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Old 02-23-2009, 09:17 PM   #16
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How To Solder Copper Pipes


was helping a friend do a quick get by fix and asked him for a piece of bread. he came back with one. the wife yelled down if you guys are hungry i can make sandwiches

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Old 02-24-2009, 12:58 AM   #17
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How To Solder Copper Pipes


Quote:
Originally Posted by thekctermite View Post
Hopefully some other folks will have some other tips or scenarios to make this thread more informative.
I'll take The KCTermite up on that.

1. The purpose of sanding the outside of the copper pipe is not to clean it of oils. The purpose is to remove the copper oxide that forms on copper when it's exposed to air. That oxide film forms slowly at room temperatures, but almost instantaneously at soldering temperatures (or from about 350 to 450 deg. F, depending on the solder you're using.)
Copper is an orangy/gold colour, but Copper oxide is brown in colour, and it's the formation of a copper oxide film over the copper that causes new pennies to turn brown in time. Ditto for copper piping and everything else made of copper.

Oxygen atoms hold onto their outer electrons very tightly. Metal atoms, on the other hand are very loose with their outer electrons, and it's this difference that prevents metals from having a high affinity for oxygen or even metal oxides. Liquid metals, like molten solder, have a very high affinity for bare copper metal, but little to no affinity for copper oxide. In order to get the solder to stick properly to the copper of the pipe and socket, it's necessary to remove all the copper oxide from both AND prevent it from forming during the soldering process. Only then will there be enough capillary pressure drawing the heavy liquid solder into the joint to fill it completely. Any copper oxide film on the pipe or socket will prevent the molten solder from sticking to the copper oxide, resulting in a leaking soldered joint.

2. Soldering flux consists of petroleum jelly (which is what "Vaseline" is) with zinc cloride powder mixed into it. The purpose of the flux is threefold:
A) it prevents an oxide layer from forming on the bare copper
B) it cleans the bare copper of any remaining oxide on it, and
C) it promotes good flow of the solder by keeping the copper metal bare until it is displaced by the solder.

3. The petroleum jelly's job is to prevent oxygen from the air from coming into contact with the bare copper metal while the joint is being soldered. So, in that respect it merely acts as a physical barrier between the copper and the surrounding air. So, you can solder using Vaseline as flux, but the solder will only flow into the joint. It'll beed up on the surface of the copper pipe because the Vaseline outside the joint quickly burns off and exposes the bare copper metal to oxygen in the air.

To prove this to yourself, next time you solder a joint, sand an entire foot (12 inches) from the end of the pipe and flux that entire foot. After you solder, allow everything to cool and clean off the residual flux from that entire foot, you'll find that the entire 12 inches before the joint is clean and bare, just like it was before fluxing and soldering. The flux on the copper pipe prevented the pipe from oxidizing and discolouring as usually happens on sanded copper piping near the solder joint (or source of heat).

4. The zinc cloride acts like an acid. At soldering temperatures it dissolves any residual copper oxide in the joint that wasn't removed by sanding. It dissolves the copper oxide much more aggressively than the copper metal.

5. When you solder a joint, what actually happens is that the molten solder has a greater affinity for the bare copper metal than the flux does, and so it's CAPILLARY PRESSURE that draws the molten solder into the joint to displace the flux inside it. Once the molten solder is in the joint, something called "amalgamation" occurs in a very thin film at the solder/copper interface. That thin film consists of an alloy of the copper and solder that results when the two dissolve in one another. Some of the tin and antimony (or lead) atoms dissolve in the solid copper and some copper atoms dissolve in the molten solder right at the surface of the copper.

(The following was told to me by my metallurgy prof in University. I tried to find a website to confirm in Google, but was unable to.)

If you ever unsolder a joint, you'll find that you cannot completely remove the old solder from the end of the pipe by heating with a torch and wiping. That's because the melting point of the alloy formed at the amalgamation plane varies from that of solder on it's outside to that of copper on it's inside. So, the "solder" doesn't wipe off because it's not molten because it's no longer pure solder with the melting point of pure solder.

6. Everything from sanding the copper pipes to adding zinc chloride to the flux is designed to prevent copper oxide from forming inside the joint. At soldering temperatures, that oxide layer will form instantaneously. So, if for some reason (like not allowing a path for the heated air inside the pipe to escape) the solder isn't drawn all the way around the joint, then adding flux and solder when the joint is hot will (at best) just plug up the leak in the solder joint. It won't end up filling the joint with solder. The reason why is that while you are soldering, the flux won't burn because there isn't any oxygen inside the joint for it to react with. If air inside the pipe expands and leaks out through the fluxed joint, the flux exposed to air will burn off, exposing the bare copper metal that will immediately form an oxide film over it. After that, the molten flux will NEVER bond properly to that oxide film because oxygen hordes it's electrons. The best that you can hope for is that you can plug the END of the leak in the joint with solder. But, that's just a leak waiting to happen.

7. So, how does this affect what you do? Understanding the process allows you to understand why it's seldom necessary to remove old solder from old pipes or sockets. If you unsolder a copper pipe from a socket, you're best bet is to NOT remove the solder from the socket or the end of the pipe. That solder in the socket or on the end of the pipe will protect the underlying bronze, brass or copper from oxidation. Just leave the solder on the end of the pipe or in the socket until you need the pipe or valve. Then, when you need that piece of pipe, just heat the end of the pipe and wipe the old solder off. If it's a valve, heat the socket of the valve and insert a piece of sanded and fluxed copper pipe into it until it goes into the socket, and then pull it out, thereby removing the old solder from the socket. (Repeat if necessary) Then clean the end of that pipe with steel wool or a piece of sandpaper to remove any oxides that may have formed while the pipe was cooling down. Brush out the socket. Flux the pipe end and the ID of the socket and fit them together (even if both appear to be still covered by solder). Now just heat and add enough solder to ensure the joint is full (by the formation of a drop of solder on the bottom of the joint as discussed by KCTermite). That solder joint will be just as strong and last just as long as had you gone to the trouble of using a new pipe and sanding the old solder out of the sockets of the old valve. In fact, it'd prolly last longer because by not sanding the old solder out of the sockets, you're not enlarging the ID of the socket.

PS:
To learn more about soldering and brazing copper, brass and bronze, go to the Copper Development Association's web site at:
http://www.copper.org
and click on the "Publications" link,
then click on the "Publications List" link
then RIGHT CLICK on the "Soldering/Brazing/Welding" link on the list on the LEFT column of links, and chose "Open in new Window".
Then download everything you want.
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Old 02-24-2009, 07:36 AM   #18
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What he said.
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Old 02-24-2009, 11:18 AM   #19
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Here is a direct link to the Copper Development Association's download page for soldering, brazing and welding copper:

http://www.copper.org/publications/p...soldering.html

There's a 1.1 MB PDF file you can download that provides helpful tips on soldering and brazing copper.

There's an 8 page PDF file that gives step-by-step illustrated instructions on soldering and brazing copper tube and fittings.

There's also an 18 minute long video you can order for $25 on soldering and brazing copper tube.

And there are other paper pamphlets you can order for a small fee or PDF files you can download free.

Also, I forgot to mention a few things in my last post:

A) Experienced plumbers will often bark at me for telling people that it's OK to use the soldered end of a piece of copper pipe. They feel that's bad advice because they believe it's "safer" to start with new pipe. All I can say is that when I discussed the matter with the department head of "Piping Trades" at the local provincial trade school here in Winnipeg, "Red River Community College", he advised me that was standard plumbing practice. He also recommended cleaning and fluxing the pipe end to remove any oxides of lead, tin or antimony that may have formed, but it's not necessary to remove all of the old solder, especially from sockets which are much harder to remove that old solder from than pipes.
In my own case, whenever I have to remove a Brasscraft compression stop in order to remove a section of wall, I always solder the old valve body back on after the work is done using the procedure described above. I've never had a leak doing that.

B) It IS true that when you're soldering in a valve, it's best to remove the cartridge from the valve to protect it from the heat. The exception is when you're soldering in a ball valve. In that case, you're more likely to cause a leak by taking the ballvalve apart to remove the ball and seals and then putting it back together than you are by soldering the valve in as is.

When soldering ball valves, Just make sure that the valve is in the open position. Also, when brushing out the sockets on the valve with a fitting brush, drop a standard #12 flat washer into the socket before brushing. A #12 flat washer will have a 1/4" ID and a 5/8" OD, and it will prevent the steel bristles of the fitting brush from coming into contact with the teflon seals inside the valve. That ensures that the seals aren't damaged by the fitting brush.

C) Some valve manufacturers are now selling globe and gate valves that don't have a fiber washer or gasket between the bonnet nut and the valve body. They simply tighten up the bonnet nut so tight that the valve doesn't leak even with a metal-to-metal contact between the bonnet nut and valve body. And, of course, they tell the user to just solder the valve in when it's partially open to protect the washer from the heat. That's dumb because when the time comes to replace the washer, you're more likely to wreck the soft copper piping the valve is soldered into than remove that bonnet nut. And, after replacing the washer, then you somehow have to tighten the by-Geezus out of that bonnet to get a water tight metal-to-metal seal again (without wrecking the copper piping).

There's a better way. Before installing the valve, put it in a vice and remove the bonnet. Now, go to any place listed in your yellow pages under Pneumatics and Hydraulics that sells rubber O-rings and inquire about "teflon back-up rings". Teflon back-up rings are used to prevent the O-ring from extruding into the empty space around it. So, some teflon back-up rings will have a contour on one side of the ring, but most are simply machined from a tube of teflon and so they are flat on both sides. Tell the guy you want a teflon back-up ring without a contoured side.

Teflon back-up rings come in a vast array of sizes starting with ID's of 1/8 of an inch all the way up to 12 inches with widths (difference between outer radius and inner radius) of 1/16", 3/32", 1/8", 3/16" and 1/4 inch, and most places will also stock popular metric sizes as well. So, you can always find a teflon back-up ring to fit your valve and serve as a gasket between the valve body and bonnet nut to prevent leaks.

Also, if the bonnet nut on a valve has 8 sides, that generally means you're not supposed to remove it, and that generally means that there is no fiber washer or gasket between the valve body and the bonnet nut. If you're wanting to use this valve inside a wall as a bathroom water shut off valve, or any other place where you can't use a wrench to remove the bonnet nut, you can modify an 8 point socket to make a tool for removing and tightening the bonnet nut. Just look for an 8 point socket you can put in a lathe and machine down the points so that each point contacts the middle of a flat on the bonnet nut. Then you essentially have a flank drive socket (like a Snap-On) to loosen and tighten eight sided bonnet nuts.

The ratio to find the size of 8 point socket needed to fit over an 8 sided bonnet nut is:

cosine of 22 1/2 degrees or 0.92388

So, if the bonnet nut is 1 1/4 inch across the flats, you'd need a:

(1.25) X (0.92388) = 1.155 inch 8 point socket.

That works out to a 1 5/32 inch 8 point socket which you won't find anywhere. So, buy the next smaller size (1 1/8 inch) socket and have the points machined down on a lathe until it just fits over the bonnet nut.
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Old 02-24-2009, 11:35 AM   #20
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Termite; TUNES man u fergot da Tunes and a doggie treat for da helper
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Old 02-24-2009, 12:17 PM   #21
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Skymaster:

Are you suggesting I'm TheKCTermite's "helper" and the doggie treat is for me?
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Old 02-24-2009, 01:44 PM   #22
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Sit Nestor, sit! Gooooood boy.

Nah, I think skymaster's referring to my little buddy in the first picture.
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Old 02-24-2009, 02:39 PM   #23
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Two points often overlooked.

Wipe the joints with a wet rag after soldering to remove the excess flux. Remaining flux will continue to etch (eat) the copper pipe.

Deburring/reaming of the cut edges of the pipe is also very important. The sharp edge will create turbulence in the water, causing friction and pipe wear.
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Old 02-24-2009, 03:16 PM   #24
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Nestor:
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Old 02-24-2009, 03:49 PM   #25
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That's it.

I'm gone.
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Old 02-24-2009, 04:56 PM   #26
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no u knot u lurkin waitin fer your shot when i knot lookin BAM!!!!!!! Nestor got me OH NO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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Old 02-28-2009, 05:04 PM   #27
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I have a question! The code in my area requires that we would use 'silver' solder, rather than 'lead'.
My question is, can I still use the 'Vaseline' paste that I have on hand, or does it require a special paste designed for silver?
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Old 03-15-2009, 01:01 PM   #28
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Great "how to" KC! Wish I had learned the "bread trick" long before I did. It would have saved me much aggravation and "spouting of obscenities"! I noticed the yellow gas bottle in your picture of supplies. It might be worth mentioning that it is Mapp gas and burns hotter than regular propane. (And is available at the big box stores.) Melts the solder quicker. Something else I learned later in my plumbing career, which thankfully, is something I only attempt at home and in emergency situations for close family and friends. I always have a contact number for a REAL plumber in my phone book.....
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Old 03-15-2009, 02:07 PM   #29
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This is probably the best thread I've read on this site so far... Very detailed 'how' and then well written and researched 'why'. And very limited anecdotes. I love it, thanks very much guys... I've stayed away from plumbing because most of my improvements END with fire... It seemed a Bad Idea to BEGIN with fire. But now understanding the chemical process and procedure, I feel I can tackle a first bathroom redo. Thanks!
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Old 03-15-2009, 05:14 PM   #30
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Quote:
Originally Posted by bjbatlanta View Post
Great "how to" KC! Wish I had learned the "bread trick" long before I did. It would have saved me much aggravation and "spouting of obscenities"! I noticed the yellow gas bottle in your picture of supplies. It might be worth mentioning that it is Mapp gas and burns hotter than regular propane.
Thank you sir! I mentioned the mapp gas in post #1 but didn't mention how it gets hotter than propane. I like the stuff.

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