INTRODUCTION TO ISO SYMBOLOGY

In addition to American Welding Society (AWS) weld symbols, a set of weld symbols has been developed for international use, identified as “International Standard Symbols for Welding.” These symbols (often referred to as ISO symbols) have been approved by the International Organi­zation of Standardization and are found in the publication International Standard 2553. They are intended for application on drawings used for the manufacture of products marketed inter­nationally.

International weld symbols fall into two prin­cipal categories: (1) elementary and (2) supple­mentary. They are illustrated in Table 26.1 and Table 26.2. In reviewing Table 26.1, note that there are two symbols unique to ISO: the single - V butt weld with broad root face, and the single­bevel butt weld with broad root face. Note also that there are variations in the descriptions of several of the weld symbols when compared to AWS descrip­tions of similar symbols. Each elementary symbol represents the shape of the weld to be made and, similarly, each supplementary symbol is indicative of the shape of the weld surface required.

In addition to elementary and supplementary symbols, ISO includes a classification of symbols entitled “Complementary Indications.” These con­sist of the (1) peripheral

weld, (2) field or site weld,

and (3) the welding process which is represented by a number included in the tail (also identified by AWS as the “tail”). The number in the tail corresponds to a welding process found in ISO publication 4063. Note that the tail is applied to the symbol only when a welding process is to be indicated.

TABLE 26.1 ■ Elementary symbols.

Note: Dashed lines are not a part of the symbol.

1Butt welds between plates with raised edges (symbol 1) not completely penetrated are symbolized as square butt welds (symbol 2) with the weld thickness shown.