When it comes to welding, the position is always a key factor. This refers to the position in which the welding is performed, or where the weld joint is located during the welding process. There are a wide variety of possibilities for this. From vertical to horizontal to everything in between—the position of the weld joints presents its own unique challenges.
How is the position of the weld joint determined or described?
The surface to be welded and the axis of the weld along which the welding is performed play a decisive role in determining how the work can be carried out. At the two extremes of the scale, there are two welding positions: the ideal position and its exact opposite.
The Tub Position—The Ideal Welding Position
The ideal position for welding is the so-called trough position. In this position, the weld lies horizontally, and the edges of the workpieces form a trough that contains the molten pool. There are various variations of the trough position.
Quite simply, a trough joint can be located between two workpieces that are joined by a butt weld. In this case, both opposing edges are chamfered so that they form a V—this is the absolute ideal scenario, the simplest of all trough joints.
A trough can also form when a fillet weld is made between two workpieces. In this case, the two workpieces are at a 90° angle to each other but are each tilted by 45°, so that the weld to be made is once again located exactly within a trough. In this way, a pipe can also be attached to another workpiece.
The overhead position—the biggest challenge
The flat position is the easiest welding position to work in. The opposite of this is the overhead position. Here, too, the weld joint lies horizontally—but it is inverted and overhead, so that the weld faces directly downward.
All other welding positions fall between the flat position and the overhead position. This has nothing to do with the geometry of the workpieces—it simply refers to the position in which the welding is performed. In addition, there is the direction of welding, which distinguishes between ascending and descending passes.
What codes are used for the welding positions?
The welding positions themselves are standardized. They are determined by the DIN EN ISO 6947. According to the standard, there are seven positions, known as the main welding positions. Each has its own code—and they apply to all welding processes, whether MAG, TIG, or other methods.
While DIN EN ISO 6947 is an internationally recognized standard, the terminology used in the United States differs from it. There, the terms used are G a butt weld and with F A fillet weld is described.
The 7 main positions according to DIN EN ISO 6947 and the American system
| German (DIN EN ISO 6947) | American | Description | Description |
|---|---|---|---|
| PA | 1G | Tub Position | The surface of the weld is at an angle of 0° to the vertical. |
| PB | 2F / 2FR (rotating tube) | Horizontal Position of the Fillet Weld | The weld is located between the 1 o'clock and 2 o'clock positions; the surface is at a 45° angle to the vertical. |
| PC | 2G | Transverse position | The surface of the weld forms a 90° angle with the vertical. |
| PD | 4F | Horizontal overhead position | The surface of the weld is at a 135° angle to the vertical. |
| PE | 4G | upside-down position | The surface of the weld forms an angle of 180° with the vertical. |
| PF | 3G, increasing | Ascent Position | The axis of the weld is vertical; welding is performed in an upward direction. |
| PG | 3G falling | Case Position | The axis of the weld is vertical; welding is performed with the weld sloping downward. |
Additional Pipe Welding Positions
There are additional, specific welding positions for pipes:
| German (DIN EN ISO 6947) | American | Description |
|---|---|---|
| PH | 5G on the rise | The pipe is secured; it is being welded as it rises. |
| PJ | 5G on the decline | The pipe is secured; it is welded as it falls. |
| PK | — (no American equivalent) | Orbital welding of a pipe. |
What challenges do welding positions present?
Not all welding positions are equally difficult. The flat position is considered the easiest: The molten pool lies in the natural direction of gravity and is easy to control. As the angle deviates further from the horizontal, the demands on the welder increase significantly.
Upward vs. Downward Welding
The direction of welding has a significant impact on the result. In upward welding (PF / 3G upward), the welder works against gravity—the molten pool tends to flow downward. In down-slope welding (PG/3G down-slope), the material flows with gravity and must be actively controlled to prevent defects such as cold joints or slag inclusions.
Overhead Welding
The overhead position (PE / 4G) is the most challenging of all basic positions: The molten pool defies gravity and is in danger of spilling out. This requires the utmost concentration, specialized technique, and, as a rule, slow, controlled work. Welders who have mastered the overhead position are among the most experienced professionals.
Pipes and Orbital Welding
When welding fixed pipes (PH, PJ), the welder moves through several positions in a single pass—from flat position to horizontal position to overhead position. This requires constant adjustment of the welding technique. Orbital welding (PK) solves this problem with an automated electrode that orbits the pipe—a method in high demand in the pharmaceutical industry, pipeline construction, and food processing.
Conclusion
From the flat position, which is the easiest to weld, to the overhead position, which poses the greatest challenge—all welding positions and directions are standardized according to DIN EN ISO 6947. While the standard is internationally recognized, the Americans follow their own approach; however, they essentially adhere to the same principles. For pipes, there are additional positions that place special demands on technique and experience. Qualified welders must be proficient in all relevant positions and be able to switch flexibly between them depending on the job.
Frequently Asked Questions About Welding Positions
The welding position describes the orientation of the weld joint and, consequently, the welder’s posture during the welding process. It plays a key role in determining how the molten pool flows and how easily it can be controlled. Depending on the position, the requirements for technique, experience, and welding parameters vary considerably. Incorrectly chosen or poorly executed positions lead to weld defects, slag inclusions, or weld defects caused by excessive fusion.
Welding positions are internationally standardized in DIN EN ISO 6947. This standard defines seven main welding positions with codes (PA, PB, PC, PD, PE, PF, PG) as well as additional positions specifically for pipes (PH, PJ, PK). It applies to all welding processes—MAG, TIG, electrode, and others. In the U.S., different designations are used (G for butt weld, F for fillet weld).
The flat position (PA / 1G) is the simplest welding position: The weld lies horizontally, and the molten pool rests in a natural trough. Gravity aids the process—the molten pool remains stable and is easy to control. This position generally yields the best welding results with the least effort.
In the overhead position (PE / 4G), gravity works against the welding process: the molten pool is at risk of spilling out. The welder must use a special technique, lower per-unit energy, and work more slowly and with greater control. This position requires a great deal of experience and is considered one of the most challenging qualifications for welders.
In upward welding (PF / 3G upward), the welder works from the bottom up—against gravity. The molten pool tends to run down, which requires greater control. In down-slope welding (PG / 3G down-slope), the welder works from top to bottom—the material flows with gravity, which increases the risk of fusion defects. Both positions are standardized and are considered more challenging than the flat position.
In orbital welding (PK), an automated electrode orbits a stationary pipe, welding all positions—from the trough position through the transverse position to the overhead position—in a single pass. It is used particularly in areas where the highest weld quality and reproducibility are required: the pharmaceutical industry, food processing, pipeline construction, and semiconductor manufacturing.