MIG Welder

• A metal inert gas (MIG) welder refers to a welding gun that uses an arc welding current. The operator feeds a wire electrode, for soldering purposes, through the welder while a gas flows through and around the electrode to prevent oxidation. An MIG welder is ideal for welding a tube steel joint due to its speed of operation and ability to produce high heat.
  
  

Tack Welds

• After spooling the welder with solid welding wire, the operator can touch the wire protruding from the MIG welder's tip to the tube steel's weld joint. Pressing the welder's trigger for no more than one second creates a tack weld. Tack welds -- temporary weld spots used to hold two pieces together and maintain a proper angle during the weld -- should be placed intermittently around the weld joint.
  
  

Building the Weld

• Building the weld in thin layers ensures an even, thorough weld around the joint. The operator moves the MIG welder no more than one-eighth of an inch across the joint, building a weld puddle, then moves the welder a subsequent one eighth of an inch while rotating the pipe until the weld joint diameter is completely soldered