Materials thicker than 12 mm will require special preparation.
Materials that are thicker than 12 mm | 0.472 " present challenges to the keyhole hole TIG process.
Lower levels of thermal conductivity found in thicker materials generally tend to require higher levels of current, however with an uneven heat distribution through the material seam, the keyhole hole either tends to not open correctly, or the keyhole hole collapses entirely. Slowing the travel speed does not remedy this.
K-TIG recommends that when welding materials thicker than 12 mm | 0.472 " using the K-TIG Welding System a 'Y' preparation is used to create a landing within the tolerances for a keyhole hole TIG weld.