easier way than trying. And the answer is a big fat no.

Back to the drawing board.
 

Last edited by Esand1; 06-10-19 at 04:56 PM.
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Old 06-11-19, 10:28 AM
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If you can't provide a picture, how about a sketch showing the 1.5mm problem?
 
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Old 06-11-19, 02:12 PM
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Old 06-11-19, 02:22 PM
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There is a picture of how it looks with the new pump installed, as you can see, with the same pipe connected to the new pump the pipe Union is located in the middle of where the cover I had previously was located.

the fundamental issue is that the house was built for a surface pump like this one:



And so using a submersible pump requires me to McGyver some sort of cover to cover the hole.

i had previously used a thick piece of sheet metal and it just so happened that the pipe Union was at the exact height where the union itself closes around the sheet metal.
 
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Old 06-11-19, 03:32 PM
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I would loose the union and use a Fernco (rubber boot). Gobs of adjustment and easy to install.
 
  #11  
Old 06-12-19, 04:52 PM
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Can't the collar with the hose clamps give you 1/16 vertical adjustment?
 
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