Weld Sizing 👨‍🏭 (Welding Symbols) 2022

Weld dimensions are represented by numbers placed next to the symbol. Sometimes they may be withing the welding symbol.

They indicate:

  • Height of an angle weld.
  • Depth or angle of the bevel to be made.
  • Root opening (Gap).
  • Effective weld penetration.
  • Length or spacing of the weld bead.

We will see below some practical examples of dimensioning.

Angle joints (Tee joints) - angle weld

a) Root penetration will be indicated in parentheses.

(1): Desired weld

(2): Symbols

b) The weld dimensions are indicated to the left of the angle weld (Filled weld) symbol.

c) In the case of uneven angle welds length, the values ​​will be indicated.

Angle joints - groove welding


  • Note that the bevel preparation depth is to the left of the joint penetration. No parentheses.
  • In bevel welds, joint penetration and weld size are identical.
  • The root opening (Root gap) must be represented within the weld symbol.

Welding symbol with root opening

Butt joints

(1): Desired weld

(2): Symbols


  • The weld dimension is indicated in the parentheses to the left of the weld symbol.
  • Bevel preparation depth is indicated to the left of the weld dimension, outside parentheses.
  • Groove joints: When there is no indication as to the size of the weld and the depth of preparation of the bevel, it means that the weld must be performed with full penetration.
  • If root opening is required, this must be indicated within the symbol ("2" and "3" in the picture below).

Corner joints - discontinuous corner welding

Angle joint in "L" and "T". Angle welding combined with groove welding

Plug welds

The location and all dimensions except the fill depth are indicated on the drawing. The fill depth is not represented in the weld symbol.

In a circular hole (plug weld), the diameter of each hole is given on the left side of the symbol while the distance between the holes is on the right side.

In slot welds ("Elongated holes"), the width of each hole is given on the left side of the symbol.

The length and distance between holes is given on the right side of the symbol (Separated by a dash). 

Note that the tail must quote a detail drawing as shown above.

The number of round or elongated holes must be indicated in parentheses above or below the welding symbol.

From the position in relation to the reference line (below or above the line) and the arrow indication, we can know which part contains the holes.

The filling depth must be indicated within the welding symbol and its omission indicates that the filling is complete.

Groove welding (In a convex surface)

Commonly used to join circular or curved parts. The depth is indicated on the left side of the symbol.

The joint depth is indicated outside the parentheses. The weld depth is indicated inside parentheses. 

The symbols below are much less used in the oil and gas industry. So I will give less emphasis and will only serve as an example of application of the symbol.

Edge weld

Spot or projection welding

Seam Welding


Learn Welding

Would you like to learn about welding? Check my Quick Welding Course.


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Hi, I'm Gelson Luz.

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Materials: Weld Sizing 👨‍🏭 (Welding Symbols) 2022
Weld Sizing 👨‍🏭 (Welding Symbols) 2022
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