How to Stick Weld Exhaust Pipes: 11 Beginner-Friendly Steps

Table of Contents#

1. Pre-Welding Prep: Safety Gear & Required Tools
2. 11 Step-by-Step Guide to Stick Weld Exhaust Pipe
3. Pro Tips for Durable Exhaust Welds
4. Common Mistakes to Avoid
5. Frequently Asked Questions
6. References

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1. Pre-Welding Prep: Safety Gear & Required Tools#

Exhaust welding carries unique risks, from toxic residual fumes in old pipes to fire hazards near vehicle fuel lines. Don’t start work before gathering all of the following:

Safety Gear#

• Welding helmet with shade 10–12 lens (auto-darkening preferred for beginners)
• Flame-resistant welding jacket and closed-toe work boots
• Heavy-duty leather welding gloves
• Safety glasses (to wear under your helmet)
• N95 or P100 respirator (old exhaust contains lead, burnt oil, and carbon deposits that release toxic fumes when heated)
• Class B fire extinguisher (for gasoline and grease fires)

Tools & Materials#

• Stick welder (110V or 220V, minimum 90A output)
• 3/32” diameter electrodes: E6013 for mild steel exhaust, E308L for stainless steel exhaust (low-amperage, low-spatter options for thin metal)
• Angle grinder with cut-off wheel and 80-grit flap disc
• Stainless steel wire brush
• Exhaust clamps (to hold pipe sections in place during fitting)
• Jack stands (if working under a vehicle)
• Marker and tape measure
• Heat-resistant barrier (to protect vehicle fuel lines, floor pans, and plastic parts if welding on the car)

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2. 11 Step-by-Step Guide to Stick Weld Exhaust Pipe#

Follow these steps to avoid burn-through, warping, and leaks:

Step 1: Prep the work area and vehicle#

Park your car on a flat, level surface, set the emergency brake, and disconnect the negative terminal of the vehicle battery to avoid electrical sparks near fuel systems. If the car was running recently, let the exhaust cool completely for at least 2 hours to avoid burns. Jack the vehicle up and secure it on jack stands if you are working under it.

Step 2: Remove the damaged exhaust section (optional but recommended)#

While you can weld exhaust on the car, removing the damaged section eliminates fire risk and makes alignment far easier. Unbolt the exhaust mounts holding the section in place, and support the remaining exhaust with jack stands to avoid sagging or damage to other components.

Step 3: Clean the pipe joints thoroughly#

Dirty, rusted, or oily metal is the #1 cause of porous, leaky exhaust welds. Use your angle grinder to grind 1 inch of material on both sides of the joint (inside and outside the pipe) until you see bright, shiny bare metal. Follow up with a wire brush to remove leftover dust and rust from crevices.

Step 4: Align and secure the pipe sections#

Fit the two pipe ends together with no gap larger than 1/32” (gaps will cause burn-through on thin exhaust metal). Use exhaust clamps to hold the sections tightly in place, and double-check that the entire exhaust system is aligned correctly with no tension on the mounts (tension will cause cracks in the weld later).

Step 5: Set up your welder#

For 18-gauge mild steel exhaust: Set amperage to 60–70A with 3/32” E6013 electrodes For 16-gauge mild steel exhaust: Set amperage to 70–80A with 3/32” E6013 electrodes Always start at the lower end of the amperage range, and only turn it up if you struggle to strike a consistent arc. Make sure your work clamp is attached directly to the exhaust pipe, not to a painted or rusted vehicle frame.

Step 6: Confirm safety checks#

Double-check that all flammable materials (gas cans, oil rags, plastic vehicle parts) are at least 10 feet away from your work area. Put on all your safety gear, and keep your fire extinguisher within arm’s reach. If welding on the car, place a heat-resistant barrier between the exhaust and nearby fuel lines or plastic components.

Step 7: Tack weld the joint#

Tack welds are small, temporary welds that hold the pipe in place while you complete the full weld. Make 4 small ¼” tack welds spaced 90 degrees apart around the pipe. Let each tack cool for 10 seconds before making the next to avoid warping. Once all tacks are done, remove the exhaust clamps and double-check alignment before proceeding.

Step 8: Weld the joint with short stitch welds#

Never run a single continuous weld around an exhaust pipe: too much heat in one spot will cause warping and burn-through. Instead, use stitch welds: make 1” long welds, then wait 30 seconds for the area to cool, before moving to a spot opposite the last weld. Work your way around the pipe until the entire joint is sealed. Use a short drag technique, holding the arc length equal to the diameter of your electrode to reduce spatter.

Step 9: Maintain a fast, steady travel speed#

Move the electrode along the joint at 3–4 inches per minute, and don’t linger in one spot. If you see a hole forming in the pipe, stop welding immediately, let the area cool for 1 minute, and turn your amperage down 5A before restarting.

Step 10: Let the weld air cool completely#

Do not quench the hot weld with water: sudden temperature changes will make the weld brittle and prone to cracking. Let the joint air cool for 15–20 minutes before handling.

Step 11: Inspect and finish the weld#

First, visually inspect the weld for cracks, holes, or porous spots. Grind out any defective areas and re-weld them as needed. Use a flap disc to grind the weld flush if you need to fit a heat shield or exhaust clamp over the joint. Reinstall the exhaust section, reconnect the vehicle battery, and test for leaks by spraying soapy water on the joint while the car is running: if bubbles form, you have a small leak that needs to be re-welded.

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3. Pro Tips for Durable Exhaust Welds#

• Coat the finished weld with high-temperature exhaust paint once it cools to prevent rust and extend the life of the repair by 2–3 years
• If you blow a hole in the pipe during welding, cut a small patch of scrap exhaust metal, hold it over the hole, and tack it in place before welding over it
• If welding stainless steel exhaust, use a stainless steel wire brush exclusively for stainless to avoid cross-contamination that causes rust

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4. Common Mistakes to Avoid#

1. Skipping cleaning: Even a small amount of rust or oil will cause porous welds that leak within weeks
2. Amperage too high: This is the most common cause of burn-through on thin exhaust metal
3. Continuous welds: Too much heat leads to warping that pulls the pipe out of alignment
4. Poor alignment: Tension on the exhaust mount will cause weld cracks after a few hundred miles of driving

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5. Frequently Asked Questions#

Q: How long will a stick-welded exhaust last?#

A: A properly done stick weld on exhaust will last 3–5 years, the same as a professional MIG weld, if you seal it with high-temperature paint to prevent rust.

Q: Can I stick weld stainless steel exhaust?#

A: Yes, use 3/32” E308L stainless steel electrodes, and follow the same amperage guidelines as mild steel.

Q: Do I need to back-purge the exhaust for stick welding?#

A: No, back-purging is only required for TIG welding stainless steel. For stick welding mild or stainless steel exhaust, standard cleaning is enough to create a solid weld.

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6. References#

1. American Welding Society (AWS). (2023). SMAW Welding Guidelines for Thin-Gauge Mild Steel. Retrieved from https://www.aws.org/standards/welding-guidelines/thin-steel
2. Automotive Service Association (ASA). (2022). Exhaust System Repair Safety Best Practices. Retrieved from https://www.asashop.org/resource-center/exhaust-repair-guidelines
3. Lincoln Electric. (2023). Stick Welding Electrode Selection for Thin Metal Applications. Retrieved from https://www.lincolnelectric.com/en-us/support/welding-how-to/pages/electrode-selection-thin-metal.aspx