Pinhole leak at elbow joint. Possible fix?

[jaws]

I have a pinhole leak in an outside copper pipe running down the outside of my house leading to an underground irrigation system. The leak is right where a straight copper section is soldered into an elbow joint, so as far as I know, a sweat coupling or a temporary clamp is not an option. The pipe also as been painted, and there is some mineral buildup in the joint area around the leak (probably the cause). My first thought was to sand/melt off as much paint and minerals as possible, and just re-solder over the area. Being a novice (I have soldered copper pipes before), I'm not sure what the likelihood of this working is (especially not being able to completely dry and clean the inner pipe, as well as the paint and mineral buildup possibly causing the solder not to adhere properly). Another thought was a temporary fix with plumber's epoxy. If I were to cut the pipe and replace the sections, I believe I'd have to cut and couple the straight pipe on both sides of the elbow joint, thereby having four joints to solder (the two couplings and the two ends of the elbow), and have to lineup the horizontal and vertical pipe sections exactly to fit. It seems too much work to simply fix a small pinhole leak, and possibly too much room for error. Since the pipe is outside, very accessible, non-potable, and has it's own cut-off valve, I'm not overly worried about potential flooding from a temporary solution. I'm just looking for the easiest way to repair it that could potentially last a number of years. Any thoughts or ideas about the best way to tackle this? Thanks!

 

[LiQuId]

Non-potablle you say... well, why not break a pencil lead off in it ? ( MUST be LEAD to work ) works awesome on black iron pinholes.

the reality though is that if there is a pinhole opening up the copper is prolly close to failing in other areas also. best fix... drain the line and sweat the elbow off, cut a new chuck of copper and re-soldier it in place ( with a new elbow and a Coupling.

 

[Chris]

Your best bet is to just cut the 90 out and replace or even un-solder it if possible and put a new 90 on. If you let it go it will eat through that copper like a lazer over time. There are several tricks that will buy you time but ultimatly you will end up replacing it if you want it fixed properly.