How to Weld Aluminum Fuel Tanks

  • 1-2 hours
  • Advanced
  • 100-400
What You'll Need
MIG welder
Aluminum wire
Safety mask and shop clothes
Carbon dioxide or other oxygen-free gas

In order to complete many household and automotive welding tasks, you will need to know how to weld aluminum. Aluminum welding differs from steel welding in several significant ways. In application to a fuel tank, you must consider even more factors. Welding a previously used fuel tank, even under the best of conditions and with proper precautions, is a dangerous task that can lead to a fire or explosion. It is extremely important that you take all necessary safety precautions before you attempt fuel tank welding. This article explains how to weld aluminum fuel tanks.

Step 1 - Understand the Differences Between Aluminum and Steel

Even if you are an experienced steel welder, you will need to know how to weld aluminum. Steel and aluminum welding are different from each other. Aluminum wire is much softer than steel, so you will find it harder to feed through the welder. The gauges of wire often differ between the two metals, and you may need to adjust settings on your welder in order for the welder to function properly with the aluminum.

You'll need to put different shielding gas into your welder's regulator; steel usually takes mixed gases or carbon dioxide, whereas aluminum works best with pure argon gas. The regulator tank will work with either.

Positive polarity settings are required for both aluminum and steel applications. Make sure that the wire electrodes you are using are designed for aluminum applications—steel electrodes will not work well with aluminum welds. When you observe these differences, you will understand better how to weld aluminum.

Step 2 - Prepare the Tank

Gasoline vapors soak into fuel tanks. Rinsing and washing with detergent will remove surface fuel, but will not stop the metal itself from leaking vapor. This is the reason that welding fuel tanks is such a dangerous job.

There are many urban myths regarding fuel tank welding that suggest tactics including running car exhaust into the tank during welding. These tactics will not improve the safety of the task and have been shown in many cases to be at fault for explosions and fires. To stabilize a fuel tank, rinse the tank thoroughly and allow it to sit overnight. Pump in a truly neutral gas that will keep oxygen away from the fuel residue and keep you safe; carbon dioxide is an excellent option.

Step 3 - Load the Aluminum Wire

Load the wire into the welder by holding the spool firmly in one hand and locking it into the drive roll. If the wire comes loose and unravels, you'll need to replace it. Set the brake tension so that the wire doesn't pull, and the spool won't turn on its own. Make sure you are wearing proper safety equipment at this point.

Step 4 - Weld the Tank

Adjust the drive roll tension so that the wire moves as the roll slips. Your clamps should be securely attached to the metal piece that you are welding on the fuel tank. Apply the weld evenly and at as straight of an angle as possible to ensure good contact and a strong weld. Once you've finished with the metal work, cut off the carbon dioxide. Leave the clamp on until the metal has cooled.