Published on 02-Mar-2024

Deciphering the true meaning of Welding Symbols

Deciphering the true meaning of Welding Symbols

Table of Content


When creating drawings for your metal fabrication, welding symbols can be used.

We need to know what weld detail is significant to you in terms of your fabrication design, dimensions, and specifications. We don't get all the information just from being told to weld where or to weld the corners.

However, alongside welding symbols, certain tests like the Rebound Hammer Test are essential for assessing the integrity of structures.

There may be situations in which strength is not as important as aesthetics. Keeping heat distortion low helps prevent buckling, for instance, by applying intermittent stitch welds or limiting the amount of Welding.

Standard welding symbols can be used in a drawing to aid the welder and give you better control over the aesthetics and mechanical characteristics of the finished fabrication.

welding symbols

Welding Symbol Standards

By following established standards, such as those defined by the American Welding Society (AWS) or the International Organisation for Standardisation (ISO), companies can ensure consistency, quality, and safety in their welding operations.

The use of a standardized NDT Test for Welding symbols eliminates ambiguity and minimizes errors in interpretation. This, in turn, reduces the likelihood of costly rework and ensures that welding projects are completed efficiently and accurately.

Additionally, standardized symbols enable welders to work across different projects and industries with ease, as they are familiar with the universally accepted symbols and their meanings.

BS EN 22553 is the British Standard for Weld Symbols. The relevant weld process code is listed in BS EN ISO 4063. Identification of the welding process is necessary as part of the welding symbol. 

As technology continues to shape the welding landscape, it's essential to stay updated with the latest advancements in weld symbol standards. The integration of digital tools and automation in welding processes brings about new challenges and opportunities.

By staying informed and continuously upgrading their skills, welders can remain competitive in an ever-evolving industry.

Definitions of Weld Symbols

1. When the use of a definite process is required the process may be indicated by one or more of the letter designations, as

Weld Symbols

Obs.: Letter designations have not been assigned to arc spot, resistance spot, arc seam, resistance seam, and projection welding since the weld symbols used are adequate.

2. When no specification, process, or other symbol, the tail may be The reference is used as an indication of a common welding process.

Field Weld Symbols

3. Other common weld symbols, as above and below, illustrate the weld-all-around and field weld symbol, and resistance spot and resistance seam

resistance spot and resistance seam weld

Welding Symbols

Here are some common welding symbols. The weld sign always consists of the following. 

1. An arrow line

2. A reference line 

3. A dashed line 

4. A symbol

Types of Welding Symbols

Welding symbols are categorized into two main types: Basic Welding Symbols and Supplementary Welding Symbols.

Each type serves a distinct purpose in conveying crucial information about welding processes and techniques.

Types of Welding Symbols

1. Basic Welding Symbols

Basic Welding symbols are fundamental representations used to communicate essential information about Weld Joints, dimensions, and other specifications.

These symbols are commonly found on blueprints and engineering drawings and play a pivotal role in guiding welders, NDT Inspectors, and other stakeholders involved in the Welding Process.

Some common examples of basic welding symbols include:

* Fillet Weld Symbol

This symbol represents a triangular weld joint between two surfaces positioned at an angle.

It provides information about the length and size of the weld, aiding in determining joint strength.

* Groove Weld Symbol

Used for joints where two pieces of metal are aligned and welded along their edges, the groove weld symbol indicates the depth and width of the weld.

This helps welders understand the required dimensions for the joint.

 * Plug and Slot Weld Symbols

These symbols are used when holes need to be Fillet Welds material.

They include details about the hole's dimensions, weld size, and length, ensuring accurate execution of the weld.

2. Supplementary Welding Symbols

Supplementary welding symbols provide additional information that complements the basic welding symbols.

They offer further clarification about specific aspects of the Welding Process, such as joint preparation, weld profile, and other critical details.

Some examples of supplementary welding symbols include:

* Backing Bar Symbol

This symbol indicates the use of a backing bar or strip in the Weld Joints.

It helps specify the type and dimensions of the backing material, which can impact the weld quality.

* Machining Symbol

Used when machining is required after welding, this symbol informs welders about the necessary machining processes and their locations.

* Field Weld Symbol

When a weld joint needs to be performed on-site or in the field rather than in a controlled environment, the Field Weld Symbol provides this information.

It ensures that welders are aware of the specific conditions under which the weld should be executed.

* Contour Symbol

The contour symbol indicates the desired weld profile or shape, guiding welders in achieving the appropriate surface finish and contour for the Weld Joints.

Location Significance of Arrow

Fillet, Groove, Flange, Flash, and Upset welding symbols. For these symbols, the arrow connects the welding symbol reference line to one side of the joint and this side shall be considered the arrow side of the joint.

The side opposite the arrow side is considered the other side of the joint.

Arrow and Side Fillet Welding Symbol

Fillet Welding Symbol

Plug, Slot, Arc Spot, Arc Seam, Resistance Spot, Resistance Seam, and Projection For these symbols, the arrow connects the welding symbol reference line to the outer surface of one part of the joint at the center line of the desired weld.

The part to which the arrow points is considered the arrow side. The other part of the joint shall be considered the other side.

Plug and Slot indicating Location and Dimension of the welds

Near Side. When a joint is depicted by a single line on the drawing and the arrow of a welding symbol is directed to this line, the arrow side of the joint is considered as the near side of the joint, in accordance with the usual conventions of drafting.

Other Side V-Groove Weld Symbol Arrow side V Groove Weld

Necessity of Weld Symbols

Here are a few reasons why weld symbols are essential. 

1. Clear Communication

Weld symbols are a universal language in the Welding industry.

They bridge the gap between different languages and enable seamless communication between stakeholders from diverse backgrounds.

A well-designed weld symbol can convey complex information in a simple and understandable manner.

2. Standardization

In an industry where precision is paramount, standardization is key. Weld symbols follow established guidelines set by organizations like the American Welding Society (AWS) and the International Organisation for Standardisation.

This consistency ensures that everyone interprets the symbols in the same way, reducing the risk of errors.

3. Safety Enhancement

Welding involves high heat and potentially hazardous materials.

Incorrect Welding Procedures can lead to structural failures or even accidents.

Weld symbols guide welders in adhering to the correct techniques, materials, and dimensions, enhancing overall project safety.

Necessity of Weld Symbols

Welding Symbol Location

The correct placement of welding symbols on engineering drawings is vital to avoid confusion and ensure uniformity in fabrication.

Incorrect symbol placement can lead to misunderstandings, resulting in weld defects and structural integrity issues.

In addition to welding symbols, the Rebound Hammer Test on Concrete is indispensable for assessing the compressive strength of concrete structures. 

1. Butt/Groove Welds

Butt or groove welds are commonly used in joints where two pieces of metal are aligned in the same plane and joined by welding along the joint.

These welds are widely used in various industries due to their strength and clean appearance.

Welding Symbol Location

2. Locating Butt/Groove Weld Symbols

The placement of butt/groove weld symbols on engineering drawings follows specific conventions.

The symbol is positioned above the reference line, and its arrow points to the joint's location.

Proper alignment and measurement are crucial to accurately conveying the weld's position and dimensions.

3. Fillet Welds

Fillet Welds are triangular welds used to join two pieces of metal at an angle.

They are commonly used for lap joints, T-joints, and corner joints. Fillet welds offer versatility and ease of implementation.

4. Locating Fillet Weld Symbols

Fillet weld symbols are placed on the reference line, and the length of the weld is specified inside the symbol's right triangle.

The size and length of the Fillet welders are indicated on the symbol, providing vital information to welders.

Advantages of Welding Symbols 

Welding symbols are graphical representations used in engineering and construction to communicate welding specifications and requirements on technical drawings.

These symbols offer several advantages that streamline the Welding Procedures and ensure clear communication between designers, engineers, and welders.

Advantages of Welding Symbols

Here are some key advantages of using welding symbols.

1. Standardization

The American Welding Society (AWS) established standards that welding symbols adhere to.

This standardization ensures consistency in communication across different industries and regions.

2. Clarity

Welding symbols provide concise and precise information about the Type of Welded Joint, welding process, dimensions, and other critical details.

This clarity reduces the chances of misinterpretation and errors in the fabrication process.

3. Time Savings

Welding symbols eliminate the need for lengthy written instructions, reducing the time required to communicate welding specifications. This results in faster decision-making and improved efficiency in the production process.

4. Reduced Errors

By using standardized symbols, the potential for miscommunication and mistakes is significantly reduced.

Welders can accurately understand the requirements, leading to better quality welds and fewer rework scenarios.

5. Cross-functional Communication

Welding symbols facilitate effective communication between various departments, such as design, engineering, and fabrication.

This promotes collaboration and ensures that everyone involved in the project is on the same page.

6. Flexibility

Welding symbols can be used on a variety of engineering and construction drawings, such as blueprints, schematics, and plans.

This versatility ensures that Welding Procedure Specifications are communicated effectively across different projects and industries.

7. Documentation

Welding symbols serve as a permanent record of welding specifications on technical drawings.

This documentation is essential for quality control, compliance with standards, and future reference.

8. Global Applicability

Since welding symbols adhere to international standards, they can be understood and interpreted by professionals worldwide. This is particularly advantageous for projects involving multinational teams or global supply chains.

Weld Symbols Dimensions

Weld Symbols Dimensions

Weld symbols are used to convey important information about weld joints and Welding Processes on Technical Drawings.

They include various elements that provide information about the Type of Welded Joints, their dimensions, and other relevant details.

Here are the key dimensions commonly found in weld symbols:

1. Length of Weld

This dimension indicates the length of the weld bead or the extent of the welded area.

A horizontal line joined to the symbol's reference line serves as the representation.

The length may be specified in inches, millimeters, or another unit of measurement.

2. Size of Weld (Optional)

If the weld size needs to be specified, it is indicated adjacent to the weld symbol.

This size can represent the width, depth, or diameter of the weld bead.

The size may be represented in inches, millimeters, or another appropriate unit.

3. Root Gap (Optional)

If applicable, the root gap dimension represents the distance between the edges of the joint at its root before welding.

This dimension is often critical for achieving proper penetration and fusion in the joint.

4. Groove Angle

For groove welds, the groove angle specifies the included angle between the two pieces being joined.

This angle helps define the shape of the joint and influences welding parameters.

5. Fillet Weld Size

In the case of Fillet Weld, the size of the weld is typically indicated as the leg length of the fillet triangle.

The legs are the two sides that meet at a right angle to form the fillet weld.

6. Pitch (Optional)

For multiple weld symbols in a row, the pitch dimension represents the center-to-center spacing between the weld symbols.

This ensures the accurate placement of welds along the joint.

7. Penetration Depth (Optional)

In cases where the depth of penetration into the base material is critical, this dimension may be specified. It indicates how deep the weld should penetrate into the joint.

8. Weld Symbol Reference Line

This line serves as the baseline for positioning the weld symbol.

All dimensions and other elements of the weld symbol are aligned with this reference line.

It's important to note that the exact appearance and positioning of these dimensions can vary based on the specific welding symbol, the Welding Processes, and the industry standards being followed (such as AWS or ISO standards).

When interpreting welding symbols, it's crucial to refer to the applicable standards to ensure accurate understanding and implementation.

Including these dimensions in welding, symbols ensures that welders have clear guidance on critical aspects of the Weld Joints, contributing to the successful execution of welding processes.


Welding symbols are crucial in metal fabrication and construction, serving as a silent language between designers, engineers, and welders.

Each symbol carries a unique message that guides the welding process and ensures structural integrity.

They also embody artistic representations of precision and craft, fusing into tangible reality.

The world of welding symbols is a fascinating intersection of technical acumen and artistic expression. Do check OnestopNDT for more information. 

To delve deeper into welder qualification certificates, refer to the article "Welder Qualification Certificates: The Ultimate Guide" for comprehensive information.

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Application Notes