A graphical representation of a weld.
Standard welding symbols are used to indicate specified welding, brazing, and nondestructive examination information on engineering drawings. The symbols convey design requirements to the welding shop in a concise manner, and provide an accurate means for welding personnel to adhere to original designs.
A welding symbol can be used, for example, to specify the type of weld, groove design, weld size, welding process, face and root contours, sequence of operations, length of weld, and other information. In cases where all information cannot be conveyed by a symbol alone, supplementary notes or dimensional details, or both, are sometimes required to provide the shop with complete requirements. The designer must be sure that the requirements are fully presented on the drawing or specifications.
Nondestructive examination requirements for welded or brazed joints can also be specified with symbols. The specific inspection methods to be used are indicated on the symbols. The appropriate inspection methods depend on the quality requirements with respect to discontinuities in welded or brazed joints.
The complete system of symbols is described in ANSUAWS A2.4, Standard Symbols for Welding, Brazing, and Nondestructive Examination, published by the American Welding Society, Miami, Florida; latest edition. This publication should be consulted when selecting the appropriate symbols for describing the desired joint and inspection requirements.
Nondestructive testing methods, procedures, and the type of discontinuities that each method will reveal are contained in ANSVAWS B1.lO, Guide for the Nondestructive Inspection of Welds, Miami, Florida: American Welding Society; latest edition.
In practice, most designers will need only a few of the many available symbols. The following information describes the fundamentals of the symbols and how to apply them.
Basic Weld Symbols– The terms weld symbol and welding symbol have different meanings. A weld symbol indicates the required type of weld or braze. The welding symbol includes the weld symbol and supplementary information. A complete welding symbol consists of the following elements:
(1) Reference line
(2) Arrow
(3) Basic weld symbol
(4) Dimensions and other data
(5) Supplementary symbols
(6) Finish symbols
(7) Tail
(8) Specification, process, or other references
All elements need not be used unless required for clarity.
Location of Elements- The elements of a welding symbol have standard locations with respect to each other.
Location Significance of Arrow- The arrow element in a welding symbol in conjunction with the reference line determines the arrow side and the other size of a weld, as shown in 7. The arrow side is always closest to the reader when viewed from the bottom of the drawing.
The symbol depicting an arrow side weld is always placed below the reference line. The weld symbol depicting an other-side weld is placed above the reference line; i.e., away froin the reader. Welds on both sides of a joint are shown by placing weld symbols on both sides of the reference line.
Some weld symbols have no arrow or other-side significance. However, supplementary symbols used in conjunction with these weld symbols may have significance. For example, welding symbols for resistance spot and seam welding have no side significance, but GTAW, EBW, or other spot and seam welds may have arrow and other-side significance.
References- When a specification, process, test, or other reference is needed to clarify a welding symbol, the reference is placed in a tail on the welding symbol. For example, the letters CJP may be used in the tail of the arrow to indicate that a complete joint penetration groove weld is required, regardless of the type of weld or joint preparation. The tail may be omitted when no specification, process, or other reference is required with a welding symbol.
Dimensions- Dimensions of a weld are shown on the same side of the reference line as the weld symbol. The size of the weld is shown to the left of the weld symbol, and the length of the weld is placed on the right. If a length is not given, the weld symbol applies to that portion of the joint between abrupt changes in the direction of welding or between specified dimension lines. If a weld symbol is shown on each side of the reference line, dimensions are required to be given for each weld, even though both welds are identical.
SI units are preferred to U.S. customary units when specifying dimensions.If a weld in a joint is to be intermittent, the length of the increments and the pitch (center-to-center spacing) are placed to the right of the weld symbol.
The location on the symbol for specifying groove weld root opening, groove angle, plug or slot weld filling depth, the number of welds required in a joint. See also WELD SYMBOL.