Compression Fitting Installation, Uses and Troubleshooting Q&A

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Dear NH,

I had a 3/4" copper pipe (leading to an outdoor spigot) in an outside wall burst due to freezing. I removed the damaged portion of the pipe, inserted a new piece, covered each connection with a 2" sleeve and attempted to solder the connections. The problem is that the pipe is pretty snug against a cinder block wall, so I can't seem to get it watertight all the way around on the ends of the sleeves. I was thinking of using a double compression fitting instead. I read the information regarding compression fittings from your site. Will expansion and contraction caused by temperature changes make compression fittings leak?

Dear BH,

You should have no problem. Temperature changes should have no effect on the compression fittings. Most leakage in compression fittings is caused by one of two things… 1) movement in the connection and 2) not completely seating the pipe in the socket. I wonder, though, if there might be a better way for you to do this job without compression fittings, since they are the least strong of plumbing connections.

Sometimes in plumbing repair, you need to "cut away" more pipe than just the repaired area to be able to reconnect everything. For example, if there is an elbow near your work forcing you to work in cramped quarters, cut the pipe "after the elbow", not between the elbow and your work, do the repair "on the bench". Reattach the "below the elbow" cut in the pipe with a union instead of a compression fitting. This is a much stronger connection and can be reused if the freezing recurs. Of course your measurements have to be fairly precise for everything to align properly but flexibility in the pipes and the small amount of "give" in the union allows for some wiggle room.