Welding symbols chart
Searchable reference for the AWS A2.4 basic weld symbols, each drawn where it sits on the reference line. Filter by category, search by name or keyword, and see arrow-side vs other-side meanings at a glance. Groove, fillet, plug, slot, spot, seam, stud, surfacing, edge, scarf, and the supplementary symbols in one place.
Updated September 2026
Quick answer
The fillet weld symbol is a right triangle on the reference line. Below the line means arrow side. Above means other side. It is the most common weld symbol in fabrication.
How to read a welding symbol
Every welding symbol starts with a reference line and an arrow that points to the joint. The weld type goes on the reference line as a shape (triangle for fillet, V for groove, etc.). Dimensions sit next to the shape: size, length, and pitch. Supplementary symbols add instructions like field weld (flag), weld-all-around (circle), or contour. A letter like G or M after the contour tells the fabricator the finish method. The tail at the opposite end calls out the welding process or WPS number.
Three rules cover 90% of reading: symbols below the reference line apply to the arrow side of the joint, symbols above apply to the other side of the joint, and a broken arrow points to the member that gets the bevel or preparation.
Simplified diagram. The fillet triangle below the reference line means “fillet weld on the arrow side.” The tail is omitted when no process or specification is called out.
Dimension callout positions
Where you place a number on the symbol changes what it means. The rules are different for fillets and grooves.
Fillet welds
- Left of symbol = leg size (e.g. 1/4)
- Right of symbol = weld length
- Hyphenated number after length = pitch (center-to-center spacing for intermittent welds)
Groove welds
- Left of symbol, plain number = depth of groove preparation
- Left of symbol, in parentheses = groove weld size (effective throat)
- Inside the symbol = root opening
- Just outside the root opening, away from the reference line = groove angle
CJP vs PJP
A CJP (complete joint penetration) groove shows no depth of preparation and no weld size, so full penetration is required. Many drawings also write CJP in the tail. A PJP (partial joint penetration) groove shows the depth of preparation to the left of the symbol, and the groove weld size in parentheses next to it, for example 1/2 (3/8).
Finish method codes
A letter placed above the contour symbol tells the fabricator how to achieve the required surface profile. The letter specifies the method, not the degree of finish.
Questions welders keep asking
How do you read a welding symbol?
Start at the reference line. The arrow points to the joint. Symbols below the reference line apply to the arrow side of the joint, the side the arrow points to. Symbols above the reference line apply to the other side of the joint. Read dimensions left to right: size, length, pitch. Check the tail for process or specification callouts. A flag at the junction means field weld. A circle means weld all around.
What does the flag mean on a welding symbol?
The flag (a solid filled pennant at the arrow-reference line junction) means field weld. The weld must be made on-site during erection, not in the shop. You will see this on structural steel prints for connections that cannot be completed until the members are in position.
What is the difference between arrow side and other side?
The arrow side of the joint is the side the arrow points to. The other side of the joint is the opposite side of that same joint. On a welding symbol, anything below the reference line applies to the arrow side, and anything above it applies to the other side. A fillet triangle both below and above the line means fillet welds on both sides. A few symbols are arrow side only (stud and surfacing), and resistance spot and seam welds sit centered on the line because they have no side.
What is the difference between CJP and PJP?
CJP (complete joint penetration) means the weld goes through the full thickness of the joint. On a groove symbol with no depth of preparation and no weld size shown, CJP is what you build, and many drawings also write CJP in the tail. PJP (partial joint penetration) only goes part way through. It shows the depth of groove preparation to the left of the symbol, and the groove weld size (effective throat) next to it in parentheses: 1/2 (3/8) means a 1/2 inch deep prep with a 3/8 inch groove weld size. CJP usually costs more because it needs backing or back-gouging and more filler. What inspection it gets, like UT or RT, is set by the code and the job spec, not by the symbol. PJP is cheaper when the design loads allow it.
What goes in the tail of a welding symbol?
The tail contains the welding process designation (like GMAW, SMAW, GTAW), the WPS number, or a specification reference. If no process or specification is needed, the tail is omitted entirely. You might also see NDE requirements, joint class references, or notes pointing to a detail on the drawing.
What does the circle at the arrow junction mean?
The open circle at the junction of the arrow and reference line is the weld-all-around symbol. It means the weld continues around the entire perimeter of the joint. You see this on pipe-to-plate connections, tube-to-tube intersections, and any joint where the weld wraps 360 degrees. Do not confuse it with the field weld flag, which is a filled pennant, not an open circle.
What do the finish method letters mean on a weld symbol?
A letter above the contour symbol tells the fabricator how to achieve the required surface finish. G = grind, M = machine, C = chip, H = hammer, P = planish, R = roll, U = unspecified (the fabricator picks the method). The letter specifies the method, not the degree of finish. If the engineer only cares about the final profile and not how you get there, they use U.
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