Last week, I had a pinhole pipe in one of the pipes (from the mid 70's) in the addition to my much older home. The insulation in that part of the house is in shambles since it was installed poorly and upside down.
Upon removing the insulation, I noticed some areas of the pipe have stretches of green corrosion. This is predominately in areas where the pipes are close to joists or gas pipes, as well as one of the pipes where it enters into the ground (I think it feeds the garage). How much corrosion is normal in this situation? A lot of the soldering looks pretty sloppy but there is no evidence of leaks or other repair jobs.
The crawlspace is very tight and difficult to do any work and I guess I'm just a little paranoid that going to the trouble of installing heat tape and reinsulating might be a waste of time if a pipe fails in the next year or so.
This green effect is usually from applying too much flux when they soldered. That and the sloppy fittings indicate that a real plumber did not do the work. I would still insulate if you are not experiencing leaks.