Copper Pipe Expansion

Ken_8

4" copper is a bear to solder. Huge tip, patience and the right solder. Most bad joints we find in large copper is from poor joint prep, excessive flux and the old, now illegal, lead based stuff.

I'd bet money it was a flawed solder job from jump street.

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Chris Schellhase

Copper Pipe Expansion

I have a domestic hot water system where all of the joints are leaking. The main problem is in the 4” copper piping between the 2,000,000 btu boiler and the 600 tank, but there are leaks elsewhere. The system is operating at 180F to 200F. The 4” copper pipe joints are soldered. The joints in the nearby cold water piping are fine so it probably is not the water quality. It is not a high velocity issue. Here is the question: The building owner decided to put the system on a time clock and turn if off every day to save energy. Could bringing the pipe temperature from 45F to 200F everyday eventually cause the joints to fail due to expansion?

Albert Huntermark

Leaking 4\" Copper

Chris,
Have you taken any of the leaking joints apart? It sounds to me like they may not have been soldered properly in the first place.

First, both fitting and pipe end must be cleaned properly. Further, when soldering large copper tubing (2-1/2" and above), both the inside of the fitting and the pipe end needs to be tinned with solder prior to be final assembly. Then the tinned parts are fluxed, put together, then heated with more solder added. Further, it is a good idea to gently tap the fittings with a wooden mallet after they are heated and the solder is in the molten state, to insure that the solder bonds. After you tap the fitting, reheat it a another time, then let the joint cool without movement. All of these steps combined, will insure that the solder penetrates completely, and bonds properly.

I think if you unsweat some of your leaking joints, you will find that there are voids in the solder. It could be the same on some of the cold water piping joints too. The expansion of the water heating is causing the leaks to show up faster on the hot water lines.

In one particular building, everytime we have a major water shut-down, we end up with a large copper fitting leaking somewhere. I always like unsweat the leaking fitting and sure enough, there are always large voids in the solder. Sometimes only the tip of the cup has solder on it! The building is over 20-years old and it amazes me that the leak didn't show up sooner!!!


Al Huntermark

Albert Huntermark

Leaking 4\" Copper

Chris,
Have you taken any of the leaking joints apart? It sounds to me like they may not have been soldered properly in the first place.

First, both fitting and pipe end must be cleaned properly. Further, when soldering large copper tubing (2-1/2" and above), both the inside of the fitting and the pipe end needs to be tinned with solder prior to be final assembly. Then the tinned parts are fluxed, put together, then heated with more solder added. Further, it is a good idea to gently tap the fittings with a wooden mallet after they are heated and the solder is in the molten state, to insure that the solder bonds. After you tap the fitting, reheat it a another time, then let the joint cool without movement. All of these steps combined, will insure that the solder penetrates completely, and bonds properly.

I think if you unsweat some of your leaking joints, you will find that there are voids in the solder. It could be the same on some of the cold water piping joints too. The expansion of the water heating is causing the leaks to show up faster on the hot water lines.

In one particular building, everytime we have a major water shut-down, we end up with a large copper fitting leaking somewhere. I always like unsweat the leaking fitting and sure enough, there are always large voids in the solder. Sometimes only the tip of the cup has solder on it! The building is over 20-years old and it amazes me that the leak didn't show up sooner!!!


Al Huntermark

BigRed

What does the tapping do?

grindog

copper piping

when you tapp the fitting it lets the solder splash around in the joint and can fill in the voids.
Would it be possible to take out all the fittings and replace them with victaulic fittings? Ridgid makes a victaulic groover that you can use to groove in place. there would be no need to take any of the pipe down also victaulic pipe has alot of deflection and can absorb expansion and contraction very well. Good luck

Chris Schellhase

These are all great suggestions. We still think it has something to do with thermal expansion caused by starting the system up cold every morning. I have already recommended replacing the pipe & fittings with Victaulic as you suggested. The owner is still looking to blame someone even though the system is 7 years old. I would like to find the exact cause of the problem so it won't be repeated on the next design. Thanks for everyone's help.

Unknown

Can you explain

what " tinning with solder " is ? I've never heard that phrase before .

I agree that it was most likely the prep of the pipe and fittings and the way the solder was applied . Could even be the solder itself ( 50-50 ? ) . A few years ago we replaced 4 big boilers in an apartment complex . The pipe was all 3 inch . We used grit cloth on pipes and fittings , went over that with steel wool , and used a good brand solder . I heated the fittings in areas - up and down on one side of the pipe till I knew the solder worked all the way down to the end . All the joints held first try .

grindog

tinning copper

Tinning copper is when you heat the pipe and run solder around it wiping off all the grapes and leaving a thin layer of solder on the pipe.
You do the same to the inside of the fitting heat it up apply solder and wipe. Make sure you use a good rag and wear gloves you can get some nasty burns if your not careful.
When you do this procedure and you fit the pipe back into the fitting you have the solder already in there and when reheated and solder is reaplied to the joint it makes a solid seal.
I recomend purchasing a good rubber mallet to ease the stress of trying to refit the piping. I use an estwing dead blow hammer it is a rubber mallet full of sand and has helped me alot with fittind big pipe.

bob young

the wrong way

tinning 4 " fittings ??????you just set pipefitting back about a hundred years. tinning was done to prepare for lead wiping not sweating. a short course at any union apprentice school is what you could use. your method is utterly ridiculous. once you tin a piece of copper & the fitting, if you think you can reassemble it without heat & muscle you are dreaming. very bad idea. if you worked for me first i beat you with your little hammer & then i fire you.

dennis02

LOL

Joe Grosso

Tinning????

WHAT ???????

Albert Huntermark

Funny, but I was taught this technique by a union plumber! In our area, they won't put large fittings together without tinning! Tinned properly, no muscle needed is needed! By the way, I wouldn't work for you anyway!

gerry gill

we tin- and thats what we were taught

by both an 82 year old master plumber who had his license before you were born most likely and is still working, and to boot, the local general motors plant union pipefitters tin anything over 1 1/4''..so if you dont want to tin Bob, then dont..the rest of you guys, do what you know works.

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Ken_8

Yeah.

Bob Young's comment is suspect.

"Tinning" is also done with soldering irons when soldering copper electrical wires/connections.

To assure the solder would flow from the soldering gun tip, which was heated so many times as to have burned flux (usually resin on electrical connections) coat the end, preventing good flow, that oxidation had to be removed by wiping it off at high temp and then refluxed and then re-"tinned" to allow proper flow of solder off the tip and into the wires. Without "tinning," the solder would not flow and "cold" electrical connections would be the result. The solder would form little spheres and simply drop to the floor or into your shoe, rather than into the stranded wire

In some very difficult situations we have "pre-tinned" copper joints of larger pipe by "coating the tubing" with a rag-wiped "solder coating" that resembles "plating" of the male tube; done the same to the socket of the female fitting, allowed them to both cool. Then very lightly sanded each inner and outer coat of solder and proceeded with typical fit-up, and because the film of solder is already in place, the possibility of "cold joints" is virtually elimintaed.

Remember, "cold joints" (leaks) are almost always caused by one of two things. Either the joint was inadequately heated in spots and the solder never really flowed into the entire joint/void; or just as likely, the joint was overheated before the solder was fully applied, and the flux was burned, making it become ANTI-FLUX!

"Burned" (overheated) flux becomes carbon. And carbon has no attraction nor cleansing atributes with regard to inducing the flow of solder. In fact it actually prevents it.

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Plumdog_2

Big Copper Joints

are not done the same way as little ones. We learned to fill the cup starting at the lowest position and draw the solder into the cup with the heat at the end of the torch while working upwards toward the top of the cup. You are not going to fill an entire 4" joint with molten solder at one time and expect it to remain in place, like you can with 1/2". I suggest you contact the Copper Institute or whatever they call it and get the proper method in hand and try it. I agree with Bob Young.

c.t.kay

larger copper fittings

why not silver solder these larger joints , much less chance of a bad joint and much faster.

Ken_8

Because...

That ain't happenin' with even the biggest Turbo Torch. At least, not with 4" 'L'.

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c.t.kay

fittings

look around ,that is why they make oxy&act torches. we use them almost daily in nyc.

Ken_8

I wonder how effective

they are with 1/2 'M'...

We're trying to solder copper tube, not anneal it!

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c.t.kay

m

lets just leave it at what was being talked about, 4 in copper. silver solder will work on all types of copper .in nyc it is code item on all water piping in bldgs over 6 stories high.

Ken_8

Next time I come

across the Hudson, work on a 6+ story building with 4" copper water lines, that happens to be in NYC, and requires silver soldering, I'll take your advice.

Until that time however...

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Unknown

You must be

a real treat to work for , Bob Young .