essential variables in WPS

1G, 2G, 3G, 4G, 5G, 6G, 1F, 2F, 3F, 4F pipe and plate welding position

What is the welding position?

Welding Position is the type or position of the connection to be welded, this welding position is based on the material or product to be welded. In welding technology, all of them have coding based on the type of connection. For fillet connections, it is symbolized with positions 1F, 2F, 3F, and 4F, while for groove or bevel connections it is symbolized by 1G, 2G, 3G, and 4G.

Fillet weld is a method for combining two parts of metal vertically or slightly at an angle. They are also known as T connections or Lap connections (Lap connections are when pieces of metal overlap and the edges are welded). Welds are in the form of triangles and are commonly used when connecting pipes. This is also called closed welding because the weld metal does not need to be cut to join. Groove welds are made in metal grooves that will be joined. Need full penetration to have strong joints. This weld is used for the tip and butt joint connections. Groove welds are stronger than fillet welds. In general, basic welding positions consist of 4 types namely flat position, horizontal position, vertical position, and overhead position.

In the following, symbols are often used to explain the welding position:

Welding Position for Groove connection.
– 1G (Flat Welding Position).
– 2G (Horizontal Welding Position).
– 3G (Vertical Welding Position).
– 4G (Welding Position Overhead or Overhead).

Welding position for Fillet connections.
– 1F (Flat Welding Position).
– 2F (Horizontal Welding Position).
– 3F (Vertical Welding Position).
– 4F (Welding Position Overhead or Overhead).

1f, 2F, 3f, 4F welding positions for plate
welding positions for plate

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.

Comparisons welding positions between ISO standard positions and ASME / AWS:

NoWelding Position (ISO)Welding Position (ASME / AWS)
1PA1G / 1F
6PF3G Uphill
7PG3G Downhill
8PH5G Uphill
9PJ5G Downhill
10H-L0456G Uphill
11J-L0456G Downhill

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.

5g pipe welding position
qualification for welder
types of welding positions
1G 2G 3G 4G 5G 6G pipe welding positions

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 weld axis in horizontal direction. The welder conducts welding from the side of the pipe with horizontal welding direction.

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. It is also named as PF in ISO/EN standards. In 5G, welding is done vertically either upwards or downwards.

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 Positions limitation in WPS

ASME Boiler and Pressure Vessel Code Section IX also makes very good guidelines and limitations about welding positions in WPS for the specific welding process. Take an example for GTAW process ( for other welding processes, we do the same thing, check each variable to know what happen on it when we change them ). For the 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 results. QW-405.1 states a change in the position qualified is essential.

welding positions and symbols
welding positions changing in WPS – essential variable

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