Connecting copper pipe to galvanized

Use a Dresser coupling, available in galv. or pvc at your local hardware store. It is a compression fitting which will seal around the existing pipe and provide either a pipe thread on the other end or another compression joint allowing you to install a pipe nipple.

Went to the internet and found the coupling. It was sent to the plumbers. They had said there was not such a thing. Now they know. This will work out just fine. Thanks

Great, glad I could help.

Are you using a galvanized of PVC fitting between the copper and steel piping?

The reason I ask is that if the two are in electrical contact the copper will accelerate the corrosion of the galvanized piping and you will and up in an even bigger mess than you already have. Generally it's a bad idea to mix copper and galvanized pipes but you can get away with it if you electrically isolate them.

That is what his dielectric union will do for him. But he should make sure he has a still has continuity to ground through both the copper and the GLV pipe; this will depend on the configuration of the dielectric union. If the union acts as a total insulator between the two materials, he should install a jumper cable to a ground source, direct to the ground rod or to the GLV pipe because of the smaller area of Copper Cable to GLV Pipe electrolytic corrosion will not be an issue. If there is an electrician on site he should be able to advise you correctly on this matter.

If the union acts as a total insulator between the two materials, he should install a jumper cable to a ground source, direct to the ground rod or to the GLV pipe because of the smaller area of Copper Cable to GLV Pipe electrolytic corrosion will not be an issue.

It doesn't matter how they are connected or the ratio of copper to steel you will accelerate the rate the steel corrodes markedly. A single piece of copper on the hull of a steel ship can cause considerable damage. Steel hulled ships actually have fairly sophisticated monitoring systems that monitors the voltage between the hull and the water. If the voltage is outside certain parameters it means that something has gone wrong and serious investigation is required. Steel hulled ships also use sacrificial zinc anodes to protect the hull in exactly the same way the zinc plating protects the steel pipes.

As for the earthing the only part of the plumbing that needs to be earthed is the bit hat has an earth wire connected to it. At any rate using the plumbing as a safety earth is not a good idea and should be discouraged. There should be a separate earth stake specially installed for this purpose and if this is the case then there is no need to earth any of the plumbing.

Now I know somebody is going to say what about electric water heaters. Well the answer to that is that they should have their own earth that will cover the eventuality of the element shorting out to the water of container.

The vent pipe, particularly if metal, can attract lightning. It would be dangerous to leave plumbing to sinks, showers and toilets ungrounded for this consideration. At the very least, the plumbing to the drain should be galvanically connected to the plumbing to the fawcets/inlet valves.

gk

"Went to the internet and found the coupling. It was sent to the plumbers. They had said there was not such a thing. Now they know. This will work out just fine. Thanks"

You are paying your plumbers too much if they don't know what a dielectric union is. This is one of those things that a plumber is supposed to know.

"Went to the internet and found the coupling. It was sent to the plumbers. They had said there was not such a thing. Now they know. This will work out just fine. Thanks"

I think the reply is to the "Dress Coupling" not the dielectric union.

MidniteFighter

If they were unaware of a compression fitting/connector -- you are still paying them too much. They should be paying you for training.

I'm glad everything worked out. Just be aware that even the Dresser is only a temporary solution. In addition to the electrolytic effect of mixing different types of metal piping in a water supply system, you must also remember that the old galvanized piping will eventually rust completely shut. Are you on a well or municipal system? If a well, you should also have your water sampled to determine if you need a treatment system. I have found that copper piping is more succeptible to low pH (acid) water than is steel. If you find that pH is anything lower that around 6.3 you need a neutralizer pronto. Otherwise you can count on getting only about 3 to 5 years out of your new copper piping. Most municipal systems monitor water quality and maintain the critical characteristics within acceptable limits, so you don't have to worry too much about it rotting your pipes. Another idea for connecting to the existing is to go back to the nearest fitting. Usually you can get the old pipe out and the threads in the fitting are still good. If this is the case, then you can put in a new nipple and connect your dielectric union to that.

Water Buffalo, Timely points. It appears that our friend n5eba has more to deal with than installation of some bathroom fixtures. I do not envy him the budget process that gets him the money to bring his water supply system to grade. Clearly the current problem is well manifested throughout his plant.