weld and welding symbols welding theory weldingtheory
GENERAL
Welding cannot take its proper place as an engineering tool unless means are provided for conveying the information from the designer to the workmen. 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 States.
The joint is the basis of reference for welding symbols. The reference line of the welding symbol .
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 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.
ELMENTS OF A WELDING SYMBOL
A distinction is made between the terms "weld symbol" and "welding symbol". The weld symbol .
3) indicates the desired type of weld. The welding symbol 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.
BASIC WELD SYMBOLS
a. General. 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 are summarized below and illustrated in figure .
b. Arc and Gas Weld Symbols. See figure .
c. Resistance Weld Symbols. See figure .
d. Brazing, Forge, Thermit, Induction, and Flow Weld Symbols.
(1) These welds are indicated by using a process or specification reference in the tail of the welding symbol as shown in figure.
