How to Weld Cast Aluminum to Pipe

Welding aluminum to aluminum pipe is possible with the right equipment.

Welding cast aluminum to an extruded aluminum pipe presents few, if any problems with the right metal inert gas (MIG) welding setup and wire. What would cause a problem is if the pipe were made of some metal other than aluminum. While it is technically possible to weld steel and aluminum together, it is an expensive process that is out of reach of all but highly experienced professional welders. For this reason, it is important to know for certain that the metal pipe you are working with is, in fact, an aluminum pipe.

Things You'll Need

• Magnet
• Rubbing alcohol
• Stainless steel wire brush
• Welding clamps
• MIG welder
• Aluminum welding MIG wire
• Welding helmet

Instructions

1. Hold the magnet against the pipe to which you will be attempting to weld the aluminum. If the magnet sticks to the pipe, the pipe's metal is ferrous, meaning that it contains iron. It is not possible with a standard MIG-welding unit to weld aluminum to ferrous metals, so you'll have to find another way to bond the cast aluminum to the pipe. If the magnet doesn't stick, however and the pipe is silver colored rather than copper, you can weld the two pieces together.

2. Clean the two pieces of aluminum that are to be welded using rubbing alcohol and a stainless steel wire brush.

3. Attach the negative ground clamp from the MIG welder onto the work piece, then clamp the two pieces of aluminum together in the way in which they are to be welded.

4. Exchange the steel welding wire in the MIG welder with the aluminum welding wire, if necessary, then set the control dials on the welder for the thickness of the metal you are welding. These settings are usually found either in the owner's manual for the welder or on the inside panel where the welding wire is held.

5. Turn on the MIG welder and lower your welding helmet. Position the electrode from the welding gun approximately 1/4 inch from the cast aluminum workpiece, then pull the trigger on the welder. At the point where the electrode touches the aluminum, you will see a pool of molten metal begin to form.

6. Move the weld electrode between the two workpieces, pushing the weld pool along the seam between the pipe and the cast metal part. The formation of the weld pool is actually the fusion of the welding wire, the pipe and the cast aluminum melting together. Complete the weld and then turn off the MIG welder.

7. Clean the welded aluminum's excess weld slag with the stainless steel wire brush to complete the weld process.

Tips & Warnings

• Make certain that the aluminum parts are well-cleaned before you attempt to weld them together. Any imperfections in the surface of the metal could cause the weld to fail.

• Wear a welding helmet when welding. The light given off by the welding electrode is extremely bright and can cause several damage to your eyesight with prolonged exposure.

References

• "Welding Complete: Techniques, Project Plans & Instructions"; Editors of CPi; 2009
• "Welder's Handbook, Revised: A Guide to Plasma Cutting, Oxyacetylene, ARC, MIG and TIG Welding"; Richard Finch; 2007
• "Welding Manual"; John Haynes; 1995