what are the 1G 2G 5G 6G pipe welding positions?
In the construction phase of a project in the oil and gas industry, we often find welding activities on pipes or welding on tanks. To maintain the quality of welding, professional organizations (ASME, AWS, ISO, JWES) make rules and classification of welding positions. All welder involved in construction needs to be certified according to these positions. In general, the pipe welding position is divided into 2 types, namely the welding position on the groove joint and the welding position on the fillet joint. Mostly welding connections on pipes use groove joints type so we often hear the term pipe welding position. The pipe welding position is divided into 4 groups, namely 1G, 2G, 5G and 6G.
There are two aspects of welding; skill and knowledge. The skill of the welder is evaluated by welder performance qualification. This is an important demonstration of the welder’s ability to deposit a quality weld. So, things like position, backing, uphill, and downhill, etc., are very important. According to ASME BPVC section IX, A welder shall be requalified whenever a change is made in one or more of the essential variables listed for each welding process.
1G pipe welding position
this is the easiest welding position. 1G welding position is a position where the pipe is in a horizontal position and the pipe can be rotated against the horizontal axis or the X-axis. The welder conducts welding from the top of the pipe. Welder position does not change.
2G pipe welding position
this is a welding position that is easy to do. 2G welding position is a position where the pipe is in a vertical direction and the pipe can be rotated against the vertical axis or Y-axis. The welder conducts welding from the side of the pipe with horizontal welding direction. Welder position does not change.
5G pipe welding position
5G welding position is a position where the pipe is in a horizontal or X-axis position but the pipe is fixed or cannot be rotated. Welder conducts welding while moving around the pipe. This position is almost the same as the 1G position, only the pipe cannot be rotated.
6G pipe welding position
This pipe welding position is the most difficult welding position. Only the welder has enough experience capable of welding with a 6G position. Pipe in a sloping position which is around 45 degrees from the horizontal axis (X-axis) or 45 degrees from the vertical axis (Y-axis). The pipe cannot be rotated so the welder must do welding while moving around the pipe.
Welding position is an important variable to determine weld quality. If a welder has the qualification of 1G position, he is not permitted to conduct welding in more difficult positions such as 6G position. But on the contrary, if the welder has a 6G position qualification, then he is permitted to carry out welding in the 1G position. A welding inspector is responsible to verify this requirement to be implemented.
1G, 2G, 5G, 6G Welding Position limitation in WPS
ASME BPVC Section IX also make very good guideline and limitation about welding position in WPS for the specific welding process. Take an example for GTAW process ( for other welding process, we do same thing, check each variable to know what happen on it when we change them ). For GTAW process, any addition of a welding position is categorized as an essential variable. This means the welding position has an important effect on weld quality result. QW-405.1 states a change in the position qualified is essential. Ex: Welders were qualified in the flat (1F) position so they can only weld in the 1F position.