Brazing aluminium pipe

[Nomolos]

Any advice on brazing thin wall aluminium pipe? As in what’s the best way to do this?

The repair needs to hold around 25 bar pressure from an air conditioning system.

New parts difficult to obtain so wanted to have a go at replacing the defective section of the pipe, as I have the time and equipment to do this, just lack the how to braze bit

 

[hotrodder]

Vid showing the traditional/proper way here. Never come across the flux cored filler he's using in the vid, usual suspects in the UK would be 4047 aluminium filler (melts at around 580C versus 640-660C for most other aluminium alloys, can be used for welding and brazing) and a suitable flux, SIF aluminium #36 for example. The flux is corrosive but as with other brazing processes provides a good telltale of when the part's the correct temp

Googling 'aluminium brazing air conditioning' will get you some hits like this. Filler wires on offer similar/same as 4047 but probably available in smaller diameters than 4047 from a welding suppliers

The flea market stuff referred to in the vid is sold as muggyweld/durafix and a bunch of others and is a zinc rich alloy more akin to soldering than brazing with a much lower melting point

 

[Nomolos]

Hi Thanks for the info will ring round and see if I can find some

 

[Flathead_Dave]

http://cgi.ebay.co.uk/ws/eBayISAPI....15770&_sacat=See-All-Categories&_fvi=1&_rdc=1

I've seen that can repair done infront of me,he'd also joined a copper pipe to an alloy piston.

They say it can be used for air con in the video.

 

[Nomolos]

Interesting video almost seems too good to be true, anyone played with this?

 

[shenion]

I've used similar rods called Alumiweld. The HTS rods look to have nearly the same alloys. I have also tried the Berzomatic rods.

There is tricks to get non-flux rods to work. you need to stir the weld pool to break up the oxidization that will occur when heated. I have done brazing with them and the "welds" were stronger than the parent metal.

Stirring with the rod just adds more metal. I ended up using some 1/16" steel wire to stir the pool after laying a bead. A piece of copper wire might work better.

Many of my first tries were real weak. Also, the weld pool is like water, so it runs all over. With a bit of practice, they work well.

My first tube of rods (2lbs) came with a video. There was a over-hyped "infomercial" on TV just after I ordered the rods. Assumed the video that came with it was the same hype.

Turns out it was the opposite, showed several connections that failed. Then showed why they failed and how to prevent the problems. No hype or fancy production, just 2 guys in their garage and a video camera.

 

[eil]

If you only have a small leak I have used a heat seal stick many a time for aluminium
http://www.ati-intl.com/htslstk.htm
http://www.bes.co.uk/products/096.asp

 

[Wendelspanswick]

Pat

Hello Nomolos!!

Must say..stainless steel is resistant to corrosion and oxidation in low and high temperature because it contains chromium. This is what makes stainless steel different from mild steel or any other steel. Although tubes are not the cheapest option on the market, they have many benefits. Apart from being resistant to corrosion, which enables them to be useful in thin wall piping, they have low fluid friction properties and are easy to maintain, making them cost effective. You can get more information by visiting these..

http://www.clintonaluminum.com/

http://www.kastenmarine.com/alumVSsteel.htm

http://www.aluminiumdesign.net/design-support/aluminium-corrosion-resistance/

Post is 6 years old.

 

[Paul G]

I believe the process is known as aluminium flame brazing and the rod is 12% silicon.

Going back to my college days, if I remember correctly 12% is the eutectic point on the relevant equilibrium diagram.


Whoops, didn't spot the age. Another 15 minuets waisted.