A Short Guide to the Most Common Welding Symbols

You have heard it said that a picture is worth a thousand words. This is undoubtedly the case when it comes to welding symbols.

Welding is a process that combines two materials using heat or pressure. Welding symbols indicate the type of weld, the size and shape of the weld, and other details.

There are dozens of different welding symbols, which can confuse someone just learning about welding. In this blog post, we will take a look at some of the most common welding symbols and what they mean.

This will help you understand the welding basics to start your next project confidently.

Welding symbols are a quick way of providing welders with important information. Just like the “check engine” or “oil change” lights on your car, these symbols use images to communicate necessary messages. Paying attention to these symbols is essential to maintaining equipment and avoiding injury.

Of course, symbols are only helpful if you know what they mean. Without this understanding, even the most valuable characters will look like Greek to you.

Here are some of the most common welding symbols you need to know about and short explanations of what they need. With this information in hand, you will be ready to get started on your next welding job.

Why Learn Welding Symbols?

To someone unfamiliar, welding symbols might look like some strange hieroglyphics. Why go through the trouble of learning how to read them?

Welding is a profitable career that requires relatively little training. According to the Bureau of Labor Statistics, average welders make almost $40,000 yearly and don’t need a degree for an entry-level position. Many specialized jobs, however, can have a much higher salary.

But even though welding doesn’t require a college education, it requires specialized training. Learning to read these symbols is one of the first steps in pursuing that training. This knowledge could provide you entry into a stable career path.

Understanding Symbol Basics

Before we look at specific weld symbols, let’s look at a basic overview of what these symbols are and how they work.

Consistency of Symbols

For the most part, symbols are consistent across the welding profession. There are some specifics. However, that may be specific to a particular shop or tool.

Even so, learning the essential elements of a welding symbol is worthwhile since most shops comply with the American Welder’s Society Society standards. Whenever you start at a new shop, check what standards they follow with their symbols. This will help you accurately read the welding drawing you have.

How Symbols Work

The purpose of a weld symbol is to give instructions about how the weld should be done. These symbols indicate the type of weld, its size, and its location.

Also, sometimes welding characters show where the welder should work and what tools the welder should use.

The Arrow

The first part of the symbol to identify is the arrow. The arrow is critical because it points to the joint that must be welded. It also identifies different sides of the joint.

In the drawing, the arrow will point at a joint. The side of the joint that the arrow is pointing at is called the “arrow side,” and the arrow it is not pointing at is called the “other side.” The drawing can instruct how to weld the arrow or the other side.

Sometimes, a drawing will have more than one arrow coming off the same symbol to save space. This is permissible if more than one joint is being welded similarly.

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The Reference Line

If the arrow indicates where the weld should be done, the reference line indicates how it should be done. The reference link is a horizontal line that connects to the arrow. The arrow can be connected to either side of the line.

The reference line can give the welder information about both the arrow side and the other side of the joint. Any information about the arrow side will appear below the reference line. Information about the other side will appear above it.

In some cases, there may be several tasks that the welder must perform in a specific order. To show this, the drawing may use multiple reference lines. The lines closest to the arrow are the tasks that should be performed first.

The Juncture

The space where the arrow and the reference line connect is called the juncture. Sometimes, additional symbols will be attached to the juncture, giving more information about how the weld should be done.

For instance, a flag growing out of the juncture indicates that the weld should be done in the field. The weld should be done back at the shop if there is no flag.

Another common symbol at the juncture is an open circle. This symbol indicates that the weld should go around the joint.

The Tail

The next part of the welding symbol to continue is the tail. The tail is a greater than (>) or less than (<) symbol. This tail is then connected to the end of the reference line opposite the arrow.

The purpose of the tail is to provide information that cannot be communicated anywhere else on the symbol. This information can appear on the left or right side of the table.

A standard reference on the tail is information about the approved welding procedure specification (WPS).

This formal document outlines how to perform a specific weld according to code requirements. Typically, the drawing represents the WPS by including specific designation letters along the tail.

Additional Information in Symbols

Most of the specific information you need about the weld can be found in the welding procedure specification. Even so, welding symbols will often include additional information.

Groove Welds

Different kinds of grooves, like J, V, and U grooves, can increase the size of a weld on a joint. The drawing might add the groove symbol to the welding symbol.

If the groove symbol is below the reference line, it only applies to the arrow side. It only applies to the other side if it is above the reference line. If it is on both sides, then it is a double weld. The groove weld symbol will usually include information about the groove’s depth and angle.

Complete Joint Penetration

There are several ways that a symbol might indicate the need for complete joint penetration (CJP). The first way is to add the letters “CJP” to the tail of the symbol. This symbol indicates that full mutual penetration is required but does not specify how to do it.

A more specific way to indicate complete joint penetration is to use the symbol for a groove weld. Then, the drawing would show the need for CJP by not recording the depth of the weld.

Fillet Weld

Fillet welds are standard in industries using boilers and pressure vessels. The primary symbol for a fillet weld is a right triangle.

Typically, this triangle appears on the reference line, and the perpendicular lead appears on the left. If the fillet weld occurs on both sides of the joint, the symbol will appear above and below the reference line.

Plug and Slot Welds

Plug and slot welds are used when welding two members together, one of which has holes. As one piece of metal is welded, the welded material fills the gaps in the other piece.

For a plug weld, the drawing will show the diameter of each plug at the left. On the right, you will see the spacing between each plug.

For a slot weld, the information on the left is the length of each slot. On the right, the drawing shows the depth and width of the slot.

For the total number of plugs or slots, there is a number in parentheses below the drawing. Also, if the plugs or slots are not filled with welded material, the appropriate depth will appear in the drawing.

Letters to Look For

We have already mentioned some letters that you may see appearing in welding symbols. There are a few more letter combinations you should be aware of.

For instance, if the weld includes air cutting, you will see the letters “AC.” Adding an A, C, or M indicates specific types of air cutting, like air-carbon, carbon arc, and metal-arc air cutting.

There are also common suffixes that may be added to specific types of cutting. AU indicates automatic cutting, while I indicate machine cutting. Also, manual cutting is shown by MA, while SA offers semi-automatic.

The Three Basic Welding Symbols

Welding symbols are used to communicate information about a welding joint. They are typically found on drawings and blueprints.

There are three basic types of welding symbols: the groove weld, the fillet weld, and the flare bevel weld.

The groove weld symbol is used to indicate a groove weld. A groove weld is made by joining two pieces of metal together in a V-shaped groove. The size, depth, and angle of the V-shape will be specified on the drawing.

The fillet weld symbol is used to indicate a fillet weld. A fillet weld is made by joining two pieces of metal together at an angle. The size of the pitch will be specified on the drawing.

The flare bevel weld symbol is used to indicate a flare bevel weld. A flare bevel weld is made by joining two pieces of metal together at an angle with a flared edge. The size and grade of the flare will be specified on the drawing.

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The Seven Most Common Welding Symbols

There are seven common welding symbols, and they are:

• The fillet weld symbol is two lines intersecting at an angle, usually 45 degrees.
• The groove weld symbol is a pair of parallel lines.
• The spot weld symbol is a dot inside a circle.
• The plug or slot weld symbol is a rectangle with rounded corners.
• The seam weld symbol is two parallel lines with a zigzag line between them.
• The surface weld symbol is a series of short lines perpendicular to the main welding line.
• The braze weld symbol is a series of small circles along the welding line.

Conclusion

Welding symbols are an essential part of every welder’s life, as they help to communicate the specific details of a weld.

This article has gone over the most common welding symbols and their meanings.

We hope this guide has helped you understand each symbol’s meaning and how to interpret them.