Welding Symbols Chart — AWS A2.4 Reference

Two parallel vertical lines representing a groove between two square-edge base metals. No beveling is required; used for thin materials and often achieves full-penetration when welded from both sides.

Two diagonal lines forming a V-shape, indicating both members are beveled to form the groove. The most common groove type for complete joint penetration (CJP) butt welds on thick base metal.

One vertical and one diagonal line — only one member is beveled. The arrow must point specifically to the member that receives the bevel cut, making arrow direction critical for this symbol.

A U-shaped groove with curved root faces on both members. Requires less filler metal and produces less distortion than a V-groove at equivalent depth; used for heavy plate and structural applications.

One member has a J-shaped curved bevel; the other is square. Like the bevel groove, the arrow must point specifically to the member that is J-grooved. Common in pipe and heavy-plate work.

Two convex arc lines representing the natural groove formed between two rounded or curved surfaces (e.g., two round bars placed side by side). The groove is the gap between the curved faces.

One straight vertical line and one convex arc — the groove between a flat surface and a rounded edge (e.g., a round bar against a flat plate). The arrow must point to the member with the curved surface.

A right-triangle symbol representing a triangular-cross-section weld used to join two surfaces at approximately 90°. The most common weld type worldwide. The left (vertical) leg dimension indicates the weld size.

A rectangle symbol indicating a weld made in a circular hole drilled through one member into the member beneath. The hole appears on the arrow-side member. Depth of filling may be specified inside the symbol.

Uses the same rectangle symbol as plug, but the hole is elongated rather than circular. A detail or cross-section drawing is typically referenced in the tail to define slot length, width, and spacing.

A circle placed on the reference line representing a resistance spot weld or arc spot weld. When centered on the line, no side preference is specified. Weld diameter and pitch may be noted beside the symbol.

A circle with two parallel horizontal lines through it, representing a continuous resistance seam weld or arc seam weld. Width and length dimensions are placed beside the symbol.

A semicircle placed on the opposite side of the reference line from the groove weld. Used either for a back weld (deposited after the groove weld) or a backing weld (deposited first to prevent burn-through, often later removed).

Three horizontal lines representing deposited layers of weld metal used to restore or build up a surface — not to join two pieces. Common for hardfacing, wear resistance, and dimensional restoration. Always arrow-side only.

A small circle placed at the junction of the arrow and reference line, indicating the weld is to continue completely around the joint. Common on structural tube, pipe fittings, and any closed-contour joint.

A filled triangular flag at the arrow–reference-line junction, indicating the weld is to be made at the erection or field site rather than in the fabrication shop. Critical for planning logistics and inspection.

A filled (solid) semicircle indicating that complete fusion through the joint thickness is required, with visible reinforcement on the opposite side. Specifies 100% penetration without a backing bar.

A straight horizontal line indicating the weld face shall be finished flush with the base metal surface. A finish symbol (C = chipping, G = grinding, M = machining) placed to its right specifies the finishing method.

A convex outward arc indicating the weld face shall be convex (crown is above flush). Often seen on fillet welds where the slightly raised profile is acceptable. A finish symbol to the right specifies the method.

A concave inward arc indicating the weld face shall be concave (hollowed). Commonly required on fillet welds that need a smooth transition to reduce stress concentration. A finish symbol to the right specifies the method.

A weld symbol placed below the reference line applies to the arrow side of the joint — the side directly touched by the arrow. This is the standard position when only the near side is welded.

A weld symbol placed above the reference line applies to the other side — the side opposite the arrow. Used when only the far (reverse) side of a joint receives the weld.

When identical or different weld symbols appear on both sides of the reference line, welding is required on both sides of the joint. Each side can carry different weld size or type specifications.

A forked or open arrow at the end of the reference line opposite the arrow. Contains the welding process (SMAW, MIG, TIG), AWS welding specification, procedure number, or other supplemental instructions. Omitted when no extra information is needed.