Welding Symbols Explained – Basics, Elements, Marks and Signs

Updated: 1 Jan 2024


Welding symbols are the graphical representations of the joints you are welding together. Many people use arrow techniques instead of symbols, impacting the weld quality

If someone says that weld here or there, it looks awkward and may be difficult to weld at the specific area.

The weld symbols play an essential role, which helps you carry more helpful information and helps the welder understand how the weld should be done quickly. 

Welders use drawing symbols to communicate essential things such as type, size, and the location of the welding where you want to weld.

Welding symbols mean placing the complete welding information on the drawing. It makes complicated welding projects easy for you. 

The tail of the welding symbols will initiate the welding cutting process, specifications, and some other information required for the welding.

Before drawing, you must understand the basics of the welding symbols. The welding symbols will help you know where to weld, how much metal you need to use, the joint type, and other plans.

The welding symbols play a vital role, which helps you to carry out the work according to your intended design easily. 

Every welder should know about the symbols of the welder to make a welding project successful.

Table of Content
  1. Key Elements of Welding Symbols: A Comprehensive Guide
    1. Reference Line
    2. Arrow
    3. Welding Symbol for Dimensions
  2. Supplementary Symbols
    1. Tail
    2. Finish Symbols
    3. Field Weld Symbols
  3. Understanding Supplementary Welding Symbols
  4. Additional Information About Welding Marks
  5. Explaining Basic Welding Symbols and Their Meanings
    1. Fillet Weld Symbol
    2. Groove Weld Symbols
    3. Square Groove Weld Symbol
    4. V-Groove Weld Symbol
    5. Bevel Groove Weld Symbol
    6. Single U Groove Weld
    7. Single J Groove Weld
    8. Edge Flange Groove Weld
    9. Corner Flange Groove Weld
    10. Plug or Slot Weld Symbol
  6. Additional Information About Types of Welding Symbols
  7. Welding Symbol Locations
    1. Arrow Side
    2. Other Side
  8. Mastering Weld Sizing: Key Dimensions for Strong & Reliable Joints
    1. Throat Thickness
    2. Leg Length
    3. Penetration
  9. Welding Symbols Placement: Guide to Proper Symbol Location
  10. Welding Symbols: Why Are They Important?
  11. Final Verdict

Key Elements of Welding Symbols: A Comprehensive Guide

key elements of welding symbols
Key Elements of Welding Symbols

The weld symbol helps you communicate the essential information about how you can join the weld. Welders engineers need to know about the symbols which allow them to carry out the welding work correctly. The critical elements of the welding marks are listed below.

Reference Line

The reference line is horizontal, which is considered the welding symbol’s main line. It represents the main joints where you want to apply the weld. The other symbols will be placed around this reference line.


This is another essential part of the welding symbol. The arrow side of the reference line is attached to the joint, which is placed at the one and the other end of the reference line.

The arrow can be in any direction, such as left, right, up, or down. The welding symbols may also have multiple arrows, so make sure you know about that. 

In the arrow, there are two crucial things you need to understand. There is an “arrow side” and “other side.” The arrow side of the reference line is the side of the weld joint where the arrow points. 

When you place the welding symbols on the arrow side, it refers to the arrow side weld joints; otherwise, if placed on the opposite side of the arrow, it indicates the other side of the weld joints.

Welding Symbol for Dimensions

welding symbol for dimensions
Welding Symbol for Dimensions

The dimensions of the weld specify the size, length, and depth. They are in millimetres, which can be placed above or below the reference line.

Supplementary Symbols

Supplementary Welding Symbols
Supplementary Welding Symbols

The supplementary symbols provide additional information about the weld. It makes welding easy and helps you determine how much filler materials should be used during a weld.


The tail of the welding symbols has all the data about the welding process and other necessary information. I usually indicated the welding method such as MIG, TIG, gas tungsten arc welding, etc.

Finish Symbols

FINISH symbol of welding
Finish Weld Symbol

The finish symbols indicate the finish of the weld that can be concave or convex. This type of symbol is usually placed below the reference line.

Field Weld Symbols

Field Symbol of Welding
Field Weld Symbol

Do you want to do the welding project on the field instead of the shop? A flag symbol will be added to the welding symbol.

Understanding Supplementary Welding Symbols

Supplementary welding symbols are additional symbols in the welding world that provide additional information about the welding joints. It will help you to clarify the various aspects of the welding joints. Let’s dive more deeply into it.

  • Flat (Flush): It indicates the final surface of the weld with the base metal. While welding, if you want a smooth surface, this technique will get a smooth result in the Fillet and other types of welding.
  • Convex: This symbol illustrates a convex contour finish. The welder must ensure that the weld crown conforms to established standards to promote the welded component’s structural integrity and desired properties.
  • Concave: It is usually used in the Fillet weld, which gives better penetration between the different welding components.
  • Smooth Blended Toes: This welding technique indicates that the end of the welding has smooth and blended transitions. You can get seamless connections between the weld and base materials for different purposes.
  • Spacer: The spacer symbol is used for the specific gap. If you are looking for a specific gap between the two components, this symbol is the best option to maintain a separation between the two parts during welding.
  • Back / Backing Weld: You can apply it on the reverse side or for the backing weld. If you are a professional welder, you can use the backing weld according to your requirements. This is used on those projects where additional strength and support are required.
  • Removable Backing & Permanent Backing: The removable backing symbol indicates that the backing material is used for welding but is later removed when the weld is completed. The permanent backing symbol represents that it stays in place after welding completion.

It’s not enough. There are also other supplementary welding symbols helping welders during the welding work.

Additional Information About Welding Marks

welding marks, elements or signs symbols explained
Welding Marks / Elements

Several vital welding signs provide specific details and information about the welding.

  • S: It indicates the different things in the world of welding. It depends on the type of welding you are working on. If you are in a Groove weld, it indicates the depth of the preparation. It also indicates the size of the Slot and Fillet weld.
  • E: It represents the throat and weld size in the case of the Groove weld. In the case of the Fillet weld, it represents the leg size. The size dimension for the Groove weld is placed inside the parenthesis, and the Fillet weld is without parenthesis.
  • R: If you are working on the Groove weld or butt joint, then the R symbol indicates the root opening. If you are working the Plug or Root weld, then it indicates the depth filling.
  • L: This one is easy to remember because you can easily imagine that it’s Length from the character. It represents the weld length, usually placed on the right of the welding.
  • P: If there is space between the weld, it represents the weld’s Pitch spacing.
  • N: The N represents the number of welds, such as Plug, Slot, Seam, Spot, etc.
  • A: The A denotes the angle, and in the case of every weld, it will represent the angle.
  • F: This represents the methods used for achieving the required contour of the weld. There are several methods, including Chipping (C), Hammering (H), Rolling (R), Grinding (G) etc.
  • —: This symbol represents a horizontal line between the A and F, which will find the contour symbol of the finished weld.

The welding symbols or marks are the shorthand used for communication about the welding joints. Understanding the welding marks and signs is essential to join the weld correctly.

Explaining Basic Welding Symbols and Their Meanings

Basic Welding Symbols Meanings
Basic Welding Symbols Meanings

You may have understood the critical elements of welding. Now, it’s time to discuss the different types of welding symbols. These are the basic welding symbols usually used in drawings.

Fillet Weld Symbol

what is a fillet weld symbol
Fillet Weld Symbol

It represents the filet weld and right-angle triangle. Fillet weld is best if you want to do two pieces perpendicularly. This symbol will also provide complete details about its size and length.

Groove Weld Symbols

Groove weld Symbols Examples
Groove Weld Symbols

This is the symbol of joining two metal pieces together with a groove. It includes other information such as the type of joint, shape, and groove weld size.

Square Groove Weld Symbol

Square Groove Weld Symbol image
Square Groove Weld Symbol Diagram

It represents the square groove weld, which can be identified from the square-shaped groove between the metal pieces. It conveys different information, such as size and other specifications about the groove weld.

V-Groove Weld Symbol

V-Groove Weld Symbol shape
V-Groove Weld Symbol

The V groove weld symbol represents the groove weld from the V-shaped groove. It provides information about the depth and angle of the V-groove.

Bevel Groove Weld Symbol

The Bevel Groove Welding Symbol
Bevel Groove Weld Symbol

It has all the information on the depth and angle of the slope in the groove weld.

Single U Groove Weld

Single U Groove Weld symbol shape diagram
The Single Groove Weld Symbol

It is usually used when preparing the edges of the metal pieces together in a U shape. It provides specific information about the weld size, length, depth, and other essential information.

Single J Groove Weld

The Single J Groove Weld Symbol shape
Single J Groove Weld Symbol

This welding technique utilizes a single J-shaped groove joining the two metal pieces together. It prepares the edges of the two metal pieces in a J groove shape.

Edge Flange Groove Weld

It’s a welding technique with a groove weld flange along the joint’s edge. The flange is created when you want to prepare the edges of the metal pieces together. This welding type is required in situations where some extra reinforcement is needed.

Corner Flange Groove Weld

It utilizes a groove weld at the corner of the joints. It conveys information about the size, depth, dimension, and corner flanged.

Plug or Slot Weld Symbol

Plug and Slot weld symbol diagram
Plug or Slot Weld Symbol Diagram

The plug and slot weld symbols provide precise instructions to the welder. The plug weld shape characterized the diameter of the weld, and the slot represented both the diameter and length of the weld.

Additional Information About Types of Welding Symbols

Here is some additional information about basic welding symbols.

Single V Groove Weld with Broad Root Face: It is a welding technique with a V-shaped groove with a wider root face. The broad root face will help to create stronger weld joints. 

Single Bevel Groove Weld with Broad Root Face: This technique involves a bevelled groove with a wide root face. This is the best option if you are doing a complicated project requiring a larger weld bead and additional strength.

Flare V Groove Weld: This technique creates a slightly wide gap at the root of the joints. This is commonly used when planning to join metal materials with irregular edges.

Flare V Groove Welding Symbol image
Flare V Groove Weld Symbol Diagram

Steep Flanked V Groove Weld: It utilizes the V-shaped with the steeply flanked sides. This is the best option if you are working on a project requiring specific angle and depth.

Arc Spot Weld: This type of weld is produced through the electrical arcs between the electrodes. If you want the desired result during welding, it’s essential to understand these symbols completely by utilizing this technique.

Resistance Spot Weld: This technique utilizes electrical resistance to create a localized weld. If you want to combine two metal pieces using the resistance spot weld technique, it requires applying pressure and electrical current to melt and join two pieces.

Resistance Spot Weld symbol diagram, size and strength
Resistance Spot Weld, Size and Strength

Resistance Seam Weld: It uses electrical resistance to create the linear weld along the butting materials. This will help you to join the two thinner metal pieces together.

Resistance Seam Weld, Spacing and Number
Resistance Seam Weld, Spacing and Number

There needs to be more. Besides this, there are some other welding symbol charts to explain, but I discussed the most essential one professional welders use.

Welding Symbol Locations

Welding symbols are placed on the reference line, and their locations give essential information about the welding joints.

Arrow Side

The side of the reference where the arrow is pointed is called the arrow side. If the welders placed the welding symbols on the arrow-pointed side, it refers to the features and requirements where the arrow is pointed.

Other Side

The opposite of the reference is very far from the arrow side, which is called the other side welding symbol locations. For a correct weld during welding work, it’s essential to understand the arrow and other side symbols.

If you didn’t get the points, I have discussed the same things differently with a graphical representation of the key elements in arrow sections.

Mastering Weld Sizing: Key Dimensions for Strong & Reliable Joints

Understanding the weld sizing is essential if you want a strong and reliable weld for your welding work. Some of the key elements related to the weld sizing are listed below.

Throat Thickness

It is the most crucial dimension in the Fillet weld, representing the short distance between the root and face of the weld. 

Leg Length

It represents the distance from the joint root to the outermost point on the face of a filet weld. 


It’s essential to achieve proper penetration while welding because it ensures that the weld is completely bonded with the base materials, contributing strength to the overall joint.

Welding Symbols Placement: Guide to Proper Symbol Location

Welding symbol’s locations play a vital role in communicating the design details. Here are the complete details about the welding symbols’ locations. We are focusing on the Groove and Fillet welds.

  • Groove Welds: If I talk about the Groove weld, the weld symbols should be placed on the reference line, which connects to the arrow, indicating one side of the joint.
  • Fillet Welds: Like the groove weld, the Fillet weld is also located on the reference line, connects to the arrow, and indicates one side of the joint. In a T joint, you can represent the Fillet weld at the arrow pointing to the weld side.
  • Dimensions in Weld Symbols: When you want to specify the weld size, the dimensions are very important. The fully penetrated and partially penetrated groove welds have specific symbols that give detailed information about the angle, gap, and size.

Welding Symbols: Why Are They Important?

Welding symbols are the graphical representations used on drawings that convey essential information about the welding process. These symbols are beneficial for the welders, engineers, and designers, and they help you understand the welding joints’ requirements.

The welding symbols will ensure clarity and consistency, which help to convey the welding requirements with ease. Weld symbols provide more comprehensive information instead of the written or oral instructions.

These brazing symbols have all the details about the weld type, location, size, and other specific requirements to help you in your welding project. The welding figures and symbols will give the accurate execution of your welding task.

Whether you use the welding symbols for pipe or any other project doesn’t matter. It will give you more accuracy during welding work. You can reduce the time and cost of the written documentation and utilize the symbols technique, saving you time in the welding process.

The welding symbols are the essential components of the welding world, which help you promote effective communication, are error-free, and ensure you complete your welding task according to your desired design.

Final Verdict

In the welding world, welding symbols convey information about welding joints, weld types, sizes, dimensions, and other essential information required during the welding project. Both standardized symbols, ISO and AWS, help communicate clearly across the welding industry.

If you want more accuracy in your welding project, welding figures are the best tools to help you achieve the best result. You may be a beginner or an expert in welding. It would help if you relied on the weld symbols that will enhance efficiency and accuracy.

Welding symbols are the key to achieving the desired weld integrity, reliable and strong weld with error-free results. What symbols have you used recently for your current welding project? Please share your experience with us by utilizing the welding symbols for your work.

Abu Bakar

Abu Bakar

Hello, Abu Bakar here, the Mastermind Behind Welding Villa. Test my years of experience through my well-written blogs, where I have covered the overall experience of welding materials and shown all the aspects of Welding, their types and equipment.

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