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
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
- Welding symbols fundamentals
- Dimensions and additional information
- Additional symbols
- Symbols of completion
- Procedures or other citations
The relative positions of welding symbol elements are depicted in Figures 3-2 above.
Some Basic 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).
These symbols are used in conjunction with welding symbols in various welding techniques, as illustrated in Figure 3-3.
Supplementary Symbols for Arc & Gas
As illustrated in Figures 3-4, these welds are indicated by including a processor specification reference in the tail of the welding symbol.
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 Processes Are Denoted by Letters
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
The tail may be omitted if no specification, process, or other symbol is specified (fig. 3-6).
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 of Resistance Spots and Resistance Seams
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
The symbol for Other Side Fillet Welding
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
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
V-groove Welding Symbol on the Reverse
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
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
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
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:
- On the drawing, a note similar to the following appears: “Unless otherwise specified, all welds shall be done in accordance with specification no…”
- The appropriate welding procedure is given elsewhere, such as in-shop instructions and process documents.
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:
- “Unless specified otherwise, all fillet welds are 5/16 in. (0.80 cm) in diameter.”
- “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
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.
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).
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.
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).
For joints with several welds, a separate symbol should be given for each weld (fig 3-21).
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).
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).
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).
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).
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).