Welding aluminum

[Thrud]

bdarin:

Better check the chemistry books. Acetylene is used because it is cheap to produce and safer to use than Hydrogen. Hydrogen line explosions are far more dangerous and the flame is much harder to adjust because it is hard to see. Acetylene has the advantage of lower cylinder pressures, greater Cu.Ft. capacity, and a highly visible flame.

[JCHannum]

Hydrogen is used underwater as hydrogen + oxygen = water. Hence no bubbles to obfuscate things.

[docsteve66]

JCH: I have never cut under water, but have seen it done several times- not as training but because the job had to be done.

As explained to me and as I remember it:
1. each 2.5 feet of water increases pressure by 1 PSI. Even 10 feet of fresh water raises pressure required to get Acyt from torch tip by 4 psi. In Salt water, the pressure goes up even faster.
Acyt is unstable at over 15 PSI. Add depth pressure to normal tip pressues and you decide to use Hydrogen.

So far as bubbles go, things looked very interesting from the top looking down. I think the torch had supplemental air or some thing to keep water away from the work area.

I was told its easier to teach a diver to cut than to teach a welder to dive (and work).

I looked in book for temps. No temp for oxy-hyd was given. Max temp for OXY- acyt was between 6000 and 6800 F. Seems you don't use a rectal thermometer or any other kind of temp measuring device for those temps. Temp is calulated by btu produced per pound of fuel consumed and (I guess) the specific heat of the gasses consumed.

Anyway:
Hydrogen provides 61K Btu/ lb or 319 Btu/cubic foot.
Actylene provides 22K Btu/lb or 1451 Btu/cubic foot.

The Original question was could you weld Al with Oxy/Act. I have done that and made some nice welds- longtime ago though. Used blue lens so you could see Al heat better. No eye damage (back then) if you wore only plain glass for protectection. The Flux was the real problem- several suposed Al flux did not work well. The good flux was weller or weldon or something with a "w" number 10.
Only the "10"am I sure of cause we said the "number ten stuff is number one".

Al welding was for grins only, welds were not tested. I was certified for ferrous stick welds- I know what a good weld looks like and sounds like going on.

[bdarin]

Thrud....I agree with you wholeheartedly. The Hindenburg probably wouldn't have blown up if it was filled with acetylene. (Wouldn't have flown either!) Mixed with O2 in a welding torch, acet. burns hotter than hydrogen. Yes, hydrogen is more expensive, more dangerous, and more inconvenient then acet., but it still burns cooler.

[Thrud]

bdarin:
...but I like explosions!

I have never been able to melt Platinum with anything but oxy-hydrogen or a well placed beer fart. Those could have jet propelled the Hindenburg but I am sure a sneeze is still faster.

[bdarin]

Never, ever underestimate the power of a beer fart.

[Peter Sanders]

Hi

<font face="Verdana, Arial" size="2">Originally posted by JCHannum:
Hydrogen is used underwater as hydrogen + oxygen = water. Hence no bubbles to obfuscate things.</font>

Well that sounds great, BUT the heat generated by the welding process will cause the surrounding water to boil and therefore oxygen bubbles will be formed.




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Kind regards

Peter

[JCHannum]

Peter, boiling produces steam, which would condense rapidly in cold water. No oxygen would be produced.
I'm going on memories from reading books on submarine warfare and recovery written and read more than 45 years ago, so things are a little hazy.

Thrud, don't try beer fart and sneeze at the same time. Guaranteed to lose control.

[Thrud]

JCHannum:

I completely understand where you are coming from - I will avoid hiccupping, sneezing and farting concurently - like trying to do something else while formating a floppy in windbloze, it is not like it is a Mac, eh?


Burning Magnesium and water is bad. Breaks the water apart and adds fuel to the fire (or so said Scientific American).

[docn8as]

will be 71 at end of summer ( i hope) & unfortunately have repeatedly proven the truth of the old man's adage.."never trust a fart"......
best wishes
docn8as

[docsteve66]

Gents: regarding cutting under water. I am certain air was pumped as well as O2 H2. The steam (water) produced by the O2 H2 is the ONLY product of combustion, and the steam bubbles are condensed inches (at most) from the torch. The scene when a welder cuts underwater looks wild- I was told the bubbles boiling to the surface were from air or other gases pumped to clear the area. If it was steam, we would have had fricassee diver.