Depends on its location and height, if it's above head level it might be easier to swage the upper end of the old pipe so it's easier to see to braze. What's your reason for replacement? If it's leak from a nail or whatnot it may be simpler to cut out a half an inch and couple it back together.


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Depends on its location and height, if it's above head level it might be easier to swage the upper end of the old pipe so it's easier to see to braze. What's your reason for replacement? If it's leak from a nail or whatnot it may be simpler to cut out a half an inch and couple it back together.

.

Pipe's already cut (...long story...) but I can easily see both ends of the cut pipe, and should be able to comfortably braze both joints. All I have is a punch-type swaging tool so expanding one end of the new pipe should be easy but have to figure out how to support the old pipe (inside a wall) so I can punch-swage one end without damaging it.

 

Punch your new piece. The old pipe will have work hardened and the punch type sucks.

Cheers!

 

The old pipe will have work hardened ...

Cheers!

Good point, never thought about that. I wonder if I could anneal it a little and then try to swage it ... but will need to practice before trying it inside the wall :surprise:

 

If he needs to anneal can he do so at a lower temp than what brazing requires, thereby eliminating risk of oxidation at least at that step?

Also...

here I go again. Could his application be one where Stay Brite 8 would work?

 

If he needs to anneal can he do so at a lower temp than what brazing requires, thereby eliminating risk of oxidation at least at that step?

I would flow N2 anyway so I don't think there would be oxidation. The issue is that if I decide to swage the old pipe, supporting it, heating it up (without burning down the house), and trying to punch-swage it quickly inside a wall would be not be easy.

Could his application be one where Stay Brite 8 would work?

It would certainly be easier but this is the high pressure liquid line of my HVAC system so I don't want to take a chance.

 

I will get trolled/flamed but lots of techs do not flow nitrogen and in my 35+ yrs have not found it to be a problem. Unless you cook the joint for 5 minutes and create lots of it IMO it is not a problem.

I do it on new units but for repairs don't bother. However I use oxy acetylene and weld QUICK.

The liquid line filter drier will catch any of it anyway. If you want to do it fine but it is not totally necessary IMO. I have seen units run 25-30 yrs and back in the 80's we did not do it.

3/8" is soft if it is new. I would swedge both ends of it and then bend it a bit and slip it over the old pipe and weld it.

Be VERY VERY careful you do not start the wall and house on fire. Put some sheet metal there and have a bucket of water and a fire extinguisher nearby.

I saw a old school plumber burn down half a house welding under a sink. He caught the wall on fire.

There is no filler material if you are using silfoss. It is a surface weld and gravity does not matter.

Using Staybrite is like solder and it will fill it. Not that easy to use as you need flux and very clean application and skills.

 

There is no filler material if you are using silfoss. It is a surface weld and gravity does not matter.

Hmm ... For brazing, doesn't the silfoss flow inside the joint (and fills it) via capillary action? Or is capillary action only for soft soldering????

 

Capillary action is only for soldering.

You can also get 3/8" copper couplings. It is such a small joint that you can do one side after another quickly. No need to swedge anything.

If you are not familiar with "silfossing"/brazing get some scrap copper and practice. Use 15% silfoss not the cheap 5%. The 15% flows a LOT better and is easier to use.

I have seen Bernzomatic torch kits that come with a oxygen bottle and MAPP gas (acetylene) in a small hand held setup with throwaway bottles.

It should give you a very hot intense flame almost as good as a full blown welding torch with big tanks.

Not sure if HDepot has them but Acklands/Grainger or other big hardware stores should. Canadian Tire has them where I am.

http://www.silfos.com/products/catalog/Sil-Fos-15-Silvaloy-15-orderby0-p-1-c-62.html

https://www.bernzomatic.com/Products/Hand-Torches/Manual-Ignition/WK5500OX

 

Thanks for this info. After reading the rest of the thread, are you saying that this combo in not advisable for new 3/8" and 3/4" copper R410A lines?

 

Yeah there is capillary action but I/we/old school techs always make sure there is a visible bead of silfoss on the outside joint so IMO it is more of a surface weld.

I would not want to advise people to think of it as soft soldering and not use enough material. I have seen hairline cracks develop from skimpy welds. Some that were so small the leak only showed up when it had 150+ psi nitrogen in on the low side.

 

Yeah there is capillary action but I/we/old school techs always make sure there is a visible bead of silfoss on the outside joint so IMO it is more of a surface weld.
..

Believe it or not, all of the certifying courses here don't want to see a bead at all. Then they cut it open and make sure that you've penetrated. They look for air gaps in between the surfaces. I still add the bead though, it looks nicer.

PS. We test with at least 250psi. (most evaps are certified to above 500psi these days.


Cheers!

 

Yeah how to weld is not something we can teach over the net.:vs_no_no_no:

I was talking about a R22 system and yeah we use higher test pressures with 410.

 

I would use two 3/8 sleeves with stay bright #8 if it's an R22 system. You have to clean it real good ( like new) and use the right acid flux. Or I would swage a piece in following the direction of flow. In addition I would replace the liquid and suction line filter dryer.

 

Follow yuri directions you can't go wrong. Well you can if you do something wrong. Do not use stay brite #8 on 410 system. Only on R22 system.

 

Staybrite is VERY difficult to work with.

You almost have to be surgically clean with it and get the flux perfect and not overheat it.

Not good for repairs as you always have oil burning in the joint from the oil in the lines.

That contaminates the weld. Silfoss is tolerant of that.

I don't really like or use it anymore and I have heard it does not stand up well to vibration. I used it when I was changing reversing valves on some old Borg Warmer/York old heat pumps in the early 80"s as they don't like heat.

I would recommend everyone use silfoss and get some copper and practice with some couplings. The OP should just use couplings and not make the whole project any more complicated then necessary IMO.

I have a set of swedges and probably used them 6X in 35 yrs. 99.9% of the time I use couplings.

 

Respectfully disagree partially with your reply. I have been using #8 for 30-50 years , lost track.. Also sil-fos depending on application. I guess it all depends on what you like to use and what condition's dictate. I have never had a problem with #8 except when I didn't pay attention . Swages are rusted in the bottom of the tool box I know where they are in a pinch.

 

I got so used to silfoss that Staybrite does not really interest me. The flux gets hard and dried out over the winter and come spring when I need it , it is shot. Silfoss never goes bad.

I also don't like oil burning in my welds and the hassle of having to be so uber clean to use it. If you are good with it I imagine it is a good product.

It is hard enough to get these young dummkopf apprentices to silfoss properly and to give them Staybrite would be a nightmare.:vs_mad:

 

...
It is hard enough to get these young dummkopf apprentices to silfoss properly....:vs_mad:

LOL!! That made my day.

I have switched to using a dual ocy-acy tip. It's C shaped and works beautifully. Small concentrated flame with similar heating characteristics of a turbo torch. (Air-Acy-vortex) Keeps me out of trouble on those ridiculously placed Heat Pumps. (10 ton heat pump wedged into the ceiling of a kitchen....)

Cheers!

 

before i had every brazed, i practiced on my old evap coil. i used map-pro with a ts8000 torch head and stay-silv 15. it worked great, took awhile to heat the suction line but did the job and has been leak free for 8+ years. i used an old t-shirt soaked in ice water and wrapped it around the txv to prevent too much heat transfer into it.

the second job was replacing my compressor, which was a little more difficult because of the space i was working in and the suction line being 7/8". it was probably borderline about the max you can do without an oxy-acetalyne or oxy-propane setup. still, the job went well and has been going string for 5 years.

 

...was a little more difficult because of the space i was working in and the suction line being 7/8". it was probably borderline about the max you can do without an oxy-acetalyne or oxy-propane setup. ....

This is the secret of choosing the right tip for the right job. I've welded everything between 1/8 and 3". I use oxy-acy or acy-air, but I know that I cold use a host of other fuels.

You will also want to use distance to control your temperature. You start off close and modulate away as you come up to temp. The idea is to keep the joint hot without burning a hole through the copper, lol. Stay-bright is less tolerant of excess heat then silfoss.

We teach to watch the joint for clues on temp. Flux will liquefy at a very specific temp, the filler at another. For silfoss, it'll glow a dark red first. (eg. if brazing dissimilar metals, the flux liquefies, then boils the water out, becomes flaky, then liquefies again, all before you even start melting the rod)



Cheers!

 

I and my boss ( old farmer guy who had LOADS of smart/clever tricks from fixing farm stuff ) welded a 2" copper MIP adaptor into the main 5" hot water supply line to our laundry in a hospital.

Took a 2" hole saw and drilled a hole in the pipe ( water off of course ) and slipped it in. He used a cutting torch with a Big Bertha sized flame and we silfossed er in.

I would have never thought of that.

Then I ran a 2" galvanized pipe to the holding tank and made a recirc line. Copper kept wearing out from the constant circulation in other areas so we tried galvanized.

Heat is heat and yeah you need a large flame when welding the big stuff.

 

Way to highjack a thread guys!!! Just kidding, it's all great information ...

If I decide to heat or anneal the new or old pipe (with N2 purge) to facilitate swaging with the punch tool, will this permanently change or discolor the outside of the pipe so that it will impossible to prep it or clean it for the final braze to join the 2 pipes? TIA.

 

Brazing is not significantly affected by any discoloration. We do this all the time. Try the tool first. Anneal if you have problems. Don't worry about refrigerant direction, as long as you ream the pipe, it won't be a factor.

Cheers!

 

With silfoss you don't have to clean it ( in theory ). Most techs use plumbers sandcloth and do so but you can weld it with little or no cleaning ( unless it is oily, oxidized is OK ). So, no you won't harm it.

Why not just order some 3/8" copper couplings from supplyhouse.com and make your life easier?

Hijacking, a lot of times the OP disappears for days or permanently so we continue the thread on for socializing and BSing.:biggrin2:

$2.20 for a box of 10.

http://www.supplyhouse.com/Copper-Fittings-for-HVAC-12753000

 

Why not just order some 3/8" copper couplings from supplyhouse.com and make your life easier?

$2.20 for a box of 10.

http://www.supplyhouse.com/Copper-Fittings-for-HVAC-12753000

Actually, I punch-swaged a new pipe at both ends but the male pipe wiggles a little bit in both joints. I fear the silfoss won't properly fill such a gap so I may have to use couplings.

So, I went to HomeDepot and Lowe's and got some straight couplings to practice with, that fit perfectly but they were labeled as 1/4" couplings. They measure 3/8" ID and the male 3/8" OD pipe fits smoothly and doesn't wiggle. Same for their 1/4", 90-degree, elbow fittings, which also fit perfectly. They seem to braze properly to the copper pipe and there is nothing in the fittings that measures 1/4" but no one at either store could explain why they are sold as such. Same story at Orchard Supply Hardware store. Are these for non-HVAC applications?

 

hvac pipe is true to size for o.d. i believe. fittings at home depot are for copper plumbing and are completely different in size and measurement.

here is how you figure out dimensions for plumbing pipe: http://www.gizmology.net/pipe.htm

 

Thanks, good info for sizing pipe. I went to the supplier's web site and they explain that for HVAC couplings their product is labeled with the NOMINAL size: "3/8" I.D. - 1/4" NOM Coupling rolled C x C Copper Fitting pressure rolled stop coupling is used in residential and commercial systems such as HVAC, ...", which is exactly what I measured on their couplings. So it looks like, for HVAC, the NOM is always 1/8" smaller than the coupling ID, across all sizes (1/8" NOM = 1/4" ID, 1/4" NOM = 3/8" ID, 3/8" NOM = 1/2" ID, 1/2" NOM = 5/8" ID, ...). On the other hand they also had some confusing notes for ordering couplings for plumbing applications but I don't wanna go there.

 

HVAC fittings have a thicker wall thickness.

Plumbing fittings should NOT be used for HVAC as they are thinner and could burst.

 

Yes, thanks. I measured the wall thickness of the new couplings and it seems to be the same as the wall thickness of the old 3/8" pipe inside the wall. Not sure if it is a type M, L, or K, though. I am assuming only type K is good for R410A?

 

i've never seen HVAC pipe in a big box store. the most i have ever found is aluminum tape, mastic and 36" plastic ties. even the pipe insulation is designed for plumbing and doesn't fit right on HVAC pipe.

you really need to go to a supply store to find the right stuff. i've done it many times and have found everything i need. in my area, they will sell to an individual. anything tied to refrigerant requires an epa card (which i have).

 

...
you really need to go to a supply store to find the right stuff. ....

Supply houses are the best sources for this stuff, but they won't sell to non- contractors and you need an account first.

I've never seen armaflex in the big box stores, but I've seen an increasing amount of refrigeration related and gas related products there. They only carry stuff that sells, and there are plenty of fly by night guys here. (I've seen them buy out all of one item in some stores because they are got a subdivision.... Plumbing, venting, wood, etc.)


Cheers!

 

I swaged a 3/8" soft copper pipe but there is some wiggle in the joint. Is the gap shown here too large to get properly filled by brazing with SilFos 15? TIA

 

It'll be fine.

Cheers!