Backing & Groove Weld Symbols

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Groove Weld Symbols

Dimensions of the welds must be shown on the same side of the reference line as the weld symbol (fig. 3-42).

When no general note governing the dimensions of double groove welds appears, dimensions shall be shown as follows:

When both welds have the same dimensions, one or both may be dimensioned (fig. 3-43)

Groove Weld Dimensions With No General Note – Fig 3-43

When the welds differ in dimensions, both shall be dimensioned (fig. 3-44).

When a general note governing the dimensions of the welds appears, the dimensions of double groove welds shall be indicated as follows:

If the dimensions of both welds are as indicated in the note, neither symbol need be dimensioned.
When the dimensions of one or both welds differ from the dimensions given in the general note, both welds shall be dimensioned (fig. 3-44).

Groove Welds with Differing Dimensions – Fig 3-44.

Size of Groove Welds

The size of the welds shall be shown to the left of the weld symbol (fig. 3-44).

Specifications for the welds with no specified root penetration are shown as follows:

The size of single groove and symmetrical double groove welds which extend completely through the member or members being joined need not be shown on the welding symbol (A and B, fig. 3-45)
Fig. 3-45. Symbols for Weld Dimensions For Welds Extending Through the Members Joined
The size of the welds which extend only partly through the member members being joined must be shown on the welding symbol (A and B, fig. 3-46).
Fig. 3-46. Symbols for Groove Weld Dimensions For Welds Extending Partly Through the Members Joined

The welds, size of the welds with specified root penetration, except square must be indicated by showing the depth of chamfering and the root penetration separated by a plus mark and placed to the left of the weld symbol.

The depth of chamfering and the root penetration must read in that order from left to right along the reference line (A and B, fig. 3-47). The size of square groove welds must be indicated by showing only the root penetration.

Fig. 3-47 – Symbols for Dimensions of Groove Welds With Specified Root Penetration

The size of flare groove welds is considered to extend only to the tangent points as indicated by dimension lines (fig. 3-48).

Fig. 3-48 – Symbols for Flare Groove Welds

Groove Dimensions

Root opening, groove angle, groove radii, and root faces of the U and J groove welds are the user’s standard unless otherwise indicated.

When the user’s standard is not used, the weld symbols are as follows:

Root opening is shown inside the weld symbol (fig. 3-49).
Fig. 3-49 – Root Opening Symbols
Groove angle of the welds is shown outside the weld symbol (fig. 3-42).
Fig. 3-42 – Symbols for Weld Dimensions

Groove radii and root faces of U and J groove welds are shown by a cross section, detail, or other data, with a reference to it on the welding symbol, in accordance with location specifications..

Back and Backing Welds

Bead-type back and backing welds of single-groove welds shall be shown by means of the back or backing weld symbol (fig. 3-50).

Back or Backing Weld Symbol

Welds that are to be welded approximately flush without recourse to any method of finishing shall be shown by adding the flush contour symbol to the weld symbol, in accordance with the location specifications given in paragraph 3-7 (fig. 3-52).

Symbol for Contours Obtained by Welding

Welds that are to be made flush by mechanical means shall be shown by adding the flush contour symbol and the user’s standard finish symbol to the weld symbol, in accordance with the location specifications given in paragraph 3-7 (fig. 3-53).