Molten weld pool behavior changes continuously. At the top (overhead), surface tension must hold the puddle against gravity. At the bottom (flat), gravity helps fill. At the sides (vertical), gravity pulls the puddle downward, risking undercut on the upper edge and overlap on the lower edge.
: Starting at the 6 o'clock position is often the hardest part, as gravity pulls the molten metal away from the joint. weld position 6g
The primary enemy in welding is gravity. In the 6G position, gravity attacks the weld puddle in varying ways as you move around the pipe circumference. Molten weld pool behavior changes continuously
| Position | Inclination | Pipe Rotation | Difficulty (1-10) | Typical Use | | :--- | :--- | :--- | :--- | :--- | | 1G (rolled) | Horizontal | Yes | 2 | Shop fabrication | | 2G (horizontal fixed) | Horizontal | No | 5 | Horizontal pipeline | | 5G (vertical fixed) | Vertical | No | 7 | Vertical risers | | | 45° | No | 9 | All-position qualifier | | 6GR (restricted) | 45° fixed | No | 10 | With backing ring removal test | At the sides (vertical), gravity pulls the puddle