Weld symbol chart shows you exactly how to interpret welding blueprints for size, type, and location of welds.
It’s a simple visual tool that tells welders and engineers what weld to apply where and how — using arrows, triangles, numbers, and lines. With a clear weld symbol chart in front of you, you can decode fillet, groove, spot, plug, seam, and all‑around welds quickly.
You’ll know which side to weld (arrow-side versus other-side) and any special flags or finish instructions. Want to nail weld specs every time? Keep reading to master the weld symbol chart!
Weld Symbol Chart Defined & Why It Matters
A weld symbol chart helps you make sense of the symbols you see on welding blueprints. These symbols spell out details about how to make welds—where, what type, and how big.
If you know how to use this chart, your work matches the design and meets safety standards. That’s a big deal in welding.
What a Weld Symbol Chart Shows
A weld symbol chart gives you a quick look at different weld types and their details. It breaks down the basics, like:
- Reference line: The foundation for all welding info.
- Arrow: Shows where or which side to weld.
- Weld symbol: Tells you the weld type—fillet, groove, plug, you name it.
- Dimensions: Size and length of welds.
- Supplementary symbols: Extra stuff like finish or contour.
All these pieces come together to show you exactly how to join materials. You’ll see symbols for every common weld, so you don’t have to guess.
Want to master fillet welds? Our Fillet Weld Symbol Guide: Meaning & How to Read breaks down everything you need to know—check it out for clear explanations and practical tips.
Who Uses It and Why
If you’re in welding, fabrication, or engineering, this chart is kind of your cheat sheet. Welders use it to follow plans and get welds right.
Inspectors check welds against the chart to make sure everything’s up to snuff. Designers and engineers use it to lay out instructions clearly in blueprints.
When everyone’s on the same page, projects stay on track and you avoid expensive mistakes. The chart cuts down on guesswork and makes teamwork easier.
The AWS Welding Symbol Chart
Anatomy of a Weld Symbol Chart
A weld symbol chart breaks the info down into simple lines, shapes, and notes. It gives you clear directions for how each weld should go.
If you understand what each part of the symbol means, you’ll read blueprints with way less stress.
Arrow, Reference Line, Tail – What Each Part Means
The arrow points right at the spot where you need to weld. It connects to the main reference line, which is kind of like the backbone for the info.
The reference line carries the basic weld symbol—a triangle, square, whatever—and lays out the weld type. You’ll also see numbers there for size and length.
If there’s something extra you need to know, it goes in the tail at the end of the reference line. That’s where you’ll find details about the welding process or special instructions.
Symbol Placement – Arrow‑Side vs Other‑Side Welding
If you see the symbol below the reference line, that means weld on the arrow side—the side the arrow points to.
If it’s above the reference line, you’re welding on the other side. Sometimes you’ll see symbols on both sides, which means you weld both sides of the joint.
This system keeps things clear about where the weld goes, so you don’t have to second-guess.
Curious about bevel welds and their applications? Dive into our Bevel Weld Symbols and Types in Welding article for detailed insights and expert advice.
Notations for Size, Length & Spacing
Weld symbols use numbers and letters to spell out the size, length, and spacing you need. These details make sure your welds are strong and match the design.
If you know how to read these notations, you’ll follow welding blueprints the right way.
Interpreting Size, Pitch, Weld Length from Chart
The weld size usually means leg length for fillet welds or depth for groove welds. You’ll see this number next to the symbol, often on the left.
Weld length shows up on the right side of the symbol. If a fillet weld shows “3” on the right, you’re making a 3-inch weld.
Pitch or spacing tells you how far apart to put multiple welds if they aren’t continuous. It’s another number on the right, after the length.
So, a weld length of 2 inches with a pitch of 5 inches means you make 2-inch welds spaced 5 inches apart.
Supplementary Symbols: Contour, All‑Around, Finishing
Supplementary symbols give more detail about weld shape and finish. A contour symbol tells you if the weld should be flat, convex, or concave.
The “all-around” symbol—a circle around the reference line or arrow—means weld all the way around the joint.
Finishing symbols let you know how to clean up the weld. You’ll see letters for grinding, machining, or hammering, usually next to the tail of the symbol.
These symbols help you get welds that look right and meet the specs.
Comparison: AWS vs ISO Weld Symbol Charts
When you work with welding drawings, you’ll notice two main symbol systems: one used mostly in the U.S., another common in Europe and elsewhere. These systems handle weld details, sizes, and positions a bit differently, which can affect how you read and use the symbols.
ANSI/AWS A2.4 Chart Basics (U.S. Standard)
The AWS A2.4 chart uses a single solid reference line for welding symbols. If you need to weld on the arrow side, the symbol sits below the line.
For the other side, you’ll see it above—no dashed lines here. Fillet weld dimensions are in inches, shown by leg length, often called ‘z’.
AWS symbols skip the process number in the tail. You’ll mostly see this system in North America, parts of Asia, and the Gulf.
ISO 2553 International Symbols & Broken‑Line Use
ISO 2553 uses two lines: one solid, one dashed. The dashed line marks welds on the other side of the joint.
Your symbol’s spot on these lines tells you if you’re welding on the arrow side or not. Here, fillet weld sizes are given as throat thickness (‘a’) in millimeters, not leg length.
ISO symbols often include a weld process number in the tail—like “135” for Gas Metal Arc Welding—giving you extra info about the method. This standard pops up in Europe, Australia, and companies following ISO or EN 15085.
Take your welding knowledge to the next level with our Decoding Symbols in Welding: Professional Welders’ Guide. Discover how to read and apply symbols like a pro.
How to Use a Weld Symbol Chart on Drawings
Weld symbol charts give you visual cues for understanding welding requirements on technical drawings. They lay out the type, size, location, and finish of welds.
Using them helps you avoid mistakes and keeps each weld up to spec.
Reading Chart Info on Blueprints Accurately
When you look at a blueprint, start with the reference line and arrow line. These lines point you to the weld location.
The weld symbol attached to the reference line tells you the weld type—fillet, groove, whatever’s needed. Important numbers show weld size and length.
For a fillet weld symbol, the size goes left of the triangle, length to the right. Watch for supplementary symbols—they add details like weld contour (flush, convex, etc.).
The tail on the reference line might include notes about the welding process or electrode type. If you get these details right, you’ll read weld instructions without getting tripped up.
Shop vs Field Weld Marks (Flag, Circle Notation)
Weld symbols tell you where to make the weld. A field weld uses a small flag on the weld symbol’s reference line.
This flag means you’ll do the welding on site after assembling the parts. If there’s no flag, you’re working in the shop.
Sometimes, you’ll see an open circle where the arrow meets the reference line. That circle means the weld should go all the way around the joint.
Always check these marks closely. You need to know if you’re welding in the shop or out in the field, since each has its own quirks and might call for special gear.
Ready to perfect your technique? Learn about different weaving methods in our Welding Weave Patterns: Types of Weaving & When to Use Them article.
Quick Tips to Master Weld Symbol Charts
Weld symbol charts can look confusing at first. Focus on reading blueprints, using cheat-sheets, and comparing symbols to the standards.
These steps build your confidence and accuracy over time. Don’t stress if it takes a bit to click.
Practice Blue‑Print Interpretation Exercises
Work with real welding blueprints as much as you can. Check how symbols show the weld type, size, position, and any special instructions.
Try to spot the arrow, reference line, and tail in each symbol. See if the weld’s on the arrow side (below the line) or the other side (above the line).
Practice with different joint types, like fillet or groove welds. You’ll find sample blueprints online or in welding books.
Repeating these exercises helps you recognize common symbols on the job. Watch for numbers that show weld size, length, and spacing—they pop up more than you’d think.
Use Cheat‑Sheets, Glossaries, Contrast Standards
Keep a welding symbol cheat-sheet or glossary nearby. They sum up the most common symbols and what they mean, so you don’t waste time flipping through manuals.
Look for charts that show the symbol shapes, which side the weld goes on, and details like root opening or contour. Compare your symbols with AWS A2.4 or ANSI standards for accuracy.
If you can, use color-coded charts. They make it easier to spot differences in weld types at a glance. Over time, you’ll start reading symbols faster, almost without thinking.
Final Thoughts
Weld symbols can seem tricky, but with this cheat sheet, you’ve got a simple guide to help you read any welding plan fast. No more guessing or wasting time—just clear info that makes your job easier. Whether you’re just starting out or have years under your belt, this chart will save you stress and help you work smarter.
Ready to upgrade your gear? Check out our powerful welding machines, auto-darkening helmets, and must-have accessories to make every weld smoother, safer, and better.
Safety and maintenance are just as important as technique. Don’t miss our Must-Read for Welders: Welding Safety Procedures and Welding Machine Maintenance Guide for essential tips every welder should know.
Frequently Asked Questions
What are the 8 elements of the welding symbol?
The eight main elements you’ll find in a welding symbol:
- The reference line
- The arrow
- The weld symbol itself (like fillet or groove)
- The tail, for extra info
- The weld size
- The weld length
- The weld contour and finish
- Additional notes or specs, sometimes in the tail
All these parts work together to show exactly what weld you need and how to do it.
What is the current standard for welding symbols?
The American Welding Society (AWS) sets the main standard in the U.S. The AWS A2.4 standard covers the shapes, placement, and meaning of symbols on blueprints.
It helps welders and engineers stay on the same page, even across different projects.
How to read weld blueprints?
Start with the reference line—it’s where all weld info sits. The arrow points to the spot you’ll weld.
Look above or below the line to see the weld type. Check for size, length, and any special notes. If you spot a flag on the arrow, that means you’re welding in the field, not in the shop.
What is the ISO standard for welding symbols?
The ISO standard for welding symbols is ISO 2553. People use it worldwide, and it sets the rules for showing welds on drawings.
It’s pretty similar to the AWS system, but it follows international guidelines. If you’re working on global projects, you’ll want to know ISO 2553.
What is the code for welding?
Welding codes lay out rules for procedures, materials, and inspection. The American Welding Society's AWS D1.1 is probably the most recognized code for structural welding.
ASME handles pressure vessel codes, while API sets the standards for pipelines. These codes help keep welds safe and up to quality, so they're not something you want to ignore.