Stitch Welding Symbol Explained: Meaning, Examples & How to Read It

Written by Dr. Sandeep Kumar

Think of stitch welding as “strategic joining.” It’s the art of placing strength exactly where it’s needed, rather than where it’s just convenient.

Why Choose the “Skip”?

🌡️ Distortion Control

Perfect for thin materials. By skipping sections, you drastically lower the heat input, preventing that dreaded “potato chip” warping.

💰 Efficiency

Save on filler metal, shielding gas, and labor time. If the code doesn’t require a 100% seal, stitch welding is your best friend.

🏗️ Temporary Fit-up

Essential for tacking large assemblies together before the final pass, ensuring everything stays square and true.

💧 Drainage & Air

Allows moisture to drain and air to escape in non-sealed industrial environments, preventing internal corrosion.

Deep Dive: Reading the Symbols

Decoding the “Length – Pitch” Formula

On a blueprint, you’ll see dimensions to the right of the weld symbol, such as 3 – 10.

Length (3): Each individual weld bead must be exactly 3 inches long.
Pitch (10): The distance from the center of one weld to the center of the next must be 10 inches.

To calculate the actual gap between weld ends, use: Gap = Pitch – Length

Continuous vs. Intermittent: The Comparison

Feature	Continuous	Stitch (Intermittent)
Heat Input	High	Low / Controlled
Joint Sealing	Hermetic (Air/Water)	Non-Sealing
Fabrication Cost	Higher	Lower
Visual Inspectability	Direct	Requires Gap Checks

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Welding Pro Tip: Never confuse the Pitch with the Gap. Pitch is always a center-to-center measurement. If you measure the clear space between welds, your layout will be out of spec!

Types of Stitch Welding Symbols

Primary Configurations

Stitch welding symbols vary significantly depending on the joint geometry. In modern fabrication, Stitch Fillet Welds are the most prevalent and are categorized into two critical types:

🔗 Chain Intermittent

Weld segments are perfectly aligned on both sides of the joint, creating a mirrored pattern.

🔀 Staggered Intermittent

Weld segments are offset on opposite sides, creating a zig-zag pattern for different heat distribution.

Figure: Dimensional representation of intermittent welds on blueprints as per AWS standards.

            Code Requirement: When intermittent welds are required in the length of a joint, they should be dimensioned by the welding symbol in a manner as shown in the above figure.
        

Master Symbol Reference Table

S.No	Symbol Type	Welding Symbol Detail	Description / Application
1	Intermittent Fillet Weld (Chain)	Fillet weld with length & pitch on same side	Weld segments are aligned on both sides directly opposite each other.
2	Intermittent Fillet Weld (Staggered)	Fillet weld with staggered indication	Weld segments are offset on opposite sides (zig-zag pattern).
3	Intermittent Single Side Weld	Fillet weld on one side only with pitch	Used when welding is required on only one side at specific intervals.
4	Chain Intermittent Weld (Double Side)	Fillet weld both sides aligned	Equal weld segments on both sides in a single straight line.
5	Staggered Intermittent Weld (Double Side)	Fillet weld both sides staggered	Welds on opposite sides are not aligned, alternating across the joint.
6	Spot Stitch Weld	Series of spot weld symbols with pitch	Used in resistance welding to indicate specifically spaced weld nuggets.
7	Seam Stitch Weld	Intermittent seam weld symbol	A continuous weld path broken into discrete segments along a seam.
8	Back Stitch Weld	Weld segments on reverse side	Used for reinforcement or controlled heat input on the back of the joint.
9	Intermittent Groove Weld	Groove weld with length & pitch	Applied where a full-depth groove weld is not required continuously.
10	Intermittent Plug/Slot Weld	Plug/slot weld with spacing	Used for joining overlapping plates at intervals through predefined holes/slots.

🛠️ Take This Reference to the Shop

Download our high-resolution Stitch Welding Symbols Chart or print it directly for your field handbook.

📄 Download PDF

Source: learnweldingsymbols.com | Professional NDT & Welding Training

Intermittent Fillet Welds Symbols

Intermittent fillet welds are applied in segments rather than as a continuous weld. They are commonly categorized into three types, with the basic form serving as the foundation for the others:

Basic intermittent fillet welds – used on a single line of weld (see Example 18)
Staggered intermittent fillet welds – weld segments are offset on opposite sides (see Example 19)

Chain intermittent fillet welds – weld segments are aligned directly opposite each other (see Example 20)

Staggered intermittent fillet welds consist of two parallel lines of intermittent fillet welds placed along a joint. The weld segments in one line are positioned so that they fall between (not directly across from) the weld segments in the opposite line.

Chain intermittent fillet welds, by contrast, also use two parallel lines of intermittent welds, but in this case each weld segment in one line is located directly opposite a weld segment in the other line.

This image illustrates how to read intermittent fillet weld symbols, which are used in engineering drawings to specify welds that are not continuous. These symbols follow the AWS A2.4 standard.

The image is divided into two primary sections: Chain Intermittent and Staggered Intermittent welding.

1. Common Components of the Symbols

In both examples, the numbers located around the triangle (the fillet weld symbol) represent specific dimensions:

Size (Leg Length): The fraction to the left of the triangle (e.g., 5/16 or 1/2). This indicates the required leg length of the fillet weld.
Length (L): The first number to the right of the triangle (e.g., 2 or 3). This is the actual length of each individual weld segment.
Pitch (P): The second number to the right of the triangle (e.g., 6 or 8). This represents the center-to-center distance between the weld segments.

2. Chain Intermittent Fillet Welding (Top)

In a Chain configuration, the fillet weld triangles are placed directly opposite each other on both sides of the reference line.

Visual Layout: The weld segments on the “arrow side” and the “other side” align perfectly.
Example interpretation (5/16, 2-6): In 1st Symbol below, You would place a 5/16″ fillet weld segment that is 2″ long, spaced every 6″ (center-to-center), mirrored exactly on both sides of the joint.

3. Staggered Intermittent Fillet Welding (Bottom)

In a Staggered configuration, the fillet weld triangles are offset from each other on the reference line.

Visual Layout: The weld segments on one side are placed in the gaps (intervals) of the segments on the opposite side. This creates a “zigzag” pattern of support, which can help reduce distortion in thin materials.
Example interpretation (1/2, 3-8): In the 2nd figure above, in a Staggered Intermittent Fillet welding symbol, You would place 1/2″ fillet welds that are 3″ long with an 8″ pitch. Because the symbols are offset, the start of the weld on the “other side” begins halfway between the welds on the “arrow side.”

The sketches associated with these types help illustrate the core concept and the rules for their application. In practice, it is generally recommended to keep both the length of each weld segment and the fillet size consistent on both sides of the joint. This approach simplifies fabrication, improves uniformity, and reduces the likelihood of errors during welding.

Understanding the Stitch Welding Symbol

The stitch welding symbol is a graphical representation used on engineering drawings to specify the stitch weld pattern required for a particular joint. It consists of several elements that convey essential information to the welder.

Let’s break down the components of the stitch welding symbol:

Arrow: The stitch welding symbol begins with an arrow, which points to the location where the stitch welds are to be applied. The arrow’s tail is connected to the reference line, indicating the joint to be welded.
Stitch Length: A number is placed above the reference line, indicating the desired stitch length in millimeters or inches. This value represents the distance between each individual weld in the stitch pattern.
Stitch Spacing (Pitch): Another number is placed below the reference line, indicating the desired stitch spacing. This value represents the distance between the centers of adjacent stitch welds.

Stitch Welding Symbol: The stitch welding symbol refers to the type of weld such as Fillet weld or groove weld. A basic weld symbol representing the weld type is placed on the reference line.

A fundamental rule in intermittent welding is ensuring structural integrity by locating welds at both ends of the joint. The following examples demonstrate how specific symbol notations translate to physical weld patterns on the shop floor.

Example A

Standard Intermittent Welding

Example A illustrates a single-sided fillet weld using the 2-4 notation.

Weld Length (2): Each individual segment is exactly 2 units long.

Pitch (4): The center-to-center distance between these 2-unit segments is 4 units[.

Calculation: 4 (Pitch) – 2 (Length) = 2 units of Gap.

Example B

Chain Intermittent Welding

Example B demonstrates a double-sided joint where the welds are perfectly aligned or “mirrored” on both sides of the plate.

Symbol (2-5): The segments are 2 units long with a 5-unit pitch on both sides.

Application: Chain welding is preferred when high joint stiffness is required across the entire length.

Example C

Staggered Intermittent Welding

Example C showcases a staggered pattern where the fillet weld triangles are offset on the reference line, indicating a “zig-zag” layout.

Offset Pattern: Welds on one side are centered on the empty spaces of the opposite side.

Dimensions (3-10): Each segment is 3 units long with a 10-unit pitch.

Pro Tip: In staggered joints, the Pitch (10) is always measured between welds on the SAME side.

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Expert Layout Advice: Always perform your layout from the center marks of each weld increment. If you measure strictly by the gaps, you risk accumulating errors that can exceed AWS D1.1 structural tolerances. For these intermittent joints, Gap = Pitch – Length.

How to Read Stitch Weld Length & Pitch on a Welding Symbol?

On a welding blueprint, stitch (intermittent) dimensions always appear to the right of the symbol. Understanding the relationship between these two numbers is critical for proper joint layout.

Reference: Dimensional layout of intermittent welds on the reference line.

📏 The Length (L)

The first number represents the actual linear length of each weld segment. If the symbol shows 2 – 5, each individual bead must be exactly 2 units long.

🎯 The Pitch (P)

The second number (5 in above example) represents the center-to-center distance between segments. It determines the frequency and distribution of the welds across the joint.

🧠 The “Gap” Calculation

While the blueprint doesn’t explicitly state the size of the “skip” or empty space, you can easily calculate it for your layout:

Gap = Pitch – Length

Example: In a 2-5 weld, your actual gap is 3 units (5 – 2 = 3). Unit can be either mm or inches or cm,anything

⚠️

Common Layout Error: Never measure the pitch as the “empty space” (gap) between welds. Measuring 10 inches of gap instead of 10 inches center-to-center will result in an under-welded joint that will fail inspection.

In technical drawing and fabrication, “Stitch Welding” is governed by three primary graphical standards. These documents ensure that the design engineer’s intent for intermittent joints is communicated flawlessly to the shop floor.

🇺🇸 AWS A2.4

Standard Symbols North America

The definitive American standard for welding, brazing, and NDT symbols. It mandates the placement of length and pitch dimensions to the right of the weld symbol.

Key Requirement

Specifically defines the “Length – Pitch” notation and provides the geometric rules for chain and staggered intermittent fillet welds.

🌐 ISO 2553

International Dual Systems

The global standard for symbolic representation of welded joints. ISO 2553 uses two systems (A and B) to accommodate different global traditions in dimensioning.

Key Requirement

Introduces brackets (e) for number of elements and utilizes specific line types (dashed vs. solid reference lines) to indicate weld sides.

🇦🇺 AS 1101.3

Australian Standard NDE Included

The Australian standard for graphical symbols in general engineering. It aligns closely with ISO principles while addressing specific regional fabrication practices.

Key Requirement

Governs the representation of intermittent welds and non-destructive examination (NDE) symbols for the Australian engineering and construction sectors.

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Technical Oversight: While these standards are largely harmonized, minor differences in symbol placement (such as the reference line orientation) can exist between AWS A2.4 and ISO 2553. Always verify the Standard of Reference noted in the drawing title block to ensure your layout calculation of $Gap = Pitch – Length$ remains in full compliance.

Conclusion

The stitch welding symbol is a valuable tool for welders, enabling them to accurately interpret and execute stitch welds as per design requirements. By understanding the components of the symbol and their significance, welders can ensure the integrity and quality of the welded joints.

Remember, proper interpretation of welding symbols is crucial for achieving the desired results and maintaining safety standards. So, the next time you come across a stitch welding symbol on an engineering drawing, you’ll be well-equipped to tackle the task at hand.

Stitch Welding: Technical FAQ

What is the stitch welding symbol?

A stitch welding symbol is identical to an intermittent weld symbol. It consists of a standard weld symbol (most commonly a Fillet weld) with two numerical dimensions placed to the right of the symbol on the reference line. These numbers represent the Length and the Pitch of the weld segments.

How do you read stitch length and pitch?

On the welding symbol, these are written as L - P.

Length (L): The first number, representing the actual linear length of each individual weld segment.
Pitch (P): The second number, representing the center-to-center distance between adjacent weld segments.

Example: A symbol reading 2 - 5 indicates 2-inch long welds spaced 5 inches apart from center to center.

What is the difference between stitch welding and intermittent welding?

In formal engineering terms (AWS/ISO), there is no difference. “Stitch welding” is the common industrial or “shop floor” term, while “intermittent welding” is the formal term used in technical standards. Both refer to a series of welds that are not continuous across the entire joint.

What is the AWS standard for stitch welding?

The primary standard is AWS A2.4: Standard Symbols for Welding, Brazing, and Nondestructive Examination. This code provides the specific rules for how dimensions must be placed on the reference line to ensure clear communication between the design engineer and the fabricator.

When should stitch welding be used?

Stitch welding is strategically used in several scenarios:

Distortion Control: To limit total heat input and prevent warping in thin materials.
Weight & Material Savings: When the structural load does not require a 100% continuous weld.
Cost Efficiency: To reduce filler metal consumption and labor time.

Ventilation/Drainage: In non-sealed joints where moisture drainage or air expansion is necessary.

About Me

Dr. Sandeep Kumar

Dr. Kumar is a PhD-qualified Welding and Materials Expert with a career spanning 18+ years across metallurgy and NDT. A triple-threat in the industry, he is an IWE, AWS-CWI, and ASNT NDT Level III certified professional. Dr. Kumar is the author of several leading technical resources and is a premier specialist in welding symbol instruction, dedicated to improving global standards in welding engineering and inspection.