Welding Symbols

Square butt weld

Two parallel strokes for a butt weld between square-cut edges with no groove preparation. Common on thin plate, where the edges are welded through without bevelling.

IND_WELDING_SYMBOLS_SQUARE_BUTT

Single-V butt weld

A V whose point sits on the reference line, for a butt weld where both edges are bevelled to form a V groove. Unless the symbol carries a penetration depth, the weld is read as full penetration.

IND_WELDING_SYMBOLS_SINGLE_V_BUTT

Single-bevel butt weld

A vertical stroke with one inclined stroke, for a butt or T joint where only one member is bevelled. The vertical stroke always stays on the left and the arrow points at the bevelled member.

IND_WELDING_SYMBOLS_SINGLE_BEVEL_BUTT

Single-V butt weld with broad root face

A Y shape: a V groove whose edges keep a straight root face below the bevel. Used for thicker plate where the root is left unbevelled to support the first run.

IND_WELDING_SYMBOLS_SINGLE_V_BROAD_ROOT

Single-bevel butt weld with broad root face

A vertical stroke with a short inclined stroke starting halfway up, for a single-bevel preparation that keeps a root face. The vertical stroke stays on the left.

IND_WELDING_SYMBOLS_SINGLE_BEVEL_BROAD_ROOT

Single-U butt weld

A stem with a semicircular cup, for a butt weld whose groove has a rounded bottom on both edges. The U preparation needs less filler metal than a V on thick sections.

IND_WELDING_SYMBOLS_SINGLE_U_BUTT

Single-J butt weld

A vertical stroke with a quarter arc, for a joint where one member is machined to a J profile and the other is left square. The arrow points at the prepared member.

IND_WELDING_SYMBOLS_SINGLE_J_BUTT

Flare-V butt weld

Two facing arcs for a groove formed between two curved surfaces, such as two round bars or two formed edges laid side by side.

IND_WELDING_SYMBOLS_FLARE_V

Flare-bevel butt weld

A vertical stroke and one arc, for a groove between a curved surface and a flat one, such as a bar or tube welded against a plate.

IND_WELDING_SYMBOLS_FLARE_BEVEL

Fillet weld

A right triangle with its vertical leg on the left, for a weld of roughly triangular section in a T, lap or corner joint. The throat thickness (a) or leg length (z) is written to its left.

IND_WELDING_SYMBOLS_FILLET

Plug or slot weld

An open rectangle for a weld that fills a round hole or an elongated slot in one member to join it to the member underneath.

IND_WELDING_SYMBOLS_PLUG_SLOT

Spot weld

A circle for a spot weld. Drawn centred on the reference line, as ISO 2553 shows it for resistance spot welding; a fusion spot weld sits on the arrow side or the other side instead.

IND_WELDING_SYMBOLS_SPOT

Seam weld

A circle with two parallel lines through it, for a continuous seam made by overlapping spots, usually by resistance welding with roller electrodes. Drawn centred on the reference line.

IND_WELDING_SYMBOLS_SEAM

Backing run

A half circle with its flat side on the reference line, for a run laid on the root side of a butt weld. It is placed on the side opposite the main weld symbol.

IND_WELDING_SYMBOLS_BACKING_RUN

Surfacing (overlay)

Two adjacent half circles for weld metal deposited on a surface rather than in a joint, for example hardfacing or buttering before welding.

IND_WELDING_SYMBOLS_SURFACING

Flanged butt or corner weld

Two curved strokes for a joint whose edges are turned up into flanges and fused together, typical of thin sheet. Known in US practice as an edge-flange weld.

IND_WELDING_SYMBOLS_EDGE_FLANGE

Double-V butt weld

An X formed by a V on each side of the reference line, for a butt weld prepared and welded from both sides. With identical welds on both sides the dashed identification line is left out.

IND_WELDING_SYMBOLS_DOUBLE_V_BUTT

Double-bevel butt weld

A K shape: one member bevelled from both sides, often in a T joint. The vertical stroke runs through the reference line and stays on the left.

IND_WELDING_SYMBOLS_DOUBLE_BEVEL_BUTT

Double fillet weld

A fillet triangle on each side of the reference line, for fillet welds on both sides of a T joint. With equal welds on both sides the dashed identification line is omitted.

IND_WELDING_SYMBOLS_DOUBLE_FILLET

Flush (flat) finish

A straight line added to the weld symbol to ask for a flat weld face, usually dressed flush by grinding or machining.

IND_WELDING_SYMBOLS_FLUSH

Convex weld face

An arc bulging away from the reference line, added to the weld symbol to ask for a convex weld profile.

IND_WELDING_SYMBOLS_CONVEX

Concave weld face

An arc curving towards the reference line, added to the weld symbol to ask for a concave weld profile, most often on fillet welds.

IND_WELDING_SYMBOLS_CONCAVE

Toes blended smoothly

Asks for the weld toes to blend smoothly into the parent metal, which may mean dressing them. Typical on fatigue-loaded joints.

IND_WELDING_SYMBOLS_TOES_BLENDED

Permanent backing strip (M)

A box with the letter M, placed on the root side to show that a backing strip is used and stays in place after welding.

IND_WELDING_SYMBOLS_PERMANENT_BACKING_STRIP

Removable backing strip (MR)

A box with the letters MR, placed on the root side to show that a backing strip is used and removed after welding.

IND_WELDING_SYMBOLS_REMOVABLE_BACKING_STRIP

Field weld (site weld)

A flag at the junction of the arrow line and the reference line, meaning the weld is made on site or at the place of erection rather than in the shop.

IND_WELDING_SYMBOLS_FIELD_WELD

Weld all around

A circle at the junction of the arrow line and the reference line, meaning the weld runs continuously around the whole joint, for example around a tube or a bracket.

IND_WELDING_SYMBOLS_WELD_ALL_AROUND

Reference line, system A

Arrow line with the dual reference line of ISO 2553 system A: a continuous line for the arrow side and a dashed identification line for the other side. The block's base point is the arrowhead tip.

IND_WELDING_SYMBOLS_REFERENCE_LINE_SYSTEM_A

Reference line, system B

Arrow line with the single reference line of system B, where a symbol below the line means the arrow side and one above it the other side, as in AWS A2.4.

IND_WELDING_SYMBOLS_REFERENCE_LINE_SYSTEM_B

Fillet weld, arrow side

Complete system A welding symbol with the fillet triangle on the continuous line, so the weld is made on the side the arrow touches. Attributes SIZE and LENGTH take the weld size and length.

IND_WELDING_SYMBOLS_FILLET_ARROW_SIDE

Fillet weld, other side

Complete system A welding symbol with the fillet triangle on the dashed identification line, so the weld is made on the side opposite the arrow.

IND_WELDING_SYMBOLS_FILLET_OTHER_SIDE

Fillet weld, both sides

Complete welding symbol with fillet triangles on both sides of the reference line and no dashed line, as used for symmetrical welds. Separate attributes take the size and length for each side.

IND_WELDING_SYMBOLS_FILLET_BOTH_SIDES

Single-V butt weld, arrow side

Complete system A welding symbol with a single-V butt weld on the arrow side. SIZE can take a penetration depth (s); left empty, the butt weld is full penetration.

IND_WELDING_SYMBOLS_SINGLE_V_ARROW_SIDE

Fillet weld all around

Arrow-side fillet weld with the all-around circle at the junction, for a fillet that runs around the full perimeter of the part.

IND_WELDING_SYMBOLS_FILLET_ALL_AROUND

Fillet weld made on site

Arrow-side fillet weld with the field weld flag at the junction, for a fillet weld made during erection rather than in the shop.

IND_WELDING_SYMBOLS_FILLET_FIELD_WELD

Welding symbol with tail and process

Arrow-side fillet weld with a tail at the end of the reference line. The PROCESS attribute takes the process reference number from ISO 4063, and the tail can also hold other complementary information.

IND_WELDING_SYMBOLS_TAIL_WITH_PROCESS