How to MIG Weld Exhaust Pipe without Gas

Are you an aspiring hobby welder with dreams of creating a custom exhaust system but are worried about the costs associated with gas welding? Don’t worry—it’s possible to weld an exhaust pipe without gas!

In this blog post, I’ll show you exactly how to MIG weld an exhaust pipe without gas. Keep reading to find out how to get the job done and impress your friends with your welding skills!

Why MIG Welding Exhaust Pipes Without Gas?

There are several reasons to MIG weld exhaust pipes without gas, also known as flux core welding. Some of them are the following:

  • It’s often easier and more convenient because it does not require a gas supply, which is expensive and not easily available if you are welding in remote locations.
  • It saves you a great amount of time. You are not supposed to stop and change the cylinder every time it runs out of gas.
  • You don’t have to spend extra money on gas; the cost significantly reduces when welding for an extended period.
  • It ensures your health safety by emitting no toxic fumes when welding the exhaust pipe inside your garage without extraction fans.

Equipment You’ll Need

  • MIG welder
  • Metal wire brush
  • Grinder (optional)
  • Flux-cored wire
  • Welding gloves
  • Welding helmet
  • Welding jacket
  • Welding or exhaust clamps

MIG Welding Exhaust Pipes without Gas – (Step-By-Step Guide)

1: Wear Safety Gear

I would advise taking proper safety precautions before you get onto your exhaust pipe welding process to save yourself from welding sparks.

First, wear a welding mask, as it will protect your face and eyes from the bright light and sparks generated during the welding process. Make sure to choose a mask with a high-quality lens to ensure clear vision while welding.

Additionally, consider wearing welding gloves to protect your hands from heat, sparks, and molten metal, but make sure these gloves are flexible enough to manipulate the welding wire effectively.

Wearing welding pants and a shirt is not necessary, though. However, it could help you save your arms and legs from welding sparks and spatters as they are made up of FR (fire-resistant) materials.

2: Thoroughly Clean the Exhaust Tubing

Consider cleaning the exhaust pipe, as dirt, oil residues, and other contaminants on the surface can result in weaker welds. So, it’s crucial to eliminate them before welding to ensure a strong and long-lasting bond.

You will use a metal wire brush to scrub the pipe surface by paying close attention to areas where dirt and debris have accumulated, as these areas can weaken the weld. After scrubbing the pipes, use a clean rag or cloth to remove any residue or debris.

Now let the pipes dry completely, as any moisture on the surface of the pipes may disturb the welding process efficacy.

3: Setting Up the MIG Welder

Now it’s time to tune the welding machine correctly. Firstly, you will select the amperage, which varies for each metal. Generally, thick gauge metals require high amperage, while thin metals use low.

Also, adjust the wire speed in accordance with the welding speed. Too fast of a wire speed can result in a weld that is too wide, while too slow of a speed can result in a narrow, weak weld.

Ensure the welder is set to the correct polarity for the type of wire you use. See the manufacturer’s instructions for more clarity.

Lastly, ensure that the ground clamp is securely attached to the workpiece and has a good electrical connection. This helps to prevent welding defects and ensure a good finish.

4: Start Welding

Begin welding by holding the welding gun at a 90-degree angle to the metal and pulling the trigger to start the arc. As you weld, maintain a consistent speed and angle to ensure that the weld is straight and uniform. You should add filler metal to the joint as you weld to build the bead and create a strong bond between the metal parts.

5: Cleanup and Inspection

Once you are done with the welding process, now clean the welds to remove any slag, oxidation, or other contaminant using a wire brush or grinder

Once the welds are cleaned, inspect them carefully to check for any defects, such as cracks, porosity, or incomplete penetration. If any defects are found, they should be fixed as soon as possible to ensure the strength and durability of the welds.

If you see any defects, fix them by welding the affected area again or by adding a filler material to the welds. Removing and replacing the affected sections of the exhaust pipe may also be necessary. It’s important to take the time to fix any defects properly to ensure the longevity and reliability of the exhaust system.

Disadvantages of MIG Welding Exhaust Pipes without Gas

Shielding gas helps to protect the weld from oxidation and other contaminants that can weaken the bond, so you may witness a compromised weld quality without using gas.

Additionally, MIG welding without gas typically offers shorter welds because the heat generated during the process can cause the metal to warp if the weld is too long.

Moreover, welding with gas gives you more control than without gas, as there is no shielding gas to protect the weld from oxidation and other contaminants, which can result in inconsistent welds or a higher risk of defects in the final product.

Extended Tips to MIG Weld Exhaust Pipe without Gas

Read the tips below to get over with the process with more precision

Cleaning the pipes is essential; ensure they are free of rust, oil, and other contaminants.

Use a welding wire appropriate for the type of metal you are welding. For example, if you are welding stainless steel, use a stainless steel wire.

Welding without gas requires a lower amperage setting to reduce the weld pool size. So, start with lower amperage and gradually increase it as needed. Also, keep the wire feed as steady as possible to ensure a consistent weld.

Start with short welds and gradually work to longer, more complex welds. Depending on the thickness of the metal and the strength required, you may need to weld in multiple passes.

Allow each pass to cool completely before starting the next one to prevent defects like porosity.

Inspect the welds after you have finished checking for any defects, such as cracks, porosity, or incomplete penetration.


MIG welding exhaust pipes without gas can be challenging, but it is possible to achieve high-quality results if you follow these steps. Cleaning the metal parts, adjusting the welder settings, welding slowly and consistently, and using a high-quality filler metal can produce a strong and secure weld that will last for many years. If you have any questions or need further assistance, please don’t hesitate to contact us.

Read Also: Other Welding Techniques to Mig Weld Exhaust Pipe

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Dave Walker is a skilled welder and passionate blogger. With years of experience in welding, he has honed his craft and developed a deep understanding of the trade. In his blog, he shares his experiences, insights, and tips on welding, offering a valuable resource for fellow welders and those interested in the field. He is dedicated to promoting the importance of welding and its applications in various industries.