Weld Symbol Chart — AWS Standard Welding Symbols Reference

AWS A2.4 defines standardized welding symbols used on structural and mechanical drawings. This reference covers all common weld symbols: fillet, groove (V, bevel, U, J, square), plug/slot, seam, spot, and surfacing welds. Includes the reference line layout, arrow side vs. other side conventions, supplementary symbols, and reading practice examples.

The Welding Symbol — Basic Structure

All AWS welding symbols are built on a reference line with an arrow pointing to the joint location.

          Tail (specification/process/notes)
           ↑
-----------┤
Reference  │        ← Finish symbol (C, G, M, R, U)
Line       │        ← Contour symbol (flush, convex, concave)
-----------├────────┐
           │  Weld  │ ← Weld symbol (above OR below line)
           │ Symbol │
           ↓
         Arrow ────→ [Joint Location]

Key rule: Weld symbol BELOW the reference line = arrow side of joint. Weld symbol ABOVE the reference line = other side of joint.

Common Weld Type Symbols

Fillet Weld Symbol — Reading and Dimensions

The fillet weld triangle is placed below (arrow side) or above (other side) the reference line.

Weld size ─┐      ┌─ Length
           ↓      ↓
    3/8    ┐ 6    │
──────────┤├──────┤  ← Reference line
           │
           ↓
         Arrow → Joint

Size = 3/8 in weld, Length = 6 in on arrow side

Information positions on fillet weld symbol:

Groove Weld Symbols — Dimensions and Positions

For groove welds, dimensions appear on both sides of the symbol:

Groove angle ─┐   ┌─ Root opening
              ↓   ↓
          60°   1/8
─────────────────────  ← Reference line (symbol below = arrow side)
           \  /         ← V-groove symbol
            \/

V-groove example dimensions:

Complete joint penetration (CJP): No size shown — full material thickness is welded. Used where (E) designation not shown.

Partial joint penetration (PJP): Size in parentheses shown left of symbol: (3/4)V = 3/4 in deep bevel preparation.

Supplementary Weld Symbols

Prequalified Joint Details (AWS D1.1)

AWS D1.1 prequalified joint types do not require procedure qualification testing if all conditions are met:

Fillet Welds — Prequalified Conditions

• Single or double fillet on lap, T, or corner joints
• Minimum weld size per AWS Table 5.7 (= AISC Table J2.4)
• Base metal: prequalified per AWS Table 5.5

Complete Joint Penetration Groove Welds

• B-L1a, B-U1a: Square butt, thicknesses ≤ 5/16 in
• B-L2a, B-U2a: V-groove, 60° included angle, 1/8 in root face
• B-L3a, B-U3a: Bevel groove, 45° bevel angle
• B-U4a: U-groove (requires machining)

Partial Joint Penetration Groove Welds

• Effective throat calculation: te = depth of prep − 1/8 in (for bevel/J/V ≤ 45°); te = depth of prep (for groove ≥ 60°)

Reading Welding Symbols — Worked Examples

Example 1: Fillet Weld Both Sides

     5/16
  ────────────  ← Other side (above line)
  ────────────  ← Arrow side (below line)
     5/16

Reading: 5/16 in fillet weld on both sides of the joint (arrow and other side).

Example 2: V-Groove, Arrow Side Only, Ground Flush

  G
  ─
  \/  (V-groove below reference line)

Reading: V-groove weld, arrow side only, ground flush (G = grinding finish).

Example 3: Intermittent Fillet, Weld All Around

     3/8   2-6
  ─────────────   + circle at elbow

Reading: 3/8 in fillet weld, 2 in long, 6 in center-to-center pitch, weld all around the section.

Example 4: CJP V-Groove with Backing Bar

  \/  (V-groove above line = other side)
  ─ backing bar symbol below

Reading: CJP V-groove on other side with backing bar on arrow side.

Common Drawing Notes and Abbreviations

Frequently Asked Questions

What is the difference between a fillet and groove weld? Fillet welds are triangular cross-section welds deposited at 90° corners (T-joints, lap joints, corner joints) without base metal preparation. Groove welds are deposited into a prepared groove between base metal pieces (butt joints) and can be CJP or PJP. Fillet welds are cheaper to make; CJP groove welds develop full base metal strength.

What does "weld all around" mean on a structural drawing? A small circle at the junction of the reference line and arrow indicates the weld is continuous around the full perimeter of the connected element (e.g., a plate welded to a column all four sides). Required when the weld must seal against moisture, when eccentric loads could peel open a partial weld, or when structural integrity requires continuity.

When is a field weld symbol required? The flag symbol indicates the weld is to be made in the field (at the project site) rather than in the shop. Structural steel is typically fabricated in the shop with most welds completed, then erected with field welds completing the splice or connection. Field welds require more stringent preheat and inspection for some joint configurations.

What is the effective throat of a fillet weld? Effective throat = 0.707 × leg size for equal-leg fillet welds. This is the perpendicular distance from the root to the hypotenuse of the weld cross-section. It is used to calculate shear stress on the weld. For unequal leg fillet welds, the effective throat is the perpendicular from the root to the face.

What does the weld symbol reference line represent? The reference line is the horizontal baseline of every AWS A2.4 welding symbol; it is the anchor from which all weld information is read. The arrow drops from one end of the reference line to point at the joint to be welded, and the optional tail at the other end carries process, specification, or procedure information. The position of the weld symbol relative to the reference line — below the line for the arrow side, above the line for the other side — encodes which face of the joint receives the weld. Without understanding the reference line convention, it is impossible to correctly interpret any weld callout on a structural drawing.

How do you read the arrow side versus other side distinction on a weld symbol? When the weld symbol (such as a fillet triangle or groove V) is placed below the reference line, the weld is to be made on the arrow side — the side of the joint that the arrow physically points to. When the symbol is placed above the reference line, the weld is on the other side of the joint, opposite the arrow. When identical symbols appear both above and below the reference line, the weld is made on both sides. This convention is universal across AWS A2.4 and is independent of the drawing orientation; always follow the arrow to identify which physical face of the joint is the arrow side.

What is the difference between a fillet weld and a groove weld symbol? A fillet weld symbol is a right-triangle shape placed beside the reference line, with the vertical leg nearest the reference line; it indicates a triangular weld deposited at an inside corner without base metal preparation. A groove weld symbol uses one of several distinctive shapes — a V, bevel, U, J, or square — to indicate the joint preparation geometry machined or cut into the base metal before welding. Groove welds are used for butt joints and can achieve complete joint penetration (CJP) developing full base metal strength, whereas fillet welds are limited by their effective throat and are always lower in capacity per unit length than a CJP groove weld of equal depth. The choice between them depends on joint geometry, required strength, and fabrication cost.

AWS A2.4 Complete Weld Symbol Reference

AWS A2.4 (ISO 2553 compatible) defines the standard system for specifying welds on engineering drawings. Every weld symbol consists of a reference line, an arrow, and the weld symbol itself. Understanding the complete reference system is essential for fabricators and inspectors.

Weld Symbol Anatomy

A complete weld symbol contains the following elements, each with a defined position relative to the reference line.

Fillet Weld Symbols

Groove Weld Symbols

Supplementary Weld Symbols

Supplementary symbols provide additional information about the weld beyond the basic type and size.

Tail Information in Weld Symbols

The tail of the weld symbol (at the right end of the reference line) provides supplementary information that cannot be conveyed by the symbol geometry alone.

Multiple Weld Symbols on a Single Joint

When a joint requires multiple welds or has different weld specifications on different segments, multiple weld symbols share the same reference line or use separate arrows.

Practical Examples of Reading Weld Symbols

The following examples demonstrate how to interpret common weld symbols found on structural steel drawings.

Example 1: Standard fillet weld

  5/16
  ___
  | /   ----→   (arrow pointing to joint)
  |/

Reading: 5/16 in. fillet weld on arrow side, continuous.
Size (5/16) is left of symbol. No length = continuous.

Example 2: Double fillet weld with all-around symbol

       ___
  5/16 | /   ○ ----→
  5/16 |/

Reading: 5/16 in. fillet weld on both sides, all around the joint.
○ = all-around symbol at junction of reference line and arrow.

Example 3: Intermittent fillet weld

  1/4  3-12
  ___
  | /   ----→
  |/

Reading: 1/4 in. fillet weld on arrow side, 3 in. long,
spaced at 12 in. centers (pitch = center to center).

Example 4: V-groove with root opening

  60°  1/8
  \  /
   \/
   ----→

Reading: 60-degree included angle V-groove, 1/8 in. root opening,
CJP (complete joint penetration) on arrow side.

Example 5: Field weld with backing

  5/16  [FLAG] "AWS D1.1, E7018"
  ___
  | /   ----→   [BACKING RECTANGLE on other side]
  |/

Reading: 5/16 fillet, field weld (flag), with backing strip.
Electrode: E7018 per AWS D1.1.

Run This Calculation

→ Weld Symbol Generator — create AWS A2.4 and ISO 2553 compliant weld symbols for drawings.

→ Welded Connections Calculator — fillet weld capacity and weld group analysis per AISC 360, AS 4100, EN 1993.

Related Calculators and References

• Fillet Weld Size Chart — minimum/maximum sizes and E70 capacity table
• Fillet Weld Size Selection — AISC 360 Table J2.4
• Weld Electrode Reference — E60XX, E70XX, E80XX
• Steel Connection Types — Shear Tab, End Plate, Moment
• HSS Connection Design — special weld symbols for HSS tube connections
• ASTM A36 Steel — Properties and Equivalents
• Steel Connection Design
• Bolt Torque Chart
• Steel Fy and Fu table

Welding symbols per AWS A2.4:2012 Standard Symbols for Welding, Brazing, and Nondestructive Examination. All welding work must comply with AWS D1.1 or the applicable structural welding code for the project.

Disclaimer (educational use only)

This page is provided for general technical information and educational use only. It does not constitute professional engineering advice, a design service, or a substitute for an independent review by a qualified structural engineer. Any calculations, outputs, examples, and workflows discussed here are simplified descriptions intended to support understanding and preliminary estimation.

All real-world structural design depends on project-specific factors (loads, combinations, stability, detailing, fabrication, erection, tolerances, site conditions, and the governing standard and project specification). You are responsible for verifying inputs, validating results with an independent method, checking constructability and code compliance, and obtaining professional sign-off where required.

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