Welding is important for joining metals in different industries, and engineers use symbols to tell welders what to do. One of these symbols is the seam welding symbol, which tells welders to join two metals together along a continuous line. In this blog, we will explain what the seam welding symbol is, how it works, and how to use it in engineering drawings and blueprints.
What is seam welding?
Seam welding is a fusion welding process that uses heat and pressure to join two or more workpieces along a continuous joint. It’s a variation of spot welding, where instead of creating individual weld spots, the welds overlap to create a leak-proof seam.
This type of welding is commonly used in applications that require a long, continuous weld and is particularly effective for sealing containers or tanks.
AWS Seam Welding Symbol
Seam welding employs a process akin to spot welding, but it is carried out in an extended manner. Unlike plug or slot welding, it doesn’t necessitate any preliminary steps. The weld penetrates the top surface and fuses with the other component via heat application. The emblem for seam welding resembles that of spot welding, though it includes two parallel lines.
Typically, a seam weld’s welding symbol will be accompanied by a size or shear strength figure. This number is usually placed to the left of the welding symbol. The size represents the width of the welding bead. Shear strength, similar to that in spot welding, indicates the minimum amount of pound-force the weld can withstand per one inch of weld.
Length of Seam weld if required is given on the right side of the seam weld symbol. The length of the intended weld can be denoted by a figure placed on the right side of the symbol. This value conveys the desired length of the weld.
If weld is to be made intermittent, a Pitch size is denoted after the weld length as shown in the below seam welding symbol example.
Seam Welding Procedure
Here’s a basic overview of the seam welding process:
- Preparation: As with any welding process, the surfaces of the materials to be welded should be clean. This means removing any paint, rust, or other contaminants that could interfere with the welding process.
- Placement: The two workpieces are placed between the rotating electrode wheels of the seam welding machine. The wheels are typically made of copper, which conducts heat very efficiently.
- Welding: The welding machine applies both heat and pressure to the workpieces. The heat is generated by electrical resistance as current passes through the workpieces, and the pressure is applied by the electrode wheels. The wheels move along the joint, creating a series of overlapping spot welds that form a continuous, leak-proof seam.
- Cooling: After the seam is created, it needs to be cooled. In some seam welding machines, the electrode wheels are water-cooled to help manage the heat produced during the welding process.