designer
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| posted on 22/3/16 at 02:32 PM |
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Acetylene alternative
Anybody out there using an acetylene alternative to braze/weld?
Am told that Propane is OK for brazing, but not welding.
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britishtrident
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| posted on 22/3/16 at 02:50 PM |
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No real viable alternative for welding the advantage is it gives a very concentrated intense point heat, although MAPP gas gives a hotter flame than
butane or propane it really isn't up to the job.
[Edited on 22/3/16 by britishtrident]
[I] What use our work, Bennet, if we cannot care for those we love? .
― From BBC TV/Amazon's Ripper Street.
[/I]
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Smoking Frog
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| posted on 22/3/16 at 02:51 PM |
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I remember using MAPP gas years ago, seemed to work well.
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Dick
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| posted on 22/3/16 at 03:04 PM |
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We use propane for cutting as its a hot gas
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r1_pete
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| posted on 22/3/16 at 03:16 PM |
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SGS do an alternative:
Link
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designer
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| posted on 22/3/16 at 03:46 PM |
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SGS sounds good, and just up the road from me now I'm in UK
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theprisioner
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| posted on 22/3/16 at 06:44 PM |
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I think this is Propylene a gas used in the refrigeration industry. I have a cylinder of it as I use it for brazing and heating up steel that is
corroded. It burns about 280 deg C less than acetylene = 3480deg C. I assure you it is virtually impossible to do any decent welding with it as it
will not concentrate the heat properly.
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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motorcycle_mayhem
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| posted on 22/3/16 at 07:11 PM |
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MAPP has changed a bit in recent years, what is labelled as 'MAPP' in B+Q et. al. (those useful little yellow cylinders), isn't what
it used to be. When I bought the kit (torches, hoses, reg., etc.) some time a ago, MAPP was a mix of methylacetylene and propadiene. It welded,
beautifully. Now, as 'theprisioner' has said, it's now a mix of (mainly) propylene and propyne. This will weld, but not beautifully
and not quickly either.
Recent MAPP is still great for brazing/silver soldering/whatever, just not really for welding. My use for it is now non-existent as I've gone
over to TIG and Plasma Cutter.
I have a fully functional MAPP assembly (Regulator, hoses, cutting torch and welding torch with an assortment of related usefuls - tips etc.), all in
good order, with MAPP gas bottles..... open to offers if you wish to acquire it.
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907
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| posted on 22/3/16 at 07:48 PM |
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The alternative to acetylene is
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electricity
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spaximus
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| posted on 23/3/16 at 07:22 AM |
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Hobby weld do acetylene in rental free bottles. If you search on line you will find a stockists but there is one in Avonmouth Bristol if you struggle.
They do oxygen as well
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hughpinder
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| posted on 23/3/16 at 08:02 AM |
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I've stolen this from a welding forum:
"Lots of conjecture out there on why you can't weld with propane. Some say Propane is not hot enough. Actually that has nothing to do with
it. Take a #7 Oxygen / Propane tip and compare it to a tiny #1 welding tip. Even though the Propane tip has a far higher BTU output you still will not
get a good weld. The reason Propane ( and other alternative fuels ) are not suitable is that when Acetylene is burning with Oxygen it creates a cone
of CO2 forming a shielding gas over the weld puddle. Propane does not produce this shielding CO2"
Also
"MAPP like all of the Liquified Petroleum gasses is not appropriate for welding of steel, due to the high concentration of hydrogen in the
flame. The hydrogen infuses into the molten steel and renders the welds brittle."
Regards
Hugh
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motorcycle_mayhem
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| posted on 23/3/16 at 01:24 PM |
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Hugh - yes, exactly so. Originally, MAPP was lovely to use, giving the protective CO2 cone.
Now that MAPP is an LPG mixture (not MAPP i.e methylacetylene-propadiene), the welds are contaminated, often porous and somewhat brittle.
Last time I used the rig in anger was the removal of a car 'dragon' clamp, utilised by an over zealous University car park
'officer'. This before the advent of the Li-ion angle grinder.
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907
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| posted on 23/3/16 at 05:05 PM |
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I always enjoyed chemistry so 'scuse me butting in.
The inner cone =
acetylene + oxy becomes two molecules of carbon monoxide + hydrogen
C2 H2 + O2 becomes 2CO + H2
Carbon Dioxide forms in the edges of the outer envelope.
( I'll take off my anorak now )
Paul G
 
Description
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