1G/2G/4G welding

Answer

The designations 1G, 2G, and 4G define standard groove welding positions according to AWS (American Welding Society) and ASME Section IX standards. The letter "G" stands for Groove weld (as opposed to "F" for Fillet weld), while the numbers specify orientation relative to gravity and plate alignment.

The plates are placed approximately horizontal, and the welder deposits the weld from above.

The plates are positioned vertically, while the groove/weld line runs horizontally.

3G – Vertical groove welding 

where the weld axis is vertical and welding may be done vertical-up or vertical-down.

The workpiece is located above the welder, and welding is carried out from underneath.