re-soldering a valve joint

rtoni

Being the king of do-overs, I assembled my shower valve and copper pipe and tested it yesterday and sure enough had a small leak in one of the solder joints at valve. I heated it up at the joint and pulled it apart. I have extra copper to refit that side of the valve so I'm not worried about that part too much (more practice for me ).

On the valve port itself, it looked pretty clean once I pulled the short piece of copper out - left couple of very tiny bits stuck on the inside surface near the edge of the valve port - I took some emory cloth and in a couple minutes I cleaned the valve out to the point where it looks ok to me (shiny, smooth inside) - didn't take much, and the new section of copper pipe fits in snug but not too tight.

Is there anything else I should do to prep the valve surface inside or can I just paste and solder as if nothing happened? In the few soldering jobs I've done before, I've only had one other leak and I just replaced the parts and did it again - easy and cheap. This time I have the valve to deal with. Hope I didn't fubar it.

Related question - is there a "due date" on solder or paste? the stuff I have is pretty old - probably 5 years. does it matter? Can I blame my crappy solder job on bad parts? guessing probably not....

secutanudu

Not sure if there's an expiration for that stuff, but i know it can separate. Did you mix it up first?

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Andrew

rtoni

not really - I didn't have a small brush so I used a q-tip to spread the paste around the pipe (someone told me once that greasy / dirt from hands getting on the pipe or in the paste can mess up the joint) - so I might have mixed it a bit in the can but if so then only by accident.

I've only done a few of these over the years but my experience is they either turn out really good (perfect bead appears around the edge of the joint, no slop, no leaks after years in service) or they turn out really bad. Seem to move along really well and then really fubar one. I'm doing something wrong there. Frustrating.

secutanudu

Might not want to use a q-tip since that can leave dust. They make really cheap brushes for that....

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Andrew

rtoni

thanks for the tip (pardon the pun) - I've been thru the rack at the box stores where they stock paste, solder, pipe dope, etc. and haven't seen any brushes in the mix (to be honest, have not really looked) - can I use any small brush - some cheap thing from the paint section?

Daniel Holzman

I have been using the same 10 cent nylon brush for five years, no problem. As for flux going bad, well some of mine is ten years old, seems to work fine. I have not had the same good luck as you resoldering joints, typically if they don't go right the first time (usually due to water in the joint), I use a new fitting and start over, but I usually presolder a short length of copper onto the valve before I put it in, it seems to be much easier to solder a 6 inch length of pipe onto a valve on the bench rather than in the run.

rtoni

Hi Daniel - I might have confused the issue - my good luck / bad luck is pretty much what happens on new work (going along well then I screw 1 joint up). In this particular case, I plan to follow your approach and throw away the pieces of copper that I pulled apart and start over. But I do need to resolder the pipe into the valve (not tossing that valve out - I hope - that was my main concern - that I can re-solder a new piece into the valve). Working from the bench with that short piece in the valve is probably a very good idea for me to try as well. I'll also pick up a brush.

Thanks Secutanudu and Daniel for the replies and the help.

braindead

Solder paste WILL go bad

Using a q-tip could leave cotton fibers in the joint

I hope you took you valve apart before you soldered anything, thats a good way to destroy the internal parts.

kenmac

You will have to get that valve area hot . It's usually thick brass. I hope you took the guts out

rtoni

braindead, kenmac - thanks for chiming in. Yes the guts (ceramic catridge, o-ring) all removed prior to doing anything - been sitting in a bag on the shelf. I also picked up a bit of extra silicone for the cartridge / o-ring figuring it wouldn't hurt to apply a bit to the parts before replacing them.

I also grabbed a brush this morning - in the shop I saw a small kit with flux, solder, brushes in the box - made by Oatey - the stuff they recommend for copper plumbing. A small kit - but more than enough to do this job for me - so I grabbed it. Will see how it goes this time around with some fresh parts and help from you all. Much appreciated....