Read a weld symbol

Tap any part of the symbol to see what it says. The symbol follows ISO 2553 system A, used on European drawings.

Fillet weld symbol

Where the weld is

View

The triangle sits on the solid line, so the weld goes on the side the arrow touches.

Tap a part of the symbol to see what it means.

Symbol cheat sheet

Printable cheat sheet (A4)

Fillet
Square butt (I)
Single V butt
Single bevel butt (HV)
Single V with broad root face (Y)
Single bevel with broad root face (HY)
Single U butt
Single J butt
Spot
Seam
Plug or slot
Surfacing

Supplementary symbols

Flat (flush) surface
Convex surface
Concave surface
M: permanent backing strip
MR: backing removed after welding

Dimensions

a5: fillet throat thickness 5 mm, written left of the symbol.
z7: fillet leg length 7 mm. For a 90° equal-leg fillet z ≈ 1.41 × a, so a5 ≈ z7.
s8: butt weld penetration depth 8 mm. A butt weld without a dimension means full penetration.
300 right of the symbol: weld length 300 mm. No number means the full length of the joint.
3 × 100 (50): three segments of 100 mm. Most European training reads (50) as the gap between segments; some sources read it as centre-to-centre pitch, so check the drawing's legend.
Z across the reference line: the segments on the two sides are staggered.

Own drawing after ISO 2553:2019, system A. The drawing's own legend and the WPS take precedence. American drawings (AWS A2.4) read the side from above or below the line, not from solid or dashed line.

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