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    Gas Welding

    Uploaded by

    Vikas Lavania
    Vikas Lavania presented on gas welding. Gas welding is a fusion welding process that uses a fuel gas, typically acetylene, and oxygen to produce a flame to melt the base metals. Oxy-acetylene welding is the most common type and produces the highest temperature flame. It uses acetylene and oxygen because it generates a flame over 3,000°C and produces an inert shielding gas to prevent oxidation. Different ratios of oxygen to acetylene produce neutral, carburizing, or oxidizing flames for welding different metals. Gas welding has advantages of low cost and portability but has lower quality welds than other processes.

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    Gas Welding

    Uploaded by

    Vikas Lavania
    74 views20 pages
    Vikas Lavania presented on gas welding. Gas welding is a fusion welding process that uses a fuel gas, typically acetylene, and oxygen to produce a flame to melt the base metals. Oxy-acetylene welding is the most common type and produces the highest temperature flame. It uses acetylene and oxygen because it generates a flame over 3,000°C and produces an inert shielding gas to prevent oxidation. Different ratios of oxygen to acetylene produce neutral, carburizing, or oxidizing flames for welding different metals. Gas welding has advantages of low cost and portability but has lower quality welds than other processes.

    Original Description:

    Describing about Gas welding

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    Vikas Lavania presented on gas welding. Gas welding is a fusion welding process that uses a fuel gas, typically acetylene, and oxygen to produce a flame to melt the base metals. Oxy-acetylene welding is the most common type and produces the highest temperature flame. It uses acetylene and oxygen because it generates a flame over 3,000°C and produces an inert shielding gas to prevent oxidation. Different ratios of oxygen to acetylene produce neutral, carburizing, or oxidizing flames for welding different metals. Gas welding has advantages of low cost and portability but has lower quality welds than other processes.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    74 views20 pages

    Gas Welding

    Uploaded by

    Vikas Lavania
    Vikas Lavania presented on gas welding. Gas welding is a fusion welding process that uses a fuel gas, typically acetylene, and oxygen to produce a flame to melt the base metals. Oxy-acetylene welding is the most common type and produces the highest temperature flame. It uses acetylene and oxygen because it generates a flame over 3,000°C and produces an inert shielding gas to prevent oxidation. Different ratios of oxygen to acetylene produce neutral, carburizing, or oxidizing flames for welding different metals. Gas welding has advantages of low cost and portability but has lower quality welds than other processes.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
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    The key takeaways are that gas welding is a process that joins metals by heating them with a flame produced from a reaction between fuel gas and oxygen. The most commonly used method is oxy-acetylene welding due to its high flame temperature. Gas welding can be used to join both ferrous and non-ferrous metals.

    The three main types of flames are neutral flame, carburizing flame, and oxidizing flame. The neutral flame is produced with equal ratios of oxygen and acetylene and has a temperature of around 3250°C. The carburizing flame has a ratio of 0.9:1 oxygen to acetylene and a temperature of 3150°C. The oxidizing flame has a ratio of 1.2-1.7:1 oxygen to acetylene and the highest temperature of around 3480°C.

    The advantages are low equipment cost, ease of use, portability and ability to be used for gas cutting. The disadvantages include low surface finish, large heat affected zones, safety issues from naked flames, and only being suitable for thin sheets with a slow joining rate.

    Presentation on

    "Gas welding“

    By Vikas Lavania
    Mechanical second year
    GAS WELDING

     Gas welding is a welding process that melts and join metals by


    heating them with a flame caused by a reaction of fuel gas and
    oxygen.
     It is a kind of fusion or non pressure welding.
     The most commonly used method is Oxyacetylene welding ,due to
    its high flame temperature.
    Composition

    Oxygen Chemical formula Heat [mJ/ m3] Temperature[°C]


    +Acetylene

    Acetylene C2H2 55 3100

    Propylene C3H6 88 2500

    Propane C3H8 93 2450

    Hydrogen H2 10 2390

    Natural gas CH4+H2 37 2350


    Oxy-acetylene welding

     In this acetylene instead of other fuels, with oxygen is used.


     Because it produces a comparatively higher temperature and also
    an inert gas envelope, consisting of CO2 and water vapours, which
    prevents the molten metal from oxidation.
    Principle of oxy acetylene gas
    welding
    When acetylene is mixed with oxygen in correct
    proportion in the welding torch and ignited flame is
    produced which is sufficient to melt the parent metal.
    The filler rod is used to build up a seam for greater
    strength.
    Systems of Oxy-acetylene welding

     High pressure system :- In this method both Oxygen and acetylene


    are drived for use from high pressure cylinders.
     Low pressure system :- In this system oxygen is taken as usual from a
    a high pressure cylinder but acetylene is generated by action of
    water on carbide usually calcium carbide in a low pressure
    acetylene generator.
    Reactions involved
     Stage 1:- oxygen and acetylene is burn in the inner white cone and form
    carbon monoxide.
     Stage 2:- carbon monoxide produce in the first stage use the oxygen from
    air and form carbon dioxide.
    Reactions-

    2C 2 H 2 + 2CO 2 4CO + 2H 2
    4CO+2H 2 +3O 2 4CO 2 +2H 2 O
    C 2 H 2 +2.5O 2 2CO 2 +H 2 O
    2.5 times of Oxygen is required for the proper burning of acetylene.
    Types of flames

    1. Neutral flame
    2. Carburizing flame
    3. Oxidizing flame
    Neutral flame
     When the ratio of Oxygen and acetylene is equal, a neutral flame is obtained.
     It has a temperature of about 3250°C. It is used to weld mild steel, cast iron,
    copper, aluminum etc.
    Carburizing flame
     The ratio of Oxygen and acetylene is 0.9 to 1.
     It has a temperature of 3150°C.
     It is not used for the metal that contain carbon because if metal absorb the
    carbon then it will release the heat which boils the metal and on cooling metal
    become brittle and subjected to cracking.
    Oxidizing flame

     The ratio of Oxygen to acetylene is 1. 2 - 1.7 to 1.


     It has a temperature of about 3480°C.
     Not used for Steel because it will form a foam and and give spark. i.
    e. is Steel burning starts and deposit metal will become porous and
    and brittle.
    S. No. Metal Flame used to weld

    1 Brass, bronze Oxidizing

    2 Lead, monel metal, high Carburizing


    carbon steel,

    3 C. I. , M. S., steel, Cu, Al, Neutral


    Ni
    Welding Rods

    The welding wire or rod used as a filler material in gas welding should
    have a chemical composition similar to that of the base metal.
    The welding rod diameter, d=(t/2+1)mm,where t is the thickness of the
    base metal in mm.
    Flux

     It is a material used to promote the fusion of metals. The primary


    purpose of weld flux is to prevent oxidation of the base and filler
    materials during the welding process
     In gas welding, the borax, sodium chloride are commonly used as
    flux material.
     It must melt at at a lower temperature than the metals being
    welded so that surface oxides will be dissolved before the the metal
    melts.
    Advantages
    •It is easy to operate and dose not required high skill
    operator.
    •Equipment cost is low compare to other welding
    processes like MIG, TIG etc.
    •It can be used at site.
    •Equipment’s are more portable than other type of
    welding.
    •It can also be used as gas cutting.
    Disadvantages
    •It provides low surface finish. This process needs a
    finishing operation after welding.
    •Gas welding have large heat affected zone which can
    cause change in mechanical properties of parent
    material.
    •Higher safety issue due to naked flame of high
    temperature.
    •It is Suitable only for thin sheets.
    •Slow metal joining rate.
    Application
    •It is used to join thin metal plates.
    •It can used to join both ferrous and non-ferrous metals.
    •Gas welding mostly used in fabrication of sheet metal.
    •It is widely used in automobile and aircraft industries.
    Thank you

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