Welding Symbols – Types, Example Diagrams & Free PDF Charts

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Learning and knowing your welding symbols well is equally important as learning to weld properly.

Unfortunately, we still have some welding professionals who are not familiar with the welding symbol chart.

Some people think that just knowing the welding process is enough. It might be for amateurs, but professional welders have to have exact knowledge about welding symbols. If your goal is to become a pro one day (read bigger salary!), then you better sit down and study. We break down all the important pieces about this topic right here.

This is a Massive article with well over 4000 words, over 50 subheadings, and symbol drawings. While I highly recommend you read it all and see all of the images, here is a handy small table of contents that links to the top sections of the article: If you don’t have the time or you don’t have an internet connection at your workplace you have a free downloadable PDF file (e-book) with all the welding symbols and their short explanation.

Just a small side note. I drew all of the drawings myself in vector-based software. Production of this article took a long time and if you decide to take an image and upload it on your website please add a link back with a source to this original article. Thank you.

Subscribe: Get FREE 30 page PDF Welding Symbols Chart With Applied Examples for Each Symbol!

Common Weld Symbols

• Fillet – The most used weld.
• Groove – Second most used. It usually involves preparing the edge pieces to form one of the groove weld shapes like V, bevel, U, J, Flare V, Flare bevel or no preparation at all with square edges to form a square groove.
• Plug/slot – These are welds used to form overlapping joints using holes in which welds get deposited.
• Flange or edge welds.
• Seam welds – They are made using high heat input and are made in linear form.
• Spot welding – Done similarly to the seam except that these welds are done in a singular spot.

• Back/Backing – They use the same symbol but are different. The backing weld is deposited before the actual weld in the groove. Something like a pre-weld. The back weld on another hand goes after the actual weld. Something like giving the weld a good back.
• Melt-thru – Indicates that the root of the weld needs to be reinforced.
• Surfacing – Specifies the welds that are made over the entire surface of the piece.
• Backing bar – Designates the backing bar to be used on the back of the weld. If it has R in it, it should be removed after welding.
• Spacer – This symbol indicates the type and the dimension of the spacer that is inserted between the welded pieces.
• Weld all around – It signals that the weld is to be made over the entire circumference.
• Flag symbol – Field weld/Made on site.
• Contour – These symbols designate the final weld end product contour.

Learning all the welding symbols may be hard as there are a lot of them. However, you should know how to read a welding chart as it is much more important than trying to memorize all of them by heart. The most important symbols that you do have to memorize are the fillet weld symbol and the groove weld symbol.

You are more than likely going to come across welds on engineering and fabrication drawings. These are a set of symbols that describe the weld, the weld leg size, as well as giving processing and finishing information. The joint is the basis for reference for welding symbols.

The complete set of welding symbols is published by the American National Standards Institute (ANSI) and the American Welding Society (AWS).

Elementary Symbols

Elementary symbols are usually added to the reference line. Their purpose is to indicate the type of weld. You can usually find them marked at the midpoint.

These symbols are combined so as to convey certain configurations. If the symbols are not clear enough, meaning that they cannot provide the information needed, there may be a drawing of the cross-section of the weld with its dimensions. Symbols for double-sided butt welds are drawn on the opposite side of each other.

Complementary Symbols

Complementary symbols exist as additional information. Their purpose is to add info about something like the shape of the basic weld and how it should be made.

Structure of Welding Symbol

Weld symbols come with an arrow that points to the direction of the drawing where a weld needs to be made. The arrow line is connected to a leader line which is intersected with a horizontal reference line.

You can also find a tail at the opposite end of the reference line which then branches off in two different directions. The tail is an optional element.

1. The Arrow

The arrow is the main element of weld symbols. The arrow line points towards the place that is supposed to be welded. The stem of the arrow should not be depicted as a horizontal line on the drawing.

Being that welding symbols specify the joint that the arrow side is pointing towards as well as a change of direction and a change of geometry of the end of the joint a multiple arrow welding symbol can be added.

2. The Reference Line

Reference lines are important welding symbols drawn as a straight line horizontally across the drawing. The reference line arrow also contains additional details about the welding itself. It can contain some valuable information like the joint design, the weld pattern, the weld size, etc.

Both the upper and the lower reference line have the same elements for both sides. The main difference is the info about where one actually needs to weld. The lower part is a narrow side where the arrow indicates what side to weld based on the provided elements. The elements given on the upper part describe the other side of the joint.

This info is very useful when each side comes with different details of the joint. Also, it helps to diminish the usage of too many welding symbols in one joint.

3. The Tail

The tail is the third weld symbol part. It is drawn at the end of the reference line opposite the arrow. It usually contains information for which there is no provision elsewhere. The tail can provide info about the welding process, the reference document, and the examination process.

However, the tail doesn’t have to be there, it depends on the need for additional information. If provisional info is not relevant, the tail is omitted.

Location of Elements of a Welding Symbol

The above image shows how a typical welding symbol may be constructed. This may differ a bit from region to region but this is the way it is done most of the time. This graph is the most important one to have on you when reading the symbols or to memorize what each of its parts means. In time you will memorize all of it and it will be like second nature to you.Now, let’s see what all of the above-shown elements mean:

• The Groove design – There are so many different groove designs that you can use. Any welding symbol is not complete without a specific symbol for what method of joining pieces together you should use. Most of the time you will be working with some type of a groove or a fillet weld but there are other symbols that can be used here too as you will learn soon.
• The Weld size – These dimensions are very important because they are directly responsible for the joint’s ability to withstand the needed load. The S (size) is mostly used with the fillet and groove welds and so is the E (Effective groove size or Effective throat). The size represents the leg size of the weld in fillet welds. It also represents the depth of preparation in groove welds. The E is used to designate the actual depth of penetration in groove welds.
• The Lenght and Pitch of weld L and P – These numbers are not common but there are definitely instances when they are needed. In certain fillet welds, it is necessary to leave some parts unwelded to help with deformation and crack avoidance. That is why the number L specifies the actual welding length and the number P the pitch or spacing between the welds (center to center). This is also used on other types of welds like stud and plug welds but in a bit of a different way. All of this will be shown in detailed examples below.
• Root opening R – This one is rather simple. Root opening is a small gap between two separate metals that you are welding together. This is done in various welds and most commonly in groove welds. Root opening can also have a backing bar that is to be removed or kept after the weld is done.
• Bevel angle A – The bevel angle information tells you what angle needs to be made between the two beveled pieces or between one beveled piece and another that has a straight edge. Or in other words between sides of a V groove (double bevel) or a single bevel joint. It is an important metric that must be done according to the engineer’s demand.
• Contour (presented above the angle number on the symbol diagram above) – This information is given in a graphical form as a straight line, convex or concave shape. It represents the contour of the finished welded bead shape after the manipulation process that produces the desired contour. It is often that two joined metal parts need to be a part of a more complex structure and a weld bead can be a problem. That is why it is necessary to produce the contour the symbol demands. This leads us further to…
• Finishing F – In order to make the desired contour, you will need to know what process to use. Achieving the desired contour is often done just by using a grinder. There is a symbol for that as you will learn later in the article but there are also other ways of getting the contour like gouging or machining and others.