Graphical Symbols

General Principles for the Presentation of Graphical Symbols

This guide is presented to establish guiding principles for the uniform presentation and propagation of graphic symbols.

It is consistent with International Standard ISO 3461.

This International Standard applies to graphic symbols which may be:

  1. Placed on equipment or parts of equipment of any kind in order to instruct the persons handling the equipment as to its use and operation;
  2. Placed on sites and ways where people may assemble or move, giving them instructions, such as prohibitions, warnings, rules or limits, regarding their behavior;
  3. Used in pictorial reproductions, such as plans, drawings, layouts, guidelines and similar documents.

Note: The standardization of letters, numerals, punctuation marks, mathematical signs and symbols, and symbols for quantities and units is excluded but such may be used as a component of a graphic symbol.

Graphic Symbols for Metal Joining (Welding)

Welding or metal joining cannot be considered as an engineering tool unless means are provided for conveying the engineering information from the designer to the workman. This is accomplished by use of nationally recognized welding symbols. In these days of extended product warranties with attendant higher reliability and safety considerations it becomes even more important that engineering processes such as welding, brazing, soldering, etc. are prescribed in exact form. Anything less relegates engineering responsibility to the workman and with it all preconceived reliability norms. Moreover, to assure economical metal joining fabrication, it is essential that exact description of the requirement is properly documented.

Nondestructive Examination Symbols (Welds)

The nondestructive examination of a weld is basic to its quality. Such examination is generally limited to critical welds. This standard provides the accepted industry practices for describing symbolically the kinds of examinations used.

Reference Documents

    American Welding Society, Symbols for Welding and Nondestructive Testing, Standard AWS A2.4-86.

Brazing Practices

This standard provides basic information depicting brazing joints. The information given here includes optimum brazing clearances, types of brazing joints, and methods ensuring mechanical soundness of joints.

Brazing is a joining process whereby fusion is produced by heating the brazing alloy or filler to a suitable temperature, usually above 840F. The temperature varies with the alloy used. The filler is distributed between the closely fitted surfaces of the pieces being joined by capillary action. The process is described symbolically in Section 14.1.1. All of the dimensional characteristics of the joint symbol need not be shown if the parts being joined are properly described on the detail drawings.

Standard Welding Terms and Definitions

This section compliments Section 14.1.1 - Graphic Symbols for Metal Joining, which provides among other things, the welding symbols structuring and orientation for specific types of weld joints. In addition to its complimentary role, this section provides specific terms and definitions for the various kinds of welds encountered in Section 14.1.1 and other derivative welds. The weld definitions shown in this section are intended to accurately reflect the welding terms used in the welding field. In addition, the definitions and terms used are intended to facilitate clearly the understanding of weldments shown on engineering drawings and those specified in engineering specifications, standards, and procedures. The overwhelming objective is to provide terms and definitions that must be communicated by the design function to the welding shop in unambiguous form.

In addition to welding processes this section also includes brazing, soldering, etc.

Electrical and Electronics Diagrams

This section is in compliance with the IEC symbols of IEEE Std 315 (formally ANSI Y32.2). For older symbols and symbols other than IEC, see IEEE Std 315. Electrical symbols are used to show graphically the functioning or interconnections of a circuit. The symbols are used on one-line diagrams or schematics. Graphic symbols are correlated with parts lists, descriptions, or instructions by means of reference designations in accordance with IEEE Std 200 (ANSI Y32.16).

Reference Documents

    American National Standards Institute (ANSI)
    ANSI Y32.16 Reference Designations for Electrical and Electronics Parts and Equipment
    ANSI Y14.15 Electrical and Electronics Diagrams.

Electrical Symbols for Architectural and Construction Drawings

This section covers General Electric standard graphic electrical wiring layouts for architectural or structural drawings. It is consistent with American National Standard ANSI Y32.9-1962.

Graphic symbols for electrical and electronic equipment used in conjunction with architectural and structural work are shown in Section 14.2, For example: motor, generator, battery, etc.

Heating, Ventilation, and Air Conditioning

This section covers standard graphical symbols for heating and ventilating.

Pipe Fittings and Valves

This section covers standard graphical symbols for pipe fittings and valves.

Plumbing Fixtures

This section covers standard graphical symbols for plumbing fixtures.

Heat-Power Apparatus

This section covers standard graphical symbols for heat/power apparatus.

For Use on Equipment

This Section covers graphical symbols for use on equipment. It is consistent with International Standards IS0 R/369 and IS0 2972.

Symbols for indications appearing on machine tools are grouped into general categories:

  1. Symbols for Movements and Speeds
  2. Symbols for Elements
  3. Symbols for Maneuvers
  4. Various Symbols
  5. Basic Symbols
  6. Symbols for Numerical Control of Machines

Many of the symbols used in this section are made up from certain basic symbols which are used repeatedly and consistently as the basis for related sets of functions. These apply particularly to the set of symbols covered for Numerical Control of Machines. The basic symbols shown in part 5 of this section are used repeatedly and consistently as the basis for symbols for related sets of functions.

Concrete Reinforcement

This Standard establishes a system of symbols for use on drawings for reinforcement in reinforced concrete and in prestressed concrete. It is consistent with International Standard IS0 3766-1977.

Formulating Graphical Safety Symbols

This specification applies to the design, application, and use of signs or symbols intended to indicate and, insofar as possible, to define specific hazards of a nature such that failure to designate them may lead to accidental injury to workers, the public, or both, or to property damage. These specifications are intended to cover all safety signs except those designed for streets, highways, railroads, and marine regulations.

The specific symbols presented in this section are intended only as general guides for the formulation of graphical symbols used in drafting practice and are not meant to imply that they are standard.

Information Systems

This Standard establishes graphical symbols for use in flowcharts for information processing systems, including automatic data processing systems. It is consistent with International Standard ISO 1028-1973 and International Standard IS0 2972-1979.

The graphical symbols included in this International Standard are intended to represent on flowcharts both

    - the sequence of operations and
    - the flow of data and paperwork
of information processing systems. This International Standard does not cover: identifying, descriptive or explanatory information written inside or adjacent to a symbol; or pictorial type flowcharts that utilize pictures or drawings to depict a system.

Gears--Symbols for Geometrical Data

This section specifies symbols for geometrical data for use in gear notation. It consists essentially of two parts:

  1. On the one hand, the principal symbols, composed either of a single basic letter, or of a basic letter and suffix or sign that are generally inseparable for the given term.
  2. On the other hand, additional suffixes or signs that may be added if necessary to the principal symbols, in order to imply a particular qualification of the given term.
Section 4.0 gives lists classified in alphabetical order, according to the Roman and Greek alphabets, of the basic letter symbols. Section 5.0 lists the suffixes and signs used in the establishment of this International Standard and a combination of which may possibly be used for the notation of any other term of geometrical data not explicitly mentioned in the Standard.

This information is consistent with International Standard ISO 701-1976.

Mathematical Signs and Symbols

This section establishes the mathematical signs and symbols to be used on drawings technical documentation. These signs and symbols apply for formulas and equations and are not intended to replace the proper use of words or abbreviations thereof in text.

Heat and Thermodynamics Letter Symbols

This section establishes the symbols for heat and thermodynamics to be used on drawings and technical documentation. When two or more quantity symbols are shown in the tables they are of equal status unless shown in parentheses in which case the symbol without parentheses is preferred.

Hydraulics Letter Symbols

This section establishes the letter symbols for hydraulics to be used on drawings and within technical documentation. It is consistent with practice approved by the American Standards Association. ASA Y10.2-1958

The letter symbols are presented below in two lists:

    Alphabetical Order
    By Concept
Within the listed symbols these rules generally apply:
  1. Greek symbols are used for fluid properties
  2. Greek letters, early in the alphabetical order, are usually applied to angles
  3. English letters are used for geometric properties
  4. English capital letters are used for the basic dimensionless parameters and numbers used in fluid mechanics. Some of these are to be in bold type face, as indicated.

    Symbols for Semiconductor Devices

    This section establishes the symbols for use in connection with semiconductor devices.

    Reference Documents

      MIL-S-l9500G Semiconductor Devices, General Specification For