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How to solder Copper (and/or Stainless)

PostPosted: Sat Mar 17, 2007 5:49 am
by Husker
Husker wrote:This was posted on yahoo Distillers forum, by Geoff Burrows, and is a VERY nice intro into proper methods of soldering copper. Pintoshine also posted a nice howto on soldering rivited sheet 304 SS, but since he posts here, I will let him post it. It might not be bad for him to post as a followup message to this thread.


Hi Everyone,

I've seen from reading the forum, that on and off people tend to have a degree of difficulty when soldering for the first time or even just soldering in general. For those that fit into this category (and don't want, or like to admit it). If you follow this guide you will/should achieve a reasonable successful job I'm an ex-plumber and soldering is no big secret as long as you follow and understand certain basic facts, methods and rules used to solder successfully.

For those who already know how to solder skip this posting. This is really for those who feel intimidated by the art of soldering. It really is easy. I've only got the use of one hand and I can still solder OK. I just a have a lot of preparation to do these days when I solder.

There are 4 areas we need to look at, they are:-
(1) The metal
(2) The solder
(3) The heat source
(4) The flux

Let's take each one separately and get to know how each one will affect us in soldering.

1. The metal i.e. copper. Copper like any metal will corrode in its own certain way when exposed to the atmosphere. (Iron or steel being ferrous will rust and turn red. Aluminium will turn powdery white and crumple) copper if left to its on devices, on a roof covered in copper will turn a beautiful bright, light, almost florescent green and stop at that coating. And in order to solder copper, this corrosion must be removed back to the base copper metal. (Remember to always keep your work fluxed, clean and shining that's the big soldering secret). Thankfully, the copper pipe we get from the stores has only the initial stages of surface corrosion started and this can easily be removed with wire wool or emery cloth, but I find coarse wire wool is best to use. Clean the copper and all surfaces to be soldered, until they shine brightly and set them aside and don't touch them with moist sweaty hands. As the salt/grease in the sweat will turn to carbon when heat is applied, not good for soldering (solder won't stick to carbon)

2. Solder. Use new relatively clean bright looking lead free solder. LEAD FREE is most IMPORTANT for the purpose we intend to use it for

3. Heat source. As a heat source you really need a butane or propane torch/burner with at least a ½" nozzle. (I think even that is very under powered)

4. Flux. A general all round soldering flux is as good as any these days, they should all work well. The flux is pretty inert when you apply it at room temperature, but when heat is applied the flux will become very corrosive and will bite into and really clean the surface of the copper, especially when it has reached 100 degrees C plus, and the flux will make the solder really flow onto the copper surface and join where the flux has cleaned it. The flux can be easily burnt, by the torch flame, and turn to carbon which is not good for us. (more about this later)

Soldering Procedure.

1. Copper fitting usually comes in 2 types, end feed or solder ring. End feed by its very name means you feed the solder in via the end of the fitting and pipe join line. All new solder integral solder ring fittings have an integral ring of lead free solder inside and this will flow in a perfect ring around the join when they are cleaned fluxed and heat is applied. They cost more but if you are unsure about your joints, this is a good way to go to get good joins. I shall deal with end feed fittings for this topic.

2. Next cut, "dry fit" and check and clean all your pipes and fittings that you intend to solder

3. Flux them all up and smearing enough flux inside the female fitting and on the part of the pipe that will be going inside the fitting, (apply the same amount of flux to the copper parts as you would antiseptic cream to a cut finger) I personally apply a lot more. But that's just my preference

4. Unroll a length of solder. A general guide as to how much each join takes is on (a 2" pipe). If you bend or kink the solder about 2 ½" from the end and when that has feed into the join that should be plenty in there. (Slightly more than the pipe diameter whatever join you are making. The same rule applies whether its ¼" or 6" it's a good general guide)

5. Now assemble and set your pipe and fittings, light the torch/burner, and with your stick of solder at the ready. (For a 2" column pipe) Apply heat first to the pipe about 3 "away from the join on the top, the sides and the underneath as equally as you can until you see the flux sizzling at the join at least.

6. Then do the same on the fitting but not as long on the fitting. And certainly not on the join line if you can help it. (because that will burn the flux)

7. If you get too close to the join the flux will burn go brown and then black and carbonize. (burnt carbonized flux will ruin a good join) The trick is to be patient and let the heat move along to the join from about the 3" away from the join and then let this heat move into the fitting and out to your solder stick. So be careful and watch out for this, because solder won't stick to carbonized flux on the pipe or join. If this happens to me. (Which it sometimes still does) I have a long stiff hog hair artist brush dipped in flux and I swish this over the join and it cleans the old carbon off and leaves it nice and bright again for the solder.

8. Things are now happening fast. Direct the heat away from the pipe and fitting. Now with your solder stick touch it to the top of the join line. Be patient and wait, let the heat get through into the solder. It should soften and squelch onto the join. Now take the solder away and apply more heat in the same sequence as before. The solder you applied will likely get sucked into the fitting. But don't panic, continue your heating.

9. Now apply more solder and wait again, it will suddenly soften and run straight into the join. Now apply more heat to the fitting this will draw all the solder to the kink mark on your solder stick into the join. Solder will run and get drawn up into and evenly between the two copper surfaces. Just the same way sap on a tree will get drawn up between the bark and the wood evenly. This is called capillary action.

10. If there is any obvious gaps, heat and feed more solder in and just flash the heat across it just enough until it smoothes nicely between pipe and fitting. (Don't get hypnotized by the flame and have it pointing at the flux and end up burning it because it is so very easy to do) Back off with the heat and solder stick, and again be patient and let it cool enough for the solder to set (because the join and fitting can and will move if you are not careful) and that's a big no-no if a 2" elbow ends up pointing the wrong way and ends up setting that way

11. While it is still slightly over hand hot but with the solder hardened use an old rag, wipe and clean off the old burnt flux, it will come off real easy when its hot like this

The master plumber who taught me said when soldering copper always think ahead and always follow the 7 "P's" Principle. Which is:-
(1) Previous
(2) preparation and
(3) planning
(4) prevents
(5) pi** or pathetically
(6) poor

Hope this hasn't been too boring guys but some people just don't know how to solder properly, and this is for them and :- (Remember to always keep your work fluxed, clean and shining that's the big soldering secret)


An extra bit.
The solder sometimes runs all the way around and forms almost a droplet at the bottom of the joint. That's OK as it's just the excess solder trying to run out of the joint at it's lowest point.

Mod edit: Original Post: viewtopic.php?f=15&t=4052

PostPosted: Thu Nov 15, 2007 10:22 pm
by byacey
A few more words on Solder - While it's been stressed many times in many different places on this forum to use lead free solder, I feel some novices should be aware that just because it's labeled "Lead-Free" doesn't necessarily mean it's safe for our purposes.

When choosing a solder to buy, obtain and read the Material Safety Data Sheet (MSDS). Some lead free solders have other harmful metals that we don't need to be coming in contact with our drinking alcohol. Cadmium and Antimony are a couple of the more common ones. These often make up only a small percentage of the total metals in the solder, but nonetheless they are harmful and should be rejected. These "bad" metals are added to ensure better wetting of the solder joint and usually have a lower melting temperature as a result of the alloy mixture. This makes soldering easier, but don't be tempted to use this stuff for your still.

Regarding silver solders - Again find out what the makeup of the solder is. Make sure the silver solder is approved for food grade usage.

PostPosted: Sat Nov 17, 2007 2:24 am
by HookLine
A list of safe solders and brazes is a damn good idea.

I know of the following in Australia:


Comweld 965 (soft silver solder). Tin 96.5%, silver 3.5%. This is your first choice for a solder, but it is expensive. It is distributed by Cigweld.

Lead Free Solder (Cat. No. N2632). Tin 99.3%, copper 0.7%.
Lead Free Silver Solder (Cat. No. N2633). Tin 95.5%, silver 4%, and copper 0.5%.
Both are sold at Dick Smith Electronics.
(I can't find the MSDS for these two. They both have a flux core and I don't know for sure if that is safe. But it should clean off okay after soldering, and I think CoopsOz used the Lead Free Solder on his still.)


Pro Silver 2
Pro Silver 5
Pro Silver 15


The SilBRAZE P is mostly copper with a small amount of phosphorous. The other SilBRAZE and all the Pro Silver are silver (2%, 5%, 15%) and copper, with a small amount of phosphorous. The phosphorous acts as flux for copper-copper joins, but copper-brass joins need a boron based flux.

In Australia Pro Silver is distributed by BOC Gas, and SilBRAZE by

PostPosted: Wed Nov 21, 2007 6:37 pm
by pintoshine
alice wrote:Anyone have any good tips on cleaning up the joint after its cooled, especially cleaning off the burnt flux crud?

I use mineral spirits whenever the petroleum jelly and zinc chloride flux is used on the outside. It cuts the petroleum crud very well. Typically I will run a 4 to 5 hour run of steam followed by a run of tails to be thrown out, for the inside. This does a pretty good job for commissioning a new still. This is for soldering copper of course.

PostPosted: Sun Nov 25, 2007 7:11 pm
by pintoshine
I saw that you referred to me for the stainless steel soldering. I have two write up for soldering stainless steel.

Starting in the spring of 2007, I came by a lot of scrap stainless steel from a scrapper gutting a grocery store. The sheeting was a lot of stainless steel shelf liners. All but one sheet was 22 ga. and the one sheet was 18 ga. This is what I did with it.

304 is hard to solder. You have to have it perfectly clean, heat it flux it and clean it again and flux it and then the solder might wet the surface if you are lucky.

My solution was:
1. Surface preparation: I used a stainless steel, soft wire, cup shaped brush in my drill to clean any surface to be soldered until it was nearly mirror shiny.
2. The heat source: I purchased a 175 watt Weller soldering iron, not a gun.
3. The flux: The flux was a surface cleaner and wetting agent. I used common, off the shelf muriatic acid used full strength. This was fairly inexpensive and did a fabulous job. It requires a small amount of clean up but applying enough water to dilute the acid to nothingness once finished with a batch of soldering. The fumes were no difficulty with adequate ventilation, proper application and careful body position. The acid itself was applied with cheap, natural hair, acid brushes. The brushes were disposed of after each round(4 hours or so) of soldering.
4. The solder: the 95%/5% silver, had one characteristic that the 96%/4% antimony did not. It had a better surface tension and would pool rather than run.

The procedure was:
1. Clean metal to be soldered to a bright shine.
2. Apply the barest minimum of acid to wet the surface to be soldered.
3. Apply the iron to start heating the metal.
4. Keep face and hand away from the fumes from the acid.
5. Feed solder at the interface of the iron and the metal to create a small pool.
6. Move the solder around with the iron feeding more as needed.

There is an observation I need to make here. The solder will adhere to the stainless anywhere the iron is applied. The surface of the stainless does not wick the solder like copper does. The solder will wet the surface at the interface of the iron and metal but does not flow much beyond that interface. For sealing up two layers of metal, the solder would wet the bottom sheet up to the junction of the two sheets and it would wet the face the iron could touch of the top sheet. Sometimes this my be just the very edge. The solder would bridge the gap nicely but would not wick down in between the sheets like it will on copper. The surfaces being soldered would have to be positioned nearly horizontal and level to prevent the solder from dripping away. In welding terms this is the flat position.
sssolder1.jpg (13.75 KiB) Viewed 63928 times

When soldering the really long runs, I use a constant, flowing motion of heating the metal and feeding the solder in a continuous motion. I can usually cover 24 inches in 30 seconds.
Next post will be a copy of soldering copper to stainless.

PostPosted: Sun Nov 25, 2007 7:23 pm
by pintoshine
This is how I connect the copper fittings to the stainless. I contrived a robust connection for copper to stainless.
1. Get a female threaded adapter for the size pipe you are using.
2. File or saw out the stop to allow a piece of pipe to slide all the way through.
3. Cut a piece of tubing a few inches longer then your connector.
4. With a pair of needle nose or small vice grips, turn an edge that is about an eighth inch outward around one end of the piper. Make the edge as perpendicular as possible.
5. Using water to keep your saw or drill cold, make a hole the size of your pipe through the stainless sheet.
6. Tin around the hole about 1/2 cm on both sides using the previous instructions.
7. Insert the pipe through the hole in the hole in the stainless until the perpendicular edge catches on the sheet.
8. Slide the female adapter over the pipe with the threaded end toward the sheet, clamping the sheet between the perpendicular pipe edge and the adapter.
9. Flux and solder the copper with a torch as usual, making sure to allow the copper to heat the sheet and not ever using the flame on the stainless.
10. Feed lots of solder between the copper and the stainless to create a nice fillet.
11. Leave very still until the solder hardens.

This should give you a very sturdy structure to solder. It will allow for some gaps to be overlapped also. If your hole is too raggedy the get a large piece of pipe and adapter and make the hole a little bit bigger. You can always use a reducer.

Here are some pics of my process.
thumper3.jpg (15.54 KiB) Viewed 63923 times

thumper4.jpg (26.87 KiB) Viewed 63921 times

This makes a very strong and airtight connection with soft solder and copper.

Re: Howto solder (beginners guide)

PostPosted: Tue Apr 22, 2008 5:32 pm
by GingerBreadMan
I just finished soldering stainless steel to stainless steel. Here's how I did it.

First the tools that are required -


Propane torch with solder iron tip (or you could use an electric solder iron as pintoshine describes)
Kester 817 liquid flux - says on label good for soldering SS (pintoshine has alternative fluxes)
95/5 tin/silver solder - your garden variety plumbing solder
Brush for applying flux
SS scrubby and SS brush on dremel tool

For this soldering project, I cut the rim off a SS bowl and I'm going to solder this rim to a SS pot. The idea is it will make it real easy to attach a SS bowl (I soldered a copper fitting to this bowl earlier) with black clips and seal with flour dough.

First step is to clean the SS surfaces to be soldered. First with the SS scrubby and then with a SS brush attached to the dremel tool. Apply some liquid flux and then attach securely with some black clips and start soldering.


Actually I found it easier to solder with the pot in this position -


Man I could solder SS to SS all day long. It's really easy to do.

Here's the final result -


Some tips -

- pieces should be clean. I had four spots where the solder didn't stick. No worries, when it cooled down, I used the SS brush to clean it up, applied some flux and resoldered.
- do not attempt with just a propane torch, you'll just scorch the SS. The trick is the soldering iron.
- I found it best to solder an inch at 12,3,6, and 9 o'clock positions. Then I soldered an inch in between those. This way I could ensure the bowl rim was perfectly aligned on the pot.
- soldering SS to SS is more like making a little pool of solder and spreading it around. Nothing like soldering copper. It's very fast once you get started. Apply liquid flux again if it doesn't stick to the SS. It should right away.

Gee, I feel like a pro after doing this. Thanks to pintoshine for the great instructions.

Here's how the pot goes together with flour paste -


A couple of black clips and this boiler is so easy to set up and break down.


Re: Howto solder (beginners guide)

PostPosted: Thu Aug 07, 2008 4:30 am
by pintoshine
I found the soldering tip(iron) to be quite necessary to push the solder around on stainless. Stainless lacks the wicking property the copper has. The solder wets quite nicely but puddles and does not run like on copper. Yes a tip or iron is necessary with stainless steel.

Re: Howto solder (beginners guide)

PostPosted: Wed Aug 27, 2008 6:01 am
by Kirko
Brazing is also called silver soldering, or vice versa.
The interchangeable terms is a source for much confusion.
Soldering is the use of a low temperature metal to join two items.
Silver soldering (or brazing) uses a higher temperature metal (still lower than the melt temp of the material to be welded) to basically weld two items.
In soldering, you stick two metals together through adhesion.
In brazing (or silver soldering) the filler material creates a new alloy at the joint, fusing the metals.
Silvaloy brand silver "solder" and many of the other silver "solders" are not silver soldering, they are soft soldering. Even if a solder does not contain lead, it can still be a "soft" solder.
A good quality silver solder will contain at least 80% silver, and melt at around 1700 F, the higher the silver content, the less oxidation of the solder while welding and the higher the temperature needed. All silver soldering (brazing) is done with the metal at or near red heat.
Whether soldering or brazing, cleanliness is of the utmost importance. When soft soldering, clean the metal with abrasive, rinse, then detergent, rinse, then rinse with solvent. One fingerprint will ruin the flow, if that happens, re flux with a wire brush and scrub the solder in as it melts.
With brazing, cleanliness is just as important but harder to maintain. You can't scrub it in because your brush will burn up, you can use a long handled scraper to scrape the seam as the braze flows but this is tricky, often necessary. Heat causes oxidation, oxidation stops the metal from joining, the key is to have everything bright (by scraping or sanding) and clean and work fast. The longer it takes you, the more the metal will oxidise.
If you get half way through and build up too much fire scale (oxidation) stop, scrape the metal bright, pickle with sodium bisulphate, re flux and start again.
The best way to avoid oxidation while brazing is "fire coat". Mix boric acid and pure alcohol 1 to 5 (one part boric 5 parts alcohol). Pour or brush this on your joints and immediately light it, the alcohol burns off and leaves a coating of boric (flux). A good flux is boric acid and borax 50/50 mixed with water or alcohol. Any commercial brazing flux should work.
Silver solder will flow towards heat, it also will draw itself along a seam by way of capillary action. Learn to use the capillary action, learn to draw the solder with heat. If you are soft soldering, I have no advice except, don't do it.
Silver soldering is also called hard soldering.
Silver solder generally comes in 3 grades, easy, medium and hard, they are all 3 hard solders.
I prefer to use hard silver solder on everything but it may be easier if you use medium or easy. All 3 melt at high temperature, the benefit of having 3 solders is you can join complex items by starting out with hard, going to medium when adding more parts, ending with easy for the last parts. This avoids earlier joins from coming apart while soldering later joins, not usually needed for still making.
My main supplier for flux, pickle (sodium bisulphate, called Sparex ) and silver is Rio Grande, in Albuquerque NM, give them a call and ask for the tool catalog, everyone should have one of their catalogs, they are the standard for the industry.
Clean it
scrape it
wash it
rinse it
fire coat it
flux it
braze it
pickle it
repeat as necessary.
I may not have explained this as clearly as you like but I'd be happy to answer any questions.

Re: Howto solder (beginners guide)

PostPosted: Mon Apr 20, 2009 7:21 pm
by Husker
I find that the cheap MAPP torches, the crappy burnsomatic things you get at the HW store, suck at doing 2". I have had problems like you, where the flux simply carbonizes up.

Since I got my oxyacetylene setup, I have been able to solder 2" super easily. The oxyacetylene flame is super tiny (thus, you can put it RIGHT where you want it), and super hot. It is very easy to heat up the pipe, and the fitting, and suck the solder right in there.

I have read of many forum members who had success at soldering with MAPP, but I have had nothing but heartache using it. For 1/2" or 3/4" water pipe repair, simple propane torch works wonders. For the larger stuff we build stills out of, I will use nothing but a good O2 torch, with a properly adjusted flame neutral flame.


Re: Howto solder (beginners guide)

PostPosted: Sat Apr 25, 2009 10:52 am
I have had scortching (flux) issues when I used an older more dried out container of flux.

Certainly the the Homo Depoe sized version of the Burnzomatic set up may not be the best unit for the 2". But it is completely doable.

Keep the heat applied to the female side of the joint and let the flame (thats bouncing off of the copper) turn green. Green flame is the key.

Once that flame is green you will only need to apply further heat every few seconds or so. Apply your solder to the joint and it will pull right into the joint quite nicely. Continue to apply heat and solder till you can conclude the joint is completely filled. Wipe around the joint with a balled up dry rag (while its hot) and your solder dribble and the like will clean right off. Or (while its hot) brush on joint surface some additional flux to allow remaining solder blobs to get sucked into the joint for a more tidy looking joint.

Re: Howto solder (beginners guide)

PostPosted: Tue Jun 16, 2009 2:47 am
by spumco
Long delay for a reply, but for two of the above questions...

To solder stainless, you need to use stainless flux. This is an acid (liquid) that cuts through the chromium oxide passivation layer. McMaster Carr or some other industrial supply place should have it. Do not try doing Oxy-fuel bazing with this crap. Be careful with the fumes - they're icky. The 16oz bottle I have will last me three lifetimes.

Warm the area, then put the flux on. It'll boil and smell like industrial death. The sold will then wet out on the stainless.

To BRAZE stainless, you need to use Grade IV filler. Flux is the same (white borax paste). Use a slightly reducing flame and take your time.

For 2" or bigger equipment and you've only got a little torch - tin the pieces first. Clean everything as usual, then apply flux and solder to each side of the joint individually. Yo do not want big globs of solder. Just let it wet out the surface.

After both sides are tinned, sand down any globs, re-flux and assemble the joint. Heat and solder the joint as usual. Heating up the entire fitting or pipe until it's fairly hot (but not so hot you've burned the flux) can reduce the heat sink effect at the joint.

Good luck.

Re: Howto solder (beginners guide)

PostPosted: Fri Nov 06, 2009 8:09 am
by Coyote
I feel like it is time to weigh in on the novice soldering issue with a couple of things that will help. I also am a former plumber.
1. Bright and shiny before you dry fit, Emory cloth or fitting brushes do a very good job at this. Fitting brushes in the 1/2,3/4 or 1" size are a couple of bucks each at the local hardware store. The average homeowner will not wear one out in their lifetime.
2. Flux brushes They are .25 cents each or less. I bought a 200 count box for $ 8.99 last month. Short camel hair brush
Never touch the fitting area to be soldered or the flux with your bare hands, even dry skin can transfer oils that can cause a joint failure months later.
3. Husker is correct in the amount of solder needed for a joint, A 1" fitting will require an inch of solder
4. Heat slowly, starting away from the joint until you see the copper just start to change color - then move your heat to the BACKSIDE of the joint and HEAT EVENLY & SLOWLY
Test with your solder - when the joint is ready the solder will be sucked into the joint - even upside down.
5. The biggest mistake anyone ever makes soldering copper is (and we all do it) thinking that more is better- IT AIN'T
You are creating a bond between 2 pieces of copper and filing a very small space The Master Plumber I trained under would have me make a solid joint on a 1" fitting using only 1/2"of solder just to prove to me it can be done. Using more solder than is required only creates drips, runs and a big mess.
6. When you have made the joint quickly run a flux brush with a small amount of flux around the joint, followed by warm wet rag. This will give you a good looking and clean joint, removes the carbon and other garbage from the flux which is much easier to remove warm than cold.
7. PRACTICE PRACTICE PRACTICE You will find that ten dollars worth of 1/2 inch fittings from Home Depot and a bit of time will teach you a lot. It is a shame to see a well thought out project end up looking like a bad accident because you tried to save ten bucks

On another note:
I was unhappy with the connection for my pot still, so here are some thought and ideas that I have found work very well.

I was uneasy with the idea of attaching the tower to my keg boiler by bolting it down - if it can blow up or out I wanted a relief system
I cut the hole in the top of the keg with my plasma cutter, smoothed up the edges with a 4" hand grinder.
Using a piece of 1/4" copper plate I bought on line ( 4" X 12" X 1/4" was like 14.00) I cut a 4 X 4" piece drilled a centered hole to accept a 2" female adapter and 4 - 5/16" holes at the corners. I soldered the 2" female adapter into the 1/4" plate. Using a 1/4" food grade cork gasket I then bolted the new adapter plate to a heavy SS bowl inverted over the keg. Again using 1/4" cork I made a gasket to seal the bowl to the boiler. Now to my relief system the inverted bowl is held down to the boiler with a heavy black tarp strap
(bungie) This gives me a very solid base and IF I should ever have a blow out the bungie will give. It does not leak.

Re: Howto solder (beginners guide)

PostPosted: Sun Nov 08, 2009 2:15 pm
by 46Ford
It's worth the time to find a water soluble flux. It tends to brush on smoother and cleans up MUCH easier, with just water.

Everflux is a very strong/acidic flux which is water soluble.

NOKORODE® Aqua Flux™ is another good water soluble flux. It stays pliable in cold weather and is a little less aggressive of an acid. Great for novice soldering.

Tony the plumber

Re: Howto solder (beginners guide)

PostPosted: Mon Dec 21, 2009 4:31 pm
by rad14701
HookLine wrote:
Nightforce wrote:I guess I'm confused, is 95/5 tin/antimony okay to use in stills. One reply here seemed to say no and the other link seemed to say that it was only harmful if present in high levels of inhalation, unless I was mistaken.

Personally I would avoid it, especially as there are easily available and cheap alternatives that are some combination of tin, silver and copper. Should be able to find them at the hardware/plumbing or electronics store.


While that solder mix is used for standard plumbing that plumbing isn't subjected to high temperature high ABV alcohol... Water at 140F is far less caustic than the ~170F+ alcohols that we deal with...

If you can find antimony free solder, use it... While antimony hasn't been proven carcinogenic and theoretically will only cause vomiting from high doses, and, yes, it's even used in drugs, I'd rest easier knowing my still was antimony free...

Welding stainless to copper

PostPosted: Fri Dec 25, 2009 9:53 am
by ozone39
Happy holidays to everyone. Not sure if this info has been posted before, but if not here's a little tech tip. Welding stainless to copper. Little more involved than doing a torch braze joint, but it looks a lot better and you end up with a cleaner product. First thing is tooling. You will need a TIG torch to do this. I used the most basic scratch start unit on the market, no foot peal or anything fancy, it's a Miller 140 power inverter (it's the size of a lunch box). Next is joint preparation, I welded a piece of 1 1/2" sch 40 s.s to a piece of 1 1/2" type L copper. A straight cut is absolute on each piece. The copper is easy, just use a tubing cutter. The stainless needs a pipe cutter (you'll find them on a pipe threading machine), do not try and use a tubing cutter on pipe. Or you can use the tubing cutter to score a cut line around to pipe in order to give you a straight line to cut bay mechanical means (saws all,band saw, grinder w/cut wheel, lathe, hack saw and so on). Next is cleaning the ends, I used emery cloth. Next is welding. I set my TIG torch to electrode negative, used an 1/8" 2% thoride (marked red) electrode and ground the tip at a 1 to 4 ratio and ran 110 AMPS with Argon gas set at 10 CFH. Focus the puddle on the s.s (it is thicker) and will take more heat, form the copper puddle into it. Tack one side, push the joint back together (it will pull apart when the weld cools) and then tack the opposite side. I then ran a perimeter weld in less than a minute. If you do not have the equipment a local welding shop should be able to do use the procedure I listed and do the same. One thing to keep in mind when ever you braze or weld these joints it is good practice to back purge the pipe with an inert gas. This will eliminate oxidation from forming on the inside. This is a standard practice in all food grade process pipe. Once the joint is welded let it cool naturally, do not quench the joint in water. now you have a good looking water tight joint. A guy could step it up and chuck it in a lathe and use a sanding disk on a grinder to feather out the joint.



here's a picture of a welded joint that I chucked up in my lathe and ran a sanding disk on.

Mod Edit: Link to original Post: viewtopic.php?f=2&t=13108