Pluming ! - I plumed my shop using 1/2 inch galvanized pipes

by Pierre
(North Hills, CA)

Hi,

I plumed my shop using 1/2 inch galvanized pipes for air distribution from my 80 gallon Husky 7.5 HP.

And i was told not to use Teflon tape but that grayish pluming compound.

The problem is after connecting everything together i have air leak from few Ts and elbows.
If you can kindly tell me what compound to use as far as connecting the joints together.

Regards
Pierre

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Bill says...

Hi Pierre.

I am against plumbing compressed air using galvanized pipe. I believe that over time the oils, water and any acids that develop in the lines causing the galvanization to crack and peel and you end up with bits in your tools, valves and air cylinders.

In terms of the Teflon tape, is care is taken not to allow the the tape to cover any of the air opening, and you add sufficient layers of this very thin material to be effective, use of Teflon is functional.

As to what to use, if not Teflon tape, any joint compound used to seal pipe joints should work, if it is applied according to directions, and the threads of the two parts of the joint are tightened satisfactorily.

Cheers,

Bill

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Replacement of 12mm copper discharge line

by Sharpster
(Huntsville, AL)

Is it possible to buy a flexible stainless steel braided discharge hose for my 12mm copper tube discharge on my current compressor. I'm always having trouble with the 45 degree flares leaking and the hard copper lines have continual issues with vibration. Have noticed several newer air compressors have the flex braided lines now.

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Bill says...

Sharpster, yes, you can use the braided stainless steel as long as that hose is rated for high temperature use. The piping from the compressor pump to the tank will get extremely hot every time the compressor is used. That's why metal tube is used in the first place.

Cheers,

Bill

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question about mixing Copper and Black Iron or Galvanized Iron.

by Rick Buss
(Raleigh, NC)

I am putting in an air compressor and lines in my basement garage and shop. I am using copper for most of the lines and drops. At the compressor air port I have 3/4" galvanized pipe with a few fittings and a flexible Stainless steel line to connect it to the copper pipe via a black iron union. So one side of the union is the flex line and the other side is a 3/4" npt to a Sweated copper fitting. Do I need to worry about corrosion between the copper and the union since they are different materials? I know in water systems you need to install a dielectric union so the pipes don't corrode. I figured it would not be a problem since there is not a lot of water in the pipes to cause the corrosion you see with water systems. Is that a correct assumption or do I need to find another way to connect the copper and the black iron union? Thanks!

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Bill says....

Rick, good question.

I would expect that you will see some galvanic type reaction over time, but not being a metallurgist, I cannot give you an expert's answer.

If it were my installation, I would simply monitor it, and if I saw advanced corrosion (which may not ever occur) then I would worry about taking remedial action.

You may want to read the pages about using galvanized pipe in an air system. It's not something I would do.

Cheers,

Bill

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