Australian Weld Symbols — AS 1101.3-2005 Standard Guide
Complete reference for welding symbols used on Australian structural steel drawings per AS 1101.3-2005 (Graphical symbols for welding). This standard is based on ISO 2553 and provides a standardised system for specifying weld type, size, length, and configuration on engineering drawings.
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AS 1101.3 Symbol Structure
The AS 1101.3 welding symbol uses a reference line and an arrow. The reference line is horizontal, and all weld information is placed relative to this line. The arrow connects the reference line to the joint on the drawing.
Symbol Layout
Finish symbol (G = grind, M = machine, C = chip)
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Contour symbol (flat, convex, concave)
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Groove angle / included angle
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Root opening or depth of penetration -|
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[Size] ---- (Weld symbol) ---- [Length] ---- [Pitch] ---- (Tail)
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Reference line
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Arrow
Arrow Side vs Other Side
The most fundamental convention: weld symbols placed BELOW the reference line indicate a weld on the ARROW SIDE of the joint. Weld symbols placed ABOVE the reference line indicate a weld on the OTHER SIDE (opposite side) of the joint.
Arrow side = the side of the joint that the arrow physically points to. Other side = the far side of the joint, opposite to where the arrow points.
A weld symbol on BOTH sides of the reference line indicates welds on both sides of the joint (usually the same size and type).
Basic Weld Symbol Table — AS 1101.3
| Weld Type | Symbol | Arrow Side Application | Other Side Application |
|---|---|---|---|
| Fillet | Right triangle | Fillet on arrow side | Fillet on other side |
| Square butt | Two parallel lines (II) | Butt weld, square edge | Square butt, other side |
| Single V butt | V | V preparation on arrow side | V preparation on other side |
| Double V butt | X | V both sides (equal) | -- (inherently double-sided) |
| Single bevel butt | \ (angled) | Bevel on arrow side | Bevel on other side |
| Single U butt | U (curved) | U-groove on arrow side | U-groove on other side |
| Single J butt | J | J-groove on arrow side | J-groove on other side |
| Plug weld | Rectangle | Plug in arrow-side member | Plug in other-side member |
| Slot weld | Elongated rect | Slot in arrow-side member | Slot in other-side member |
| Stud weld | Circle with dot | Stud on arrow side | -- (studs are one-sided) |
| Seam weld | Parallel arcs (⌇) | Seam on arrow side | Seam on other side |
| Backing run | Semicircle | Backing on arrow side (welded first from other side) | -- |
| Surfacing / build-up | Wavy line | Surfacing on arrow side | Surfacing on other side |
Dimension Conventions
Fillet Weld Dimensions
The fillet weld size (leg length) is placed to the LEFT of the fillet symbol:
"6" with fillet symbol = 6 mm continuous fillet weld (leg length = 6 mm, equal leg assumed unless otherwise noted).
Unequal leg fillet welds: "8 x 6" with fillet symbol = 8 mm vertical leg, 6 mm horizontal leg. The dimensions are placed in the order: [vertical leg] x [horizontal leg].
Weld Length and Spacing
Length is placed to the right of the symbol:
"6 100" with fillet symbol = 6 mm fillet weld, 100 mm long (single run)
Intermittent welds: "6 75 (200)" with fillet symbol = 6 mm fillet, 75 mm long segments, 200 mm centre-to-centre spacing
Staggered intermittent welds: "6 75 Z 200" with fillet symbol = 6 mm fillet, 75 mm long, staggered, 200 mm c/c. The "Z" indicates the staggered pattern on opposite sides.
Butt Weld Dimensions
For butt welds, the groove dimensions are placed around the weld symbol:
"//" (square butt) with no size = full penetration butt weld, square edge preparation
"V 60 12" = single V butt, 60 degrees included angle, 12 mm root opening
Supplementary Symbols
| Symbol | Meaning |
|---|---|
| Hollow circle at arrow-reference line junction | Weld all around (continuous weld around the entire periphery) |
| Solid flag at arrow-reference line junction | Field weld (weld on site, not in shop) |
| Hollow flag (open flag) | Site weld (alternative to solid flag, less common in Australian usage) |
| G (on tail) | Grind flush (finish symbol) |
| M (on tail) | Machine finish |
| C (on tail) | Chip finish (less common, primarily manual arc welding) |
Field Weld vs Shop Weld
In Australian practice, the notation FW (field weld) or a solid flag at the arrow-reference line junction indicates a weld made on site. The absence of a flag or notation SW (shop weld) indicates a weld made in the fabrication shop.
Field welds are generally more expensive per metre due to access difficulties, weather protection requirements, and the need for mobile equipment. Where possible, connections are detailed to maximise shop welding and minimise field welding.
Australian Notation Conventions
In Australian structural steel detailing, it is common to see simplified notation that includes both the AS 1101.3 symbol and written descriptions:
| Notation | Full Description (AS 1101.3) |
|---|---|
| 6 FW | 6 mm fillet weld, field weld |
| 8 SW | 8 mm fillet weld, shop weld |
| 10(FW)-100 | 10 mm fillet weld, field weld, 100 mm long |
| 8-75-200(3) | 8 mm fillet, 75 mm long, 200 mm pitch, 3 welds |
| 1/2 V-60-12 | Single V butt, one side only, 60 deg included angle, 12 mm root opening (partial penetration) |
Worked Example: Weld Symbol Interpretation
Problem: Interpret the following Australian weld symbols commonly found on structural steel shop drawings and translate them into plain English for a fabrication foreman.
Notation A: "8(FW)" with fillet symbol, hollow circle at junction, solid flag
Interpretation:
- 8 mm fillet weld, leg size = 8 mm, equal leg
- (FW) = field weld (welded on site)
- Hollow circle = weld all around (the entire perimeter of the connected member)
- Solid flag on the reference line = field weld (redundant with FW but common to include both)
Fabrication instruction: "This is an 8 mm fillet weld to be welded on site all around the perimeter of the connected part."
Notation B: "6-75-200(2)" with fillet symbol, arrow side
Interpretation:
- 6 mm fillet weld
- 75 mm long individual weld segments
- 200 mm centre-to-centre spacing between segments
- (2) = two welds (beginning and end segments, with the 200 mm spacing between them)
- Arrow side = weld on the near side as indicated by the arrow
Fabrication instruction: "This is a 6 mm intermittent fillet weld on the near side, with two segments each 75 mm long, spaced at 200 mm centres."
Notation C: "V 60 (GP)" with 1/2 above, no size
Interpretation:
- Single V butt weld
- 60 degrees included angle
- (GP) = general purpose weld category per AS/NZS 1554.1
- No size indicated = full penetration assumed
- 1/2 above the symbol = half the plate thickness as the effective throat... actually, "1/2 V" typically means partial penetration to half the plate depth.
Fabrication instruction: "Single V butt weld with a 60-degree preparation angle, partial penetration to half the plate thickness, general purpose category."
Result: The three notations have been correctly interpreted. Australian weld symbols are compact but precise once the conventions of AS 1101.3 are understood.
Frequently Asked Questions
What does "8 FW" mean on Australian structural drawings?
"8 FW" denotes an 8 mm fillet weld, field weld (FW). The "8" is the leg length of the fillet in millimetres. "FW" indicates the weld is a field weld (to be performed on site, not in the fabrication shop). If "SW" (shop weld) were indicated instead, the weld would be made in the workshop before delivery to site. Field welds are more expensive and require more inspection attention than shop welds.
How are intermittent fillet welds specified per AS 1101.3?
Intermittent fillet welds are specified with the format "size-length-pitch(number)". For example, "6-75-200(3)" means a 6 mm leg fillet weld, with each weld segment 75 mm long, spaced at 200 mm centre-to-centre, with 3 weld segments total. Staggered intermittent welds on opposite sides of the joint use a "Z" designation: "6-75Z200" means staggered welds, 6 mm fillet, 75 mm long at 200 mm centres, alternating side to side.
What is the difference between arrow side and other side in weld symbols?
The arrow side is the side of the joint physically pointed to by the arrow. The other side is the opposite side of the joint. Weld symbols placed below the reference line apply to the arrow side. Symbols placed above the reference line apply to the other side. If a fillet symbol appears on both sides of the reference line, fillet welds are required on both sides of the joint (typically the same size unless different dimensions are specified). The distinction matters because the arrow side is generally more accessible for welding.
What Australian standard governs welding symbols?
AS 1101.3-2005 (Graphical symbols for welding) is the Australian standard that governs welding symbols on engineering drawings. It is based on ISO 2553 (Welding and allied processes -- Symbolic representation on drawings -- Welded joints) and is consistent with the international symbol system. AS/NZS 1554.1 (Structural steel welding) references AS 1101.3 for the correct symbolic representation of welds and adds requirements for the written information that must accompany the symbols.
How are field welds distinguished from shop welds on Australian drawings?
Field welds are indicated by a solid flag (filled triangle) at the junction of the arrow and the reference line, or by the notation "FW" (field weld) adjacent to the weld symbol. Shop welds typically have no flag, or may be explicitly noted as "SW" (shop weld). In recent Australian practice, the solid flag is becoming the standard for field welds, replacing the older "FW" text notation. The flag or "FW" should appear on the drawing to clearly communicate to the fabricator and erector which welds are to be performed at each stage of construction.
Educational reference only. All weld symbols must be verified against AS 1101.3-2005 and the project specification. This information does not constitute professional engineering advice.