Final answer:
The correct answer for the qualification test on a pipe assembly is 'welded in the 6G position at 45°,' testing the welder's skills in horizontal and vertical planes.
Step-by-step explanation:
The correct answer about a qualification test on a pipe assembly is welded in the 6G position at 45°. The 6G position is a fixed position where the pipe is inclined at a 45° angle and it cannot be turned or moved during welding. This position is considered one of the most difficult because it requires the welder to be proficient in all welding positions. The 6G position tests the welder's ability to perform a weld in both the horizontal and vertical planes, which is why it is commonly used for qualification tests.