Solving Copper Pipe Leaks

Can plumbing just "spring a leak" if there's been no stress on it?  My 30 year old townhouse has copper pipes and I noticed a wet spot in the ceiling in the basement last night.  Got the ladder out and peered up into the ceiling from the work room (could see the pipes going around the area of the wet spot from there) and could see a slow drip coming from the elbow joint of one of the pipes.  The thing is that it is in a part of the house that would have not outside stresses on it (e.g. Temperature swings, movement, etc.).  Before I rip open the ceiling and get out the torch to start sweating one elbow joint (not a problem for my skills) I want to make sure it isn't something bigger (beyond my skills and more expensive).
rvanh  12-22-06 7:57am

While it seems that your dripping pipe may have "no stress on it," that's not completely true.  Plumbing systems are constantly subjected to stresses that, while they may not be obvious, certainly can contribute to the wear and tear factor.  For example:

Expansion/Contraction - If this is a hot water pipe (or next to one) it is constantly expanding and contracting due to the changing water temperature.  Even if it is a cold water pipe, going from room temperature to ground temperature cold causes the pipe to move. While this is not an issue mid-span in the pipes, the elbows and other joints can find this particularly stressful as section of the pipe joint will move at a slightly different rate. 

Abrasion - While it hard to think of water as an "abrasive", it most certainly can cause erosive effects including leaks.  Think of the power of a pressure washer for example.  While extreme, this shows you just how abrasive water can become.  At lower flows and lower volumes, water, over time, can erode section of pipes and joints and cause a leak.  Have you ever seen a copper downspout?  The next time you do, look at the elbows and you will see how simple rain water can erode holes in this soft metal.

Water Hammer - Water weighs about eight pounds per gallon.  When a faucet is opened, the waterrushes forward in the pipe building up centrifugal force.  When the valve is closed, that mass of water screeches to a stop, sometimes shaking the pipes.  This is generally referred to as "water hammer" and, while unusual, can on occasion break a pipe joint free.

Pinhole Leaks - as I wrote on just last week, pinhole leaks, believed to be cause by the corrosive chemical reaction between water and some copper pipes, can also cause leaks.

So as you see, there are actually quite a number of things that can put "stress" on a plumbing system.  If you can handle the repair, open the ceiling and make it.  Just be darn careful with that blow torch!

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