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Brazing or torch welding

Discussion in 'Welding' started by Old Doug, Apr 14, 2021.

  1. Welder Dave

    Welder Dave Senior Member

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    Never knew about this forum. On cast iron brazing or actually using cast filler rod should both break in the parent metal and not the welded or brazed area. Right at the edge is a fail too. Not much gas cast iron welding is done but it is the best if heat is involved like on a manifold. If heat isn't a factor brazing is a good option. Know a specialty shop that brazed a steel plate onto the side of a Kohler engine block with a hole the size of baseball in it. LOTS of preheat and wrapped in a fire blanket for slow cooling. Put back together and no problems. Balance gear exploded which caused the hole.
    For hyd's brazing can work but you need to build it up 3 or 4 times thicker because it doesn't have near the tensile strength of steel. Gas welding hyd. Is good as the heat from the torch stress relieves the steel somewhat. Silver brazing is also good and used a lot on factory steel lines with fittings. O/A welding and brazing is becoming lost art.
     
  2. Welder Dave

    Welder Dave Senior Member

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    Tig rod will work fine for generak gas welding. Typical rod is RG45 but there is also RG60 which has higher tensile strength. Coils for oilfield heaters are gas welded. I think it makes the tubing easier to coil and no hard spots like Tig might produce. The tube is only about 1" dia. Place I worked at used a big old lathe with a guide to make the coils. Most important part to gas welding is balancing the torch tip so you don't get back firing. Most books and even owners manuals don't tell you how to balance a torch tip. You don't look at gauges, you look what the flame is doing. Small tips will barely register on the regulator gauge. Basically when the pure acetylene flame jumps from the end of the tip tells you that is the max. flow of gas the tip can handle. Then you adjust O2 to get a neutral flame. Doesn't matter what the gauge on the reg. says. Most books or manuals tell you adjust the pressures the same using the gauges. Wrong. Gauges aren't as accurate as what the flame is telling you. Never did aluminum O/A welding but it is an art. Oh and a perfectly cleaned tip with a long straight outer flame is essential.

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    56wrench and dirty4fun like this.
  3. Old Doug

    Old Doug Senior Member

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    I got some aluminum rods that have flux cores havent tryed them yet.
     
  4. Welder Dave

    Welder Dave Senior Member

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    There are aluminum brazing rods that don't actually require the base metal to actually melt/fuse. Then there is O/A aluminum welding that actually is a fusion/melting process of the base metal. I think there's a name for it but can't think of it. Might be fusion but my my mind is a blank right now. It is a real art form to do though.
     
    56wrench likes this.