Under the code, what are welders certified in 3G and 4G actually certified for?

Welders certified in 3G and 4G positions are specifically trained and tested for vertical and overhead welding applications. The 3G certification pertains to vertical welding, where the welding is performed in a vertical position, which requires the welder to skillfully control the molten weld pool to ensure proper penetration and bonding. The 4G certification is for overhead welding, which presents unique challenges, as the welder must work from below the weld joint. This position requires a different technique and a high level of proficiency to prevent issues like slag entrapment and poor bead appearance.

The options that refer to flat and horizontal positions, or only flat positions, do not apply to the 3G and 4G certifications. These specific certifications demonstrate the welder's capability to handle the increased difficulty of vertical and overhead welding tasks, which are crucial in many structural applications where joint positions vary. Thus, the focus on vertical and overhead in the certification reflects the requirements outlined in the code for welders who are expected to perform in these challenging positions.