Welding Symbol Dictionary
Welding cannot take its proper place as an engineering tool unless
means are provided for conveying the information from the designer to
Welding symbols provide the means of placing complete welding information on drawings.
The scheme for symbolic representation of welds on engineering
drawings used in this manual is consistent with the "third angle" method
of projection. This is the method predominantly used in the United
The joint is the basis of reference for welding
symbols. The reference line of the welding symbol (fig. 3-2) is used to
designate the type of weld to be made, its location, dimensions, extent,
contour, and other supplementary information. Any welded joint
indicated by a symbol will always have an arrow side and an other side.
Accordingly, the terms arrow side, other side, and both sides are used
herein to locate the weld with respect to the joint.
The tail of the welding symbol is used for designating the welding and cutting
processes as well as the welding specifications, procedures, or the
supplementary information to be used in making the weld. If a welder
knows the size and type of weld, he has only part of the information
necessary for making the weld. The process, identification of filler
metal that is to be used, whether or not peening or root chipping is
required, and other pertinent data must be related to the welder. The
notation to be placed in the tail of the symbol indicating these data is
to be establish by each user. If notations are not used, the tail of
the symbol may be omitted.
Standard Locations of Elements of a Welding Symbol - Figure 3-2
Elements of a Welding Symbol
A distinction is made between the terms "weld symbol" and "welding
symbol". The weld symbol (fig. 3-3) indicates the desired type of weld.
The welding symbol (fig. 3-2) is a method of representing the weld
symbol on drawings. The assembled "welding symbol" consists of the
following eight elements, or any of these elements as necessary:
reference line, arrow, basic weld symbols, dimensions and other data,
supplementary symbols, finish symbols, tail, and specification, process,
or other reference. The locations of welding symbol elements with
respect to each other are shown in figure 3-2 above.
Basic Weld Symbols
Weld symbols are used to indicate the welding processes used in metal
joining operations, whether the weld is localized or "all around",
whether it is a shop or field weld, and the contour of welds. These
basic weld symbols (arc and gas weld symbols, resistance weld symbols, brazing, forbe Thermit, Induction and Flow Weld Symbols) are summarized below and illustrated in figure 3-3.
These symbols are used in many welding
processes in congestion with welding symbols and are used as shown in
Arc and Gas Supplementary Symbols
Basic and Supplementary Arc and Gas Weld Symbols - Figure 3-3
These welds are indicated by using a process or
specification reference in the tail of the welding symbol as shown in
When the use of a definite process is required (fig. 3-5), the process
may be indicated by one or more of the letter designations shown in
tables 3-1 and 3-2.
Definite Process Reference - Figure 3-5
Designation of Welding Processes by Letters
Letter designations have not been assigned to arc spot, resistance spot,
arc seam, resistance seam, and projection welding since the weld
symbols used are adequate.
Designation of Cutting Processes by Letters
When no specification, process, or other symbol, the tail may be omitted (fig. 3-6).
Other Common Weld Symbols
Figures 3-7 and 3-8 illustrate the
weld-all-around and field weld symbol, and resistance spot and
resistance seam welds.
Weld All Around and Field Weld Symbols
Resistance Spot and Resistance Seam Welds
Location Significance of Arrow
Fillet, Groove, Flange, Flash, and Upset welding symbols. For these
symbols, the arrow connects the welding symbol reference line to one
side of the joint and this side shall be considered the arrow side of
the joint (fig. 3-9).
Arrow Side Fillet Welding Symbol
The side opposite the arrow side is considered the
other side of the joint (fig. 3-10).
Other Side Fillet Welding Symbol
Projection Welding, Resistance Spot, Resistance Seam, Arc Seam, Arc Spot and Plug Welding Symbols
For these symbols, the arrow connects the
welding symbol reference line to the outer surface of one member of the
joint at the center line of the desired weld. The member to which the
arrow points is considered the arrow side member. The other member of
the joint shall be considered the other side member (fig. 3-11).
Plug and Slot Welding Symbols
When a joint is depicted as an area parallel to the
plane of projection in a drawing and the arrow of a welding symbol is
directed to that area, the arrow side member of the joint is considered
as the near member of the joint, in accordance with the usual
conventions of drafting (fig. 3-11).
Near Side Welding Symbol
When a joint is depicted by a single line on the drawing
and the arrow of a welding symbol is directed to this line, the arrow
side of the joint is considered as the near side of the joint, in
accordance with the usual conventions of drafting (fig. 3-12 and 3-13).
Arrow Side V-groove Welding Symbol
Other Side V-groove Welding Symbol
Location of Weld With Respect to Joint
Welds on the arrow side of the joint are shown by placing the weld symbol on the side of the reference line toward the reader (fig. 3-14)
Welds on the Arrow Side of the Joint
Welds on the other side of the joint are shown by placing the weld
symbol on the side of the reference line away from the reader (fig.
Welds on the Other Side of the Joint
Welds on both sides of the joint are shown by placing weld symbols on
both sides of the reference line, toward and away from the reader (fig.
No Side Significance
Resistance spot, resistance seam, flash, weld symbols have no arrow side
or other side significance in themselves, although supplementary
symbols used in conjunction with these symbols may have such
significance. For example, the flush contour symbol (fig. 3-3) is used
in conjunction with the spot and seam symbols (fig. 3-17) to show that
the exposed surface of one member of the joint is to be flush.
Resistance spot, resistance seam, flash, and upset weld symbols shall be
centered on the reference line (fig. 3-17).
Spot Seam and Flash or Upset Weld Symbols
References and General Notes
Symbols With References
When a specification, process, or other
reference is used with a welding symbol, the reference is placed in the
tail (fig 3-4).
Symbols Without References
Symbols may be used without specification, process, or other references when:
- A note similar to the following appears on the
drawing: "Unless otherwise designated, all welds are to be made in
accordance with specification no...."
- The welding procedure to be used is described elsewhere, such as in shop instructions and process sheets.
General notes similar to the
following may be placed on a drawing to provide detailed information
pertaining to the predominant welds. This information need not be
repeated on the symbols:
- "Unless otherwise indicated, all fillet welds are 5/16 in. (0.80 cm) size."
- "Unless otherwise indicated, root openings for all groove welds are 3/16 in. (0.48 cm)."
When use of a definite process
is required, the process may be indicated by the letter designations
listed in tables 3-1 and 3-2 (fig. 3-5).
Symbol Without a Tail
When no specification,
process, or other reference is used with a welding symbol, the tail may
be omitted (fig. 3-6).
Weld All-Around and Field Weld Symbols
Welds extending completely around a joint are indicated by mans of
the weld-all-around symbol (fig. 3-7). Welds that are completely around a
joint which includes more than one type of weld, indicated by a
combination weld symbol, are also depicted by the weld-all-around
symbol. Welds completely around a joint in which the metal intersections
at the points of welding are in more than one plane are also indicated
by the weld-all-around symbol.
Field welds are welds not made in a shop or at the
place of initial construction and are indicated by means of the field
weld symbol (fig. 3-7).
Extent of Welding Denoted by Symbols
Symbols apply between abrupt changes in the
direction of the welding or to the extent of hatching of dimension
lines, except when the weld-all-around symbol (fig. 3-3) is used.
Welding on hidden joints may be
covered when the welding is the same as that of the visible joint. The
drawing indicates the presence of hidden members. If the welding on the
hidden joint is different from that of the visible joint, specific
information for the welding of both must be given.
Location of Weld Symbols
Weld symbols, except resistance spot and resistance seam, must be
shown only on the welding symbol reference line and not on the lines of
b. Resistance spot and resistance seam weld symbols may be placed directly at the locations of the desired welds (fig. 3-8).
Use of Inch, Degree and Pound Marks
Inch marks are used for indicating the diameter of arc spot, resistance
spot, and circular projection welds, and the width of arc seam and
resistance seam welds when such welds are specified by decimal
In general, inch, degree, and pound marks may or may not be used on welding symbols, as desired.
Construction of Symbols
Fillet, bevel and J-groove, flare bevel groove, and corner flange
symbols shall be shown with the perpendicular leg always to the left
In a bevel or J-groove weld symbol, the arrow shall point with a
definite break toward the member which is to be chamfered (fig. 3-19).
In cases where the member to be chamfered is obvious, the break in the
arrow may be omitted.
Information on welding symbols shall be placed to read from left to
right along the reference line in accordance with the usual conventions
of drafting (fig. 3-20).
For joints having more than one weld, a symbol shall be shown for each weld (fig 3-21).
The letters CP in the tail of the arrow indicate a complete
penetration weld regardless of the type of weld or joint preparation
When the basic weld symbols are inadequate to indicate the desired
weld, the weld shall be shown by a cross section, detail, or other data
with a reference on the welding symbol according to location
specifications given in para 3-7 (fig. 3-23).
Two or more reference lines may be used to indicate a sequence of
operations. The first operation must be shown on the reference line
nearest the arrow. Subsequent operations must be shown sequentially on
other reference lines (fig. 3-24).
Additional reference lines may also
be used to show data supplementary to welding symbol information
included on the reference line nearest the arrow. Test information may
be shown on a second or third line away from the arrow (fig. 3-25).
required, the weld-all-around welding symbol must be placed at the junction of
the arrow line and reference line for each operation to which it applies
(fig. 3-26). The field weld symbol may also be used in this manner.
References for Welding Symbol Dictionary
Welding Symbols and Conventions
Page Author: Jeff Grill