Gas Welding Anyone?

[1965_MGB]

While browsing around my local HD store, I came across a Bernzomatic cutting, welding, and brazing kit. It has two tanks of fuel, and the hoses,etc.

I was wondering if anyone has had any luck with one of these. I would like to invest in a better setup of course, but one must choose their battles wisely, if you catch my meaning.

I have enclosed a pic of what I was looking at.

 

[Bayless]

Can't say for sure but my bet is you'd end up disappointed.

 

[GregW]

My guess, you'll be changing the tanks just as the metal starts to melt.

 

[Roger]

I have one of those, and for very small jobs it's fine. The oxygen runs out pretty fast, and you don't get more than 10 minutes or so. But I've used it for brazing and welding sheet metal brackets and the like, say 18 or 20 gauge, and it's fine. It's also very useful for large-scale soldering, like radiator supports, and I find it much better for that than those propane torches that spit and go out whenever you move them.

 

[TR3driver]

If you can live without being able to weld, I'd suggest a MAPP-gas torch (no oxygen) instead. Much cheaper to run and IMO works about as well for soldering and brazing.

 

[AweMan]

Blue cylinders indicate Propane, Yellow ones are propylene {Mapp Gas}. Mapp Gas burns hotter and has a tendency to last a bit longer than propane.
As stated, weld time is limited with these small outfits. However for Lead and Silver soldering or brazing and even welding light gauge steel they will get the job done. It might be a good idea to have extra cylinders on hand just in case you run out in the middle of a project.
For small light gauge projects this outfit will get you by.

 

[TR3driver]

Yellow ones are propylene {Mapp Gas}.

My understanding is that MAPP gas is a proprietary mix of LPG and methylacetylene-propadiene; which is not the same as propylene. Eg, https://en.wikipedia.org/wiki/MAPP_gas

According to that article, it's also not suitable for welding steel (which matches what I was told long ago). It's apparently no longer readily available (wish I'd known that so I could stock up).

But it's always dangerous to disagree with Kerry, so I could be mistaken.

 

[AweMan]

Ok just for clarification here is the msds for Mapp gas,
https://www.weilerwelding.com/MSDS/2015.pdf
Notice Propylene is but one of it`s components among others.
My fault for ASSUMING A simple explanation would suffice, Sorry.
Randall is right about Welding steel with Mapp Gas. Not a good idea, it does introduce elevated hydrogen levels into the weld causing a brittle condition.
But, My fault again for ASSUMING we are only welding gauge sheet metal {small brackets and the like} where brittle may not be too much of a factor in performance. By no means would I suggest that we try and fabricate critical high stress parts using Mapp Gas.
What Benzomatic is selling in those yellow cylinders may not be a true Mapp Gas in the fact that it may contain more propylene than anything else. Yet they trade mark it as Mapp Gas.
Benzomatic`s Propylene gas may or may not be suitable for welding steel, I could not say without further research.

 

[TR3driver]

What Benzomatic is selling in those yellow cylinders may not be a true Mapp Gas in the fact that it may contain more propylene than anything else. Yet they trade mark it as Mapp Gas.

Again, I could be mistaken. But best I can tell, they have changed what is in the yellow cylinders; or at least changed what they call it. My old one actually says "MAPP" and "56% LPG, 43% methylacetylene-propadiene". The ones on their web site say "Propylene".

The MSDS is different as well. Here's the current "yellow label":
https://www.bernzomatic.com/Portals/8/Resources/2009%20Propylene%20Gas.pdf
while here is MAPP gas:
https://www.bernzomatic.com/Portals/8/Resources/msdsSheets/eng-Mapp_Gas_MSDS_2008.pdf

And according to my Dad (who used to be a chemist working with this stuff; even did some of the research that led to MAPP gas many years ago) the acetylene radical in the MAPP gas component makes it considerably different stuff than the ethylene radical in the "propylene". The problem isn't so much flame temperature as how well it transfers heat to the metal.

How much difference it actually makes when using the stuff, I have no idea. My experience is that it takes a much bigger flame, but MAPP/air will heat fairly heavy gauge (like 1/8") steel to brazing temperature in a reasonable length of time. Quick enough anyway that I wasn't motivated to get out the OA setup the next time. But my OA setup is pretty small (what they used to call an "aircraft torch") so perhaps it's not a fair comparison.