sweating copper pipe - leaks

[Blackhawk]

I am adding a bathroom to my basement. I installed all new copper plumbing to serve the new bathroom. I had about 6 leaks when I turned on the water for the first time. This is not my first rodeo working with copper. I have plumbed 3 other complete bathrooms in copper and have cut into existing copper on several occasions to add in a faucet. Until this basement project, I had never soldered a copper fitting that ever leaked, no kidding. I do not know what has happened to me. I ran out of solder about a 1/4 of the way through and bought a different brand, but I did have a couple of leaks with my first solder brand. I am using flux, cleaning the pipes diligently, and following all the standard procedures. Once during the install, I had one length of pipe break loose from a T-fitting while I was using a tubing cutter on the other end. The solder had not wicked into the joint and was just sitting around the edge of the fitting. I always heat the fitting and not the pipe so that the heat pulls the solder into the fitting. What could be going on?

I have started repairing the leaks, I have just been reheating the fittings so that the solder re-flows and at the same time I add a little more solder around the joint. So far this has been working. Is it OK to seal the joint up this way or could there be problems down the road?

[HayZee518]

there might be a problem down the line if there is vibration to the joint.(s) - when you prepared the tubing for solder did you apply flux to both the pipe and inside the fitting? did you touch the pipe with your finger in applying the paste flux? I'm assuming you got both the fitting and pipe end a bright finish with a fine grit emery or fitting brush. try sanding the fitting end and then solder it.

[Blackhawk]

I did apply flux to pipe and fitting. I have not been touching the flux after it is applied. I used a wire brush made for cleaning the fittings. For the pipe, I used 220 grit sandpaper to shine it super bright. That is one thing that I did differently, I have always used steel wool or a scotch brite pad in the past. But I don't see how the sandpaper would make a difference. Could it be bad to have too rough of a surface finish?

[HayZee518]

they say to have shiny copper, but the scratchy finish afforded by the emery cloth maintains "teeth" for the solder joint. you see sweat soldering isn't just applying a "coating" of solder material, it is actually joining or alloying the filler metal with the copper, much in the same way brass rod is used for brazing two dissimilar metals but at a lower temperature.

[LazyPup]

Having read all the previous posts here I see three possible causes for your problem.
1.Sandpaper should never be used. As the silica grit breaks down it leaves a micro-fine dust on the pipe making it difficult for the solder to flow. Always use Emery paper or a wire brush, then wipe the joint with a clean rag before applying flux with a flux brush.
2. If you are using MAPP that may also be a problem. MAPP burns considerably hotter than propane and will often result in burning the flux, leaving a carbon residue in the space between the pipe and fitting wall making soldering almost impossible.
When soldering copper pipes under 1" in diameter Propane is the proper fuel.
3. You may not be holding the flame of your torch in the proper orientation. For best results the torch burner should be under the pipe with the flame pointing towards the fitting and begin concentrating the heat at the point where the pipe and fitting meet. Allow a few moments for the pipe to preheat then move the flame onto the fitting with the torch still under the pipe. This will put the direction of heat flow in the same direction as the solder will need to flow. Remember that solder flows in the direction of the heat. While you are heating the underside test the heat by touching your solder to the top of the pipe. If the solder melts, pull the heat away and let the heat carry the solder.

I find the best way to clean the pipe is to use the precut "Plumbers Roll" emery cloth. It comes in a roll 2"w x 25'...They make it in both a solid backing and an open weave "screen backing". I prefer the open weave screen backing because it does load up nearly as quick as the solid backing. While a roll of he open weave will cost a couple dollars more, I think you would find that it lasts much longer and proves to be the economical choice in the end.

[Blackhawk]

I have only used propane on the fittings. (May have got the MAPP mixed up with another thread.) I will quit using the sandpaper as you suggested, that is definitely something that I had never used before. I did wipe most of my pipes with a rag after sanding, but I am sure that I missed a few. I also had not heard the tip about pointing the flame in the direction of the solder flow, so I will keep that in mind.

Of course, when I found my leaks I had already finished soldering everything. I reheated my last hot water joint with a leak to re-flow the solder. I turned the water on ever so slowly until full blast. My re-flow attempt is holding thus far. I left it on under full pressure for about an hour with no leaks and I have strong water pressure.

Do you think that I am safe?

After all this, I turned the valve on to my tub/shower valve and the threaded connection leaked! I cut the pipe, turned the threaded fitting a full 360, soldered in a coupling, and the threaded connection still leaked. I can't catch a break on this job.

[LazyPup]

Did you apply pipe dope or PTFE (Teflon) tape to the threads?

If you use teflon it should be the Red "Triple Density" type. The white single density teflon should only be used on threaded fittings 3/8" or less.

I much prefer to use thread dope for fittings in a concealed location.

[Blackhawk]

Lazypup - I used the white teflon tape wrapped three times around the 1/2" male thread on the valve. How many times do you wrap the red tape around the threads? Does the heat of sweating a joint affect the sealing of either the teflon or pipe dope? Is one or the other better in taking the heat? Any certain type of pipe dope that you recommend?

I had another question on applying the torch heat when sweating. You mention to remove the heat once the solder begins to melt and flow. Whenever I solder a tee, the heat dissipates before I can solder all three joints. I heat then solder the first joint, reheat then solder the second joint, reheat then solder the third joint. As I finish the third joint I go back and touch a little solder to the previous two joints. Is it normal to reapply the heat in this situation to get all three joints soldered?

Back to my original post, is re-flowing the solder on my leaking joints an OK rework? The solder seems to re-flow pretty well and appears to be sucking back into the joint.

[LazyPup]

You asked a number of good questions so let us try to take them one at a time.

QUESTION: PIPE DOPE OR TEFLON TAPE?

Whether you chose to use Pipe Dope or PTFE tape is purely a matter of choice however, I prefer to use the Teflon on joints which we can anticipate will require changing occasionally, such as when installing a threaded angle stop or a shower arm. Anytime I must make a permanent threaded joint in a concealed space in my opinion it is a hands down choice to use pipe dope.

If you elect to use the Red Teflon the ASTM specification calls for RED triple density tape and you must wrap 3 full turns under tension in the direction of the thread turn.

QUESTION: WHAT BRAND OF PIPE DOPE DO I RECOMMEND?

While I normally do not make any product endorsements I do make exception for pipe dope.

Technically any pipe dope, which is labeled as ASTM certified for use on "Potable Water", Natural Gas or Sanitary Sewer lines will basically meet the needs of a homeowner, but not all pipe dopes are rated for potable water, and not everyone using the dope bothers to read the labels. By example, in my local hardware they have an inexpensive gray pipe dope that is labeled "for gas only" but people grab it thinking it will work on any pipe. Would it seal a water line? No doubt it will, but consider this fact. The first responsibility of a Plumber is to insure the continued safety of the public or private water supply. If the product we use to make a pipe joint is not listed as approved on the potable water supply can we really be certain that the water would then be safe to drink? God forbid our wives or children should ever get sick because we skimped a few pennies on a cheaper material.

Of the types commonly found in the hardware stores the PTFE Paste (white Teflon paste) type is perhaps the most universally accepted. This material works fine but my singular reservation is that it is runny and extremely messy to work with. Put it on a joint and before you know it, it is on your tools, your hands and ultimately all over your clothing.

WHAT DO THE PRO’S USE?
Keep in mind that your Plumber may be working on your house today, but tomorrow he/she may be helping to build a gas station, boiler room, school, a hospital or an airport. He/she will then be faced with piping systems that the average homeowner will never see in a lifetime. In order to meet the demand the professional tradesmen needs a product with the broadest range of acceptance.

For most Plumbers, Pipe Fitters, HVAC techs and Electricians the obvious choice of pipe dope is a product called “RectorSeal”

Rector seal is listed as approved for Potable water, non-potable water, industrial process water, sanitary water, saturated live steam, high-pressure steam, super heated steam. Natural Gas, Propane-liquid and gaseous, Butane, MAPP gas, gasoline, diesel fuel, heating oils in grades 1 through heavy bunker oils, aviation fuel, jet fuel, low pressure air, high pressure air, vacuum, most refrigerants, a long list of medical and industrial gasses, electrical conduits plus a long list of other products. Needless to say, it is rare that we run into a piping system that RectorSeal is not approved to handle.

RectorSeal is primarily made in two formulas, Hardening and non-hardening. The hardening type is principally used in the HVAC and pipe fitting trades for high temperature steam applications while we use the non-hardening formula for most of the other applications. The non-hardening type has two distinct advantages, 1. It remains soft so it is not quite as difficult to later disassemble a joint if the need should arise and 2. It won’t dry out in the can if someone should happen to forget to put the lid on tight. (A small 4oz can is probably enough to last a homeowner for the life of the house).

For reasons known only to the retailers RectorSeal is often very difficult to find in the hardware or big box store, but if you were to walk into almost any Plumbing Supply, HVAC Supply or Electrical Supply house and ask the counter man for a can of pipe dope in most instances the only question they ask is “hardening or non-hardening” and almost without exception it will be RectorSeal that they set on the counter.

QUESTION: IS RE-FLOWING THE SOLDER ON MY LEAKING JOINTS AN OK REWORK?

The simple answer is “NO”. The problem you encounter here is that unless you used compressed air or compressed nitrogen to test for leaks you had to turn the water on. As the water leaked through the joint it washed out all the remnants of the flux so you are now confronted with attempting to get solder to wick into a joint that has no flux. The likelihood of that happening is slim to none.

The proper method would be to heat the joint and disassemble it. As the pipe comes out of the joint quickly wrap a rag around the pipe, then quickly wipe the pipe towards the open end. This will serve two purposes. It will,:1. Remove excess solder from the pipe and 2. It will leave a smooth shiny layer of solder on the end of the pipe. This results in Pre-tinning the joint, which will make it easier to re-solder. Brush a liberal layer of flux on the pipe, then heat the fitting and re-insert the pipe into the fitting. You can then apply solder to the joint in the conventional manner and you will end up with a good joint.

In my previous post I stated that you should pull the heat away from the fitting as you apply solder. Let me explain that in a bit more detail so you will understand the reasoning.

Per ASTM specification we are now required to use certified “Lead Free” solder. While there are a number of different alloys that meet the ASTM specifications the one most commonly used is Alloy Type “SB5” which is a 95/5 blend of tin and antimony and it has a melting temperature range of 452 – 464degF. In turn the flux has a maximum working temperature of about 550degF and it will begin to burn and leave a carbonizing residue at about 575degF.

If you will notice in my illustration I have shown the solder bent into a J hook. The trick is to preheat the pipe and the fitting, which will bring it to about 400 to 450degF, then you move the flame onto the fitting and continue heating. Keep the end of the solder well away from the torch flame so as not to preheat the solder. You then use the J hook to momentarily touch the point where the pipe and joint intersect on the opposite side of the pipe from the torch flame. If the pipe and fitting have reached the melting temp of the solder the solder will begin to flow instantly, if not, pull the solder back and continue heating. If the solder does flow, quickly pull the flame back and allow the heat of the fitting to suck the solder into the joint. If you were to continue heating there is a high risk that the joint will be overheated, thereby burning the flux and in a worst case it will anneal the copper.

A ½” copper pipe joint should take in about ½” of the solder wire before you see excess solder dripping from the bottom of the joint. If the joint does not appear to be filled properly you may carefully apply a bit more heat and more solder, but keep in mind that you are trying to maintain the present temperature rather than continue heating the pipe beyond the range of the solder and flux.

When soldering a TEE all three sides of the tee should be fluxed and fitted to the pipe before the soldering begins. Preheat both one end and the side opening of the tee first, then, move the point of your torch flame until the flame is centered at the intersection of one end and the side outlet of the tee. Solder the end and side opening and by that time the opposite end of the tee is normally hot enough to properly wick the solder in. If not, you can carefully apply a bit more heat and additional solder, as discussed above.

Here is a trick to judge the heat. When you touch your solder to the pipe watch the solder wire carefully. If the heat is correct the tip of the solder will instantly melt and flow as it touches the pipe. If it doesn’t melt and if the solder appears to be getting a bit limp towards the end but not flowing that is indicating it is not quite hot enough. In which case you would pull the solder back and apply a bit more heat.

If the heat was correct the solder joint will have a bright silver appearance. If the appearance is dull, gray and has tiny beads or fragments it was not hot enough, in which case you may be able to apply a bit more heat and add additional solder.

[Blackhawk]

OK, I need just one clarification on re-connecting the joints that have leaked. You mention re-applying flux to the pipe and then re-inserting into the fitting. Should I always use a new fitting?

If it is OK to re-use the old fitting, I assume that it should also have the flux re-applied.

[HayZee518]

Old fittings will probably work, but copper when heated become annealed, that is they soften and expand. Fittings are no different then the tubing. The inside diamters witll expand opening up a gap that the solder WON'T fill in no matter how much heat you apply.

[LazyPup]

While there is technically no reason not to reuse the fittings in actual practice attempting to do so can present a real challenge.

Whenever we heat a joint and take it apart we can quickly wipe the exterior of the pipe wall to remove excess solder. When doing so we will still have a slight layer of solder left on the pipe wall, but that layer is generally little more than a molecule or two in thickness and won't present a problem in fitting the new joint. On the other hand, when we heat the pipe and pull it out of a fitting there will be a slight amount of liquid solder in the joint that will pool at the lowest point in the fitting or cling to the opening of the fitting by surface tension and thereby reducing the ID of the female end, making fitting the pipe in very difficult.

Keep in mind that the normal tolerance between the OD of the Pipe and the ID of the fittings range in the order of 0.001 to 0.010 inches. By comparison, human hair has an average diameter of 0.002 inches so you can see that it wouldn't take much solder buildup to make fitting difficult.

In regards to your question about flux. When applying flux we should apply a light film of flux on both the pipe and the fitting, however in actual practice, when using 1/2" or 3/4" it is common to apply the flux to the pipe, then insert the pipe into the fitting and rotate the pipe back and forth a bit to insure an even distribution of the flux. For larger diameters it would be a good habit to apply the flux to both the pipe and fitting.

Another point that I should have mentioned earlier. When working with smaller diameter fittings (fittings 1" or less) it is vitally important to use a stainless steel ID fitting brush to clean the fittings. Fittings should be cleaned and fluxed immediately before using. Do not be lulled into thinking the pipe or fitting is new, or that you cleaned it yesterday because copper will oxidize within 6 to 8 hours when exposed to air. The best practice is to never clean more fittings than you intend to use in 2 hours or less, and you should apply flux as soon as you complete the cleaning process.

I like to buy the "El Cheapo" simple wire handled cleaning brushes which are usually $1 or less, and rather than buy one i like to have 5 or 6 in my toolbox at all times. This way if I should happen to drop one in the dirt i can discard it and use a clean one. Another reason that i keep spares is because if i have a lot of fittings to clean I cut the loop off the handle , then chuck the shaft of the brush in a cordless drill and i can power clean a bunch of fittings very quickly.