Testing water lines...

[Ernest_T._Bass]

Hi everyone! I've got a plumbing question to ask..

We are finishing up all of the copper water lines in our new home. I felt like I got the hang of soldering pretty quick and did a decent job, but we wanted to test the lines for leaks before covering all the walls. Since we won't be hooking the water up to the house for a while, a friend of ours recommended we fill the system with air. So, we pieced together an adapter at the hardware store that went from a compression fitting to a bicycle-type air valve. I installed all the shut-off valves, hooked up our fitting and pumped the pipes up to 50 psi with a good bicycle pump. And, the system keeps losing pressure slowly.. I examined each joint carefully, and don't hear or see anything. There was one joint near the shower diverter that had some bubbles coming out, which I repaired. (I assume there may have been a bit of moisture in the pipe at that point that prevented a good solder joint or something..)

Anyway, I'm wondering if the compression fittings on the shut-off valves are air tight? Perhaps they are only water tight? Like I said, it's a slow decrease in pressure... About a pound or two a minute. Any ideas?

Thanks,
Andrew

[MarkAndDebbie]

You said bubbles - did you put soapy water on the fittings/joints. I think I've seen someone do that to check for leaks.

[Ernest_T._Bass]

I haven't tried soapy water yet, but I think I'm going to. I'm not exactly sure what caused those bubbles, though..

[peg_688]

Ya mix some soap up in a squrit bottle , spray joints it will bubble if theres a air leak, we used to do that trouble shooting pitot static lines on Prowlers , think altimeters / airspeed stuff.

PITA to find a leak that way , but yes if your leaking air , you'd be leaking water. Anyway to hook up a small water pump / sump pump to put water in the lines ?? Borrow some water from the neighbors  

[Ernest_T._Bass]

Ok, I applied the soapy water to every joint, and found leaks in a threaded joint and a union. I used more tape and tightened 'em up and we seem to be good. At least an hour with no noticeable decrease in pressure. We're running a few lines through the gravel base for our earthen floor, so I sure hope the joints don't fail!

[glenn-k]

Lines that went under the floors in the old days had to be hard soldered - like silver solder - usually takes a higher heat torch, but best is to use a coil of soft copper so there are no joints under the ground.  Better yet is to use PEX - No joints - bends around corners and won't corrode under ground like copper --- copper should be sleeved with plastic if you put it under ground.  It won't last around here -- the ground eats holes in it.  Pex can be put together with compression sleeves if you don't have a crimper.

The others covered the testig well -- good luck.

[Ernest_T._Bass]

What exactly is "silver solder"? My roll says "Do-it-Best Silver" on it. It seemed like the typical stuff when I got it..

We will be wrapping all the pipes in foam. Does this count as a plastic sleeve?

[glenn-k]

Silver solder used to mean it had some silver in it and was a much stronger higher heat solder than regular solder.  Since lead is outlawed in water pipe solder now, most regular solder is a mix of tin and antimony I believe.

Silver solder was a higher heat application pretty well considered as similar to brazing (using brass to torch weld things with).  Now there are very good substitutes for silver solder which flow very well and make a very strong joint.

The mix of metals in your solder should be stated on the pack or roll.  Possibly it has silver in it or is a silver solder.  It would take a flux of some sort and more heat usually if that is what it is.  Flux keeps the metal from oxidizing after you have cleaned it and as you apply the torch heat to it.  Some contains a tinning compound such as zinc also.  Oxidized metal won't accept solder -- that is why it has to be cleaned with sandpaper, emery cloth or a wire brush.

[glenn-k]

the foam should separate it from the ground and help to keep it from deteriorating -- usually by electrolysis in the case of copper.

[Ernest_T._Bass]

After 12 hours, we lost a pound of pressure. Is this something to be concerned about? I could not detect any bubbles with the soapy water anywhere. I would be willing to bet that the threaded joints of my adapter are the culprit, though there's no way to be sure. The adapter consists of about 4 or 5 fittings, including a couple galvanized couplings that took a lot of tape and wrenching to stop (noticeable) leaking.

[desdawg]

Soapy water should work on the adaptor as well as anywhere else. We used to test gaslines that way. A little breeze will make the bubbles disappear as fast as the air pressure can create them in an outdoor application on a small leak. It can get pretty frustrating.

[glenn-k]

I quit using Teflon tape due to problems with it not sealing reliably - mostly on high pressure - hydraulic connections,  I use pipe dope with Teflon in it instead now.  Teflon tape is still recommended for PVC pipe as the paste pipe dope can cause problems with it.

I would like to see no pressure loss - I have seen pressure go up in a non-leaking pipe as temperature came up during the day.

[Ernest_T._Bass]

Could it be that my pressure loss was due to the cooling overnight? Perhaps I ought to let the pipes sit for a day or two and then check..

desdawg, I tried the water everywhere, including the adapter. I'm wondering if the bubbles might not be too obvious if there was a leak this slow?

[glenn-k]

That is a possibility.  

[desdawg]

Pressure will rise and fall in a pipe with heating and cooling temperatures, especially if it is in direct sunlight. How many psi are you testing at?

[Ernest_T._Bass]

No direct sunlight, bu the temperature does fluctuate quite a bit with all the windows open all the time..

I've got it at 50 psi. Isn't household water pressure usually from 40-60 psi or something like that?

[glenn-k]

That is a high average setting -- low average would be 20 to 40.

[Ernest_T._Bass]

So, do I have the pressure too high? I mean, the pipes still shouldn't leak at that pressure, right?

[glenn-k]

Test pressure is fine.  There should not be leaks.

[Ernest_T._Bass]

Ok, it's definitely still leaking.. We're down two pounds after 24 hours. I'm thinking we'll have to pump up the lines with water and probably replace the teflon tape with dope. Thanks for all the help, I'll letcha' know what happens...

[Ernest_T._Bass]

Here's an update. We pumped the lines up to 30 psi with water, and there are no leaks. I would have to bring in a different pump to get the pressure any higher. Is that something I have to do, or would any leaks have showed up with 30 pounds?

[glenn-k]

I think they would show at 30.  At the worst if one shows you will have to shut the system off and drain it and fix it.  I'd say carry on.

[Ernest_T._Bass]

I'm just worried about the couple runs through the floor.... I did notice a drop or two leak from a galvanized bushing in the adapter we put together to pump up the lines with water, even though I used plenty of thread compound. Probably where the air was leaking out in the other adapter. (I have two, one for air and one for water. Both use the same type of galv. bushing.)

[glenn-k]

If you still have them open with the pressure on you could give each joint a good visual inspection also .  Clean them well and use an inspection mirror if necessary to see underneath.  I have had one joint leak in thte past that had been sealed with flux which finally gave way and dripped a bit , requiring resoldering.  Doesn't happen often though.

[Ernest T. Bass]

Yes, I have checked everything carefully. There are only a few joints in the floor, and all of the pipes will be insulated with foam, but I'm still a little nervous about them... Probably wouldn't hurt to check the consistency of the water pressure every so often to make sure there aren't any leaks that we aren't aware of. Being that we have about a foot or two of gravel under the whole house, you'd probably never know about a leak down there. (Not saying that's a good thing...)