voids in solder

[Plumberx]

Hi,

Is there anyone knowing the cause(s) of voids in soldered copper joints?
On the picture it's a 3/4" copper fitting (90 elbow) from a cold peeled joint :
(One straight cut on the length of the fitting with a 4 1/2" x 3/64" disc then the 3/4" pipe has been cut and separated from the fitting with pliers).

The voids are often near the base of the fitting so I suppose it's not caused by a bad cleaning job (also simply because I cleaned everything very well, using nitrile gloves, 120 emery cloth and scotch brite, wire brush, dust was removed. Flux was stired and applied with a clean brush.

Tried to keep the flame moving (pencil flame 1/2 , ts8000 on a low setting) and on the base of the fitting at an angle (towards the pipe) but it didn't help.

Maybe the tube is becoming too cold because of the cold solder entering the joint...

Or the flux is removed because of overheating, how to avoid this if it's the case?

I tried a lot of different things...

Thanks

 

[Geofd]

Hi,

Is there anyone knowing the cause(s) of voids in soldered copper joints?
On the picture it's a 3/4" copper fitting (90 elbow) from a cold peeled joint :
(One straight cut on the length of the fitting with a 4 1/2" x 3/64" disc then the 3/4" pipe has been cut and separated from the fitting with pliers).

The voids are often near the base of the fitting so I suppose it's not caused by a bad cleaning job (also simply because I cleaned everything very well, using nitrile gloves, 120 emery cloth and scotch brite, wire brush, dust was removed. Flux was stired and applied with a clean brush.

Tried to keep the flame moving (pencil flame 1/2 , ts8000 on a low setting) and on the base of the fitting at an angle (towards the pipe) but it didn't help.

Maybe the tube is becoming too cold because of the cold solder entering the joint...

Or the flux is removed because of overheating, how to avoid this if it's the case?

I tried a lot of different things...

ThanksView attachment 17109

was there any closed ends causing pressure when there is pressure sometimes itsharder to solder what kind of flux was it paste or liquid you keep the flame moving wipe the excess flux and by that time it should be hot enough
is the solder balling up and falling off that means there no flux

 

[Mr_David]

could be type of solder you are using.
What type of flux are you using.
Solder alloys have a variety of alloy mixes.
The lead free solders don't flow as nicely as the leaded version but most solder these days are lead free.
I have several photos of burnt joints that I have collected over the years but yours look like a problem with the flow.

 

[Plumberx]

No closed ends.
I tried several fluxes (nokorode water soluble and regular, laco water soluble, oatey#5 and 95 tinning (not the water soluble stuff). All were pastes. With water soluble bernzomatic flux, only with this one the voids were blackened. For the solder I took oatey safeflo and sterling premium. The problem was there more or less with all of these.

On the picture oatey #5 and safeflo were used but it's the same with other brands.

Solder was pulled in the joint and a drip came out on the bottom of the joint at the end (I'm no more saying when full). On the picture the drip is located on the middle, I cut the fitting on the opposite side of the drip. The joint was soldered in horizontal position. Usually I put the solder on the opposite side of the flame.

I didn't wipe the excess flux while heating the joint if it's what you meant. Should I?
I'm heating 15-20 secs before the solder is melting.

25 years ago I soldered a few joints with liquid flux and 95-5 solder (both kester) all are still functional, no leak. Then 10 years ago I did a whole bathroom + laundry room and water heater with oatey#5 and oatey solder and no leak yet.

Recently came to replace the water heater and had to use lead free fittings. This is when I started to cold peel joints...

Here is an article saying very few joints are 100% covered:
https://www.reevesjournal.com/artic...ree-solder-joints-for-high-stress-performance

in this video at 37:15 there's a void:

 

[Mr_David]

that was a nice video. Never really peeled joint apart.
The voids could be from the size of the void between the pipe and the fitting.
The capillary action of the fluid solder looses it ability to bond with both surfaces.
Does the matching side of the void of that joint also void of solder as though it flowed across one surface but not the other?

a couple pics of burned joints.

 

[Geofd]

was there any closed ends causing pressure when there is pressure sometimes itsharder to solder what kind of flux was it paste or liquid you keep the flame moving wipe the excess flux and by that time it should be hot enough
is the solder balling up and falling off that means there no flux

not sure what your using for a torch i just use a hand held map gas set up similar to what you can get at hd or lowes map is the yellow bottle

 

[Geofd]

was there any closed ends causing pressure when there is pressure sometimes itsharder to solder what kind of flux was it paste or liquid you keep the flame moving wipe the excess flux and by that time it should be hot enough
is the solder balling up and falling off that means there no flux

not sure how many joints you have solder but it does take some time to get the hang of it i do it on a daily basis

 

[Plumberx]

Thanks for the posts and pics.
The voids on the fitting matched exactly those on the tube. Sometimes I'm wondering if there is enough space for the solder.

Or maybe I'm slightly overheating so the flux evaporates where the voids are. I can see some smoke (more with water soluble flux).

I practiced daily for months and stopped because it's too expensive. Repeating the same error over and over makes no sense. Sometimes I have no voids but it's too rare and I don't know why. I need some help.

It's a cheat but turning the tube in the fitting fills the voids. Not easy to achieve because you must constantly keep the heat while doing this and it's hard to turn anyway.

I'm using MAPP with
- TS8000 torch on a low setting (the bright blue at the base of the flame is barely visible) and try to keep 1" from the base of the flame to the fitting.
or
- Basic pencil flame 1/2"(width) x 1"bright blue cone at the base.
Also tried a mt575c torch from a friend but it's the same result.

 

[Plumberx]

you keep the flame moving wipe the excess flux and by that time it should be hot enough

I wiped the excess flux while heating, here is the result on a 90 elbow (fitting on the left and pipes on the right)

 

[TomFOhio]

Are you touching the pipe any with your bare hands. If so the oil from your skin will cause this. Do you use wd-40 or anything
like this on your copper cutters? This will definitely cause a problem.

 

[Plumberx]

Are you touching the pipe any with your bare hands. If so the oil from your skin will cause this. Do you use wd-40 or anything
like this on your copper cutters? This will definitely cause a problem.

Thanks. I was cleaning the pipe and fitting with electric contact cleaner to remove any grease but stopped doing this because it made no difference for those voids. I'm not touching with bare hands and my cutter is clean, tried all sorts of sand paper, scotch brite, emery, wire brush for the same result. Also I don't think it's a cleaning problem because the voids are very often on the bottom of the fitting. On the pictures posted here the first 1/4" is fully covered with solder.

 

[Matt30]

Are you blasting one spot on the fitting with heat? Move your torch around to prevent scorching the fitting and once solder starts to flow, take the heat away

 

[voletl]

Heating up only one side or partly heating the fitting will cause this flame needs to hit all sides evenly for full penetration

 

[Matt30]

Aside from peeling the fitting, what does the pipe look like when you sweat it off? I’m getting the feeling part of the missing solder could be from peeling it off the pipe cold. I have a hard time believing there’s this many discrepancies in your work

 

[Plumberx]

Are you blasting one spot on the fitting with heat? Move your torch around to prevent scorching the fitting and once solder starts to flow, take the heat away

Heating up only one side or partly heating the fitting will cause this flame needs to hit all sides evenly for full penetration

it's true one side is more empty than the other...

For the last picture:
I first put heat all around the tube (staying 3/4" of the fitting) till I saw the flux boiling.
Then constantly moved around the fitting for a longer time than the tube.

(I'm not convinced moving around makes a big difference since the flame even on low setting is quite large for this 3/4" fitting so it's possible I scorched it anyway).

I removed the flame for 1 second when I saw some smoke.

I wiped the excess flux while heating and the solder started to flow after this (not the first time I touched but the second time 1-2 seconds later). Then I immediately removed the flame and put it back as needed.

I initially applied the solder on the opposite side of the flame and then slightly all around.

In the past I tried heating only the other end of the elbow (without pipe on the heated side), an other time I heated the middle of the elbow and nothing else, but still had voids (located near the base of the fitting).

Thanks

 

[Plumberx]

Aside from peeling the fitting, what does the pipe look like when you sweat it off? I’m getting the feeling part of the missing solder could be from peeling it off the pipe cold. I have a hard time believing there’s this many discrepancies in your work

Didn't try to sweat off but when I turned the pipe inside the fitting while heating (not something easy), then cold peeled there were no voids.

 

[voletl]

Sweating it off isn't going to show you anything you're reheating the solder and sliding it against the pipe so it may seem like you're actually filling The voids

 

[Geofd]

can you show us a pic of your torch??????thanks

 

[Matt30]

Sweating it off isn't going to show you anything you're reheating the solder and sliding it against the pipe so it may seem like you're actually filling The voids

If it didn't take on the first go around, it's not going to take on a reheat. Leaks I've had in solder joints and brazing I've found by sweating the fitting off.

 

[voletl]

Well I hope you would have found the leak first by the water gushing out of the fitting. All I'm saying is desoldering a fitting off of a copper pipe youre going to spread the solder in the fitting and on the pipe making it appear that the sodder has been wrapped around fully. Whenever I desolder a fitting for whatever reason it looks like I have completely filled the joint