A Brief Intro to Welding Symbols for Those Interested in Welding Training

August 18, 2020

When you first look at welding symbols, you may be overwhelmed by the seemingly arbitrary shapes and numbers. However, despite what you initially think, these symbols do have deeper meaning—and knowing this meaning will work wonders for your future welding career.

These symbols are often found on welding project blueprints, and are used to communicate between the designer and the welder. Without understanding these symbols, you won’t know what specifications a weld requires.

If you’re interested in becoming fluent in the language of welding symbols, read on!

Welding Symbols 101 for Those in Welding Training

Welding figures generally consist of five main figures: arrow, leader line, reference line, tail, and weld symbol (not to be confused with the welding symbol, which represents the entire diagram). Confused yet? Let’s explain them figure by figure.

The arrow, for starters, points to the part of the diagram where the weld is needed. Attached to the arrow is the leader line, which intersects with the reference line. In the middle of the horizontal reference line is the weld symbol: this represents the type of weld required. Finally, at the opposite end of the reference line, you may find the tail—it is only required for special instructions—which forks off in opposite directions.

How to Interpret Welding Symbols

As you’ll learn in welding training, the location of the weld symbol vis-à-vis the reference line determines which area of the joint you should perform the weld.

If the weld symbol is under the reference line, you should make the weld on the same side as the arrow. However, if the weld symbol is located above the reference line, you should make the weld on the opposite side of the arrow. But if the symbol is on both sides of the reference line, then, as you can imagine, you must perform the weld on both sides.

Learning welding symbols takes time, but is well worth it in the long run

Understanding Dimensions and Angles in Welding Symbols

In addition to shapes and lines, welding symbols can also include numbers that communicate the depth, diameter, and length of a weld–along with the beveling angle, if applicable.

In many cases, you will find the weld diameter (or width) on the left-hand side of the weld symbol. The length of the weld is found on the right. If the length is not indicated on the welding symbol, you should conduct the weld from the beginning of the joint to the end.

The reference line also plays a part in understanding the dimensions of a weld, just as it did for the weld type. Any dimensions indicated below the reference line pertain to the joint on the side of the arrow. Dimensions above the reference line pertain to the joint on the opposite side. If dimensions are indicated on both sides of the reference line, then you should weld both sides of the joint.

If these numbers, figures, and placements seem complicated, fret not—welder technician training is there to help you decipher these symbols with ease.


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