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Symbols For Size Of Fillet Welds

In the case of welding, symbols are often used as guides and instructions to complete the project. The symbols are the graphical representation of the project outline alongside precise information on the welding joint.

Since the symbols are technique-specific, fillet welding also has its own symbols. As per the American Welding Society, a fillet weld is a weld of triangular cross-sections of two surfaces, which lay perpendicular to one another in the corner or the fusing joint.

If you need to complete a fillet welding project successfully, you need to understand the fillet welding symbols and use them in the right way. So, let’s start the journey to understand and learn more about the fillet weld symbols that are commonly used.

Symbols For Size Of Fillet Welds

A fillet weld symbol comprises a reference line, an arrow line, the tail and the weld symbol, including the leg size. The reference line denotes the joint line of the fused two work pieces. It is usually drawn horizontally and comes with weld-type information. The reference line then connects with the arrow line and the tail. The arrow line indicates the welding location or where the bead is formed.

Fillet weld symbols are used with an arrow side to denote the area below the reference line, and the other side denotes the area above the reference line.

The arrow is sometimes given on both sides to signify the area above and below the reference line. If the arrow is placed on both sides of the reference line, the weld is called a double fillet weld.

In general, fillet welds come with size. It is noted on the left of the fillet weld symbol. The deposited fillet weld size should not be led than the size described in the image.

In case of unequal legs, you must display the parentheses to the left of the welding symbol. Please remember that the symbol does not denote the orientation of the welding. You may need to denote that separately.

For a double fillet weld, you will have to denote the size on both sides of the joint; the weld size should be displayed on both sides. If the welds vary in size, you mention that too.

If there is a root opening, you will have to denote the penetration depth with further details and specifications.

Length Of Fillet Welds

The length of the field weld is mentioned on the eight of the filler weld symbol. The length dimension is not usually mentioned if the welding is entirely through the length with changing directions due to intricate joints.

Sometimes, the specific lengths are also mentioned with symbols along the dimension lines.

The Extent Of Fillet Welding

To display the extent of the welding in the symbol, shaded hatchings are used. While some welders use definite lines, others may not use the lines.

If you need to weld at different corners of the work piece, you must use additional arrows for each joint. On top of that, you must also indicate the direction of the welding with the arrows.

Dimensioning Of Intermittent Fillet Welding

The pitch of the centre-to-centre spacing length in the case of intermittent fillet welding is displayed through the space between the increment centres of one side. It is usually denoted on the right side of the reference line.

In the case of chain intermittent fillet welding, you will have to specify the dimension of both sides of the reference line. Please note that chain intermittent fillet welds are usually opposite to each other. So, denote those as per that condition.

Similarly, you must indicate the welding dimensions on both sides of the reference line for staggered intermittent fillet welding. On top of that, try to place the welds asymmetrically through the welding length.

Termination Of Intermittent Fillet Welding

In the case of intermittent fillet welding, you must indicate the termination of welding at the end of the dimensional length of the diagram. You must keep the space if you are using intermittent welding in between the continuous fillet welding. The space you need to keep is equal to pitch space minus the length of one single increment.

Furthermore, distinct symbols are used to differentiate between the intermittent and the continuous fillet symbol.

Surface Contour Of The Fillet Welds

Fillet welds are usually done on flat, concave or convex surfaces without recourse. So, add a symbol of the surface type alongside the arrow.

If the field welds are made flat-faced mechanically, you must use the flush contour and the standard finish symbols beside the weld symbols. Indicate the surface specifically at the locations on the diagram.

If the welds are finished on a convex surface, welders use the convex contour symbol and standard finish symbol.

Similarly, the concave contour symbol and the standard finish symbol are used for concave surfaces.


For welders, the filler welding symbols serve as a rough project outline and guideline. Hence, welders must prepare the diagram sincerely with proper calculation and patience. On top of that, having a clear understanding of the diagram and symbols also allows you to understand any fillet welding project to make it successful quickly.

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