Soldering copper pipe, and misc.

I have pretty good experience soldering electrical devices, so I didn't think soldering copper would be too much different. After having tried it today, I dont know if I'm doing it right. All the internet research states to apply flame to the fitting, and remove before applying solder. I could never get it to do this, so most of the time, i had flame on the fitting while i was putting the solder on. It seems to work, I ran out of solder before I could finish and run some water, so I dont know 100 percent. The only thing is the existing pipe and fittings look a lot different, like more solder was used on them then what I did. I tried to put as much solder as they did, but it just dripped right off the pipe, so I could never get it to look like that. I just think maybe I'm not doing it right. What are some tips you guys have for me? I'm having fun doing this though, so I guess it's all worth it.

Also, when tapping into an existing 3/4 inch supply, what are some tips for bending the pipe enough to slip the t-fitting on?

Also, sorry, when cementing pvc, how long do I have to correct a mistake before it's too late? I'm going to be installing a toilet tomorrow, and cutting the 3 inch stub out to slip the flange on it, and i'm worried that I may not be able to get the flange How far under the concrete should I cut the pvc? Is there some sort of cutting tool that I can use from the inside in, because it's going to take a while cutting the pipe past the first cut that will be level with the concrete. maybe thats all I need????

PVC...you have less than 5 seconds to adjust a glue joint.


On the copper....I assume you have cleaned the pipe and the inside of the fitting with wire brushes or emory cloth. Then applied a good paste flux to both pieces. On a 3/4" fittiing, it should be hot enough within 1 minute or less typically. Once it it hot, apply the solder to the joint and it should run. You will see it drawn into and all around the joint. You are done. If you keep applying solder and perhaps a little more heat, excess solder will run out, but possibly will also run inside the fitting, so you should avoid too much solder.
Most plumbers wipe the finished joint with a rag while the solder is still molten. This can give the joint a polished look, but you must avoid moving the joint. It is not necessary to wipe the molten joint. You should wipe it clean afterwards to remove flux residue.

I'm with Jimbo, if you haven't cleaned and fluxed the joints properly then the solder just will not take. As far as the 3/4" connection, they make a 3/4" copper coupling to slide down the copper, slide it past your cut line, fit your pieces then slide it back ( mark the halfway point of the coupling on the pipe so you know where to stop your coupling when sliding back). As far as the 3" cut, yes there is an inside pipe cutter available that usually fits on the end of a drill. You may want to specify that you want a flush fit floor flange which doesn't have to sink into the concrete as much. There are also floor flanges available that glue inside the 3" pipe, which means a flush cut to the floor is adequate.

edj said:

I'm with Jimbo, if you haven't cleaned and fluxed the joints properly then the solder just will not take. As far as the 3/4" connection, they make a 3/4" copper coupling to slide down the copper, slide it past your cut line, fit your pieces then slide it back ( mark the halfway point of the coupling on the pipe so you know where to stop your coupling when sliding back). As far as the 3" cut, yes there is an inside pipe cutter available that usually fits on the end of a drill. You may want to specify that you want a flush fit floor flange which doesn't have to sink into the concrete as much. There are also floor flanges available that glue inside the 3" pipe, which means a flush cut to the floor is adequate.

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I thought that I got a flush fit flange, but after cutting it about 10 minutes ago, it looks like I will have to cut the pipe about a half inch into the floor. I looked into the inside the pipe flange, but it seemed too small for the waste to pass. Maybe I will revisit this again tomorrow.

Thanks for the advice on the copper, both of you. I'm sure I cleaned it pretty dang good, and polished it, as applied a healthy dose of flux. I guess It will just be a learn as I go type deal. If I need to fix something, oh well. My main shutoff valve is only about 20 feet away, so I could run and turn it off pretty quick if needed.

The inside floor flange opening is no less than the outlet of the toilet bowl itself and I haven't heard of any problems when I've had to use them. Another soldering tip is if there is still water present it will cause problems, if this is the case you may try stuffing some bread down the lines, it will stop the water long enough to solder and then eventually will dissolve.

The biggest problem I have seen with DYI soldering is they try and heat copper with a pencil tip flame, which can take a lot longer, and they never get the fitting hot enough.

Oatey No. 95 Tinning Flux

My soldering got a lot easier and better when I started using Oatey No. 95 tinning flux. Because it is a tinning flux, it protects the copper from oxidation as soon as it melts.

A drip can mean it's done...

I'm a total novice, but I've sweated some pipe successfully. Most of the advice I got said that when a drip forms, you're done soldering.

My question is about the need to flare rigid copper pipe. Is a flaring tool only used for soft copper pipe? Do you just deburr the inside of a new cut in rigid copper pipe with a file?

Where did the question about flaring come from? We are talking about soldering, and there is no flaring involved. Soft copper can be flared for a mechanical joint, but that is a different ballgame from soldering.

Well, I finished the cold water piping. I guess my soldering wasn't all that bad. I dont see a leak. How long does it typically take for something to spring up, if there is a leak?

Normaly about as long as it takes to pressure up. Once in a blue moon you will get a leak hrs. or days later but it is very rare and I haven't had any of thoes since I switched to Oatey 95 pretinning solder.

Soldering copper pipe has some similarities to solding electrical connections. You heat the joint until the hot joint melts the solder and it flows into the joint. Just like electrical work, you don't want a cold joint and you don't move the joint until the solder is set. Of course with copper pipe we have to clean the pipe end and the inside of the fitting and apply flux, but the basics are about the same.

On the PVC, if you still are working on that, don't worry if you cut the pipe 1/8" or even 1/4" short, there's still plenty of surface left to make a good joint. Be careful to orient the flange when you slip it on. There was a guy posted a message a couple of days ago about a plumber that installed a flange set in concrete 90 degress out! You have a little wiggle room, but not that much.

JohnyChevyEG said:

My main shutoff valve is only about 20 feet away, so I could run and turn it off pretty quick if needed.

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I've gotten wet by a leak before ... after any plumbing work, I shut off the faucets and I only turn on the shutoff a smidgen while I inspect my work. I usually spray a little soapy water on the joint after intially turning on the water. The air in the pipe will bubble before the water gets there if there is a leak. I turn on a faucet or two and still look for leaks before going full on.


Maybe its not necessary because it never leaks when I do this, but when I just go full on, I've always missed a joint

question answered...

My question was answered. Sorry if you found it silly, but a lot of books on plumbing include flaring in their soldering instructions as a method of smoothing out ridges on the inside of a rigid copper pipe after cutting it.

It didn't make sense to me, hence my question.

Apples and oranges

coach606 said:

My question was answered. Sorry if you found it silly, but a lot of books on plumbing include flaring in their soldering instructions as a method of smoothing out ridges on the inside of a rigid copper pipe after cutting it.

It didn't make sense to me, hence my question.

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Perhaps it's a badly edited book -- but I can't see why it would have deburring a rigid copper pipe before soldering in the same context as flaring soft copper, which is a completely different form of fastening pipes/fittings. Flaring means to spread or widen -- neither of which you do when you deburr a copper pipe when prepping to solder.

Gary Swart said:

Soldering copper pipe has some similarities to solding electrical connections. You heat the joint until the hot joint melts the solder and it flows into the joint. Just like electrical work, you don't want a cold joint and you don't move the joint until the solder is set. Of course with copper pipe we have to clean the pipe end and the inside of the fitting and apply flux, but the basics are about the same.

On the PVC, if you still are working on that, don't worry if you cut the pipe 1/8" or even 1/4" short, there's still plenty of surface left to make a good joint. Be careful to orient the flange when you slip it on. There was a guy posted a message a couple of days ago about a plumber that installed a flange set in concrete 90 degress out! You have a little wiggle room, but not that much.

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I've learned to be more patient in heating up the fitting, so it has made the last few joints a lot better. The hot water pipe is going to be a breeze, since I have the pipe ready to tap into the supply.

As far as the PVC, I have one of those rotating flanges, so I will be able to orient it however I need. I gave it a little bang with the hammer, and it went in all the way, so it looks good.

I cannot even express how great this site is for helping newbies like me in this stuff. If I didn't have personal tips from real people, and not just a book, I dont think I would have had the courage to do this stuff. I cant wait till i'm done with this bathroom, because the kitchen is next. I'm on a steak!!