welding positions 5G – What Is Piping

A welding position is a technique by which a welder joins the metals in the positions or angles. The welding position is very important as it affects the flow of molten filler material. It's desirable that the welding operator understands the types of welding positions to smoothly accomplish the task. Also, at a certain position of the welder different welding processes are performed. In this article, we will learn about the common welding positions used in the industrial application of welding. The guidelines and limitations regarding welding positions in WPS is covered in Section IX of ASME Boiler and Pressure Vessel Code. Types of Welding Positions Some welding processes can be performed at all positions; while some are possible in one or two positions only. According to the positions of the welding joint on sections, the American Welding Society (AWS) and ASME define four types of welding positions. They are Flat welding positionHorizontal welding positionVertical welding position, andOverhead welding position The welding position is defined by a number (1 to 6) followed by one letter from F, G, or S. Here, the letter "F" stands for fillet welding, "G" denotes Groove welding, and "S" refers to the Stud welding.The numbers denotes welding positions as follows: "1" indicates a flat position. For example, 1F, 1G or 1S"2" refers to a horizontal welding position; Example 2F, 2G or 2S"3" denotes a vertical position; Example 3F or 3G"4" denotes an overhead position; for Example, 4F, 4G, or 4S.Letters "5" and "6" are specifically used for piping welding positions in a horizontal fixed position and inclined position respectively. Pipe welding positions will be discussed towards the end of the article. The following table shows the various welding symbols for welding positions used for different types of welding methods Welding Position SymbolWelding PositionWeld Type1 FFlat positionFillet weld1 GFlat positionGroove weld1SFlat positionStud Weld2 FHorizontal positionFillet weld2 GHorizontal positionGroove weld2SHorizontal positionStud Weld3 FVertical positionFillet weld3 GVertical positionGroove weld4 FOverhead positionFillet weld4 GOverhead positionGroove weld4SOverhead positionStud WeldTable 1: Welding position symbols with respect to Welding types Welding Positions 1G or 1F (Flat welding positions) In Flat Welding position 1G or 1F, the welding is done from the top side of the joint. The head of the welder remains above the test coupon and the weld face is approximately horizontal. The flat welding position is easier and faster and the molten metal is drawn downward. Flat welding position is also known as down hand welding position. The following image in Fig. 1 shows the welding positions used during welding. Fig. 1: Weld Joint Positions for plate Welding Positions 2G or 2F (Horizontal welding positions) In horizontal welding position, the weld axis is almost horizontal. As compared to flat welding position, this is more difficult position for welding. Welding position 2F is for a fillet weld where the welding is performed on the upper side of a horizontal surface and against an approximately vertical surface keeping to welding torch at a 45-degree angle. Welding position 2G is for a groove weld when the welding face lies in an approximately vertical plane with weld axis in a horizontal plane. Welding Position 3G or 3F (Vertical welding positions) In vertical position welding, the weld axis is almost vertical. Both the weld and the plate will lie vertically. For welding vertical surfaces, the molten metal runs downward by gravity and pile up. Welding in an upward or downhill vertical position can resolve this problem. Also, by pointing the flame upward at around a 45-degree angle to the plate, the metal flow can be controlled. Welding position 3G is used for groove weld and 3F is used for fillet welding. Welding Position 4G or 4F (Overhead weld position) When the welding is done from the underside or the joint, it is known as overhead welding position. It's the most difficult position for a welder to work and the most complicated one. Welding Position 4G refers to the groove welding and 4F indicates the fillet welding. In overhead welding positions, the metal deposited tends to drop or sag on the plate that results a bead with a high crown. To get rid of this difficulty, the molten puddle should be kept small. When puddle becomes too large, one can remove the flame momentarily for molten metal to cool. Pipe Welding Positions The above-mentioned welding positions, i.e, flat, horizontal, vertical, and overhead are the most basic types of welding positions used for plate welding. However, these do not completely describe pipe welding positions. As far as pipe welding is concerned, there are four types of piping welding positions. They are: Horizontal Rolled Pipe Weld Position 1GVertical Position 2GHorizontal Fixed Position 5G, andInclined Weld Position 6G Pipe Welding Positions 1G Welding Position 1G is the easiest pipe welding position as the pipe is in horizontal position. In 1G pipe welding position the pipe can be rotated against its horizontal axis (X-axis). The welder perform pipe welding from the top without changing his position while the pipe is slowly rotated manually or by equipments. Pipe Weld Position 1G is the most basic pipe welding. The image in Fig. 2 below explains all the pipe welding positions. Fig. 2: Pipe Welding Positions Pipe Welding Positions 2G In pipe welding position 2G, the pipe will be in the vertical position (Pipe axis in Y direction) and weld axis in horizontal direction. The welder performs the welding from the side by remaining stationary or moving around the pipe. The welding method is easy in case of 2G pipe welding position and most frequently welded by the back hand method. Welding Positions 5G Pipe welding position 5G is a weld position where the pipe axis is fixed in a horizontal position and the operator weld vertically either downward or upward. In this welding position the pipe is kept fixed and can not be rotated unlike 1G welding. 5G welding position is difficult as the pipe can not be rotated. Welding Positions 6G In pipe welding position 6G, welding is performed in a sloping pipe. The pipe slope is normally 45 degrees from horizontal or vertical axis. 6G welding positions, being the most difficult pipe welding positions, require certified and highly experienced welders. The pipe remains fixed and the operator need to move around the pipe for welding. This is the most challenging and complex pipe welding position for welders. There is another form known as 6GR where welding is done in a ring mode by placing a steel plate below the weld with a 1-inch gap. This requirement comes while welding pipes near impediments like walls, brackets, or other structures. Comparisons of welding positions between ISO standard and ASME / AWS standard Sometimes, the weld positions by professional organization ISO is found in industries. The weld position nomenclature in ISO system is a bit different. The following table provides a comparison between ISO and AWS standard welding position symbols. AWS Welding PositionISO Welding Position1G / 1FPA2FPB2GPC4FPD4GPE3G UphillPF3G DownhillPG5G UphillPH5G DownhillPJ6G UphillH-L0456G DownhillJ-L045Table 2: AWS vs ISO welding positions Why care about Pipe Welding Positions? Welding position is one of the most important variables that determine weld quality. For each pipe weld position, welders need to undergo certification processes. If a welder is qualified to weld in a 1G position, he is not allowed to weld hard positions like 6G position. But on the other hand, if the welder is certified for the hardest 6G position then he can work in the 1G position. So, expertise over each weld position levels up a welder's skills and qualifications. 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