MAPP vs MAP//PRO for welding?

I've been using MAPP gas to weld, but it's not readily available any more.
(I only do occasional small scale work, and buy it in disposable
canisters - sure it's not as good as acetylene, but I can make it weld okay, and acetylene cylinders cost a whole bunch of 's here in the UK, mainly for rental)
There is a replacement, MAP//PRO from Rothenberger, which is stabilised propylene - any good?
I've heard the flame temp with oxy is about 100-200 degrees less than MAPP, which would make it at best even more marginal for welding than MAPP.
Thanks
-- Peter Fairbrother
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Any fuel gas other than acetylene will inject way too much hydrogen into the weld pool, leading to hydrogen embrittlement. This is the reason they still have acetylene around - you have to have it to weld steels.
As they say in the western US, cowboy up! Buy acetylene.
Grant
Peter Fairbrother wrote:

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"Grant Erwin wrote: As they say in the western US, cowboy up! Buy acetylene. ^^^^^^^^^^^^^^^^^^^^^^ For the occasional small jobs you do, your best bet is one of those small Prestolite cylinders--the kind plumbers use. If you already have oxy to use with Mapp gas, or planned to buy it to use with Mapp gas, you are most of the way there already. And you'll never regret it. Having the hotter, more concentrated flame doesn't just get you by--it gets you BETTER.
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Leo Lichtman wrote:

Sorry I didn't make it clear - yes, I have oxygen in abundance (from a concentrator).
I have been using oxy/MAPP gas for years (for welding steel and nickel alloys), but I just ordered some more MAPP gas and they sent propylene instead today - should I send it back?
Oxy/propylene is no use to me if it won't weld, as oxy/propane is fine for the brazing I do, and a lot cheaper.
-- Peter Fairbrother
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"Peter Fairbrother" wrote: Sorry I didn't make it clear - yes, I have oxygen in abundance (from a

^^^^^^^^^^^^^^^^^^^^ I have an oxygen concentrator sitting around not being used. Do you find that it works well connected to a torch?
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Leo Lichtman wrote:

A *small* equal pressure torch, yes - can just weld up to 1/8" with oxy/MAPP, (probably more, or perhaps better, with acetylene).
Brazes well up to 3/16" with oxy/propane, plus brazes a good bit thicker (3/8"+) with a bit of help from a propane/air torch, which is all I need.
Won't cut though, the pressure and flow are too low.
5 litres per minute, DeVilbiss. 200 on eBay, used for 400 hours, but they work for 50,000 (I think?) hours before needing servicing.
I don't know the exact time, but it's something like 5 years continuous use, and I use it less than 1/24 of the time - I should live 120 years to see it need it's first service!
-- Peter Fairbrother
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Peter Fairbrother wrote:

As best as I can tell from our local gas supplier CeeKay, their propylene is IDENTICAL in every way to the trademarked name "MAPP". They just can't call it MAPP as they'd be using somebody else's trademark.
Jon
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Jon Elson wrote:

That's simply incorrect. Dow Chemical's original MAPP was a mixture of MethylAcetylene, Propadiene and Propane, while "propylene" is simply propylene.
MAPP gas is UN 1060, "methylacetylene/propadiene mix, stabilised".
Methylacetylene/propadiene mix is too dangerous by itself, and propane/butane/LPG/etc were added for safety reasons. Another afaik untrademarked name for UN 1060 is MPS gas.
Propylene is UN 1077, "propylene", btw.
The propane in MAPP was soon replaced with LPG, a mixture of propane and butane.
Dow originally held the MAPP trademark, and licensed it to Rothenberger, Bernzomatic, etc. The trademark was later transferred to Petromont (which was half owned by Dow, half by a Canadian corporation).
Rothenburger's brand of MAPP gas was different to the usual Dow-supplied product, with up to 40% propylene added and less LPG (the formula varied).
Bernzomatic MAPP gas was closer to the original, with slightly more LPG but no propylene - despite all of these different mixtures actually being made by Dow/Petromont, and all being sold as MAPP gas. Bernzomatic also sold UN 1060 under the name MPS gas, presumably for trademark reasons - I don't know who they got it from.
BOC sold a closely-related gas containing just LPG, methylacetylene and propadiene, but I don't know who made it. It wasn't officially called MAPP gas afaik, but it was widely known as MAPP, which had become a generic name.
Several other welding gas supply companies also sold "generic MAPP" gas, of varying blends - again, the better ones were simple methylacetylene/propadiene mix stabilised with LPG. They were sometimes referred to as LPG-MAPP mixtures.
I believe all the methylacetylene/propadiene was supplied by Dow, later Petromont, whose Varennes plant was certainly the Western world's only large-scale producer of methylacetylene/propadiene, and who owned the MAPP trademark.
Petromont closed down all it's operations in March, which is why it's hard to get proper MAPP gas now.
(not because of the alternative use of propadiene in plastics, which had only a small effect on the price - higher oil and propadiene prices had meant that the market for MAPP gas had shrunk, but it was still profitable. Petromont made many other products, MAPP and methylacetylene/propadiene were only a small part of their turnover).
I think that propylene is probably nearly as good as MAPP for air/gas torches, and cheaper - but it's not as good for oxy/gas torches, especially for welding, the inner flame is cooler and the outer flame is hotter.
-- Peter Fairbrother
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Peter Fairbrother wrote:

OK, well, all I have to go by is what they told me at the welding store, obviously not the real truth! Lots of other details in your post I didn't know. Thanks,
Jon
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I always thought you could not weld with MAPP gas. I've been taught that there are too many contaminants in it and your weld will get either oxidized or carbonized (can't remember which) even with a neutral flame.
I know you can braze / solder with MAPP, but the only gas I thought you could weld with was acetylene?
--
Tin Lizzie
"Elephant: A mouse built to government specifications."-Lazarus Long
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Perhaps you're thinking of Propane?
Propane - and even gasoline - can be used for cutting but not welding.
Of course, the thickness - and melting temperature, for that matter - of the material to be welded can make a lot of difference.
--
I used to be an anarchist but had to give it up: _far_ too many rules.

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replying to Peter Fairbrother, 6G Jedi Master Open Root Assasin wrote: Very Impressive you must be the brains of this operation... .. .. .. Do you know by any chance of a A/C amperage amplifier of some,type for 110/120 V A/C 60Hrz Current ?? I have an old craftsman electric push mower that ive restored and had to invest in a 50Ft 10AWG cord, and I plan on getting one more to be able to go out a little further, and i know the voltage drop will be substantial,
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Leo Lichtman wrote:

I'm not familiar with Prestolite - what is it?
I doubt it's available in the UK anyway, or at least I've never heard of it.
-- Peter Fairbrother
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"Peter Fairbrother" wrote: I'm not familiar with Prestolite - what is it? (clip) ^^^^^^^^^^^^^^^^^ Prestolite is a name carried over from the old acetylene headlamp days. Early automobiles often had a tank of acetylene mounted horizontally on the running board. Since you could open a valve and have "instant headlights," the brand name "Prestolite" was adopted, and survives to this day. The commonest use today is with a small regulator and a single hose leading to a Prestolite torch, for soldering copper pipe. You buy the tank, full, initially, and then just hand it over the counter in exchange for a full one as necessary. Check plumbing or welding suppliers. May be available in the UK, possibly under a different name. Check also on what jewelers use.
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replying to Leo Lichtman, 6G Jedi Master Open Root Assasin wrote: Not so, the welding procedure that map was used for and quite effectively was ALUMINUM TORCH WELDING theres a company that developed rods for this, but if you can't torch weld it wouldn't do any good youd just make a mess...... I just tried it with a bottle i got from the parts monkeys exited mistakingly thinking they now carried map..... Nothin doin not hot enough..... Well guess its time to find a Cobramatic Lil Green Giant ....Anyone have one for sale please hmu tiresmoker at Gee Meyl u know the rest.......and what's this about needing acyteline to Weld ??? What is this 1955 ?? What are u going to do with the acyteline ? I know your not talking about welding with it oxy-fuel torch steel welds are inferior, obsolete and eat up enough consumables to put u in the poor house... And saying the reason they still have acetylene around is u have to have it to weld steels is patently assinine at best .. They still have it around because it's cheap to produce and because there will always be shade tree ham & eggers who use it to cut pieces, and for the Ironworkers doing commercial erections where the asme code doesnt prohibit metal weakening torch cuts .. .. So Pony Up Greenhorn who buys his picante sauce in New York City on some 7018 Low Hydrogen rods and a DC machine or a couple car batteries wired in series
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Grant Erwin wrote:

Not a problem for me - I stress-relieve everything anyway as soon as it's welded, which gets the hydrogen out as well (mostly nickel alloys, which are supposed to be particularly bad for hydrogen cracking, but some steel too - however the parts are small and I've never had a problem with it using MAPP gas even without stress relieving).
What I really want to know is whether it's *possible* to weld with propylene. Is the inner flame hot enough? Is the outer flame too hot?

That would cost me maybe $400 upfront then $250 per year in rental etc - and I as I only use one or two of the small disposable cylinders per year, maybe $30 worth, it would be highly uneconomic!
(yes, I'd love to have acetylene available, but it isn't practical)
-- Peter Fairbrother

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I bought a used acetylene tank. I just take it in a swap for a filled one as necessary. No rental fees at all.
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Bob F wrote:

You can't do that in the UK, you have to rent acetylene tanks. I don't think you can buy and refill tanks anywhere in the EU either.
(though you can buy oxygen tanks, and maybe get them refilled, if you're lucky enough to live in the right place or know someone)
- but (I think) it's illegal in the UK to fill acetylene tanks unless you have a licence and the documentation for the tanks - which, inter alia, includes certificates for the materials which they were made from!.
-- Peter Fairbrother
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Peter Fairbrother wrote:

BTW, BOC charges for a size H (about 7 cu m, 250 cu ft) acetylene cylinder are:
118.62 cylinder rental, per year 77.44 contents 38.19 delivery - note, this is for delivery to the local stockist, not to your door 12.63 collection - this is what the local stockist charges you for collecting the bottles from them - if they deliver to your door it costs more.
So the initial outlay would be 247.88 + 43.37 VAT, or 291.25; which is $514.69, not $400.
!
There are some slightly cheaper options, but none much cheaper.
Which is why I used to use MAPP gas, and would like to use propylene if possible.
-- Peter Fairbrother
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Peter you missed something.
I own my Tig gas tank. It is a sale bottle. It has a thick ring on top of the bottle top. I walk it in - they put it aside (in the back for all of this) and they take from their filled rack a tank and put it in my truck.
I go in and pay for the gas. I own the tank. I swap it out. I do that before I have to test the tank. They do that themselves due to their volume and safety.
So tank is owned. We can buy them lots of places. Home Depot is one. Welding supplies others and best.
Martin
Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com /
Peter Fairbrother wrote:

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