I cringe whenever I see a galvanized pipe in a plumbing project I’m involved in, I cringe. It is difficult to work with because it is almost always corroded, all joints are threaded and you either have to make the lengths you can buy at the store work or you have to buy expensive threading tools. It is best to go back to a joint you can get apart and switch over to something else – I prefer PEX. Note that if you are moving to copper you need to use something called a dielectric union, otherwise bad things happen between the two metals.
An Example of the Problem
I got called to work on a plumbing problem for a relative and after I got the crawl space opened up my son declared “We have a PSO”. I had never heard of that so I had to ask “What is a PSO?” My son is taking robotics classes at the local Community College and one of them was fluid power. That is the class where he learned about “Pressure Squirting Out”, or PSO which is used to describe a leak under pressure.
If you look just to the left of the elbow you will see the hole. And since the hole is a result of corrosion I didn’t think I could get the joint you see apart. The pipe then goes into a concrete footing, so going back to the next coupling was not an option. Plus the pipe ran right next to a block foundation so even if I had pipe thread cutting equipment there wasn’t room to use it.
What you need
If you ever run into a situation like mine where you have to cut the galvanized pipe in place I have found a way to repair it that doesn’t require cutting threads. The item you need is a “Galvanized Pipe Compression Coupling” and I found it at Menards. Interestingly the staff at Menards didn’t know it existed, I had to find it on their website and show it to the person that worked in the plumbing department. Make sure you know what size pipe you have so you can get the right coupler. Supply is probably 3/4″. Also get a 6″ nipple and cut the threads off of one end. The compression coupling has an inner rubber ring that gets compressed against the outside of the pipe to form a watertight seal.
Preparing the Pipe
Cut the pipe off square and make sure there are not any burs and use sandpaper to clean the outside of the pipe. I used a right angle grinder with a cut-off disc. This produces a much cleaner cut than a hack-saw. Plus I’m much better and keeping the cut straight with a disc than a saw blade and it is quick.