The Ultimate Guide to MIG Welding a T Joint: A Comprehensive Hands-On Approach

MIG welding a T joint is a fundamental technique in the world of metalworking, requiring a specific process to ensure a strong and consistent weld. This comprehensive guide will take you through the step-by-step process, providing advanced hands-on details and technical specifications to help you master this essential skill.

Prepare the Metal

Before you begin welding, it’s crucial to properly prepare the metal. This includes:

  1. Cleaning the Surface: Remove any rust, oil, or debris from the surface of the metal using a wire brush, degreaser, or other appropriate cleaning methods. A clean surface is essential for achieving a strong, high-quality weld.

  2. Aligning the Pieces: Ensure that the metal pieces are properly aligned and clamped in place. This will help maintain the desired joint configuration and prevent any distortion during the welding process.

  3. Checking for Fit: Inspect the fit of the T joint to ensure that the pieces are in full contact with each other. Any gaps or misalignment can lead to incomplete fusion and weaker welds.

Set Up Your Welder

how to mig weld a t jointImage source: Mig weld example

Choosing the correct settings on your MIG welder is crucial for a successful T joint weld. Consider the following:

  1. Wire Feed Speed: The wire feed speed determines the amount of filler material being deposited into the weld pool. For a T joint, you’ll typically want a wire feed speed between 200-300 inches per minute, depending on the thickness of the metal.

  2. Voltage: The voltage setting controls the heat input and penetration of the weld. For a T joint, a voltage range of 18-22 volts is generally recommended, with the higher end of the range used for thicker materials.

  3. Gas Flow Rate: The gas flow rate, typically between 20-30 cubic feet per hour (CFH), helps shield the weld pool from atmospheric contamination and ensures proper bead formation.

  4. Transfer Mode: For a T joint, you’ll want to use a short-circuit transfer mode, which creates a stable arc and minimizes spatter, resulting in a cleaner, more consistent weld.

Tack Weld the Joint

Begin the welding process by tack welding the T joint. This serves two important purposes:

  1. Holding the Pieces in Place: The tack welds will hold the metal pieces securely in the desired position, preventing any movement during the main welding pass.

  2. Checking Alignment: Tack welding the joint allows you to inspect the alignment and make any necessary adjustments before proceeding with the full weld.

When tack welding, use short, evenly spaced beads to ensure a strong, stable foundation for the final weld.

Lay the First Bead

With the T joint tacked in place, you can now begin laying the first weld bead. Follow these steps:

  1. Start Position: Position the welding gun at a 45-degree angle, with the tip pointed towards the end of the weld path.

  2. Travel Speed: Maintain a consistent travel speed, typically around 10-15 inches per minute, to ensure even bead deposition and proper fusion between the base metals.

  3. Bead Pattern: Use a stringer bead pattern, moving the welding gun in a straight line along the joint. This will result in a simple, consistent weld profile.

  4. Electrode Distance: Keep the welding electrode about 1/4 inch from the workpiece to ensure proper fusion and penetration.

  5. Weld Bead Size: Adjust the speed and distance from the weld to produce the desired bead size. If the weld is too small, there may not be sufficient fusion between the base metals. If the weld is too large, you’ll be using unnecessary filler material.

Complete the Weld

After laying the first bead, you may need to grind and finish the weld to remove any slag or unevenness. If the materials are particularly thick, you may need to lay multiple beads to ensure proper penetration.

  1. Grinding and Finishing: Use a grinder or other appropriate tool to remove any slag or irregularities on the weld surface. This will help ensure a smooth, consistent finish.

  2. Multiple Beads: For thicker materials, you may need to lay multiple weld beads to achieve the required penetration. Ensure that each subsequent bead overlaps the previous one to create a strong, uniform weld.

  3. Gas Lens: Utilize a gas lens on your welding gun to improve gas coverage and reduce the risk of porosity in the weld.

  4. Welding Helmet: Wear a welding helmet with an auto-darkening lens to protect your eyes from the intense arc.

  5. Welding Table: Use a welding table or other fixture to hold the pieces in place and maintain the desired joint configuration during the welding process.

By following these detailed steps and incorporating the advanced techniques and specifications, you’ll be well on your way to mastering the art of MIG welding a T joint. Remember to practice regularly and refer to the provided resources for additional guidance and troubleshooting.


  1. MIG Welding Basics part 6 Tee Joint Drill – YouTube
  2. MIG Welding Common Joints – Instructables
  3. The Beginner’s Guide to Welding a Tee Joint (With Tips) – Red-D-Arc