AWS A2.4 §11

Spot Weld Symbol

How to read a spot Simbolo di Saldatura — diameter, pitch spacing, number of spots, and the critical process designation. RSW vs arc spot weld distinction per AWS A2.4.

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Spot Weld Symbol — Anatomy

Arrow side — arc spot

Centered — RSW

With 2" pitch, 6 spots

Joint cross-section

Key rule: The spot weld symbol is a plain circle. Do not confuse it with the seam weld symbol, which has a horizontal line through the center. The process designation (RSW, GTAW, GMAW, etc.) is required in the tail per A2.4 §11.1.3.

How to Read

Spot Weld Symbol Dimensions

A spot weld joins overlapping members at a single point of fusion. Per AWS A2.4 §11, spot welds have three placement options depending on the Processo di Saldatura used.

Symbol Placement

Below the reference line — arrow-side member. Used for arc spot welds (GTAW, GMAW) where the weld is made from the arrow side.

Above the reference line — other-side member. Arc spot welds from the other side.

Centered on the reference line — no side significance. Used for resistance spot Saldatura (RSW) only. Per A2.4 §6.1.3, only RSW (and RSEW for seam welds) have no side significance. EBW has side significance and is placed above or below the reference line.

Where Each Dimension Goes

Diameter — to the LEFT of the circle symbol. For RSW, this is the weld nugget diameter. For arc spot welds, this is the weld diameter at the faying surface.

Pitch — to the RIGHT. Center-to-center spacing between spots.

Number of spots — in parentheses, placed above or below the symbol. Example: (6) means six spot welds.

Process — in the TAIL. This is mandatory per A2.4 §11.1.3. Common designations: RSW (resistance spot), GTAW (TIG), GMAW (MIG).

Process Types

RSW vs Arc Spot Welding

Feature	Resistance Spot (RSW)	Arc Spot (GTAW/GMAW)
Process	Electrode pressure + current	Arc melts through top member
Filler metal	None	Yes (Consumabile Elettrodo)
Symbol placement	Centered on reference line	Above or below reference line
Side significance	No	Yes — arrow/other side
Industry	Automotive, sheet metal	Steel deck, light structural
D1.1 scope	Outside D1.1 scope	Arc processes within scope

Steel deck note: Arc spot welds (puddle welds) attaching steel deck to structural framing are governed by AWS D1.3 (Codice di Saldatura Strutturale — Sheet Steel), not D1.1. If you see spot Simboli di Saldatura on structural steel deck drawings, D1.3 is the applicable Codice.

Common Questions

Spot Weld Symbol FAQ

What is a spot weld symbol?

A spot weld symbol is a plain circle placed on the reference line of a welding symbol. It indicates a weld made at a single point between overlapping members where coalescence occurs at the faying surfaces. The process designation (RSW, GTAW, GMAW, etc.) is required in the tail. Spot welds are the dominant joining method in automotive sheet metal and are also used as arc spot welds (puddle welds) for steel deck attachment.

What is the difference between a spot weld and a seam weld symbol?

A spot weld symbol is a plain circle. A seam weld symbol is a circle with a horizontal line through its center. Both can be placed below the reference line (arrow side), above it (other side), or centered on it (no side significance). The seam weld produces a continuous linear weld along the joint, while a spot weld produces a discrete point of fusion. Both require the welding process to be specified in the tail of the symbol.

What is the difference between RSW and arc spot welding?

Resistance spot welding (RSW) uses electrode pressure and electrical current to fuse overlapping sheets at a point — no filler metal is added. The symbol is centered on the reference line because there is no arrow-side or other-side significance. Arc spot welding (puddle welding) uses an arc welding process like GTAW or GMAW to melt through one member into the other — it has side significance and the symbol goes above or below the reference line. The tail must specify which process: RSW, GTAW, GMAW, etc.

Where do spot weld dimensions go on the symbol?

Per AWS A2.4, spot weld diameter goes to the left of the circle symbol. Pitch (center-to-center spacing) goes to the right. The number of spot welds appears in parentheses above or below the symbol. When the symbol is centered on the reference line (RSW), dimensions may go on either side. The process designation is always required in the tail — omitting it is a common drawing error.

Related Reference

Spot Weld Symbol

Spot Weld Symbol Dimensions

Symbol Placement

Where Each Dimension Goes

RSW vs Arc Spot Welding

Spot Weld Symbol FAQ

More Weld Symbol Pages