Because the pipe is fixed at 45 degrees, gravity affects the weld puddle differently at every point around the pipe’s circumference.
Fun fact: Some codes require — one with the pipe in a "fixed" position and another where the welder must start at the bottom (6 o'clock) and weld uphill both sides. That's called a 6G Uphill — even more brutal. 6g welding position definition
Welding in 6G requires extreme physical dexterity and mental focus. The primary hurdles include: Because the pipe is fixed at 45 degrees,
Here is a deep dive into the definition, physics, and career implications of the 6G welding position. 6g welding position definition