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Welding Symbols Reference Guide

AWS-compliant welding symbols with practical interpretation examples

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Anatomy of a Welding Symbol

Welding symbol anatomy diagram

Standard welding symbols consist of several key elements that communicate specific instructions to the welder:

1. Reference Line

Reference line

The foundation of the welding symbol where all other elements are attached.

2. Arrow

Arrow

Points to the joint or area to be welded, connecting to the reference line.

3. Tail

Tail

Optional element used to specify the welding process or other reference information.

Basic Weld Symbols

The following table shows the most common weld symbols according to AWS A2.4 standards:

Symbol Name Description Common Applications
Fillet weld symbol Fillet Weld Triangular cross-section joining two surfaces at right angles T-joints, lap joints, corner joints
Square groove symbol Square Groove Butt joint with square edges Thin materials, automatic welding
V-groove symbol V-Groove Beveled edges forming a V shape Thicker materials, single-side preparation
Bevel groove symbol Bevel Groove One edge beveled, one square When only one side can be prepared
U-groove symbol U-Groove Curved preparation resembling a U Very thick materials
Plug weld symbol Plug or Slot Weld Weld made in a hole or slot Overlapping members where fillet welds aren't sufficient

Supplementary Symbols

These symbols provide additional information about the weld:

All around symbol

All Around

Weld extends all around the joint

Field weld symbol

Field Weld

Weld to be made in the field (not in shop)

Melt through symbol

Melt Through

Complete joint penetration required

Contour symbols

Contour Symbols

Flat, convex, or concave finish specifications

Welding Position Symbols

Welding position diagram

Welding positions are indicated by numbers that follow the weld type:

Position Code Description Difficulty
Flat 1 Weld on upper surface of horizontal plane Easiest
Horizontal 2 Weld on vertical surface moving horizontally Moderate
Vertical 3 Weld moving vertically up or down Difficult
Overhead 4 Weld on underside of horizontal plane Most Difficult

Practical Interpretation Examples

Example 1: Simple Fillet Weld

Fillet weld example

Interpretation: 6mm fillet weld on the arrow side of the joint, with convex contour and no post-weld finishing specified.

Example 2: V-Groove Weld with Backing

V-groove weld example

Interpretation: Double V-groove weld with 60° included angle, 1/8 inch root opening, with backing bar on the opposite side. Weld to be ground flush after completion.

Pro Tips for Reading Welding Symbols

1. Arrow Side vs. Other Side

Symbols below the reference line apply to the arrow side of the joint. Symbols above apply to the other side.

2. Tail Information

Always check the tail for process specifications (SMAW, GTAW, etc.) or reference documents.

3. Dimension Order

For fillet welds: leg size is first, length is second (if specified). For groove welds: root opening, groove angle, etc.