Gas welding with propane?


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    Default Gas welding with propane?

    So i've read different things saying if you can weld with propane or not instead of acetylene. I am looking to get a full torch setup and am torn between a traditional acetylene setup or going with one of the propane oxygen configurations. Its my understanding the propane is much cleaner and less expensive not to mention a bit easier to refill. Well that and avoiding buying another tank for the acetylene.

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    Propane does not deliver nearly the BTU s that acetylene does. You won't be happy with it unless all you want to do is solder and braze.



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    How does Map gas compare? I was thinking of maybe using propane for my brazing work which will be 90% of what i end up doing and switching to one of the small map bottles from the box stores when i need to weld. I haven't looked but how many cubic feet are in the smaller bottles and what kind of time could be expected to get from them? Is it even worth it or should i just be going straight to acetylene? What is the average cost of a 20lb bottle from a welding supplier store for acetylene empty? I"ve seen around $80 on harbor freight but wasn't sure how that stacked up.



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    http://en.wikipedia.org/wiki/Mapp_gas

    MAPP gas is liquefied petroleum gas (LPG) mixed with methylacetylene-propadiene. In Australia, it is known as RazorGas and is a trademark of ELGAS.

    According to BernzOmatic, a similar fuel gas MAP/Pro stands for Max Power Propylene.[1]

    The gas can be used in combination with oxygen for heating, soldering, and brazing due to its high combustion temperature of 2927 °C (5300 °F) in oxygen. Although acetylene has a higher combustion temperature (3160 °C, 5720 °F), MAPP has the advantage that it requires neither dilution nor special container fillers during transport, allowing a greater volume of fuel gas to be transported at the same given weight. MAPP was advantageously used in underwater cutting, which requires high gas pressures (under such pressures acetylene polymerizes explosively, making it dangerous to use). However underwater oxy/fuel gas cutting of any kind has been replaced by exothermic cutting due to the much faster cut rate and greater safety.

    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.


    The gas was also used for brazing and soldering, under combustion in ambient air, where it has considerable advantage over competing propane fuel due to its higher combustion temperature. A typical MAPP gas brazing operation would involve metals such as aluminum, copper, et al. braze (sometimes colloquially and inaccurately called silver solder) steel parts together.

    The biggest disadvantage of MAPP gas is cost; it is between two and four times as expensive as propane (depending on quantity, supplier, and bottle size). While nine kilogram propane cylinders are common, the largest MAPP cylinder available in Australia is three kilograms. Additionally, MAPP gas torches often cost more than propane torches, around 3 times as much.

    MAPP is colorless in both liquid and gas form. The gas has a pronounced garlic or fishy odor at concentrations above 100 ppm, due to the addition of Mercaptans for safety, and is toxic if inhaled at high concentrations.

    MAPP gas has been replaced in industry by other LP gas mixes, because one of the constituent gasses, Propadiene, is becoming more valuable to the plastics industry than the welding industry. Flamal, Chemtane, and MAP/Pro are three of the newer LP gas mixes on the market.



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    Quote Originally Posted by jhowelb View Post
    Propane does not deliver nearly the BTU s that acetylene does. You won't be happy with it unless all you want to do is solder and braze.
    ? You can cut with a oxy/propane torch, why wouldn't you weld with a oxy/propane set-up?

    Maximum neutral flame temperature of acetelyne in oxygen is about 5720*F.
    Maximum neutral flame tempature of propane in oxygen is about 5112*F.



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    Looks like it's not a good idea to weld with Propane. Snipped from "Andy's place"

    "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."



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    Quote Originally Posted by mc-motorsports View Post
    ? You can cut with a oxy/propane torch, why wouldn't you weld with a oxy/propane set-up?

    Maximum neutral flame temperature of acetelyne in oxygen is about 5720*F.
    Maximum neutral flame tempature of propane in oxygen is about 5112*F.
    You can"t weld properly with oxy/propane because of the hydrogen infusion as jhowelb pointed out. When cutting with oxy/propane, the propane simply heats up the steel to a red heat. The oxygen actually does the cutting through a chemical reaction. After the cut was started you could theoretically shut off the propane and continue the cut with pure oxygen.

    A Mapp gas setup is great for soldering and brazing all but the heaviest parts. For welding, I prefer my acetylene/oxygen outfit which will weld from sheet metal to about 1/4" thickness efficiently. Above that it's time to wheel out the electric welder.



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    Default Theramlly Assisted Machining

    dear all
    hi
    i want to know that whether oxy acetelyene welding can be used a heating source for thermally assisted machining of hard materials like SS321 or inconel or even Titanium



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    Default Re: Gas welding with propane?

    Its my understanding the propane is much cleaner and less expensive not to mention a bit easier to refill. Well that and avoiding buying another tank for the acetylene.



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Gas welding with propane?

Gas welding with propane?