Melt-thru and Back or Backing Weld Symbols


Overview

Back and Backing Weld Symbol

The backing or back weld symbol (fig. 3-50) must be used to indicate bead-type back/backing welds of single-groove welds.

Back/backing welds of single-groove welds must be shown by placing a back or backing weld symbol on the side of the reference line opposite the groove weld symbol (fig. 3-50).

Dimensions of back or backing welds should not be shown on the welding symbol. If it is desired to specify these dimensions, they must be shown on the drawing.

Back or Backing Weld Symbol

Surface Contour of Back or Backing Welds. The contour symbols (fig. 3-55) for back or backing welds are indicated in the same manner as that for fillet welds.

Overview Melt Thru Weld Symbol

Melt-Thru Welding Symbol

The melt-thru symbol shall be used where at least 100 percent joint penetration of the weld through the material is required in welds made from one side only (fig. 3-56).

Melt-thru welds shall be shown by placing the melt-thru weld symbol on the side of the reference line opposite the groove weld, flange, tee, or corner weld symbol (fig. 3-56).

Melt-thru Weld Symbol

Dimensions of melt-thru welds should rot be shown on the welding symbol. If it is desired to specify these dimensions, they must be shown on the drawing.

Surface Contour of Melt-thru Welds. The contour symbols for melt-thru welds are indicated in the same manner as that for fillet welds (fig. 3-57).

Surface Contour of Melt

Overview Surfacing Weld Symbol

The surfacing weld symbol shall be used to indicate surfaces built up by welding (fig. 3-58), whether built up by single-or multiple-pass surfacing welds.

Symbol for Size of Surfaces Built Up By Welding

The surfacing weld symbol does not indicate the welding of a joint and thus has no arrow or other side significance. This symbol shall be drawn on the side of the reference line toward the reader and the arrow shall point clearly to the surface on which the weld is to be deposited.

Size of Built-up Surfaces

The size (height) of a surface built up by welding shall be indicated by showing the minimum height of the weld deposit to the left of the weld symbol. The dimensions shall always be on the same side of the reference line as the weld symbol (fig. 3-58). When no specific height of weld deposit is desired, no size dimension need be shown on the welding symbol.

Extent, Location and Orientation of Surfaces Built Up By Welding

When the entire area of a plane or curved surface is to be built up by welding, no dimension, other than size, need be shown on the welding symbol. If only a portion of the area of a plane or curved surface is to be built up by welding, the extent, location, and orientation of the area to be built up shall be indicated on the drawing.

Welding Jobs in Your Area

Powered by ZipRecruiter

For Additional Reading on the Surfacing, Melt-thru and Backing Weld Symbol

Ask a Welder Now
4 Welders are Online Now.
A Question is Answered Every 12 Seconds!
Ask A Welder >


Page Author:

Welding Jobs in Your Area