What soldering technique is right?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by petrie, Mar 17, 2014.

  1. petrie

    petrie New Member

    Messages:
    56
    Location:
    Wisconsin
    I was reading the AWS guide on soldering and it talks about when soldering a horizontal joint that you should heat from the bottom of joint and then pushing solder in at bottom of joint and going up one side to top, then return to bottom and go up the other side to top. Two half circle swipes with the solder.

    However, I have several diy books and from watching Richard Trethewey (This old house plumber) and other plumbers do online soldering demos they just apply heat to one side of joint moving flame back and forth, and apply the solder to the other side by just sticking it in and allowing capilary action to bring it around towards the heat.

    I only ever solder 1/2 and 3/4 lines. And I do it the later way because a lot of times obstructions dictate where I can apply flame and solder. Although I do try to move my solder around whole pipe to get a full joint. Also it seems with small pipes the flame is kind of everywhere at once, curling around the whole pipe.

    Is the start at the bottom technique really only worth doing on large pipe?

    appreciate any info.
    Last edited: Mar 17, 2014
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,289
    Location:
    Bothell, Washington
    I pull a lot of joints that others have done, with solder mainly on one side, and the away side showing lots of copper.
    I have always heated both sides, and the pipe. Four sides is even better. I tend to touch the solder on the part that I think is the coolest.

    Back when all I did was run copper in new construction, I went eight months without a leak. The other plumbers were not happy about that.
    Well......at least the Journeyman I was working with was happy. No leaks, no down time fixing things. We were destroying budgets.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,032
    Location:
    Cave Creek, Arizona
    Heat rises so holding the torch to the bottom of the joint and applying the solder at the top, should give the best joint. You NEVER want to apply the heat at the same place you are applying the solder. Holding the torch on one side and applying the solder to the other may not always insure that the bottom is adequately heated. It depends on the size of the copper tubing.
  4. petrie

    petrie New Member

    Messages:
    56
    Location:
    Wisconsin
    So many people on youtube with how to solder videos it gets kind of confusing. Some guys get the joint hot enough to melt the solder and then remove the flame and push in the solder and that's it. Others get it hot enough to melt the solder, push some solder in and hang around with the torch all the while trying to keep pushing solder in and going around whole joint. Heating on bottom seems to be a very common technique though.

    I've ruined ball valves and threaded connections by pushing too much solder/getting too hot maybe on vertical solder joints. Now I try and solder valves and threaded connections tipped up a little from horizonal so excess solder doesn't run into them, and then sweating them into place.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,032
    Location:
    Cave Creek, Arizona
    You do NOT "push" the solder into the joint. With the right temperature, it will flow by itself. If we had to "preassemble" our joints and then install them, we would never get anything done.
  6. petrie

    petrie New Member

    Messages:
    56
    Location:
    Wisconsin
    I get what your saying. Several years ago I moved some water lines around to put in a new powervented water heater and I soldered all my joints assembled with a 3/4 ball valve and female threaded connectors in the vertical position. Didn't wreck the threads or the valve. My joints joints look clean and solid.

    When I think about the stuff I soldered for my cousin and friend recently I went kinda heavy on the solder trying to get more solder up onto the pipe and covering the face of the fitting. I think somewhere along the line I watched too many videos of guys pouring the solder to the joints till it ran out bottom and trying to "heap" it up on the sides of the pipe and cover the face of the fitting. Kinda had a technique "drift" . I guess that happens when it's years inbetween when you solder small projects. Should just take care of my own stuff and tell others to hire a plumber, but I'm very interested in the skill of soldering, and I like to try and help friends and family out. I'd never go out and try and drum up work soldering as I believe that's the domain of pros.
  7. Bill Shack

    Bill Shack 30years plumbing 10years plumbing inspector

    Messages:
    53
    Location:
    montreal quebec Canada
    If you are soldering very large pipes then you must do as stated first you must pretinn both inside and outside before putting the pipes together let the pipe cool then and then put together , heat from the bottom of joint and then pushing solder in at bottom of joint and going up one side to top With the torch following so that the solder goes into the joint running inside then damming inside the joint finishing at the top then repeat this Technic on the other side. I had to do this when i connected a water tower to a air condition system with 4 inch copper pipes. It worked very well
  8. craigpump

    craigpump Active Member

    Messages:
    1,031
    Location:
    ct
    My grandfather taught me to warm the pipe all the way around, then put the torch to the bottom and apply the solder to the top. He also taught me to put a little bend in the end of the solder, 1/2 bend for 1/2" pipe, 3/4 bend for 3/4 pipe etc and to wipe the joints.
  9. Hammerlane

    Hammerlane Member

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    262
    Location:
    Ohio
  10. Terry

    Terry Administrator Staff Member

    Messages:
    15,289
    Location:
    Bothell, Washington
    [​IMG]

    This is one example of a bad solder joint.
    This was from a leaking tub spout. The spout pulled right out of the wall.
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,032
    Location:
    Cave Creek, Arizona
    soldering

    quote; I had to do this when i connected a water tower to a air condition system with 4 inch copper pipes.

    When I soldered large joints, depending whether it was 1 1/2 or 2", or 3 and 4", I used either the small or large Prestolite staghorn 4 burner tips to heat the entire joint properly.
  12. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,032
    Location:
    Cave Creek, Arizona
    Looks like the made a neat bead on the joint, so it at least "looked good". There are probably half the joints in the industry made just a little bit better than that.
  13. petrie

    petrie New Member

    Messages:
    56
    Location:
    Wisconsin
    My soldering stuff is at someone else's house right now, but when I get it back I'm going to solder a piece of pipe into an elbow several different ways and then see what it looks like when I take it apart.
  14. petrie

    petrie New Member

    Messages:
    56
    Location:
    Wisconsin
    Bought a 10ft stick of 1/2 and a big bag of elbows. soldered and took apart about a dozen joints. coverage looks real good on both the pipe and the fitting. For the hell of it I tried to solder a clean joint without flux. Wow, no way you could ever forget the flux and not know it. No solder goes into the cup and what adheres to the pipe next to fitting crumbles off. However, a pipe and fitting that havent been cleaned will solder together and look ok when taken apart if flux is used. Of course I knew this because when I moved my Water Heater several years ago I cleaned all the pipe, but forgot to clean the fittings and none of them leaked.
  15. dj2

    dj2 Member

    Messages:
    426
    Location:
    California
    " Of course I knew this because when I moved my Water Heater several years ago I cleaned all the pipe, but forgot to clean the fittings and none of them leaked."

    New, clean and shining fittings out of the box that you don't clean sometimes catch, absorb the solder and don't leak. However, it's important and better practice to sand them too.
  16. petrie

    petrie New Member

    Messages:
    56
    Location:
    Wisconsin
    Totally agree with above. I would never intentionally cut corners and not clean a fitting.
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,262
    Location:
    New England
    It doesn't take much to prevent solder from flowing and bonding to the metal surface...a thin layer of oil, even some from your fingers, can sometimes mess up a joint. Clean is important. The flux helps, but is not a cure-all. Flux helps to prevent oxidizing while heating the joint, but assumes it was clean in the first place.
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