Couple of questions for you. There is nothing in your page about your qualifications. Are you a licenced tech ? If not,and you are working in a public building, a very serious liability issue if anything happends. Your kids kids will die of old age before the law suet is payed off. Compression fittings in hot water heating is an absolute NO - NO. As in emergency heat to keep things from freezing they might cut you some slack but you had better get a qualified tech in A.S.A.P. to make the repairs permament. Without seeing your pipe it could be stainless steel ( i dought it )aluminum, galvanize, or tin plated copper. If it won't take solder it could be steel.You need a special flux. Actually on second thought i'd dought it is aluminum. It would have melted before your silver solder would have. Good luck and hope to hell nothing happends before you get a permenant fix.

It would appear that some of the aforesaid posts are mixing apples and oranges. While it is true that electrolosys will always produce corrosion it is also true that not all corrosion is a result of electrolosys. Under ordinaary circumstances electrolosys occurs inside the pipe wall at the point of a ferrous metal to non-ferrous metal connection I.E. iron pipe or vessel to copper pipe or fitting. The effects of electrolosys only occur at the actual point of contact and it will have absolutely no influence on the service life of other pipe, fittings or components of your piping system. While nothing is truely permanents, the intent of the building codes is to construct a structure with an anticipated life of 50 to 100 years. With that thought in mind it becomes necessary for the codes to address known problems in the worst case scenario. For that reason the codes define that we must use galvanized hangers or strapping on iron pipe, copper or copper clad hangers or strapping on copper pipe and plastic hangers or strapping on plastic pipe. In the case of plastic piping the concern is that all pipes will undergo a certain amount of movement or vibration and over the course of time the use of metal hangers or strapping can cut into the pipe wall. As Brickeye has already pointed out, there must be water present at the point of contact for electrolosys to occur. With this in mind the code requires that we use copper or copper clad strapping on copper pipe because there is a potential that "Condensate moisture" may occur on the outside of the pipe wall on a cold water line. In actual practice, even in the worst csse scenario where the condensate moisture occurs since the point of contact is on the outside of the pipe it is also exposed to a constant source of oxygen from the atmosphere and the presence of moisture will enhance the formation of iron-oxide (rust) on the steel strapping. The effects of iron-oxide occur much quicker than what electrolosys would occur and the end result is that the stap hangers will rust through and break, rendering the hanger ineffective. In regards to the original question about a galvanized iron strap on a copper pipe inside the wall, based upon what I have seen in my experience I would feel confident that you have absolutely no cause for concern.

"Baloney, I don't believe it. What is the source of the information for these claims?" A common example is that water heaters last an average of 1.5 to 2.5 years around here. We're on a water system that runs from 25 gpg to 35 gpg hardness. Replaced my WH in 1995 and still on the same one so that's 7 water heaters I haven't paid for at an average cost of $800 installed or around $5600. My softener cost me around $700 so I'm $4900 ahead... even considering that softener salt cost me about $60 a year... good enough cost offset for you? I haven't has to touch a faucet to fix a drip or open the toilet tank once since 1995. Appliance repair people I know tell me that hard water kills tankless water heaters and front load washers and dishwashers. Oh yea, our dishwasher was installed in 1995 also and it hasn't skipped a beat and the ice maker in my 1995 fridge works great while my neighbors who don't have a softener don't have ice cubes but they do buy bottles and bottles and bottles and bottles of bottled water. People tell me, and my wife agrees, that clothes last significantly longer when washed in soft water. I can tell you that clothes washed in soft water are markedly more comfortable to wear... far less stiff and scratchy. "Some also think it should be plumbed to hot only because the elevated salt level isn't healthy to drink, but opinions are divided on this..." They may think but they don't know what they don't know. No ion exchange softener that is operating properly adds ANY salt to the softened water. Got it, that's ANY salt added. What is added are sodium or potassium ions not salt. So, for you who think, how much sodium (not salt) is really added to soften water? The formula for added sodium is 7.85 mg/l (about a quart) of softened water per grain per gallon of compensated hardness. EXAMPLE 20 gpg * 7.85 = 157 mg of sodium added per liter of softened water, not salt. How does this sodium content of softened water compare to sodium found in common foods? The table demonstrates the usual range of sodium in common foods. Food Amount Mg of Sodium Ketchup 1 tablespoon 204 Milk 2 Cups 226 Frozen Peas 1/2 Cup 295 Bread 2 Slices 322 Corn Flakes 1 oz. 260 Parmesan Cheese 1 oz. 528 Tomato Juice 4 oz. 504 Tomato Soup 1 Cup 932 Chili 1 Cup 1194 Beef Broth 1 Cup 1152 Get a softener and stop eating tomato soup. Softening only the hot water will give you hard water at every appliance and fixture where hot and cold are mixed. You'll pay for soft water and not get it. Any water treatment pro who advocates softening only hot water is either stupid, a scam artist, or to install a softener correctly would be too difficult or too expensive for the homeowner and they don't want to lose a sale (see scam artist). That you don't like the feel of soft water is a valid criticism for some and data suggests that there is an acclamation curve of about 6 weeks and getting used to using far less soap and detergent.

In the upper photo where the top galvanized pipe connects to the copper riser on the left there is severe corrosion on the iron pipe threads which appears as if it may be a problem, but aside from that, the corrosion on those pipes is not near as bad as one might think. The green color on the pipes is called "Patina" and it is not a problem at all. In fact, that is the same green patina that gives the statue of liberty her famous green color and in the art world it is highly sought after. At the floor you have a cast iron pipe hub flush with the floor and the copper pipe is set into the cast hub by means of oak and poured lead. You can cut the pipe as you describe and attach your new PVC by means of a rubber Fernco coupling or you could cut the copper pipe flush with the floor, then clean the pipe stub and lead out of the cast iron hub and connect your new PVC into the hub by means of a Fernco PVC x CI donut connector.