Question about a difficult to solder type of copper

[amanda11270]

This is sort of a plumbing question, but I dont belong to a plumbing forum so I thought I would ask it here since I have been on this forum in the past and us refrigeration guys are very good solderers of various types of metals, more so than the average plumber I feel. I am almost embarassed to ask this question, however twice I have run into a problem soldering this old type of copper tubing. I call it old because both houses I have ever tried to solder this tubing in were built in the fifties. I have been working in refrigeration since 1990 and just recently started working for myself. And I now do all types of home repair and maintenance as well as refrigeration. But recently I had a job where a lady wanted some new cabinets installed and all the plumbing in them had to be replaced to install a new configuration of faucet and dishwasher, well im thinking excellent install some new copper (she specified copper), well when it came to soldering a coupling on the 1/2 inch pipe that was the "old stuff" the solder, just would not stick, flow or anything, whether I used my mapp gas or oxy-acetylene with regular plumbing solder. So I did what I did when I ran into this problem once in the past, I used my 45% silver solder and wahlah, it sticks. Anyone ever run into this, this tubing im talking about is black in color due to age, but when you rough it, its definitely copper. The only other time I've ran into to this is in a house my folks owned. I can only explain it as a weird make up of elements or the alloy in the tubing or something, it makes me feel like an idiot though as I can solder really well. All my new fittings after the old connection are a piece of cake, its like I know how to solder again. I knew as soon as I saw this tubing it was gonna be an issue because I saw it once before.

[Capz]

Here's what I would do. I would clean the tubing the best I could, flux it, heat it as if I am soldering, cool it with cold water on a cloth or heavy paper towel. This will help get it very clean. Then go at it a 2nd time for real. Sounds like your older copper may have some ferrous metal in it? I am assuming you are using 95/5?

[IFRZAIR]

Dont use water based flux!!!! I use the Johnsons flux, it looks like petroleum jelly... Not sure what flux your using but I soldered some inch and a half with the water based and well I thought i sucked at soldering too.... good luck!

[tinman]

tin the old pipe first this way you'll know for sue if the solder will flow.

[2sac]

If the copper has annealed it will not take solder.

[tinman]

if all else fails use sharkbites.

[Brent Ridley]

Tinman hit the nail on the head. Sharkbite fittings. No soldering needed. They are a bit more expensive but they save a headache in situations like yours.

http://www.sharkbite.com/usa/

You can find them @ Home Depot, Lowes and any plumbing supply house.

[timebuilder]

Tinman hit the nail on the head. Sharkbite fittings. No soldering needed. They are a bit more expensive but they save a headache in situations like yours.

http://www.sharkbite.com/usa/

You can find them @ Home Depot, Lowes and any plumbing supply house.

I like the sharkbite idea.

I didn't know that annealed copper won't take solder. This is why I love this site. That said, I've never run into annealed copper, apparently.

[koolkahuna]

On old dirty ACR copper I automatically apply silver solder paste even when just using SilFos. You did well to use silver solder assuming you used the ss paste but you can also clean copper very well with TSP (trisodium phosphate) mixed with water. I saw plumbers do this on brand new fittings when they were installing medical gas piping in a hospital. Oxygen systems need a totally oil/grease free environment to prevent explosions and the TSP solution ensured that. They rinsed the fittings off afterwards and then let them airdry before brazing them with SilFos.

[craig1]

I didn't know that annealed copper won't take solder.

I don't believe that is true. soft copper like linesets are annealed and they solder just fine. If the copper is overheated to the point of oxidizing then it will not solder, but the oxides can be cleaned off.


Here in the Chicago area, we have a lot of houses that were build in the 50's that have hot water baseboard system that are piped in something that is not the copper pipe we are familiar with today. I suspect it is the same stuff that the OP has run into. I have never seen it used for fresh water, only heating systems.

It seems to be some kind of tin plated steel, but at the same time looks like there is copper in it. All the original joints look like $#!& too, so it must have been just as hard to solder in the 50's as it is now.

Sharkbites are a lifesaver when you run into this garbage. However I have had luck using oil based paste flux, and a high quality solder like staybrite or canfields

[Joehvac25]

I have a house from the 50s, I had a hard time soldiering some old stuff, some of the old stuff won't come apart either when you try to unsweat them. I had a few joints I heated the hell out and wouldn't come apart.

[2sac]

I don't believe that is true. soft copper like linesets are annealed and they solder just fine. If the copper is overheated to the point of oxidizing then it will not solder, but the oxides can be cleaned off.

Let me rephrase it to "field annealing" lol. If my terminology is incorrect then please correct me. Annealing is the process of heating a metal until it's properties change. Field annealing would have occured when trying to solder with maybe water in the copper. The solder won't take and the copper becomes a greenish purpleish color. Also hard and brittle. Even after cleaning the copper and adding flux, the solder won't take. I practice my annealing skills normaly repairing condensate drains in freezers when there is residual ice in the line. I've heard an old plumbers trick is to stick bread in the pipe to absorb the water while the joint is being soldered, then just flush it out with a little pressure. Never tried that.

[2sac]

I have a house from the 50s, I had a hard time soldiering some old stuff, some of the old stuff won't come apart either when you try to unsweat them. I had a few joints I heated the hell out and wouldn't come apart.

I have also had this happen with freezer/cooler drains

[craig1]

Let me rephrase it to "field annealing" lol. If my terminology is incorrect then please correct me. Annealing is the process of heating a metal until it's properties change. Field annealing would have occured when trying to solder with maybe water in the copper. The solder won't take and the copper becomes a greenish purpleish color. Also hard and brittle. Even after cleaning the copper and adding flux, the solder won't take. I practice my annealing skills normaly repairing condensate drains in freezers when there is residual ice in the line. I've heard an old plumbers trick is to stick bread in the pipe to absorb the water while the joint is being soldered, then just flush it out with a little pressure. Never tried that.

annealing is the process of softening a metal. To anneal copper, you heat it until it glows and then cool it either slowly or quickly.

To anneal steel, you use the same process, but it must not be cooled quickly or it will re-harden.

Copper cannot he hardened uniformly in the field. Copper pipe is rolled in the factory to make it hard. Once you anneal it, theres no going back.

What you may have experienced was hydrogen embrittlement in which hydrogen from the water damaged the hot copper. This is more prominent with low grade copper.

[2sac]

Thank you for clearing that up.

[Eddie1KRR]

. I've heard an old plumbers trick is to stick bread in the pipe to absorb the water while the joint is being soldered, then just flush it out with a little pressure. Never tried that.

Man, I have tried that trick a whole lot of times now, for me at least, it almost never works. I think I have got about a 10% success ratio with it at very best.
I always have to leave an open joint while sweating like a union of some sort, or sweat in a shut off where it's legal, leaving it open until I get the upstream side sweat in, then close it and move on to the rest. Between dripping and steam holes, that migrating water seems never ending most times.

[koolkahuna]

Okay, here it is.
USE WHITE BREAD ONLY. Remove the crusts. Squash the bread between your hands and roll it around until it becomes a gummy ball of dough larger than the pipe hole. Force it into the end no more than a fingerlength. Watch to see that you have the flow stopped. Any water in the pipe will cause the dough ball to expand and form a seal that stops nonpressurized water from ruining your solder or braze joint for the five or ten minutes you need. Once joint is done, flush water through and the dough ball dissolves quickly. If you can't flush it the standing drain water just takes longer to dissolve it. It always dissolves.

If the pipe is full of water I use a CO2 pipe freezer to form an ice plug and keep it in place until repairs can be made.

[monkeyspanners]

Man, I have tried that trick a whole lot of times now, for me at least, it almost never works. I think I have got about a 10% success ratio with it at very best.
I always have to leave an open joint while sweating like a union of some sort, or sweat in a shut off where it's legal, leaving it open until I get the upstream side sweat in, then close it and move on to the rest. Between dripping and steam holes, that migrating water seems never ending most times.

Last bit of plumbing i did on used pipes moving a sink in my kitchen i used a wet and dry vacuum and a thin pipe fed down the copper to suck out enough water so that it didn't cause problems when soldering. A small syringe would have been better but had to work with what i had!

[koolkahuna]

Last bit of plumbing i did on used pipes moving a sink in my kitchen i used a wet and dry vacuum and a thin pipe fed down the copper to suck out enough water so that it didn't cause problems when soldering. A small syringe would have been better but had to work with what i had!

That's a pretty good idea! That one goes in my mental tool box for sure.

[passintyme]

Most of the issue on old water line comes from the cleanliness of the inside of the pipe... I know it sounds crazy but the junk built up inside acts as a heat sink and drains your heat away from the work and inhibits the path that the solder will flow to.