Welding Reference Library · Wall Charts

Welding Symbols Chart

The parts of an AWS A2.4 welding symbol, the basic weld symbols and where dimensions go, so staff and customers can read a drawing callout.

Ref WG-0208AWS A2.4

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

AWS A2.4 sets the symbols used on drawings to tell the welder what weld to make, where, and how big. A welding symbol is built on a horizontal reference line with an arrow pointing to the joint. The weld symbol (the shape of the weld) sits on the line, and sizes, lengths and notes are placed around it in set positions.

How to read it

Arrow: points to the joint. The side it touches is the "arrow side".
Reference line: weld symbol below the line = arrow side. Above the line = other side. On both sides = both sides.
Tail: optional. Holds the process, specification or WPS reference.
Size goes to the left of the weld symbol. Length and pitch go to the right (for example 2-6 means 2 in welds on 6 in centers).
Groove depth and weld size for groove welds go to the left, with the weld size in parentheses.
For bevel and J grooves, a broken arrow points to the member to be prepared.

Basic weld symbols

Weld	Symbol shape
Fillet	Right triangle, vertical leg always on the left
Square groove	Two parallel vertical lines
V-groove	V shape
Bevel groove	Single slanted line with a vertical leg on the left
U-groove	U shape
J-groove	Vertical leg with a curve
Flare-V	Two curves back to back
Flare-bevel	Vertical line and one curve
Plug or slot	Rectangle
Spot or projection	Circle
Seam	Circle with two horizontal lines through it
Back or backing	Small half circle on the opposite side
Surfacing	Two small connected half circles
Edge	Two vertical lines joined by a curve

Supplementary symbols

Symbol	Meaning
Circle at the arrow-to-line junction	Weld all around
Flag at the junction	Field weld (made at the site)
Filled half circle opposite the weld	Melt-through
Line or curve over the weld symbol	Contour: flush, convex or concave
Letter by the contour	Finish method (for example G grind, M machine)

Key points

Arrow side versus other side is the most misread part of a symbol.
Fillet and bevel legs are always drawn vertical on the left, whichever way the joint faces.
Untoleranced sizes and lengths follow the drawing's general notes.

Common mistakes

Welding the wrong side because the symbol was above the line.
Missing the weld-all-around circle.
Reading pitch as weld length.

Governing standards: AWS A2.4; AWS A3.0 (terms).

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

More in Wall Charts

← All Welding sheets