Comprehensive A2.4 Symbol Reference

Q: Where does the process designation go on a welding symbol?

Per A2.4 section 6.12.1, the welding process letter designation (e.g., SMAW, GMAW, FCAW-S) is placed in the tail of the welding symbol. An application mode suffix from Table A5 may be added (e.g., GTAW-AU for automatic gas tungsten arc welding). The tail may be omitted when no process reference is needed per section 6.12.5.

The complete AWS A2.4:2020 Symbole de soudage reference for fabricators and inspectors. Covers every Type de soudure including groove, fillet, plug, slot, spot, seam, stud, surfacing, Support envers, and edge welds, plus 10 NDE examination methods, 9 supplementary symbols, 136 process designations, 7 finishing designators, and D1.1:2025 cross-references for Acier de construction.

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This reference covers every symbol type defined in AWS A2.4:2020 (8th Edition), with D1.1:2025 Article cross-references for structural steel applications. Print this page for a complete multi-page desk reference.

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`Section 1`Symbol Anatomy — A2.4 §4.1

Reference Line Horizontal baseline — all symbol elements attach to it. Arrow side = below, other side = above.

Arrow Points to the joint location. For bevel/Chanfrein en J, a break in the arrow indicates the prepared member.

Symbole de soudure Graphic indicating weld type (triangle = fillet, V = groove, etc.). Placed below or above the line.

Dimensions Taille to the left of the weld symbol. Length and pitch to the right. Depth/throat in parentheses.

Tail Forked end — contains process (SMAW, FCAW), WPS number, or Spécification reference. Omit if unused.

Weld-All-Around Circle at reference/arrow junction — Soudure must continue completely around the joint.

Drapeau de soudure sur chantier Filled triangle at reference/arrow junction — weld to be made in the field, not in the shop.

Symbole de profil Same side as the weld symbol, on its outer face — Arasé, flat, Convexe (outward arc), or Concave (inward arc). Paired with finishing designator letter (G, M, C, H, P, R, U).

`Section 2`Weld Symbol Types — A2.4 `Figure 4.1`

Type	A2.4 Clause	D1.1 Cross-Reference
Fillet	`§8`	`Table 7.7` min size, `§4.5.2.9` max on edges
Chanfrein droit	`§7`	Fig 5.1 Préqualifié CJP/PJP joints
Chanfrein en V	`§7`	Fig 5.1 B-U2, B-U2a (CJP single-V)
Chanfrein en demi-V	`§7`, `§6.3` perp leg	Fig 5.1 TC-U4a (Joint en T bevel CJP)
Chanfrein en U	`§7`	Fig 5.1 B-U6 (single-U CJP, backgouge)
J-Groove	`§7`, `§6.3` perp leg	Fig 5.1 B-U8 (single-J CJP, backgouge)
Chanfrein en V évasé	`§7.2.10`	`Table 4.1:` 3/4R (GMAW), 5/8R (SMAW/FCAW-S). Process-dependent.
Chanfrein en demi-V évasé	`§7.2.10`, `§6.3` perp leg	`Table 4.1:` 5/8R (GMAW/FCAW-G), 5/16R (SMAW/FCAW-S). Process-dependent.
Plug	`§9`	`§4.11` min hole dia, `§5.4.4`
Slot	`§10`	`§4.11` (same rules as plug)
Spot / Projection	`§11`	N/A (D1.3 for arc spot on sheet steel)
Seam	`§12`	N/A (D1.1 does not cover seam welding)
Stud	`§14` (arrow-side only)	`Clause 9` (drawn-arc stud welding)
Surfacing	`§15`	`§7.25` (Réparation welding provisions)
Back / Backing	`§7.7`	`§5.4.1.3` backgouge to sound metal (Fig 5.1 note d)
Edge	`§13`	N/A (D1.3 for sheet steel edges)
Scarf (brazing)	`§16`	N/A (brazing only, not D1.1)

`Section 3`Size Notation Quick Reference — A2.4 §7.2, §8.2

Soudure d'Angle Notation

6Leg size — 6mm equal-leg fillet both sides when on both sides of reference line
6×8Unequal fillet — both sizes appear to the left as S1×S2. Orientation not specified by the symbol; a drawing detail shows which leg goes on which member.
6 left + 50-150 rightIntermittent — leg size (6mm) to left of symbol; length–pitch (50mm weld, 150mm c/c) to right.

Soudure sur chanfrein Notation

D(S)D = groove depth (preparation depth). (S) = Dimension de soudure/Gorge utile (design dimension)
12(10)12mm groove depth, 10mm effective throat — D without parentheses, (S) in parentheses
RÉcartement à la racine value — often shown in tail or drawing note, not symbol
αAngle d'ouverture — shown on the symbol to the left of the weld symbol (e.g. 45°). Per §7.3.

Intermittent Weld Notation

length-pitchWritten right of symbol. Length = each weld run. Pitch = center-to-center spacing
50-15050mm long welds, 150mm apart (center). Net gap = 100mm
staggeredIntermittent symbols offset on arrow side vs other side = chain or staggered

`Section 4`Supplementary Symbols — A2.4 `Figure 4.2`

Weld-All-Around

Circle at arrow/reference junction. Weld extends around entire joint perimeter. Per §6.11.

Soudure sur chantier

Flag at junction. Weld made at erection site, not shop. Per §6.9.

Melt-Through

Filled semicircle opposite weld symbol. CJP with visible Surépaisseur à l'Envers (Renforcement de Racine). Per §6.14.

Consommable Insert

Square symbol. Placed before Passe de fond for CJP groove welds. Per §7.10.

Backing

Rectangle. Permanent or removable Barre support. R inside = removable. Per §7.8.

Spacer

Rectangle (same as backing but placed inside groove). Metal spacer between root faces. Per §7.9.

Flush/Flat Contour

Straight line above weld symbol. Face de Soudure flush with Métal de Base. Per §6.13.

Convex Contour

Outward arc. Weld face crowns above base metal surface. Per §6.13.

Concave Contour

Inward arc. Weld face dips below base metal surface. Per §6.13.

`Section 5`NDE Examination Method Symbols — A2.4 `Table A6`, `Clause 17`

Code	Method	Catégorie	Side Significance	D1.1 Reference
`RT`	Contrôle par radiographie	Volumetric	Centered — no side preference (`§17.5.5`)	`Clause 8`, Part E
`UT`	Contrôle par ultrasons	Volumetric	Centered — no side preference	`Clause 8`, Part F
`MT`	Contrôle par magnétoscopie	Surface	Arrow/other side — surface access matters (`§17.5.2`)	`§8.14.4` (procedure), Part C (Acceptation)
`PT`	Ressuage Essai	Surface	Arrow/other side — surface access matters	`§8.14.5` (procedure), Part C (acceptance)
`VT`	Examen visuel	Surface	Arrow/other side — surface access matters	`§8.6` (obligations), Part C (acceptance)
`ET`	Electromagnetic (Eddy Current) Testing	Surface	Arrow/other side — surface access matters	Per Engineer specification
`AET`	Contrôle par Émission Acoustique	Specialized	Varies by application	Per Engineer specification
`LT`	Leak Testing	Specialized	Varies by application	Per Engineer specification
`NRT`	Neutron Radiographic Testing	Volumetric	Centered — no side preference	Per Engineer specification
`PRT`	Proof Testing	Specialized	Varies by application	Per Engineer specification

Surface methods detect what you can almost see. Volumetric methods find what you never will. The symbol tells you which side matters — and for RT and UT, neither side does. — CWI field perspective, based on A2.4 §17.5

`Section 6`Arrow Side & Other Side Rules — A2.4 §6.2–6.5

Arrow Side vs Other Side

Symboles de Soudage placed below the reference line specify the arrow side of the joint (the side the arrow points to). Symbols placed above the reference line specify the other side. Per §6.2.

Broken Arrow Rule

When only one joint member is to be prepared (bevel-groove, J-groove, flare-bevel), the arrow shall have one break and point toward that member. The arrow need not be broken if it is apparent which member is to be prepared, and shall not be broken if there is no preference. Per §6.4.1.

Fillet Weld Arrow

For fillet welds, the arrow may or may not be broken to indicate weld locations. There is no requirement to break the arrow for fillet welds as there is for single-bevel or J-groove welds. Per §6.4.2.

Combination Weld Symbols

For joints requiring more than one weld type (e.g., fillet + groove), a symbol shall be used to specify each weld. Per §6.5.

Multiple Arrows

Two or more arrows may be used with a single reference line to point to locations where identical welds are specified. Per §6.6.

`Section 7`Tail Contents — A2.4 §6.12

Process Designation

SMAWSoudage à l'Arc avec Électrode Enrobée (stick)
FCAW-SSelf-Shielded Soudage à l'Arc avec Fil Fourré
GMAWSoudage MIG/MAG (MIG)
GTAWSoudage TIG (GTAW) (TIG)
GTAW-AUAutomatic GTAW (suffix from Table A5)

References & Special Types

WPS-01Refers to specific Descriptif de Mode Opératoire de Soudage document. Per §6.12.2.
TYP"Typical" — avoids repeating identical symbols. User must identify all applicable joints. Per §6.12.3.
DET ACross-section or detail reference when basic symbols are inadequate. Per §6.12.4.

Omission Rule

(no tail)When no references are required, the tail may be omitted from the welding symbol entirely. Per §6.12.5.
Drawing noteDrawing notes may provide weld information without repeating it in the symbol. Per §6.12.6.

`Section 8`Multiple Reference Lines — A2.4 §6.7–6.8

Sequence of Operations

Two or more reference lines indicate a sequence of operations. The first operation is specified on the reference line nearest the arrow. Subsequent operations are specified sequentially on additional reference lines. Per §6.7.1.

Supplementary Data

The tail of additional reference lines may be used to specify data supplementary to welding symbol information (e.g., process data, standards references). Per §6.7.2.

Symbols on Each Line

Symbols (including supplementary symbols such as field weld flags) shall be placed on the reference line for each operation to which they are applicable. Per §6.7.3.

Subreference Lines (Distinct from Multiple Ref Lines)

For joints transitioning from one type to another (e.g., pipe), multiple subreference lines branch from a single reference line. Unlike multiple reference lines, the sequence of welding is undetermined — subreference lines indicate joint type variation, not welding order. Per §6.8.

`Section 9`Process Letter Designations — A2.4 `Table A2`

Placed in the tail of the welding symbol per §6.12.1. Application mode suffixes (Table A5) may be appended: -MA Manual, -SA Semiautomatic, -AU Automatic, -ME Mechanized, -RO Robotic, -AD Adaptive Control.

Soudage à l'Arc Processes (most common)

Code	Process	Notes
`SMAW`	Shielded Metal Arc Welding	Stick/manual. D1.1 prequalified for all positions.
`GMAW`	Gas Metal Arc Welding	MIG/MAG. External Gaz de protection required.
`GMAW-P`	Pulsed Gas Metal Arc Welding	Pulsed transfer. Better control on thin material.
`GMAW-S`	Short Circuiting Gas Metal Arc Welding	Short-circuit transfer. Sheet metal, root passes.
`GTAW`	Gas Tungsten Arc Welding	TIG. High-quality root passes, thin materials.
`GTAW-P`	Pulsed Gas Tungsten Arc Welding	Pulsed TIG. Better heat control.
`FCAW`	Flux Cored Arc Welding	Fil tubulaire. Higher deposition than SMAW.
`FCAW-G`	Gas Shielded Flux Cored Arc Welding	Dual-shield. External gas + flux core.
`FCAW-S`	Self-Shielded Flux Cored Arc Welding	Innershield. No external gas. Field/outdoor use.
`SAW`	Soudage à l'Arc sous Flux	Highest deposition. Flat/horizontal only.
`SAW-S`	Series Submerged Arc Welding	Dual-wire SAW for wider coverage.
`PAW`	Soudage Plasma	Constricted arc. Keyhole technique for CJP.
`EGW`	Soudage Électrogaz	Vertical-up, single pass. Heavy plate.
`SW`	Arc Stud Welding	Shear connectors. D1.1 `Clause 9.`
`CAW`	Carbon Arc Welding	Copper alloy backing. Repair applications.

View all 136 process designations (Table A2 complete) ▼

Code	Process
`AB`	Adhesive Bonding
`AAW`	Air Acetylene Welding
`ABW`	Arc Braze Welding
`AC`	Arc Cutting
`AG`	Arc Gouging
`ASP`	Arc Spraying
`AW`	Arc Welding
`B`	Brazing
`BB`	Block Brazing
`B-CA`	Controlled-Atmosphere Brazing
`BW`	Braze Welding
`CAC`	Carbon Arc Cutting
`CAC-A`	Air Carbon Arc Cutting
`CAG`	Carbon Arc Gouging
`CAW`	Carbon Arc Welding
`CEW`	Coextrusion Welding
`CW`	Cold Welding
`DB`	Dip Brazing
`DFB`	Diffusion Brazing
`DFW`	Diffusion Welding
`DS`	Dip Soldering
`EBB`	Electron Beam Brazing
`EBBW`	Electron Beam Braze Welding
`EBC`	Electron Beam Cutting
`EBW`	Electron Beam Welding
`EBW-HV`	High Vacuum Electron Beam Welding
`EBW-MV`	Medium Vacuum Electron Beam Welding
`EBW-NV`	Nonvacuum Electron Beam Welding
`EFW`	Electrofusion Welding
`EGW`	Electrogas Welding
`ESW`	Soudage Électroslag
`ESW-CG`	Consumable Guide Electroslag Welding
`ESW-NG`	Narrow Gap Electroslag Welding
`EW`	Extrusion Welding
`EXB`	Exothermic Brazing
`EXBW`	Exothermic Braze Welding
`EXW`	Explosion Welding
`FB`	Furnace Brazing
`FCAW`	Flux Cored Arc Welding
`FCAW-G`	Gas Shielded Flux Cored Arc Welding
`FCAW-S`	Self-Shielded Flux Cored Arc Welding
`FFW`	Flow Fusion Welding
`FLSP`	Flame Spraying
`FLSP-P`	Powder Flame Spraying
`FLSP-W`	Wire Flame Spraying
`FOW`	Forge Welding
`FRW`	Friction Welding
`FRW-DD`	Direct Drive Friction Welding
`FRW-I`	Inertia Friction Welding
`FS`	Furnace Soldering
`FSW`	Friction Stir Welding
`FW`	Flash Welding
`GMAC`	Gas Metal Arc Cutting
`GMAW`	Gas Metal Arc Welding
`GMAW-P`	Pulsed Gas Metal Arc Welding
`GMAW-S`	Short Circuiting Gas Metal Arc Welding
`GTAC`	Gas Tungsten Arc Cutting
`GTAW`	Gas Tungsten Arc Welding
`GTAW-P`	Pulsed Gas Tungsten Arc Welding
`HEBC`	High Energy Beam Cutting
`HEBW`	High Energy Beam Welding
`HGW`	Hot Gas Welding
`HIPW`	Hot Isostatic Pressure Welding
`HPW`	Hot Pressure Welding
`HTW`	Heated Tool Welding
`HVOF`	High Velocity Oxyfuel Spraying
`IB`	Induction Brazing
`INS`	Iron Soldering
`IRB`	Infrared Brazing
`IRS`	Infrared Soldering
`IRW`	Infrared Welding
`IS`	Induction Soldering
`IW`	Induction Welding
`LBB`	Laser Beam Brazing
`LBBW`	Laser Beam Braze Welding
`LBC`	Laser Beam Cutting
`LBC-A`	Laser Beam Air Cutting
`LBC-EV`	Laser Beam Evaporative Cutting
`LBC-IG`	Laser Beam Inert Gas Cutting
`LBC-O`	Laser Beam Oxygen Cutting
`LBW`	Laser Beam Welding
`MIAW`	Magnetically Impelled Arc Welding
`OAC`	Oxygen Arc Cutting
`OAW`	Oxyacetylene Welding
`OC`	Oxygen Cutting
`OC-F`	Flux Cutting
`OC-P`	Metal Powder Cutting
`OFC`	Oxyfuel Gas Cutting
`OFC-A`	Oxyacetylene Cutting
`OFC-H`	Oxyhydrogen Gas Cutting
`OFC-N`	Oxynatural Gas Cutting
`OFC-P`	Oxypropane Cutting
`OFW`	Oxyfuel Gas Welding
`OG`	Oxygen Gouging
`OHW`	Oxyhydrogen Welding
`OLC`	Oxygen Lance Cutting
`PAC`	Plasma Arc Cutting
`PAG`	Plasma Arc Gouging
`PAW`	Plasma Arc Welding
`PEW`	Percussion Welding
`PGW`	Pressure Gas Welding
`PSP`	Plasma Spraying
`PW`	Projection Welding
`RB`	Resistance Brazing
`RFW`	Radio Frequency Welding
`ROW`	Roll Welding
`RS`	Resistance Soldering
`RSEW`	Resistance Seam Welding
`RSEW-HF`	High-Frequency Seam Welding
`RSEW-I`	Induction Seam Welding
`RSEW-MS`	Mash Seam Welding
`RSW`	Resistance Spot Welding
`RW`	Resistance Welding
`RW-PC`	Pressure-Controlled Resistance Welding
`S`	Soldering
`SAW`	Submerged Arc Welding
`SAW-S`	Series Submerged Arc Welding
`SMAC`	Shielded Metal Arc Cutting
`SMAW`	Shielded Metal Arc Welding
`SPW`	Spin Welding
`SSW`	Solid-State Welding
`SW`	Arc Stud Welding
`TB`	Torch Brazing
`TC`	Thermal Cutting
`TG`	Thermal Gouging
`THSP`	Thermal Spraying
`TS`	Torch Soldering
`TW`	Thermite Welding
`USS`	Ultrasonore Soldering
`USW`	Ultrasonic Welding
`UW`	Upset Welding
`UW-HF`	High-Frequency Upset Welding
`UW-I`	Induction Upset Welding
`VPSP`	Vacuum Plasma Spraying
`VW`	Vibration Welding
`WS`	Wave Soldering

`Section 10`Finishing Designators — A2.4 §6.13

Added adjacent to the contour symbol. Specifies the mechanical method to achieve the required weld face contour. Does not specify quality of finish.

Chipping

Grinding

Hammering

Machining

Planishing

Rolling

Unspecified

Method left to Fabricant

FAQFrequently Asked Questions

What is included in the comprehensive A2.4 symbol reference?▼

All A2.4:2020 weld symbol types (fillet, 8 groove variants, plug, slot, spot, seam, stud, surfacing, backing, edge), 10 NDE examination method symbols (RT, UT, MT, PT, VT, ET), 9 supplementary symbols, 136 process letter designations, 7 finishing designators, and D1.1:2025 clause cross-references for each symbol type.

How do I print this as a multi-page PDF?▼

Press Ctrl+P (Windows/Linux) or Cmd+P (Mac) and select Save as PDF. The reference is optimized for print with automatic page breaks between sections, a footer on each page, and all expandable sections fully opened.

What is the difference between surface and volumetric NDE methods?▼

Surface methods (MT, PT, VT, ET) examine the weld surface or near-surface region and have arrow-side or other-side significance on the symbol. Volumetric methods (RT, UT) penetrate the full weld Épaisseur and are typically centered on the reference line with no side preference per A2.4 section 17.5.5.

Where does the process designation go on a welding symbol?▼

Per A2.4 section 6.12.1, the Procédé de Soudage letter designation (e.g., SMAW, GMAW, FCAW-S) is placed in the tail of the welding symbol. An application mode suffix from Table A5 may be added (e.g., GTAW-AU for automatic gas tungsten arc welding). The tail may be omitted when no process reference is needed per section 6.12.5.

What is the arrow side vs other side rule?▼

Weld symbols placed below the reference line specify the arrow side of the joint (the side the arrow points to). Symbols placed above the reference line specify the other side. For welds requiring preparation of only one member (bevel-groove, J-groove, flare-bevel), the arrow shall have a break and point toward the member to be prepared, per A2.4 section 6.4.1.

What goes in the tail of a welding symbol?▼

The tail may contain: the welding process letter designation from Table A2 (e.g., SMAW, GTAW-AU), a specification or code reference, a WPS number, or a detail/cross-section reference when basic symbols are inadequate. The designation TYP (typical) avoids repeating identical symbols. When no references are required, the tail may be omitted entirely, per A2.4 section 6.12.

How do multiple reference lines indicate sequence?▼

Two or more reference lines indicate a sequence of operations. The first operation is specified on the reference line nearest the arrow; subsequent operations are specified sequentially on additional reference lines. This is distinct from subreference lines, where multiple weld types branch from a single reference line and the welding sequence is undetermined, per A2.4 sections 6.7.1 and 6.8.

All data verified against 80 welding standards in the Clause5 corpus. Powered by Flux.

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Process Designations

Interactive lookup for all 136 process codes with descriptions and application mode suffixes.

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ISO 2553 vs AWS A2.4

Side-by-side Comparaison of international and American welding symbol conventions. System A, System B, and the arrow-side flip.

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Contour & Finishing Symbols

All 7 finishing designators (G, M, C, H, P, R, U) and flush, convex, concave contour symbols Expliqué.

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Multiple Reference Lines

First, second, and third reference lines — sequence of operations explained with diagrams.

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Section 1Symbol Anatomy — A2.4 §4.1

Section 2Weld Symbol Types — A2.4 Figure 4.1

Section 3Size Notation Quick Reference — A2.4 §7.2, §8.2

Soudure d'Angle Notation

Soudure sur chanfrein Notation

Intermittent Weld Notation

Section 4Supplementary Symbols — A2.4 Figure 4.2

Section 5NDE Examination Method Symbols — A2.4 Table A6, Clause 17

Section 6Arrow Side & Other Side Rules — A2.4 §6.2–6.5

Arrow Side vs Other Side

Broken Arrow Rule

Fillet Weld Arrow

Combination Weld Symbols

Multiple Arrows

Section 7Tail Contents — A2.4 §6.12

Process Designation

References & Special Types

Omission Rule

Section 8Multiple Reference Lines — A2.4 §6.7–6.8

Sequence of Operations

Supplementary Data

Symbols on Each Line

Subreference Lines (Distinct from Multiple Ref Lines)

Section 9Process Letter Designations — A2.4 Table A2

Soudage à l'Arc Processes (most common)

Section 10Finishing Designators — A2.4 §6.13

Chipping

Grinding

Hammering

Machining

Planishing

Rolling

Unspecified

FAQFrequently Asked Questions

What's NextTools Built on This Data

Symbol Reader

CWI Practice Quiz

Process Designations

ISO 2553 vs AWS A2.4

Contour & Finishing Symbols

Multiple Reference Lines

Quick Chart

`Section 1`Symbol Anatomy — A2.4 §4.1

`Section 2`Weld Symbol Types — A2.4 `Figure 4.1`

`Section 3`Size Notation Quick Reference — A2.4 §7.2, §8.2

`Section 4`Supplementary Symbols — A2.4 `Figure 4.2`

`Section 5`NDE Examination Method Symbols — A2.4 `Table A6`, `Clause 17`

`Section 6`Arrow Side & Other Side Rules — A2.4 §6.2–6.5

`Section 7`Tail Contents — A2.4 §6.12

`Section 8`Multiple Reference Lines — A2.4 §6.7–6.8

`Section 9`Process Letter Designations — A2.4 `Table A2`

`Section 10`Finishing Designators — A2.4 §6.13