Soldering/brazing: Aluminum To Copper?

[seravitae]

Hi, just wondering if anyone's done aluminum to copper.

I have seen some youtube videos of people doing aluminum to copper fittings and it looks just like doing copper to copper... I was thinking of buying an aluminum cooking pot for my HERMS heat exchanger and soldering/brazing the copper coil through it with butt solder joints.

Has anyone done anything like this? Anyone know what sticks or flux to use? I'm not even sure who to ask about this.

I realise i can use bulkheads, but at $40-50 a pop and requiring at least 4 for my project it seems reasonable to at first consider all possibilities



Cheers

 

[Gavo]

Have a look here. It has been discussed quite a bit. I still would be concerned about corrosion of the ally. You would be surprised how much aluminum corrodes because of dissimilar metals.

Cheers
Gavo.

 

[seravitae]

Ok.

I'll just solder copper to copper, and make my herms container out of some 8" copper pipe i have here instead. Better to play it safe.

 

[chappo1970]

Actually you can attempt to braze silver solder copper to alumium BUT (sorry sera but there is always the out clause) you are dealing with 3 different metal types that expand differently, react differently and have the real potential to fail due to the environment you are going to subject them to. So in answer to your question yes you can if you MUST. If you can braze well then go for it but your choice of base materials is doomed to failure as their properties will be constantly fighting each other. Think metal fatigue.
I hope that helps?

 

[seravitae]

Yeah, that makes sense. More degrees of freedom = more degreees to fail.

I'll stick with copper to copper. I didnt want to use this pipe seeing as its.. Pretty massive and... copper.... but i guess i just need to get over myself. Rather be using the pipe than sitting here staring at it, no matter how pretty it is

 

[browndog]

I would imagine the galvanic corrosion would be hell. One of the eggheads could probably explain it better, but it works on the same principal as a sacrificial anode I think. The more reactive metal will corrode.

cheers

Browndog

 

[chappo1970]

I would imagine the galvanic corrosion would be hell. One of the eggheads could probably explain it better, but it works on the same principal as a sacrificial anode I think. The more reactive metal will corrode.

cheers

Browndog

:lol:
This comes from a guy who is directly involved with puttin' together some of the biggest arsed, hard core most sophisticated miltary aircraft our country has seen for our flyjockeys to fly! Sorry mate but your way too modest. But very correct BTW.

 

[seravitae]

Cool, i dig. Should have my herms heater together as soon as i can find a spare nanosecond to whip down to the shop and drill some holes in this copper.

 

[Thirsty Boy]

I am planning on braisig/soldering the brass fittings into my aluminium kettle -

personally, I think the galvanic corrosion and differing expansion arguments are just a bit silly. Both those things exist.. but how much are they going to affect a brew kettle really? We are talking about a non load bearing joint that is wet for maybe a couple of hours a week.

I have every confidence that when I solder my brass fitting into my aluminium kettle - I couldn't pull it out if I tried and it will last 10 years+ If thats not durable enough for you, then fair cop, you need to find another solution.

Its all about finding the proper rod - I don't know which one it is, I am in the experimental stage at the moment, and I might be forced to come back here and say how wrong I was - but I don't think I will.

I've seen quite a few examples of soldered/braised brew kettles - think there is just a culture of "welding is best" which has become so prevalent that other options that might be more accessible to people without expensive equipment, have simply been discounted. Not "as good" doesn't equate to not good enough

google durafix - and have a look here at this utube clip - I'd say that is strong enough

 

[Apparition]

I am planning on braisig/soldering the brass fittings into my aluminium kettle -

personally, I think the galvanic corrosion and differing expansion arguments are just a bit silly. Both those things exist.. but how much are they going to affect a brew kettle really? We are talking about a non load bearing joint that is wet for maybe a couple of hours a week.

I have every confidence that when I solder my brass fitting into my aluminium kettle - I couldn't pull it out if I tried and it will last 10 years+ If thats not durable enough for you, then fair cop, you need to find another solution.

Its all about finding the proper rod - I don't know which one it is, I am in the experimental stage at the moment, and I might be forced to come back here and say how wrong I was - but I don't think I will.

I've seen quite a few examples of soldered/braised brew kettles - think there is just a culture of "welding is best" which has become so prevalent that other options that might be more accessible to people without expensive equipment, have simply been discounted. Not "as good" doesn't equate to not good enough

google durafix - and have a look here at this utube clip - I'd say that is strong enough

Gents
You can do it i have just made up my new mash tun (false bottom) stainess mesh coper tube. the trick is use silver solder rods. it will handle the temp easy. only problem is the rods are more$$$$ but it works
cheers
App

 

[newguy]

Never mind corrosion, designing a system that can be broken down for cleaning/maintenance is probably the best choice. My HERMS coil just sits in my old-pot-turned-heat-exchanger and the ability to remove it for cleaning is very convenient.

 

[browndog]

personally, I think the galvanic corrosion and differing expansion arguments are just a bit silly. Both those things exist.. but how much are they going to affect a brew kettle really? We are talking about a non load bearing joint that is wet for maybe a couple of hours a week.

You could be right there TB, it may last 10yrs, it may last one depending on the skill of the maker. If you want to see results of galvanic corrosion, start checking out piss troughs ususally older ones. You have brass and copper parts coming in contact with the S/S trough. Usually the first to go is the chrome plating on the copper pipe or spray fitting, then the copper or brass starts to go. I would say that the dissimilar metals do not have to be wet all the time for the corrosion to occur. Speaking as a matal worker it's not good practice, speaking as a brewer, it may be a suitable solution.


cheers

Browndog

 

[seravitae]

is removing the HERMS coil something you need to do regularly though? I mean, if i hard-solder my coil in but my herms unit is detachable via cam-lock valves, will this be okay? I can take the unit outside and spray it inside/out + spray water through the coil... I wont be able to physically remove from the container though..

 

[newguy]

is removing the HERMS coil something you need to do regularly though? I mean, if i hard-solder my coil in but my herms unit is detachable via cam-lock valves, will this be okay? I can take the unit outside and spray it inside/out + spray water through the coil... I wont be able to physically remove from the container though..

I'll I will say is that you never know - your coil may clog or perhaps build up a layer of crud or..... I've just found that it's almost always better to design things so they can be broken down, just in case.

Some advice regarding the coil: be as neat as possible if you're winding it by hand. It makes it easier to drain the thing afterward as standing water in copper is supposedly a cause of verdigris which is poisonous.

 

[chappo1970]

I'll I will say is that you never know - your coil may clog or perhaps build up a layer of crud or..... I've just found that it's almost always better to design things so they can be broken down, just in case.

Some advice regarding the coil: be as neat as possible if you're winding it by hand. It makes it easier to drain the thing afterward as standing water in copper is supposedly a cause of verdigris which is poisonous.

+1 NG

I like the ability to pull down and maintain my equipment anyway. If a part/widget fails life is so much easier if you can easily detach it and replace it rather than going to find the grinder. Just last weekend I pulled down and striped all of my taps, hoses etc for a thorough clean and flushing. I always clean and sanitise before and after. I was shocked with the amount of gunk there was ready present in the little nooks and crannies only after 5 AG brews.

FWIW build you gear with redunancy and servicability in mind and you can't go wrong.

 

[seravitae]

mm, i think in this circumstance i'll hardwire it in. The herms container being 8" is relatively small so it will be easy to move around, lift and reorient for cleaning.

If the coil clogs then i can try hosing it out, or blasting it out with compressed air. (Also a good way to dry the coil).



Verdigris is pretty hard to form on dry copper in suburban air, and I intend to clean and take care of my equipment, fushing it out after each run and drying it to the best I can.


On the note of being able to 'take things apart', the only thing being "permanently" connected is the herms coil inlet and outlet via butt weld/solder joint thru the side of the container. I'm pretty darn sure it'll be easily servicable. Everything else is quick disconnects and dismantleable. (Even the heating element will be BSP screw-in for easy replacement).

 

[chappo1970]

Verdigris is pretty hard to form on dry copper in suburban air, and I intend to clean and take care of my equipment, fushing it out after each run and drying it to the best I can.


On the note of being able to 'take things apart', the only thing being "permanently" connected is the herms coil inlet and outlet via butt weld/solder joint thru the side of the container. I'm pretty darn sure it'll be easily servicable. Everything else is quick disconnects and dismantleable. (Even the heating element will be BSP screw-in for easy replacement).

Yep I agree sera. I can see no harm in what you plan to do. +1 on the compressed air I'm gunna steal that one mate.

When I get around to my herms and new mash tun set up there are certain elements that I will hard wiring (welding) them in as well and certainly static elements such as bulkheads, pipes and coils would be PITA to make them in a fashion that can be pulled down.

 

[seravitae]

Yeah, i actually toyed with the idea of using bulkheads + hose barbs on the inside of the container but the logic/reasoning section of my brain thought that was extremely overkill!

Anyways, pics as soon as i can get to the shop.

 

[mash head]

Gents
You can do it i have just made up my new mash tun (false bottom) stainess mesh coper tube. the trick is use silver solder rods. it will handle the temp easy. only problem is the rods are more$$$$ but it works
cheers
App

Ive had people trying to sell browny sticks as silver solder. While it is it isnt what you would need to solder disssimilar matals. Ensure that you get a rod with high percentage silver plus the liquid flux to suit. Rod are expensive but for a propper job it what you need. Browny sticks are for copper to copper. I have soldered hydraulic fittings together with high silver solder that will with stand 2 to 3 thousand psi so its obviously good gear. For above solder sticks seek out welding supply store not hardware store who will most probably palm you off with brownys. HAPPY BREWING GREG

 

[chappo1970]

...high silver solder that will with stand 2 to 3 thousand psi so its obviously good gear...

Wow greg! 3000psi!

I use Peal's Welding Supplies in Moss St I am sure they would have what you want Sera.