Easy to Remember Welding Symbols Everyone Should Know

Welding cannot take its due place as an engineering tool until communicating information from the designer to the workers is established. Welding symbols enable the inclusion of comprehensive welding information on drawings.

The methodology employed in this document for the symbolic representation of welds on engineering drawings is consistent with the “third angle” projection approach.

It is the most often utilized approach in the United States.

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The joint serves as the focal point for welding symbols. The welding symbol’s reference line (fig. 3-2) is used to indicate the sort of weld to be made and its location, size, extent, contour, and other auxiliary information.

Any welded joint denoted by a symbol will always have two sides: one with an arrow and one without. As such, the words arrow side, another side, and both sides are used in this section to refer to the location of the weld with relation to the joint.

The welding symbol’s tail is used to denote the welding and cutting processes and the welding requirements, methods, or supplemental information required to complete the weld.

If a welder is simply aware of the size and type of weld, he is only equipped with a portion of the information essential to complete the weld.  The welder needs to know the method, the filler metal, whether or not peening or root chipping is needed, and any other important information about how to complete the job.

Each user is responsible for establishing the notation to be included in the tail of the symbol signifying these data. If no notes are used, the symbol’s tail may be omitted.

Symbols for Welding

Welding Symbols

A Welding Symbol’s Components

The phrases “weld symbol” and “welding symbol” are interchangeable.

  • The weld symbol (fig. 3-3) denotes the sort of weld intended.
  • The welding symbol (fig. 3-2) depicts the weld symbol on designs.

The assembled “welding symbol” is composed of the following eight elements or any combination of these elements:

  • Line of reference
  • Arrow
  • Welding symbols fundamentals
  • Dimensions and additional information
  • Additional symbols
  • Symbols of completion
  • Tail,
  • Specification
  • Procedures or other citations

The relative positions of welding symbol elements are depicted in Figures 3-2 above.

Some Basic Welding Symbols

Welding Symbols

Weld symbols are used to denote the welding procedures used in metal joining operations, the location of the weld (localized or “all-around”), the type of weld (shop or field), and the shape of welds.

The following table summarises and illustrates these fundamental weld symbols (arc and gas weld symbols, resistance weld symbols, brazing, forge thermit, induction, and Flow Weld Symbols).

Additional Symbols

These symbols are used in conjunction with welding symbols in various welding techniques, as illustrated in Figure 3-3.

Supplementary Symbols for Arc & Gas

Welding Symbols
Welding Symbols

As illustrated in Figures 3-4, these welds are indicated by including a processor specification reference in the tail of the welding symbol.

Welding Symbols

When a specific procedure is required (fig. 3-5), it may be denoted by one or more of the letter designations listed in tables 3-1 and 3-2.

Welding Symbols

Welding Processes Are Denoted by Letters

Welding Symbols

Since the weld symbols employed are adequate, no letter names have been allocated to arc spot, resistance spot, arc seam, resistance seam, or projection welding.

Using Letters to Denote Cutting Processes

Welding Symbols

The tail may be omitted if no specification, process, or other symbol is specified (fig. 3-6).

Welding Symbols

Other Frequently Used Weld Symbols

The symbols for weld-all-around and field welds and resistance spot and resistance seam welds are shown in Figures 3-7 and 3-8.

Symbols for Welding All-Around and Field Welding

Welding Symbols

Welding of Resistance Spots and Resistance Seams

Welding Symbols

The Arrow’s Geographical Significance

The arrow connects the welding symbol reference line to one side of the joint in the case of the Fillet, Groove, Flange, Flash, and Upset welding symbols, and this site is referred to as the arrow side of the joint (fig. 3-9).

The symbol for Arrow Side Fillet Welding

Welding Symbols

The symbol for Other Side Fillet Welding

Welding Symbols

Symbols for Projection Welding, Resistance Spot Welding, Resistance Seam Welding, Arc Seam Welding, Arc Spot Welding, and Plug Welding

The arrow connects the welding symbol reference line to the outside surface of one joint part at the desired weld centerline. The arrow side member is the member to which the arrow points. The opposite joint member is the “other side member” (fig. 3-11).

Symbols for Welding Plugs and Slots

Welding Symbols

Member in close proximity

When a joint is portrayed in a drawing as an area parallel to the projection plane and an arrow of a welding sign is directed to that area, the arrow side member of the joint is deemed to be the near member of the joint, following standard drafting practices (fig. 3-11).

The symbol for Near Side Welding

When a joint is represented on a drawing by a single line and the arrow of a welding sign is directed to this line, the arrow side of the joint is considered to be the near side, by standard drafting practices (fig. 3-12 and 3-13).

V-groove Welding Symbol on the Arrow Side

Welding Symbols

V-groove Welding Symbol on the Reverse

Welding Symbols

The Position Of The Weld-In Relation To The Joint

Side of the Arrow

Welds on the arrow side of the joint are indicated by positioning the weld symbol on the reader’s side of the reference line (fig. 3-14)

Welds on the Joint’s Arrow Side

Welding Symbols

The Alternate

Welds on the opposite side of the joint are indicated by positioning the weld symbol on the reference line opposite the reader (fig. 3-15).

Welds on the Joint’s Other Side

Welding Symbols

Both Parties

Welds on both sides of the joint are indicated by positioning weld symbols toward and away from the reader on both sides of the reference line (fig. 3-16).

No Secondary Importance

The resistance spot, resistance seam, flash, and weld symbols do not have an inherent arrow or other side value, although extra symbols used in conjunction with these symbols may have such importance.

For instance, the flush contour symbol (fig. 3-3) is used in conjunction with the spot and seam symbols (fig. 3-17) to indicate that the exposed surface of one joint member should be flush.

The symbols for the resistance spot, seam, flash, and upset weld shall be centered on the reference line (fig. 3-17).

Symbols for Spot Seam and Flash or Upset Weld

Welding Symbols

References And General Notes

Symbols With Contextual References

When a welding sign is used in conjunction with a standard, method, or reference, the reference is inserted in the tail (fig 3-4).

Without References Symbols

Symbols may be used in the absence of a specification, process, or other references when the following conditions apply:

  1. On the drawing, a note similar to the following appears: “Unless otherwise specified, all welds shall be done in accordance with specification no…”
  2. The appropriate welding procedure is given elsewhere, such as in-shop instructions and process documents.

General Notes

On a design, general remarks similar to the following may provide specific information about the primary welds. These details do not have to be repeated on the symbols:

  1. “Unless specified otherwise, all fillet welds are 5/16 in. (0.80 cm) in diameter.”
  2. “Unless otherwise specified, all groove welds have root holes of 3/16 in. (0.48 cm).”

Indication of the Process

When a specific procedure is required, it may be denoted by one of the letter designations mentioned in Tables 3-1 and 3-2. (fig. 3-5).

Without a Tail Symbol

The tail may be omitted when a welding symbol is not associated with a standard, method, or reference (fig. 3-6).

Symbols For Welding All-Around And Field Welding

The weld-all-around sign denotes welds that extend entirely around a joint (fig. 3-7). Welds that completely encircle a joint and incorporate multiple types of welds, as indicated by the combination weld sign, are also represented by the weld-all-around symbol. 

Additionally, the weld-all-around symbol denotes welds surrounding a joint and having metal crossings in more than one plane at the welding locations.

Field welds are not performed in a shop or at the initial location of construction and are denoted by the field weld symbol (fig. 3-7).

Symbols Denote The Extent Of Welding

Sudden Changes

Unless the weld-all-around symbol (fig. 3-3) is used, symbols apply between sudden changes in the direction of welding or the extent of hatching on dimension lines.

Joints That Are Not Visible

Welding on hidden joints may be concealed if identical to the visible joint’s welding. The illustration denotes the presence of concealed members. If the hidden joint requires a different type of welding than the visible joint, you must have specific information for both types of welding.

Where Are The Weld Symbols Located?

Weld symbols must be displayed exclusively on the welding symbol reference line and not on the drawing lines, except for resistance spot and resistance seam.

Resistance spot and resistance seam weld symbols may be positioned immediately over the desired weld areas (fig. 3-8).

Utilization of Inch, Degree, and Pound Marks

When decimal dimensions define such welds, inch marks are used to indicate the diameter of arc spot, resistance spot, and circular projection welds, as well as the width of arc seam and resistance seam welds.

In general, inch, degree, and pound symbols may be utilized or not on welding symbols, depending on the application.

Symbol Construction

Fillet, bevel, J-groove, flare bevel groove, and corner flange symbols should always be drawn in the same place every time. With the parallel leg to the left (fig. 3-18).

Welding Symbols

The arrow in a bevel or J-groove weld sign must point directly toward the member to be chamfered (fig. 3-19). If the member to be chamfered is readily apparent, the break in the arrow may be omitted.

Welding Symbols

The information on welding symbols shall be arranged in a left-to-right direction along the reference line, in accordance with standard drafting practices (fig. 3-20).

Welding Symbols

For joints with several welds, a separate symbol should be given for each weld (fig 3-21).

Welding Symbols

The letters CP in the tail of the arrow denote a fully penetrated joint (CJP) weld independent of the type of weld or joint preparation (fig. 3-22).

Welding Symbols

When the basic weld symbols are insufficient to represent the intended weld, the weld shall be represented by a cross-section, detail, or other data regarding the welding symbol following the placement standards set out in paragraphs 3-7. (fig. 3-23).

Welding Symbols

Two or more reference lines may denote a sequence of operations.

The initial operation must be depicted on the reference line immediately adjacent to the arrow. Subsequent operations must be depicted in sequence on additional reference lines (fig. 3-24).

Welding Symbols

Additionally, additional reference lines may be utilized to illustrate data not included in the welding symbol information on the reference line closest to the arrow.

Test results may be displayed on a second or third line to the right of the arrow (fig. 3-25).

Welding Symbols

When applicable, the weld all-around welding symbol must be put at the intersection of the arrow and reference lines for each operation (fig. 3-26). 

Welding Symbols

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