Oxy fuel welding of aluminum with propylene instead of acetylene .

[berkshire]

I have been asked about welding aluminum with propylene instead of acetylene.
I have only ever used acetylene, so I have no experience with this gas.
The switch seems to be driven by the insurance companies looking at acetylene with an ever more jaundiced eye.
All of my research says that it is harder to get a neutral flame with this gas, but that non the less there are companies out there using this process.
Has anybody in this group had any practical experience welding with this process, if so what are the drawbacks .
This is what I can find on line " Although acetylene is best, for most processes and most metals, propylene can be used in place of acetylene and is cheaper and more cost effective. Propylene burns cooler than acetylene, at about 2,870 degrees C in pure oxygen, compared to the 3,300 degree C flame of acetylene. "
However this is from a company selling the gas, and I cannot get any specific answers about welding aluminum with it..
B.E.

You are judged not by what you know, but by what you can do.

 

[SwinnyGG]

Drawbacks?

You'll use a lot more oxygen.

 

[berkshire]

That is part of the dilemma , everything I read on this gas says that you will have more trouble obtaining a reducing flame, that you are more inclined to get an oxidizing flame. I am not sure that will fly with aluminum , it oxidizes fast enough without any encouragement. unless you just rely on the flux to get around this.
That is why I am looking for input from people who actually have done or supervised this process.
B.E.


You are judged not by what you know, but by what you can do.

 

[EdStainless]

You will use a little more Propylene and Oxy, to make up for the lower flame temp.
If you are working in thin material it is probably suitable.
Since the temp for propylene is similar to MAPP I don't see major issues.

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P.E. Metallurgy, Plymouth Tube

 

[berkshire]

Hi Ed,
I have used MAPP gas for welding steel, it tends to throw hydrogen into the flame which makes steel a little more brittle , I have been told that
propylene can do this too. I am not sure if this matters. The application here is thin gauge welding of aluminum fuel tanks . Apparently when these are Tig welded the owners are seeing some porosity in the welds they do not like , which they do not get with oxy acetylene welding. All was going good until their insurance company had a hissy fit about stored acetylene tanks.
B.E.

You are judged not by what you know, but by what you can do.

 

[EdStainless]

My concern would be controlling the temp and pressure of the Poly well enough to keep a uniform flame.
It might require line heaters and dual stage regulators.
The fuel/oxy balance with some of these gasses is touchier.
Your issue with MAPP and steel is why people tend to run slightly oxidizing, which would not work with Al.

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P.E. Metallurgy, Plymouth Tube

 

[chicopee]

My advise is to do trial runs and have the welds inspected, radiographed and tested for mechanical strength. The results, I am sure is worth the investment (expenses).

 

[berkshire]

Chicopee,
That is my feeling too, what I am trying to avoid is being the stuckee. ( Brian , you know about this stuff, can you just run some weld samples for us.) I do not want to get any deeper into this than I have to.
B.E.

You are judged not by what you know, but by what you can do.

 

[IFRs]

You mean brazing aluminum?

 

[berkshire]

No I mean Welding Aluminum usually 1100 series or 3000 series.
B.E.

You are judged not by what you know, but by what you can do.

 

[IFRs]

Just curious - what weld process are you using? I am used to MIG / TIG where the gas is Argon.

 

[berkshire]

IFRs,
This inquiry is for a business associate who is not a member of Eng Tips; they weld thin gauge Aluminum fuel tanks using Oxy Acetylene. The reason for this is to avoid a small problem that shows up from time to time when Tig welding these thin metals, porosity in the weld causing fuel leaks at a later date.
Their insurance company is giving them a hard time about having D/A on the premises , so they were asking me about using Propylene as the fuel gas, since I did not really know, I thought I would ask on here.
However it appears that most of the responders so far also do not have much practical experience with this particular gas.
B.E.


You are judged not by what you know, but by what you can do.

 

[EdStainless]

Sounds like they need to improve the cleaning and purging for their TIG and just do it correctly.

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P.E. Metallurgy, Plymouth Tube