Copper pipe question

[projectPONY]

I'm trying to expand the copper line that I have coming off my compressor. Does anyone know if this will get me an air tight seal?

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[Piper27]

As long as you put pipe dope on the threads it will.

 

[projectPONY]

Pipe dope??

 

[imnutz]

Thread sealer or teflon tape

 

[Oakster]

Plumbers putty

 

[pattenp]

Plumbers putty

Plumbers Putty ..... NO.

Pipe Dope .... YES.

 

[akdiesel]

What they said but I can't see a reason for that from your compressor. Instead i would use a union.

 

[pattenp]

What they said but I can't see a reason for that from your compressor. Instead i would use a union.

akdiesel got me thinking.... Why are you using a threaded connection if you are just extending a line? Why not solder in a coupling? Do you want to be able to disconnect it later? If you need it to be easily disconnected then the Union would be best.

 

[projectPONY]

Yes, I wanted something to easily disconnect but now that I think about it, with a "t" I plan on having off this line, disconnecting it will be impossible. So I guess a union is the way to go.


Thanks fellas.

 

[akdiesel]

Ok so that works, but even with a union, they can leak some times as well. Use a little pipe dope on the sealing surface of the union to help get it sealed tight.

 

[projectPONY]

ok now I'm really confused. pipe dope instead of solder for the union??? or pipe dope along with the solder??

please pardon my ignorance. I actually taught myself to solder just a few months ago, so all this is new to me.

 

[djjsr]

There are 2 methods to normally connect copper pipe.

This is a union. Both ends get soldered onto the pipes but it can be unscrewed to disconnect the joint. Pipe dope is not necessary.

This is a coupling. Both ends get soldered and it can not be disconnected unless you unsolder. That little dimple in the middle is there so each pipe goes into the coupling halfway.

Those fittings in your first picture are called adapters and are used for connecting a copper pipe (soldered) to a threaded pipe.

 

[Lhorn]

I used the unions above (green colored one) for both my air and for a water filter I installed outside my home. In both cases I used no sealant and had trouble getting rid of leaks. I don't care too much about the air system because it's a slow leak and I shut off the ball valve when I'm not using it. with the water leak, it was only with a lot of muscle that I was able to get it to stop leaking. I looked after the fact online and see that those types of unions can be a bit prone to leaking if the mating surfaces aren't made well.

 

[pattenp]

ok now I'm really confused. pipe dope instead of solder for the union??? or pipe dope along with the solder??

please pardon my ignorance. I actually taught myself to solder just a few months ago, so all this is new to me.

The pipe dope is only used on the mating surfaces where screwed together if you find you have a small leak. The two halves are soldered onto the pipe as normal... flux and solder. I have a union on my line from the compressor and even with a good tightening it still leaked a little. So a little pipe dope smeared on the mating surfaces stopped the leak. The quality of some unions aren't as good as others.

 

[Spareparts]

The more Chinese **** we get the more leaks we are going to have be it air water or fluid. Their tolerances are not as close as good old USA.

 

[JakeKohl]

There are 2 methods to normally connect copper pipe.

This is a union. Both ends get soldered onto the pipes but it can be unscrewed to disconnect the joint. Pipe dope is not necessary.

This is a coupling. Both ends get soldered and it can not be disconnected unless you unsolder. That little dimple in the middle is there so each pipe goes into the coupling halfway.

Those fittings in your first picture are called adapters and are used for connecting a copper pipe (soldered) to a threaded pipe.

It should also be pointed out that in that pictured union, (the puke green colored) nut is freewheeling and not connected to the other puke green part...there is usually an o-ring between the two pipes and the nut threads one pipe to the other and compresses the o-ring for a air/water tight seal. You can completely separate the two by unthreading the nut....

and always remember to install the nut before you solder on the fitting that captures it!

 

[akdiesel]

The pipe dope is only used on the mating surfaces where screwed together if you find you have a small leak. The two halves are soldered onto the pipe as normal... flux and solder. I have a union on my line from the compressor and even with a good tightening it still leaked a little. So a little pipe dope smeared on the mating surfaces stopped the leak. The quality of some unions aren't as good as others.

Thanks for correcting my some what confusing comment.

 

[R6 Racer]

I used a few unions in my air line system & have had no leaks in them at all.
An old plumber told me to use both teflon tape & pipe dope on all threaded joints. He basically guaranteed me that "you will never have a leak".

Wrap the threads with teflon tape, 2 layers only, then put your dope on top of the tape filling all the thread groves. Of course you have to make sure to tighten the coupler tight enough to seal but not too tight as to start to strip threads.

Go with the unions, Its way easier to take a section down to work on it, than to try to work on it while its still hung. (In most cases).

Steve