Welding Symbols Explained: Know Your Way Around Blueprints

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Welding Buddy Experts

May 17, 2022
welding symbols explained - Welder studying a blueprint on a desk

Looking over your blueprints may leave you confused as you start a metal fabrication project. Metal fabrication drawings, diagrams, and blueprints often have undecipherable symbols which almost look like cuneiform. However, learning what they mean can take some time and effort. Spending time looking over these welding symbols will be worth it in the long run.

If you are new to the metal fabrication industry, you ought to know what these welding symbols mean. Fortunately, most of the symbols have become standardized throughout the years. So you don't have to worry about memorizing new symbols with each new fabrication plan or engineering drawing.

In this short guide, you will find these welding symbols explained. So scroll down and get to know each basic welding symbol!

What Is a Weld Symbol?

If you work as a metal fabricator in a vast factory, you may already realize how important consistency is. Without a practical way to communicate standard practices among metal fabricators, projects would have poor quality and become prone to safety hazards. That's why welding symbols have become a part of engineering drawings and blueprints.

The commonly used welding symbols came from the American Welding Society and the American National Standards Institution (ANSI). These welding symbols comprise the ANSI/AWS A24:2012 standard. Once you peruse relevant documentation about this standard, you will notice that it's divided into three parts, welding symbols, brazing symbols, and non-destructive examinations.

The following section will tackle some of the commonly used welding symbols in engineering drawings and project diagrams, as defined in the first part of the standard.

Basic Welding Symbols Explained: What Types of Welding Symbols Should I Know?

welding symbols explained - Chart with different welding symbols

It would be best if you understood what the structure of a weld symbol looks like before we move on to the individual welding symbols themselves. At first glance, a weld symbol looks like a fishbone. It has a tail and a head in the shape of an arrow. If there's a need for it, additional information about the joint can be written on either side of the reference line (also known as the “horizontal line”).

Reference Line

Also known as the horizontal line, the reference line is where everything starts. All other welding symbols are attached to this very important line. Even the instructions about the specific weld are written along the two sides of the reference line. The reference line ends in an arrow that can go up or down and right or left.

Arrow Line

When analyzing an engineering drawing, you would have noticed how each joint is accompanied by an arrow line. The arrow line always points to a joint that you need to weld. You can find the arrow connected to one of the ends of a reference line. The arrow also divides the area into the "arrow side" and the "other side." Both sides (left side or the other) contain relevant information about the joint.

The Tail

The tail can be found where the reference line terminates, directly opposite the arrow. Depending on the weld, you may find the corresponding designation for the Welding Procedure Specification (WPS) you have to employ at the end tail of the welding symbol. Aside from its location, you can spot the tail by its shape. It is usually drawn as a greater-than or less-than symbol.

Fillet Weld

When you see a right triangle (a kind of triangle that forms a 90-degree angle) along the reference line, you should do a fillet weld for that joint. If you work in industries that manufacture pressure vessels, you will encounter the fillet weld symbol frequently. Due to their high load-carrying capacity, the fillet weld saw widespread use in the industries mentioned above.

Groove Weld

If you see two parallel lines along the reference line, that's a groove weld. Metal fabricators use the groove weld for corner joints, among other types of joints. Like you would for a bevel weld, you can do a groove weld depending on the groove angle, weld depth, shape and size of the two parts you will weld together. As the name implies, you make a groove where the weld metal fills up.

Complete Joint Penetration

Similar to a groove weld, the complete joint penetration weld goes through the entire thickness of the joint. Metal fabricators employ this kind of weld when they want to fully utilize the load-carrying capacity of the base metal they are working on. This weld is represented by the letters "CJP" written on the tail of the welding symbol.

Plug Weld (Slot Weld)

Sometimes you need to weld two metal pieces that also have to be overlapping. Most likely, they have holes in them as well. In these instances, you need to do a plug and slot weld. Plug and slot welds can be found on diagrams as a rectangular symbol along the reference line. The specifics of the weld, such as plug diameter and slot width, are written beside the welding symbol.

Final Thoughts

Knowing the basics of metal fabrication takes some time. Aside from knowing the techniques, you also have to grapple through industry jargon. Fortunately, standardization has swept through the industry, implementing standard terms and symbols to help metal fabricators convey and understand any welding process (like a MIG weld or spot weld) and technique.

The relevant documentation covers way more than what this article tackled. For instance, the article didn't tackle other welding symbols such as those for the backing weld, square groove weld, intermittent weld, butt weld, v groove weld, intermittent fillet weld, and bevel groove weld.

If you're looking for more in-depth information to have any welding symbol explained thoroughly, grab a copy of the ANSI/AWS A24:2012 standard online. Spend the time between your projects to get to know what the rest of those symbols mean.

Now that you have the basics down, why not browse welders that may suit your metal fabrication needs? Head over to our welders section for our welder machine reviews.

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