Guide to Fillet Weld Symbols

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Dimensions of fillet welds must be shown on the same side of the reference line as the weld symbol (A, fig. 3-27).

When fillet welds are indicated on both sides of a joint and no general note governing the dimensions of the welds appears on the drawing, the dimensions are indicated as follows:

  1. When both welds have the same dimensions, one or both may be dimensioned (B or C, fig. 3-27).
  2. When the welds differ in dimensions, both must be dimensioned (D, fig. 3-27).

When fillet welds are indicated on both sides of a joint and a general note governing the dimensions of the welds appears on the drawing, neither weld need be dimensioned. However, if the dimensions of one or both welds differ from the dimensions given in the general note, both welds must be dimensioned (C or D, fig. 3-27).

Dimensions of Fillet Welds
Dimensions of Fillet Welds – Figure 3-27

Symbols for Size of Fillet Welds

The size of a fillet weld must of a fillet weld be shown to the left of the weld symbol (A, fig. 3-27).

The size of the fillet weld with unequal legs must be shown in parentheses to the left of the weld symbol. Weld orientation is not shown by the symbol and must be shown on the drawing when necessary (E, fig. 3-27).

Unless otherwise indicated, the deposited fillet weld size must not be less than the size shown on the drawing.

When penetration for a given root opening is specified, the inspection method for determining penetration depth must be included in the applicable specification.

Length of Fillet Welds

The length of a fillet weld, when indicated on the welding symbol, must be shown to the right of the weld symbol (A through D, fig. 3-27).

When fillet welding extends for the full distance between abrupt changes in the direction of the welding, no length dimension need be shown on the welding symbol.

Specific lengths of fillet welding may be indicated by symbols in conjunction with dimension lines (fig. 3-28).

Combined Intermittent and Continuous Welds
Combined Intermittent and Continuous Welds – Figure 3-28

The extent of Fillet Welding

Use one type of hatching (with or without definite lines) to show the extent of fillet welding graphically.

Fillet welding extending beyond abrupt changes in the direction of the welding must be indicated by additional arrows pointing to each section of the joint to be welded (fig. 3-29) except when the weld-all-around fillet weld symbols are used.

Extent of Fillet Welds
Fillet Weld on 3 Sides, No Weld at Corners – Figure 3-29

Dimensioning of Intermittent Fillet Welding

The pitch (center-to-center spacing) of intermittent fillet welding shall be shown as the distance between centers of increments on one side of the joint.

The pitch of intermittent fillet welding shall be shown to the right of the length dimension (A, fig 3-27).

Dimensions of chain intermittent fillet welding must be shown on both sides of the reference line. Chain intermittent fillet welds shall be opposite each other (fig. 3-30).

Symbols for Dimensions of Chain Intermittent Fillet Welds
Symbols for Dimensions of Chain Intermittent Fillet Welds

Dimensions of staggered intermittent fillet welding must be shown on both sides of the reference line as shown in the fillet weld symbols pictured in figure 3-31.

Dimensions of Staggered Intermittent Fillet Welds
Dimensions of Staggered Intermittent Fillet Welds

Unless otherwise specified, staggered intermittent fillet welds on both sides shall be symmetrically spaced as in the fillet weld symbols in figure 3-32.

Length and Pitch of Increments of Staggered Intermittent Welding
Applications of Dimensions to Intermittent Fillet Weld Symbols

If required by the actual length of the joint, the length of the increment of the welds at the end of the joint should be increased to terminate the weld at the end of the joint.

Termination of Intermittent Fillet Welding

When intermittent fillet welding is used by itself, the symbol indicates that increments are located at the ends of the dimensioned length.

When intermittent fillet welding is used between continuous fillet welding, the symbol indicates that spaces equal to the pitch minus the length of one increment shall be left at the ends of the dimensioned length.

Separate symbols must be used for intermittent and continuous fillet welding when the two are combined along one side of the joint (fig. 3-28).

Surface Contour of Fillet Welds

Fillet welds that are to be welded approximately flat, convex, or concave faced without recourse to any method of finishing must be shown by adding the flush, convex, or concave contour symbol to the weld symbol, in accordance with the location specifications given here (A, fig. 3-33).

Surface Contour of Fillet Welds
Finish symbols used here indicate the method of finishing (” c” = chiping, “G” = grinding, “H” = hammering, “M” = machining), not the degree of finish.

Fillet welds that are to be made flat-faced by mechanical means must be shown by adding both the flush contour symbol and the user’s standard finish symbol to the weld symbol, in accordance with location specifications given in paragraph 3-7 (B, fig. 3-33).

Fillet welds that are to be mechanically finished to a convex contour shall be shown by adding both the convex contour symbol and the user’s standard finish symbol to the weld symbol, in accordance with location specifications given in paragraph 3-7 (C, fig. 3-33).

Fillet welds that are to be mechanically finished to a concave contour must be shown by adding both the concave contour symbol and the user’s standard finish symbol to the weld symbol in accordance with the location specification given here.

In cases where the angle between fusion faces is such that the identification of the type of weld and the proper weld symbol is in question, the detail of the desired joint and weld configuration must be shown on the fillet weld symbols on the drawing.


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About Jeff Grill

Jeff Grill hails from Long Island, a 118 mile stretch of land that starts just off the coast of Manhattan and stretches deep into the Atlantic ocean. He has always been interested in welding from an early age and has the cuts and bruises to prove it as he set out to work with a variety of metals.


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