Welding Symbols and Codes 231

“Welding Symbols and Codes” describes how welding blueprints represent welding requirements. A weld is represented in a blueprint using a welding symbol. Welding symbols, which were created by the American Welding Society, include a reference line, arrow element, weld symbol or symbols, tail, and weld dimensions. When needed, the welding symbol will also have supplementary symbols and finish symbols.

The welding symbol includes various components on the reference line to show the characteristics of the weld and provide specific instructions to the welder. After taking this class, users should be able to explain the many types of welding symbols and their characteristics, as well as the welding codes and specifications used in the welding industry.

Class Details

Class Name:
Welding Symbols and Codes 231
Description:
“Welding Symbols and Codes” describes how welding blueprints represent welding requirements. A weld is represented in a blueprint using a welding symbol. Welding symbols, which were created by the American Welding Society, include a reference line, arrow element, weld symbol or symbols, tail, and weld dimensions. When needed, the welding symbol will also have supplementary symbols and finish symbols.

The welding symbol includes various components on the reference line to show the characteristics of the weld and provide specific instructions to the welder. After taking this class, users should be able to explain the many types of welding symbols and their characteristics, as well as the welding codes and specifications used in the welding industry.
Version:
2.0
Difficulty:
Intermediate
Number of Lessons:
22
Related 1.0 Classes:
Overview of Weld Types 130, Arc Welding Symbols and Codes 250

Class Outline

  • Blueprint Welding Symbols
  • Welding Symbol Components
  • Reference Line and Arrow Element
  • Weld Types
  • Weld Symbols
  • Weld Components
  • The Parts of a Welding Symbol
  • Fillet Weld Dimensions
  • Groove Weld Dimensions
  • Intermittent Weld Dimensions
  • Welds and Weld Symbols
  • Tail
  • Supplementary Symbols
  • Contour Symbols
  • Finish Symbols
  • Elements of a Welding Symbol
  • Nondestructive Examination Symbols
  • Interpreting Blueprints
  • Welding Code
  • Bill of Materials
  • Base Metals
  • Classification Review

Objectives

  • Define welding symbols.
  • Identify welding symbol components.
  • Explain the reference line of a welding symbol.
  • Describe the five basic weld joints and their welds.
  • Identify the different weld symbols.
  • Identify the important components of fillet and groove welds.
  • Describe fillet weld dimensions in a welding symbol.
  • Describe groove weld dimensions in a welding symbol.
  • Describe intermittent weld dimensions in a welding symbol.
  • Describe the tail of a welding symbol.
  • Identify supplementary symbols used in welding symbols.
  • Identify contour symbols used in welding symbols.
  • Identify the finish symbols used in welding symbols.
  • Identify the nondestructive testing symbols used in welding symbols.
  • Describe welding codes and their sources.
  • Describe a welding bill of materials.
  • Identify base metals from a bill of materials.

Job Roles

Certifications

Glossary

Vocabulary Term Definition
AISI-SAE classification system A method for identifying steel that was developed by the American Iron and Steel Institute (AISI) and the Society of Automotive Engineers (SAE). AISI-SAE designations are usually four-digit numbers based on the contents of a steel.
alloying elements The materials added to a metal that change its properties. Common alloying elements include chromium, manganese, molybdenum, and nickel.
American Iron and Steel Institute AISI. An association responsible for setting standards and creating numbering systems for various ferrous metals. The American Iron and Steel Institute developed the AISI-SAE classification system along with the Society of Automotive Engineers.
American Petroleum Institute API. The institution that sets the quality standards for the petroleum industry. The American Petroleum Institute controls standards for welding oil and gas pipelines.
American Society of Mechanical Engineers ASME. An organization that publishes technical materials and sets industrial and manufacturing standards. ASME codes are used when welding pressure vessels or piping.
American Welding Society AWS. A non-profit organization that regulates the industrial standards for welding and promotes the welding industry in the United States. The American Welding Society developed the use of welding symbols.
arrow element The part of a welding symbol that points to the diagram of the joint to be welded. The arrow element can extend from either end of the reference line.
arrow side The part of the welding symbol that is below the reference line and indicated by the arrow element. Instructions that appear on the arrow side of the welding symbol correspond with the arrow side of the base metal to be welded.
ASTM grade A steel specification system developed by ASTM International. ASTM grades include an "A" followed by two or more numerals.
ASTM International An organization that publishes standards on a variety of materials, products, and services. ASTM International developed the primary classification system for specifying structural steel for steel structures and bridges.
AWS American Welding Society. A non-profit organization that develops the industrial standards for welding buildings and bridges and promotes the welding industry in the United States. The AWS developed the use of welding symbols.
base metals The metal to be joined by welding. Base metals, once welded together, form the joint.
bill of materials BOM. A managerial accounting report that lists the materials required to make a particular product and the cost of each individual component. A welding bill of materials includes information on base metals.
blueprint A document that contains all the instructions for a particular part and communicates all requirements necessary to manufacture and inspect a quality part. Blueprints usually include views, dimensions, and notes.
BOM Bill of materials. A managerial accounting report that lists the materials required to make a particular product and the cost of each individual component. A welding BOM includes information on base metals.
bronze A nonferrous alloy of copper and tin. Bronze is the most weldable copper alloy.
butt joint A type of joint between two metal parts that lie in the same plane. A butt joint is a very common joint type.
carbon A common, non-metallic element that is combined with iron to create steel. Carbon content typically increases hardness in metal.
chain-intermittent weld A type of intermittent weld that requires a sequence of welds on each side of the joint that line up with each other. A chain-intermittent weld is noted in a welding symbol by having the weld symbols on the arrow and other sides of the reference line match up exactly.
chipped The act of cutting or breaking small pieces, or chips, with an edged tool. "C" is the finish symbol for chipping.
complete joint penetration The condition in which a weld completely fills the joint. If a joint requires complete joint penetration, "CJP" appears in the tail of the welding symbol.
concave symbol A contour symbol that indicates the need for a weld bead that curves inward. The concave symbol is a line that arcs towards the reference line.
consumable insert A type of filler metal or specifically shaped insert added to the welded joint. Consumable inserts often add strength to the welded joint.
consumable insert symbol A supplementary symbol that instructs the welder that the welded joint requires a consumable insert be used as part of the filler metal. The consumable insert symbol is a square located on the reference line opposite the weld symbol.
continuous fillet weld A fillet weld that extends along the entire length of the joint to be welded. A continuous fillet weld does not require a length measurement in its welding symbol.
contour symbol A supplementary symbol that tells the welder the shape of the finished weld bead. The contour symbol appears above or below the weld symbol.
contract A written agreement between two or more parties. A welding contract outlines all of the specific requirements and codes for a particular welding application.
convex symbol A contour symbol that indicates the need for a weld bead that curves outward. The convex symbol is a line that arcs away from the reference line.
copper alloy A metal consisting of two or more elements, one of which is copper. Most copper alloys are electrically conductive and corrosion resistant like copper, but without the drawbacks of copper.
corner joint A type of joint that fuses two metal parts at right angles to one another. Corner joints require large amounts of weld metal.
dimensions The desired measurement of a feature on a part. Dimensions are listed on a blueprint as numerical values.
edge joint A type of joint that fuses the surfaces of two metal parts at parallel angles to one another. Edge joints appear at the common edges of the parts.
face The exposed surface of a weld on the side from which the welding occurred. The face is usually flat or convex.
ferrous A metal in which iron is the main ingredient. Ferrous metals are the most commonly used commercial metal.
field weld symbol A supplementary symbol that instructs the welder to perform a weld on the job site. The field weld symbol resembles a flag and is placed at a right angle to the reference line.
filler metal Metal deposited into the weld that often adds strength and mass to the welded joint. Consumable insert is a type of filler metal.
fillet welds A type of weld that is triangular in shape and joins two surfaces at right angles to each other. Fillet welds can be used on lap joints, T-joints, and corner joints.
finish symbol The part of a welding symbol that specifies the required appearance of the weld when needed. The finish symbol is a single capital letter.
finishing A final process performed to obtain the proper tolerance and surface finish. Finishing processes required for a weld contour are indicated by the appropriate finish symbol.
flush symbol A contour symbol that indicates the need for a flat weld bead. The flush symbol, or flat symbol, is a straight line located above or below the weld symbol.
gas metal arc welding GMAW. An arc welding process in which a bare wire electrode and inert or active shielding gas are fed to a weld through a welding gun. If a joint requires gas metal arc welding, "GMAW" appears in the tail of a welding symbol.
grinding The use of an abrasive to cut away the surface of a part and change its shape. "G" is the finish symbol for grinding.
groove angle The total included angle of the groove between parts. In a welding symbol, groove angle measurement is located below the weld symbol on the arrow side and above the weld symbol on the other side.
groove welds A type of weld that consists of an opening between two part surfaces, which provides space to contain weld metal. Groove welds can be used on all joints except lap joints.
heat treatment The controlled heating and cooling process used to change the structure of a material. Heat treatment alters a material's physical and mechanical properties.
inspection The examination of a part during or after its creation to confirm that it adheres to specifications. During inspection, welders can identify and correct defects.
intermittent welding Welding that does not require one continuous weld along the length of the entire joint. Intermittent welds are short welds spaced evenly along the joint.
J-groove welds A groove weld with an opening in the shape of the letter "J." For a J-groove weld, the edge of one metal part is concave and the other is square.
joint The meeting point of two materials that are joined together. Welding creates a permanent joint.
joint penetration The measurement between the face of the joint and the root of the weld, exclusive of any reinforcement. Joint penetration indicates how far into the joint the weld will enter.
lap joint A type of joint that fuses two overlapping metals that run in parallel planes. Lap joints are often used to weld sheet metal.
legs The distance from the root to the toe of a weld. The length of the legs determines the size of a fillet weld.
machining The process of removing metal to form or finish a part. "M" is the finish symbol for machining.
magnetic particle testing An assessment that involves magnetizing a part to detect surface defects. The symbol for magnetic particle testing is "MT."
melt-through symbol A supplementary symbol that instructs the welder that complete joint penetration is required on one side of the joint. The melt-through symbol is a solid half-circle located on the reference line opposite the weld symbol.
metal classification system A method used to identify different types of metal in documents by giving each metal a separate code. Metal classification system codes are used in a bill of materials to indicate base metals.
nondestructive testing A form of inspection that tests a part without damaging its integrity. Nondestructive testing symbols may be included in a welding symbol.
nonferrous A metal that does not contain a significant amount of iron. Aluminum and copper are the most commonly used nonferrous metals.
notes An additional instruction or general comment added to a blueprint. Notes contain information about design aspects.
other side The part of the welding symbol that is above the reference line and opposite the arrow side. Instructions that appear on the other side of the welding symbol correspond with the other side of the base metal to be welded.
pitch The distance from the center of one weld to the center of the next weld. Pitch is located to the right of the length value in a welding symbol.
plain carbon steel The basic type of steel that contains less than 3% of elements other than iron and carbon. Plain carbon steel is 20% carbon.
plug welds A weld made by joining one metal part with a circular hole to another metal part positioned directly beneath it. Plug welds are not common in arc welding.
pressure vessels A closed container whose contents are held at a pressure different from the pressure of the air outside the vessel. Welding that occurs on pressure vessels follows ASME codes.
proof testing An assessment that involves applying pressure to a part that is great enough to match usage expectations but not great enough to cause damage. The symbol for proof testing is "PRT."
radiographic testing An assessment that involves using X-rays and gamma rays to produce an image of the interior of a part. The symbol for radiographic testing is "RT."
reference line The horizontal line in a welding symbol that contains all information about the weld. The reference line is a straight line with the tail on one end and the arrow element on the other end.
reference line The horizontal line in a welding symbol that contains all the information about the weld. The reference line is a straight line with the tail on one end and the arrow element on the other end.
root The point at which the back of a weld intersects the surfaces of the base metal. The root is one of the end points of a weld leg.
root opening The separation at the joint root between the base metals. In a welding symbol, the root opening measurement is located inside the weld symbol.
root penetration The measurement between the joint root and the back of the weld. Root penetration indicates how far beyond the joint root the weld will extend.
seam welds A continuous weld made between or upon overlapping metal parts. Seam welds are not common in arc welding.
Society of Automotive Engineers SAE. An organization that writes specifications and other data used in a broad range of industries. The Society of Automotive Engineers developed the AISI-SAE classification system along with the American Iron and Steel Institute.
spot welds A single weld made between or upon overlapping metal parts. Multiple spot welds are generally required to join parts.
square groove welds A groove weld placed in a square-shaped opening between two parts. Square groove welds are one of the most common types of groove welds.
staggered-intermittent weld A type of intermittent weld that requires a sequence of alternating welds on each side of the joint. A staggered-intermittent weld is noted in a welding symbol by having the weld symbols on the arrow and other sides not occur in the same exact location on the reference line.
standards An established policy regarding a particular practice or method. Welding codes are a type of standard.
steel A ferrous metal consisting of iron and carbon, usually with small amounts of manganese, phosphorus, sulfur, and silicon. Steels are classified using AISI-SAE numerical designations.
supplementary symbols A symbol that appears within the welding symbol to give further information about a weld. Supplementary symbols are included in the welding symbol only when necessary.
supplementary symbols A symbol that appears within the welding symbol to give further information about the weld. Supplementary symbols are included in the welding symbol only when necessary.
surface finish The degree of roughness and variation on the surface of a part after it has been manufactured. Due to irregularities created when machining a part, surface finish cannot be perfectly smooth.
symbols An item used instead of words to signify something else. Blueprints use symbols to convey production instructions.
tail The part of a welding symbol that provides further instructions on specifications, processes, or other information about a weld. The tail is located at the end of the reference line opposite the arrow element.
throat The distance between the root and the face of a weld. The throat is used to note the size of a groove weld.
T-joint A type of joint produced when two metal parts are perpendicular to each other. A T-joint always forms the shape of the letter "T."
toe The point at which the weld face and the base metal meet. The toe is one of the end points of a weld leg.
U-groove welds A groove weld with an opening in the shape of the letter "U." U-groove weld edges are concave.
ultrasonic testing An assessment that involves using high-frequency sound waves to discover surface and interior defects. The symbol for ultrasonic testing is "UT."
Unified Numbering System UNS. A common classification system that is used for both ferrous and nonferrous metals. The Unified Numbering System identifications include a prefix followed by five digits.
V-groove welds A groove weld with an opening in the shape of the letter "V." V-groove welds require more joint preparation but less weld metal.
views The part of a blueprint that consists of all the lines that illustrate the shape of the part. A blueprint often contains multiple views to convey all of a part's design elements.
visual testing An assessment that involves closely examining a part for defects. The symbol for visual testing is "VT."
weld A mixture of metals that joins at least two separate parts. Welds can be produced by applying heat, pressure, or both heat and pressure.
weld backing A strip of metal located on the side opposite the weld that stops molten metal from escaping through the joint. Weld backing is used for complete penetration welds.
weld backing symbol A supplementary symbol that indicates the need for weld backing for the weld. The weld backing symbol is a rectangle located on the reference line opposite the weld symbol.
weld bead The end product of a joint that has been welded. The weld bead can be flat, convex, or concave in shape.
weld dimensions A numerical value in a welding symbol that provides the weld size or the length of the weld. Weld dimensions appear beside the weld symbol.
weld dimensions Numerical value in a welding symbol that provides the weld size or the length of the weld. Weld dimensions appear beside the weld symbol.
weld length The measurement that indicates the span that the weld covers along the joint. Weld length appears to the right of the weld symbol in a welding symbol.
weld size The measurement of the shorter of the two weld legs of a fillet weld and the measurement of the joint penetration for a groove weld. Weld size appears to the left of the weld symbol in a welding symbol.
weld size The measurement of the shorter of the two weld legs of a fillet weld, and the measurement of the joint penetration for a groove weld. Weld size appears to the left of the weld symbol in a welding symbol.
weld spacer A metal strip that acts as weld backing and is inserted in the root of a joint. A weld spacer maintains a joint's root opening during welding.
weld spacer symbol A supplementary symbol that indicates the need for a weld spacer. The weld spacer symbol is a rectangular symbol that overlaps the reference line.
weld symbol The part of a welding symbol that indicates the type of weld required for the joint. The weld symbol can appear on either side or on both sides of the reference line.
weld-all-around symbol A supplementary symbol that instructs the welder to weld on all sides of the joint. The weld-all-around symbol encircles the point where the reference line and arrow element meet.
welding codes A standard used to govern welding processes. Welding codes ensure safe welding practices and high-quality welded products.
welding procedure specification WPS. A print publication that contains codes, guidelines, and recommendations for welding procedures. The WPS includes information on base and filler metals.
welding symbol A systematic grouping of symbols that denote welding instructions on a blueprint. Welding symbols include all the necessary information required to create a specific weld.