How to fix bad solder joints?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by bigelow, Mar 21, 2005.

  1. bigelow

    bigelow New Member

    Messages:
    5
    Location:
    Bellevue, WA
    I have just spent a weekend running copper lines for a small house. First time soldering. I tested the cold line only, it resulted in a monsoon in the basement. Had several large leaks. I have fixed about half of them.

    My dilemma is this. I ran the hot and cold lines at the same time. The cold line failed in many locations. I do not have water in the hot line. I have obvious reason to believe the hot lines will leak just as much.

    Is there anything I can do to the hot line solders to try and reinforce the joints before I fill the lines with water and add the "water in the lines" dimension to fixing the joints?

    A co-worker told me his father used some kind of liquid to coat the outside of an existing soldered joint, heated the joint, hit it with solder and it sealed the joint. The problem is he doesn't remember what the liquid is and his father is dead........does such an product exist?

    Thanks
  2. Terry

    Terry Administrator Staff Member

    Messages:
    14,889
    Location:
    Bothell, Washington
    There isn't anything you put over the fittings, it's what is inside.
    Did you use flux on the pipe?
    To solder, you need clean pipe, pipe cleaner (flux) and even heat.

    If the heat on the fitting and pipe is uneven, the solder will not flow all the way around.
    Last edited: May 30, 2005
  3. bigelow

    bigelow New Member

    Messages:
    5
    Location:
    Bellevue, WA
    Thanks Terry.

    Like I said I am not experienced, therefore I was not very disciplined in all the aspects. I skimped on flux in some spots. The even heat was another problem. All these little details have bitten me in the butt. The only thing I know I did well every time was clean the joints.

    Knowing that my technique was less than stellar on the hot line, what do you suggest I do before I test it? Anything? Should I just go with it and fix the damage as it appears?
  4. Terry

    Terry Administrator Staff Member

    Messages:
    14,889
    Location:
    Bothell, Washington
    If you have not added water yet, I would consider reheating joints that look bad. You can check around the fittings to see if the solder is beaded there.

    If you have added water, the fitting will need to be removed and the process started over again.
    Last edited: May 30, 2005
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,486
    Location:
    Cave Creek, Arizona
    solder

    You may have a problem with the leaky joints in the cold water pipe, because once water enters a "bad joint" it contaminates the copper so the solder will not adhere to it, even though the surface of the joint where you put the solder is no longer leaking. Normally the only good repair to a joint that has leaked is to take it apart, reclean it, flux it and then put it back together and solder it properly. The hot water, since it has not had water in it, should not have the same problem, but unless you pressurize it with air, you will not know if you have any leaks or where they are, in which case you will have to "redo" all the joints, not just the ones that do not look good.
  6. Oatey tinning flux

    [​IMG]

    Oatey tinning flux in the plastic green jar is the absolute best for beginners...


    and everyone at any level

    Its water souluable and also completely tins the whole joint for you......

    I have soldered for 40 years and dont really need to use it, but I still do

    because it definitely gives you an extra "edje" and you absolutlely know

    you arent going to have any leaks. whatsoever.
    Last edited by a moderator: Mar 22, 2005
  7. bigelow

    bigelow New Member

    Messages:
    5
    Location:
    Bellevue, WA
    I was looking at the Oateys No. 95 Tinning flux last night. I have been using Oateys No. 5. It appears the No. 95 contains flux and solder mixed? I was at Home Cheapo and of course nobody really new what the difference was between the two, except that they were different.

    Thanks.
  8. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,328
    Location:
    Yakima WA
    I've used mostly paste flux of various brands and once I used the water based type. I didn't really care much for the latter, but it worked. I don't know how really important the type of flux is for a DYIer, but without flux solder won't work. The main points of soldering are to clean the surfaces well immediately before applying flux, insert the pipe fully into the fitting, apply heat evenly around the joint until the joint is hot enough to melt the solder, keep the joint immobile while it cools naturally (no water added). Skimp or cheat on any of these steps can give a bad joint.
  9. chipshot

    chipshot New Member

    Messages:
    36
    Location:
    North Carolina
    What kind of torch is suggested? I had difficulty with the blue propane tank getting the copper hot enough to melt the solder without the flame on the fitting.
  10. Terry

    Terry Administrator Staff Member

    Messages:
    14,889
    Location:
    Bothell, Washington
    Just put the flame on the fitting.

    I keep a water spray bottle handy.
    1) I can cool the fitting quicker after it's been soldered.
    2) I can wet down the wood or drywall before I solder
    3) Helps to put out small fires
    4) I can cool off my burning hands when I forget how hot that thing is or if I find there is a hole in my glove when I wipe the pipe and fitting down afterwards .

    by the way, I don't get the pipe wet before I solder, only after they've "been" soldered.
    If water hurt pipes after they have been soldered, we would be in serious trouble. They are water lines, right?
    Last edited: May 30, 2005
  11. captwally

    captwally New Member

    Messages:
    102
    Location:
    Florida
    Once water has been introduced to the line, or if it already exists in ANY amount it makes the sweating of copper joints much more difficult. I absolutely hate sweating wet copper, as long as I've been doing this. Master Plumber Mark is right in recommending #95, as it has solder in it and tins the copper as it approaches the temp needed for a good joint. It is good stuff.

    Propane is only good, in my lowly experience, for sweating absolutely dry copper such as you would have in a new construction house or remodel. Better if you spent a few more dollars on the yellow cannister of MAPP gas. It's hotter and solders better. I use it almost exclusively, since I do mostly work on older systems. If you have a really bad case, then it's time to resort to Oxygen/Acetylene mix and a brazing rod. But that is absolutely the last resort.

    Never listen to the folks at Home Depot or especially Lowe's. They have no clue. I once asked them for a fish tape as I was wiring new garage lights. He took me to the aisle where they stocked Duct Tape...
  12. chipshot

    chipshot New Member

    Messages:
    36
    Location:
    North Carolina
    I did all of my connections outside at a work bench taking alot of time to do them properly. I only had to do two in place and one leaked. Luckily, somehow I was able to re-solder the connection without taking it apart. So far so good but I will invest in a yellow tank.
  13. captwally

    captwally New Member

    Messages:
    102
    Location:
    Florida
    Resoldering a joint is an iffy thing. Sometimes you can do it and sometimes you can't - more often than not. I'm glad you got it. It's more easy just to toss the fitting, use a new one and resurface the previously solder tinned pipe that you have been trying to solder. The new fitting will fit and sweat better.
  14. captwally

    captwally New Member

    Messages:
    102
    Location:
    Florida
    New Sweat method

    I just discovered the greatest thing since sliced bread. I've been doing a lot of A/C work lately and we all know that you can't use a soft solder in that application. I was buying Teensy copper/phosphorus brazing rods at a local Depot type home center for way too much money. While at a welding supplier I picked up some hefty silver brazing rods and a phosphate based flux. Works great on A/C units with my Oxy/Acetelyne setup, so I thought I'd try it in a plumbing situation on some 'wet' copper (older and with water in the lines.) It worked like magic! I've always used MAPP gas because it is hotter than propane and was always worried that oxy/acetelyne would be WAY too hot to the point I would risk damaging the plumbing by melting a hole in it, but this stuff just flows into the joint like water and seals perfectly. Even in wet lines.
  15. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,486
    Location:
    Cave Creek, Arizona
    brazing

    There are two problems with brazing. First you will never be able to take the joint apart, and second the process of heating the fitting cherry red anneals it and weakens the fitting. You will find that afterwards the fitting can be bent or twisted almost anyway you want to, but it also makes it susceptible to cracking and breaking. But you will never have to worry about the joint coming apart.
  16. Taylor

    Taylor New Member

    Messages:
    143
    Location:
    Northern Joisey
    Taking apart soldered joint

    I think this is a related question: Is there a "trick" to taking apart an existing soldiered joint? Two times today I heated a joint (with MAPP gas) and tried to take it apart, to no avail. The joint was hot enough that I had to remove my fire-proof gloves because they were starting to smoke, and soldier outside the joint was quite liquid.

    One of the joints I had to take apart was a soldier that I don't trust.... Light went out in the middle of soldiering, so there was a short delay before I got the soldier to the joint..... Is the absence of solider on the outside, except a bead at the bottom of the joint, a sure sign of a screwed-up job?
  17. Terry

    Terry Administrator Staff Member

    Messages:
    14,889
    Location:
    Bothell, Washington
    You can always cut the section out and start over.

    Any water in the pipe will prevent "even" heating and prevent the fittings from being removed.
  18. Taylor

    Taylor New Member

    Messages:
    143
    Location:
    Northern Joisey
    Thanks, in my various practice jobs, I finally yesterday managed to pull apart a soldered joint. I think my mistake has been overheating with the MAPP gas, this time I used it more gingerly. Not sure if I welded pipe and fitting previously or if it was just oxidation holding the joint, but I twisted with pliers until the pipes were like wet spaghetti. I think I can pull apart a soldered joint now, but I've given up on pulling a fitting off a pipe.

    On the bright side, when I took apart that last joint, the solder was 100% into the fitting :D.
Similar Threads: solder joints
Forum Title Date
Plumbing Forum, Professional & DIY Advice, Tips & pre soldered copper joints Jan 16, 2006
Plumbing Forum, Professional & DIY Advice, Tips & Outdoor Prier faucet threaded or soldered? Jul 1, 2014
Plumbing Forum, Professional & DIY Advice, Tips & Soldered joint or thread on valve body? Jun 5, 2014
Plumbing Forum, Professional & DIY Advice, Tips & Sillcock leak; threaded or soldered? May 2, 2014
Plumbing Forum, Professional & DIY Advice, Tips & HELP! Solder nightmare - using wrong solution? Apr 29, 2014

Share This Page