155+ Welding Blueprint Symbols: Complete Chart, Guide, and Examples

Welding blueprint symbols are a standardized visual language used on engineering drawings, fabrication plans, and technical blueprints to tell welders what to weld, where to weld it, how large the weld should be, how long it should run, and what additional requirements apply.

For a beginner, a welding drawing can initially look like a collection of confusing lines, triangles, numbers, arrows, and circles. Once you understand the reference line, arrow, basic weld symbols, dimensions, and supplementary symbols, however, the drawing becomes much easier to read.

This guide explains the most common welding blueprint symbols, how to interpret their placement, how weld dimensions work, and how to read complete welding callouts. It also explains the difference between a weld symbol and a complete welding symbol, common blueprint abbreviations, and mistakes that can lead to incorrect fabrication.

Important: Welding-symbol conventions can depend on the standard specified by the drawing. In the United States, AWS A2.4 is a major reference for welding, brazing, and nondestructive examination symbols. Always follow the standard and requirements identified on the actual project drawing.

What Are Welding Blueprint Symbols?

Welding blueprint symbols are graphical instructions placed on a technical drawing to communicate welding requirements without writing a lengthy description beside every joint.

A complete welding symbol can communicate:

• The type of weld required
• Which side of the joint receives the weld
• Weld size
• Weld length
• Intermittent weld spacing
• Groove dimensions
• Weld contour
• Weld finishing method
• Whether welding is required all around
• Whether welding is performed in the field
• A welding process or specification

The key is to read the entire welding symbol, not just the small shape representing the weld.

Weld Symbol vs. Welding Symbol

These terms are related but not identical.

A weld symbol identifies the type of weld, such as a fillet weld or V-groove weld.

A welding symbol is the complete notation. It can contain the reference line, arrow, weld symbol, dimensions, supplementary symbols, and tail information.

Understanding this distinction makes technical drawings easier to interpret.

Basic Parts of a Welding Symbol

Before memorizing individual weld symbols, learn the components that make up a welding callout.

Reference Line

The reference line is the main horizontal line in a welding symbol.

It provides the foundation for the other information. The basic weld symbol is placed in relation to this line, and its position can communicate which side of the joint is involved.

Arrow

The arrow connects the reference line to the joint or location on the drawing where the welding requirement applies.

The arrow is particularly important when the drawing distinguishes between the arrow side and the other side of the joint.

Tail

The tail is the optional forked section at the opposite end of the reference line from the arrow.

It can contain information such as:

• Welding process
• Welding procedure
• Specification
• Other instructions

When no additional information is needed, the tail may be omitted.

Basic Weld Symbol

The basic weld symbol identifies the type of weld.

Examples include:

• Fillet weld
• Square groove weld
• V-groove weld
• Bevel groove weld
• U-groove weld
• J-groove weld
• Plug weld
• Slot weld
• Spot weld
• Seam weld
• Stud weld

Dimensions

Numbers associated with the welding symbol communicate requirements such as weld size, length, spacing, groove dimensions, or depth.

The position of the number matters. Do not assume that every number near a weld symbol means weld size.

Welding Blueprint Symbols Chart

Use the following as a quick-reference guide to the most common weld symbols.

The table is a study aid. When fabricating an actual part, use the exact graphical symbol and requirements shown on the applicable drawing and governing standard.

Common Welding Blueprint Symbols Explained

Fillet Weld Symbol

The fillet weld symbol is represented by a triangular shape.

Fillet welds are extremely common in fabrication because they can join members that meet at an angle. Typical applications include:

• T-joints
• Lap joints
• Corner joints

The symbol alone does not tell you everything about the weld. You may also need to determine its size, length, side, contour, finish, and whether it is continuous or intermittent.

Square Groove Weld Symbol

A square groove weld is used when the joint edges have a square or essentially unprepared configuration.

The drawing may provide additional information about:

• Root opening
• Weld size
• Joint dimensions
• Length

The symbol should always be interpreted together with the joint geometry shown in the drawing.

V-Groove Weld Symbol

The V-groove symbol resembles the letter V.

It indicates a joint prepared with a V-shaped groove.

V-groove joints are commonly used when a deeper weld is needed, particularly with thicker material.

A drawing can provide additional requirements such as:

• Groove angle
• Root opening
• Depth of preparation
• Weld size
• Length

Bevel Groove Weld Symbol

A bevel groove indicates that one member of the joint is prepared with a bevel.

The orientation of the symbol is important because it identifies the side or member associated with the bevel.

This is different from a V-groove, where both sides of the joint may be prepared to form the V.

U-Groove Weld Symbol

A U-groove uses a curved U-shaped preparation.

It can provide deep joint penetration while potentially reducing the amount of weld metal needed compared with some other groove preparations.

The drawing can specify the required groove dimensions and weld requirements.

J-Groove Weld Symbol

A J-groove has a joint preparation resembling the letter J.

It is another form of deep groove preparation and can be useful when the design calls for a specific joint geometry.

Flare-Groove Weld Symbols

Flare-groove welds are associated with joints involving curved or rounded surfaces.

Two common forms are:

• Flare-V groove
• Flare-bevel groove

These symbols can be encountered in applications involving rounded edges, pipes, tubes, or other curved components.

Plug Weld Symbol

A plug weld joins two members by filling a hole in one member with weld metal.

Plug welds can be used when components overlap and access to the joint is provided through an opening.

The drawing may specify the hole diameter, weld size, number, or other requirements.

Slot Weld Symbol

A slot weld is similar to a plug weld but uses an elongated opening rather than a simple round hole.

The drawing can provide the slot dimensions and other requirements.

Spot Weld Symbol

The spot weld symbol is associated with resistance spot welding.

Spot welding is widely used for sheet metal and manufacturing applications.

A drawing may specify the:

• Weld size
• Number of spots
• Spacing
• Location
• Other resistance-welding requirements

Seam Weld Symbol

A seam weld is associated with joining along a continuous or overlapping seam, particularly in resistance seam welding.

It is commonly encountered in manufacturing and sheet-metal applications.

Stud Weld Symbol

A stud weld identifies a requirement to attach a stud or similar component to a base material.

Stud welding can be used to attach threaded or unthreaded studs without creating a conventional joint between two large plates.

Arrow Side and Other Side Welding Symbols

One of the most important concepts in blueprint reading is determining which side of the joint is to be welded.

The relationship between the weld symbol and reference line communicates this information according to the applicable welding-symbol standard.

Symbol on the Arrow Side

When the weld symbol is positioned on the appropriate side of the reference line for the arrow side, the drawing indicates that the weld is associated with the side of the joint identified by the arrow.

The exact convention should be confirmed against the governing standard used by the drawing.

Symbol on the Other Side

When the symbol is placed on the opposite side of the reference line, it indicates the other side of the joint.

This distinction is critical. A welder should not assume that moving the symbol above or below the reference line has no significance.

Symbols on Both Sides

When weld symbols are shown on both sides of the reference line, the drawing can indicate that welding is required on both sides of the joint.

For example, a T-joint might require fillet welds on both sides of the vertical member.

Why This Matters

A correctly sized weld made on the wrong side is still an incorrectly fabricated joint.

When reading a welding blueprint, always check:

1. Which joint the arrow identifies
2. Where the weld symbol is positioned
3. Whether a symbol appears on one or both sides
4. Whether additional notes change the requirement

Understanding Welding Blueprint Dimensions

Weld dimensions tell you how much welding is required, not simply what type of weld to make.

Fillet Weld Size

For a fillet weld, a number placed in the appropriate position next to the symbol can specify the required weld size.

For example, a drawing may call for a 1/4-inch fillet weld.

The number must be interpreted according to its position and the drawing’s applicable standard.

Weld Length

A dimension can specify how long the weld must be.

This is especially important when the weld does not extend over the entire joint.

Intermittent Weld Length and Pitch

Intermittent welds consist of separate weld segments.

A drawing may specify both:

• Length of each weld segment
• Pitch, or center-to-center distance between segments

For example, a callout could specify a weld segment length followed by a pitch value.

The pitch is not simply the empty gap between welds. It is generally the center-to-center distance between adjacent weld segments under the applicable convention.

Number of Welds

Some drawings may specify the number of welds required in addition to their dimensions.

Do not assume that a dimension automatically tells you the number of weld segments. Check the complete symbol and drawing notes.

Continuous vs. Intermittent Welds

Continuous Welds

A continuous weld extends along the specified joint for the required length.

When a design requires welding along the complete applicable joint, the drawing and symbol will communicate that requirement.

Intermittent Welds

An intermittent weld is made using separate segments.

Intermittent welding can be useful when a continuous weld is unnecessary and the design permits separated welds.

The drawing may specify the segment length and pitch so that the welder knows exactly how the welds should be distributed.

Supplementary Welding Symbols

Supplementary symbols add information to the basic weld symbol.

Weld-All-Around Symbol

A small circle at the junction of the arrow and reference line is commonly used to indicate a weld-all-around requirement.

This means the joint is to be welded continuously around the applicable joint or feature as defined by the drawing.

It should not be confused with the circle used as a basic symbol for a spot weld.

Field Weld Symbol

A flag at the junction of the arrow and reference line indicates a field weld.

This means the weld is intended to be performed at the construction or installation location rather than in the fabrication shop.

Contour Symbols

A drawing may specify the required shape of the finished weld.

Common contour requirements include:

• Flush or flat
• Convex
• Concave

A contour requirement tells the fabricator what the finished weld profile should look like.

Finish Symbols

A drawing may also specify how the weld is to be finished.

Depending on the applicable standard and drawing, finishing requirements can involve methods such as:

• Grinding
• Machining
• Chipping
• Hammering
• Rolling
• Other specified methods

The required contour and the method used to obtain it are related but are not necessarily the same instruction.

Welding Blueprint Symbol Examples

The easiest way to learn welding symbols is to work through practical examples.

Example: A Basic Fillet Weld

Suppose a drawing specifies a fillet weld with a 1/4-inch size.

The reader needs to determine:

1. The triangular symbol identifies a fillet weld.
2. The 1/4 dimension specifies the required weld size.
3. The symbol’s position determines the applicable side.
4. Any length information determines how far the weld should extend.
5. Additional contour or finish symbols provide further requirements.

The actual graphical callout should be read as one complete instruction.

Example: Fillet Weld on Both Sides

If fillet weld symbols appear on both sides of the reference line, the drawing can require fillet welds on both sides of the joint.

A welder should not interpret this as one larger weld. It represents welding requirements on two sides.

Example: Intermittent Fillet Weld

An intermittent fillet-weld callout can specify both the length of each weld segment and its pitch.

For example, if a drawing specifies 2-inch welds on a 6-inch pitch, the 2 inches describes each weld segment while the 6 inches describes the center-to-center spacing between adjacent segments.

The exact notation and placement should be read according to the governing symbol standard.

Example: All-Around Weld

If an all-around circle appears at the junction of the arrow and reference line, the symbol indicates that the applicable joint is to be welded around its perimeter.

The welder should then inspect the drawing geometry to understand exactly what perimeter is included.

Example: Field Weld

A field-weld flag indicates that the specified weld is to be made at the installation or construction site.

This can be important for planning, sequencing, inspection, equipment, and access.

How to Read a Welding Blueprint Step by Step

You can use the following process whenever you encounter an unfamiliar welding callout.

Step 1: Find the Joint

Start by identifying the physical joint or feature the arrow points toward.

Look at the section, detail, or view if necessary.

Step 2: Find the Reference Line

Locate the horizontal reference line that forms the basis of the welding symbol.

Step 3: Identify the Basic Weld Symbol

Determine whether the symbol represents:

• Fillet
• Groove
• Plug
• Slot
• Spot
• Seam
• Stud
• Another weld type

Step 4: Determine the Side

Check the symbol’s position relative to the reference line.

Determine whether the requirement applies to the arrow side, other side, or both sides.

Step 5: Read the Dimensions

Look for numbers specifying:

• Weld size
• Length
• Pitch
• Groove dimensions
• Depth
• Other requirements

Step 6: Check Supplementary Symbols

Look for:

• All-around
• Field weld
• Contour
• Finish

Step 7: Read the Tail

If a tail is present, determine whether it contains a process, specification, procedure, or other instruction.

Step 8: Read the Notes

Check the general drawing notes and welding-specific notes.

These can contain requirements that are not repeated in every individual welding symbol.

Step 9: Check the Applicable Standard

If anything appears ambiguous, consult the welding-symbol standard referenced by the drawing rather than guessing.

Welding Blueprint Abbreviations You May Encounter

Symbols are only part of a welding drawing. Abbreviations can also communicate important requirements.

CJP

CJP generally means Complete Joint Penetration.

It indicates that the joint is designed to achieve complete penetration through the joint thickness as specified by the applicable requirements.

PJP

PJP generally means Partial Joint Penetration.

It indicates a groove weld designed for penetration that does not extend completely through the joint.

SMAW

SMAW stands for Shielded Metal Arc Welding, commonly called stick welding.

GMAW

GMAW stands for Gas Metal Arc Welding, commonly known as MIG welding when used with the appropriate process and terminology.

GTAW

GTAW stands for Gas Tungsten Arc Welding, commonly known as TIG welding.

FCAW

FCAW stands for Flux-Cored Arc Welding.

SAW

SAW stands for Submerged Arc Welding.

NDT and NDE

NDT means Nondestructive Testing, while NDE means Nondestructive Examination.

These terms can appear when the drawing specifies inspection requirements in addition to welding requirements.

How Welding Symbols Work With the Rest of a Blueprint

A welding symbol should never be viewed independently from the rest of the drawing.

A complete fabrication drawing can also contain:

• Overall dimensions
• Detail dimensions
• Section views
• Material specifications
• Tolerances
• General notes
• Welding notes
• Inspection requirements
• Revision information
• Surface-finish requirements
• Parts lists

Section Views

Section views are particularly useful when the joint configuration is difficult to understand from an exterior view.

A section can show:

• Groove preparation
• Root opening
• Material thickness
• Weld profile
• Joint configuration

Detail Views

A detail view enlarges a specific area of the drawing.

It can clarify a welding joint that is too small or complicated to understand in the main view.

Drawing Notes

General and welding notes can modify or supplement individual symbols.

Always check them before beginning fabrication.

Common Welding Blueprint Reading Mistakes

Ignoring the Reference Line

The reference line is the foundation of the welding symbol. Ignoring it can cause incorrect interpretation of the weld location.

Confusing a Weld Symbol With the Entire Welding Symbol

The triangle or V shape is only part of the information.

The dimensions, placement, supplementary symbols, and notes can be equally important.

Assuming Every Number Means Weld Size

Numbers can describe size, length, pitch, depth, angle, or another requirement.

Always consider where the number is placed.

Confusing Pitch With Gap

Pitch is generally measured from the center of one intermittent weld segment to the center of the next, not simply from the end of one segment to the beginning of the next.

Ignoring Arrow-Side Information

A weld can be correctly sized but placed on the wrong side of a joint.

Always determine which side the symbol applies to.

Forgetting the All-Around Symbol

A small circle at the reference-line/arrow junction can significantly change the welding requirement.

Ignoring the Field-Weld Flag

The field-weld symbol indicates where the welding is intended to occur. This can affect fabrication planning and installation.

Looking Only at the Welding Symbol

A welding symbol does not replace the rest of the engineering drawing.

Material, dimensions, tolerances, joint geometry, notes, and inspection requirements all matter.

Tips for Learning Welding Blueprint Symbols

If you’re new to blueprint reading, don’t try to memorize every symbol at once.

Start with the most common:

1. Fillet weld
2. Square groove
3. V-groove
4. Bevel groove
5. Plug weld
6. Slot weld
7. Spot weld
8. Seam weld
9. All-around
10. Field weld

Then practice reading dimensions and determining arrow-side versus other-side requirements.

Build a Personal Welding Symbol Cheat Sheet

A useful study sheet should contain:

• Symbol image
• Weld name
• Meaning
• Typical application
• Dimension location
• Arrow-side/other-side explanation
• Supplementary symbols

A visual reference is particularly helpful because welding symbols are graphical information.

Practice With Complete Drawings

Once you know the basic symbols, practice on actual fabrication drawings.

For each callout, ask:

What is the weld? Where is it? How big is it? How long is it? Is it intermittent? Is there a contour or finish requirement? Is there a process or specification in the tail?

This approach turns symbol recognition into a repeatable blueprint-reading process.

Frequently Asked Questions

What are welding blueprint symbols?

Welding blueprint symbols are standardized graphical instructions used on engineering and fabrication drawings to communicate weld type, location, size, length, spacing, contour, finish, and other requirements.

What is the most common welding symbol?

The fillet weld symbol, represented by a triangle, is one of the most frequently encountered welding symbols because fillet welds are widely used in T-joints, lap joints, and other common connections.

What does a triangle mean on a welding blueprint?

A triangular symbol generally represents a fillet weld. The symbol’s position and accompanying dimensions provide additional information about where and how the weld should be made.

What does a V mean on a welding blueprint?

A V-shaped weld symbol represents a V-groove weld. The drawing may provide additional information about groove angle, root opening, depth of preparation, weld size, and length.

How do I know which side of the joint to weld?

The location of the weld symbol in relation to the reference line, together with the arrow and the applicable welding-symbol standard, indicates whether the weld applies to the arrow side, other side, or both sides.

What does a circle mean on a welding symbol?

A circle at the junction of the arrow and reference line commonly means weld all around. A circle used as the basic weld symbol can represent a spot weld, so the context and location of the circle are important.

What does a flag mean on a welding blueprint?

A flag at the junction of the arrow and reference line indicates a field weld, meaning the weld is intended to be made at the installation or construction site.

What does the number before a welding symbol mean?

The meaning depends on the type of weld and the number’s position. For a fillet weld, a number in the appropriate location commonly specifies weld size. Other numbers can specify length, pitch, depth, or other dimensions.

How do you read an intermittent weld symbol?

Look for the specified length of each weld segment and the pitch or center-to-center spacing between segments. Also determine which side of the joint the intermittent weld applies to.

What is the difference between a fillet weld and a groove weld?

A fillet weld joins surfaces that meet at an angle, while a groove weld fills a groove prepared between members. Their symbols and dimensional requirements are different.

What does CJP mean on a welding drawing?

CJP generally means Complete Joint Penetration. It describes a joint designed to achieve complete penetration through the joint thickness according to the applicable requirements.

What does PJP mean on a welding drawing?

PJP generally means Partial Joint Penetration. It describes a groove weld designed to achieve specified penetration without complete penetration through the joint.

What standard is used for welding symbols?

In the United States, AWS A2.4 is a major standard for welding, brazing, and nondestructive examination symbols. Other standards can apply depending on the country, industry, project, or drawing requirements.

Why are welding blueprint symbols important?

They allow designers, engineers, welders, fabricators, and inspectors to communicate welding requirements in a standardized visual format. Correct interpretation helps ensure that the fabricated joint matches the design.

Can welding symbols tell you what welding process to use?

They can include process information, particularly through the tail or other drawing instructions. However, the complete drawing, welding procedure, specification, and applicable standard should be consulted rather than assuming the basic weld symbol identifies the process.

Conclusion

Welding blueprint symbols are a practical language used to communicate exactly how welded joints should be fabricated. The most important foundation is understanding the reference line, arrow, tail, basic weld symbol, dimensions, and supplementary symbols.

From there, welders and fabricators can learn the common symbols for fillet, square groove, V-groove, bevel, U-groove, J-groove, plug, slot, spot, seam, and stud welds. Understanding arrow-side and other-side notation, intermittent weld dimensions, weld-all-around symbols, field-weld flags, contours, and finishes adds another level of blueprint-reading ability.

The most effective way to learn is to combine a visual symbol chart with real drawing examples. Instead of memorizing symbols in isolation, practice asking four questions every time you see a welding callout: What type of weld is required? Where does it go? What are its dimensions? What additional requirements apply?

Finally, remember that the welding symbol is only one part of an engineering drawing. Always check the joint geometry, dimensions, material specifications, notes, welding procedures, inspection requirements, and governing standard before beginning fabrication.

Asher Monroe

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