Brazing and soldering aluminum

[Kern Dog]

My recent experiences with automotive air conditioning installations have me curious about modifying hard lines to make a more custom fitted system.
Here is an example.....My own '70 Charger.

The #8 aluminum line is prebent by Classic Auto Air to fit around a battery. My battery is in the trunk. I would like to have the ability to shorten the hard line like this:

To do that, I need to learn how to braze aluminum.
I've never welded with a torch so I'm learning as I go here. I can stick and MIG weld, I can solder wires but that is about it.
I have a few Propane and Mapp gas cannisters like these:

So far, the most commonly found nozzles look like these:

The cannisters warn against inverting them when in use but how am I supposed to apply the flame when the work I'm doing is barely above waist high? I'm not trying to do the work overhead where the nozzle points. It would be great if there were nozzles that had a swivel.
With these types of nozzles, You have to tilt the nozzle to get it where you want it. There are those nozzles with a hose that I could try.

I recently was at an A/C shop helping out a friend with his Coronet. You might remember the guy....

He had a line shortened and brazed back together and it got me thinking.
What ONE man can do, another man can do. If I can get good at doing this, I'll be able to route A/C lines wherever I want and not be limited by the stock sizes that you buy at the store.

My first effort SUCKED though.

 

[Kern Dog]

I cut a spare #6 A/C line to practice and set it up in the vice. This leads me to another problem....How do I position the lines in a way so that I have more access to the area I'm brazing? Sitting in the vise, only 1/3 of the diameter of the joint is accessible due to the jaws of the vice holding them in place. I figured that I'd have to braze, rotate the lines, braze, rotate again....doing it all in short steps.
Is that right or should the molten aluminum filler rod just flow all around the joint?

Secondly....
I have 5 or 6 cannisters here from almost empty to new. I have 3 nozzles, two of them have igniters in them.
The igniters don't work despite one of them only having minimal use. I can start the flame with one of those candle lighters but if I turn off the candle lighter flame, the nozzle loses the flame. (Most of the time) It seems odd. I'd expect if there is a flame going, it would stay going until the flow of gas stops. This happens with every cannister, even the new one.

 

[1 Wild R/T]

https://www.amazon.com/Propane-Cyli...d1d2b4d887b236339a225fd829afdb79&gad_source=1

Be aware refrigerants can react badly with open flame... R12 when passed through a flame becomes phosgene gas... I just did a quick search & it appears R134 does as well... Be careful.... The refrigerant oil can hold small quantities of refrigerant...

 

[Kern Dog]

Thank you.
My plan is to use new lines when possible or to properly clean any used line as needed. I'll need to research how to properly clean a used line to avoid killing myself.

 

[Demonic]

The good chlorinated carb cleaner you can't get in CA will clean the inside of the line of oil. But aluminum can be porous, and if it absorbed oil, it can come out when heated and ruin the brazed joint, never sealing. Easier to have another line made. Purge the line with nitrogen while you braze it. Aluminum melts at a very low temperature. Get scrap and practice first.

 

[Geoff 2]

I am not sure Propane has a hot enough flame. I have tried to braze alum & was not very successful. The biggest problem I found is that unlike steel or copper, there is no colour change to warn you that you are approaching the critical temperature. All of a sudden, the alum has melted! I would look for another method.....

 

[Photon440]

Aluminum solder usually needs less heat. Far less than the melting point of aluminum.
Aluminum Soldering: The Basics - Weld Guru

 

[Kern Dog]

I am not sure Propane has a hot enough flame. ...

I did also mention Mapp gas.

 

[kiwigtx]

That term 'soddering' sends a chill up my spine....

 

[Kern Dog]

The soldering/brazing that I want to do won't be subjected to high loads, just pressure and temperature.
I've never soldered a stock type radiator yet.
It would be a nice skill to develop even though almost every aftermarket one on the market is aluminum.

 

[493 Mike]

Can you source hard line tubing fittings to do this? Most refrigerant lines are steel on the older models and aluminum is commonly not rated for high pressures. I will admit to not knowing all I could about newer materials. Flare fittings are common in refrigeration systems.
Mike

 

[pnora]

I have used these with good results. Super Alloy 5 Aluminum Welding and Brazing Rod | Muggy Weld

 

[rebel513r]

vintage air makes custom lines also, just a thought

 

[Fran Blacker]

Was thinking of doing A/C in Garage. Watched install video they put a atmosphere around the brazed joint. Think not doing that, the joint would be porous.

 

[Beekeeper]

A flare connection would be simple and reliable although the look wouldn’t be as clean

 

[toolmanmike]

My recent experiences with automotive air conditioning installations have me curious about modifying hard lines to make a more custom fitted system.
Here is an example.....My own '70 Charger.

View attachment 1696908

The #8 aluminum line is prebent by Classic Auto Air to fit around a battery. My battery is in the trunk. I would like to have the ability to shorten the hard line like this:


View attachment 1696909

To do that, I need to learn how to braze aluminum.
I've never welded with a torch so I'm learning as I go here. I can stick and MIG weld, I can solder wires but that is about it.
I have a few Propane and Mapp gas cannisters like these:


View attachment 1696910

So far, the most commonly found nozzles look like these:


View attachment 1696911
The cannisters warn against inverting them when in use but how am I supposed to apply the flame when the work I'm doing is barely above waist high? I'm not trying to do the work overhead where the nozzle points. It would be great if there were nozzles that had a swivel.
With these types of nozzles, You have to tilt the nozzle to get it where you want it. There are those nozzles with a hose that I could try.

I recently was at an A/C shop helping out a friend with his Coronet. You might remember the guy....

View attachment 1696912

He had a line shortened and brazed back together and it got me thinking.
What ONE man can do, another man can do. If I can get good at doing this, I'll be able to route A/C lines wherever I want and not be limited by the stock sizes that you buy at the store.

My first effort SUCKED though.

It looks like a lot of work for not much gain but whatever. What does the line end look like? Someone with the right flaring tools can form a new end and no "brazing" is necessary.

 

[Kern Dog]

A flare connection would be simple and reliable although the look wouldn’t be as clean

Well, sort of. The flare shape in the lines I have seen are outside of the design that I'm familiar with. I was at an automotive A/C shop to have a line modified and they chose to cut and braze rather than reflare.
The advantage that I see is that brazing allows one to route lines in shapes and positions that look cleaner and are tucked away. Most A/C systems that I see look a bit cluttered. I'm just trying to improve the look.
Sometimes the fittings available don't have the shape needed or the pressure fittings are in the wrong spot. For example...

The blue cap on the right side of the picture is the low pressure side. In this fitting, it aims down and toward the valve cover instead UP for easy access for service. There are no fittings that have that service port on the inside of the curve 180 degrees of where it currently is. It would be great to be able to relocate the fitting to a better position.

 

[diesel_lv]

I fooled around w a bit of brazing in my past. That said, I'm lucky that less than 1/8th mile from my house is a hose shop. Had all my a/c n p/s n brake lines done there, very reasonable. Brazing works though if done properly obviously.

 

[Kern Dog]

I went back to the welding supply store to ask a few questions.
The nozzles that I have for the gas cannisters seemed to have inconsistent performance. First off, the man looked at the screw collars that secure them and noted that they ALL read "For PROPANE use only" despite them fitting other cannisters. He wasn't sure why and they didn't stock any nozzles that stated that they were compatible with all gases.
The flame quality varies depending on how the cannister is positioned. He agreed but had no solution.
I did learn that to ignite the flame, one must turn on the flow of gas to the low setting, then increase it after it starts burning. I didn't know that. He said the high flow can just blow right past the igniter spark and not even start the flame.
It is a learning process, for sure....

 

[RJRENTON]

The soldering/brazing that I want to do won't be subjected to high loads, just pressure and temperature.
I've never soldered a stock type radiator yet.
It would be a nice skill to develop even though almost every aftermarket one on the market is aluminum.

The best thing for you to do is professionally have the work done. First, WHAT GRADE IS THE ALUMINUM?? The filler metal used is determined by the base metal of the tubing. The pressure in the discharge line can approach 250 psi on a hot day at highway speeds....defiantly high stress. If shortened, it should be spiced with a sleeve connector or butt welded (NOT BRAZED), and correctly prepared bevel ends and using a TIG torch, and 75%-25% (Argon-C02) shield gas or 100% helium as in heli-src, gas backed to prevent slag inclusion, in a fixture to maintain alignment. If you cannot do it correctly.....don t do it. Aluminum oxidizes easily at elevated temps. THE METHODS YOU NOTED IS STRICTLY A SHOE MAKER APPROACH.....it's not like soldering copper water pipe....who ever suggested using a MAPP torch is wrong. MAPP = Methyl Acetylene Propo Pylene gas blend.....hotter than propane. Just my opinion of course.....
BOB RENTON