Welding Symbols and Codes 231
Welding Symbols and Codes describes how welding prints represent welding requirements. A weld is represented in a print using a welding symbol. A welding symbol includes a reference line, arrow element, weld symbol or symbols, and weld dimensions. A welding symbol may also have supplementary symbols and/or a tail when needed to indicate additional information. The American Welding Society developed the welding symbol to indicate different weld requirements. Many of the requirements for a weld depend on which welding code is being used.
The various components of a welding symbol indicate the characteristics of the weld and provide specific instructions to the welder. After taking this class, users will be able to describe the requirements for a weld based on the different parts of its welding symbol.
Number of Lessons 21
- Prints for Welding
- Joint Diagrams
- Welding Symbol Components
- The Welding Symbol and Weld Diagrams Review
- The Reference Line and Arrow Element
- The Tail
- Supplementary Symbols
- Contour Symbols
- Finish Symbols
- Nondestructive Testing Symbols
- Welding Symbol Components Review
- Weld Symbols
- Weld Components
- Fillet Weld Dimensions
- Groove Weld Dimensions
- Intermittent Welds
- Weld Symbols and Dimensions Review
- Welding Codes
- Welding Project Documents
- Metal Classification Systems
- Welding Codes and Documents Review
- Describe welding symbols and prints.
- Describe joint types and their related weld types.
- Identify welding symbol components.
- Describe the reference line and arrow element of 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 finish symbols used in welding symbols.
- Identify nondestructive testing symbols used in welding symbols.
- Identify weld symbols used in welding symbols.
- Identify major components of fillet and groove welds.
- Describe fillet weld dimensions used in welding symbols.
- Describe groove weld dimensions used in welding symbols.
- Describe intermittent weld dimensions used in welding symbols.
- Describe welding codes and their uses.
- Describe documents required for a welding project.
- Describe metal classification systems used to identify base metals.
acoustic emission testing
A nondestructive testing method that detects sound waves created by stress in a material. The symbol for acoustic emission testing is "AET."
The distance between the deepest point of penetration at a weld's root and the highest point on the weld's face. Actual throat, theoretical throat, and effective throat are all ways of measuring a weld's throat, but the effective throat measurement is most important because it determines weld strength.
AISI-SAE classification system
A steel identification system that was developed by the American Iron and Steel Institute (AISI) and the Society of Automotive Engineers (SAE). The AISI-SAE classification system uses four-digit designations to identify different types of steel.
A material that is intentionally added to a metal in order to change its properties. Alloying elements, such as chromium, manganese, molybdenum, and nickel, can improve the strength, ductility, hardness, and toughness of a finished weld.
American Iron and Steel Institute
AISI. An organization that issues general classification standards for irons and steels. The American Iron and Steel Institute developed the AISI-SAE classification system with the Society of Automotive Engineers (SAE).
American Petroleum Institute
API. A non-profit organization that regulates industrial standards for the oil and natural gas industry. The American Petroleum Institute publishes codes that are used for welding operations on oil and gas pipelines or related materials.
American Society of Mechanical Engineers
ASME. An organization that publishes technical materials and sets industrial and manufacturing standards. The American Society of Mechanical Engineers publishes codes used for welding pressure vessels and piping.
American Welding Society
AWS. The non-profit organization that regulates industrial standards for welding and promotes the welding industry in the United States. The American Welding Society developed the welding symbol for use in prints.
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.
The part of a welding symbol that is below the reference line. Instructions that appear on the arrow side apply to the side of the joint indicated by the arrow element.
A designation used to identify steels in the ASTM classification system. ASTM grades consist of an "A" followed by two or more digits.
An organization that publishes standards on a variety of materials, products, and services, including metals. ASTM International produces the primary classification system for specifying structural steel for steel structures and bridges.
American Welding Society. The non-profit organization that regulates industrial standards for welding and promotes the welding industry in the United States. The AWS developed the welding symbol for use in prints.
The metal to be joined by welding. The base metal and its properties influence the weld type, welding process, and electrode.
bevel groove welds
A groove weld made in an opening with one angled side and one square side. Bevel groove welds use one base metal with an angled edge and one base metal with a straight edge.
bill of materials
BOM. A report that lists the materials required to make a particular product and the cost of each individual component. A bill of materials for a welding project includes information on the base metals.
Bill of materials. A report that lists the materials required to make a particular product and the cost of each individual component. A BOM for a welding project includes information on the base metals.
An alloy of copper and another metal, usually tin. Bronze is strong and highly corrosion resistant.
A joint created between two parts that lie in the same plane. Butt joints are simple, common joints.
A common nonmetallic element that is combined with iron to create steel. Increasing the carbon content of a metal typically increases hardness.
An intermittent weld that consists of a sequence of welds that line up with each other on either side of a joint. The welding symbol for a chain-intermittent weld includes two weld symbols that line up with each other on either side of the reference line.
The process of cutting or breaking off small pieces, or chips, of material with an edged tool. The finish symbol for chipping is "C."
complete joint penetration
CJP. A weld condition that occurs when weld metal extends throughout the full thickness of the base metals, completely filling the joint. If a weld requires complete joint penetration, the abbreviation "CJP" appears in the tail of the welding symbol.
A contour symbol that indicates that a joint requires a weld bead that curves inward. The concave symbol is a line that arcs towards the weld symbol.
A type of filler metal that consists of a specifically shaped insert added to the welded joint. Consumable inserts often add strength to the welded joint.
consumable insert symbol
A supplementary symbol that tells the welder that the joint requires a consumable insert 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 weld length measurement in its welding symbol because the length of the weld is the same as the length of the joint.
A supplementary symbol that tells the welder the shape of the finished weld bead. The contour symbol resembles the shape of the finished weld.
A written agreement between two or more parties that is legally binding. A welding contract outlines all of the specific requirements and codes for a particular welding application.
A contour symbol that indicates that a joint requires a weld bead that curves outward. The convex symbol is a line that arcs away from the weld symbol.
A metal consisting of two or more elements, one of which is copper. Common copper alloys include aluminum-silicon-copper-magnesium and zinc-aluminum-copper-magnesium.
A joint created between two parts located at angles to one another. Corner joints require large amounts of filler metal.
The desired measurement of a part feature. Dimensions are listed as numbers given in the appropriate units.
A joint created between the aligned edges of two parallel parts. Edge joints, now known as parallel joints, are useful for joining plate metal workpieces.
The distance between the deepest point of penetration at a weld's root and the lowest point on the weld's face. Effective throat, actual throat, and theoretical throat are all ways of measuring a weld's throat, but the effective throat measurement is most important because it determines weld strength.
A nondestructive testing method that uses an electric current or magnetic field to determine if a weld is defective. The symbol for electromagnetic testing is "ET."
The exposed surface of a weld. The face of a weld may be flat, convex, or concave.
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 at the point where the reference line and arrow element meet.
Metal deposited into the weld that often adds strength and mass to the welded joint. Filler metal can be provided by consumable electrodes, consumable inserts, and filler rods.
A triangular weld made to join two surfaces at right angles to each other. Fillet welds can be used on lap joints, T-joints, and corner joints.
A supplementary symbol that appears within a welding symbol when it is necessary to specify required finishing processes. A finish symbol is a single capital letter.
A final process performed on a part to obtain the proper tolerance and surface finish. Any finishing processes required for a weld contour are indicated by a finish symbol.
A contour symbol that indicates that a joint requires a flat weld bead. The flat symbol, or flush symbol, is a straight line located above or below the weld symbol.
A contour symbol that indicates that a joint requires 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. Gas metal arc welding is also sometimes referred to as metal inert gas welding (MIG welding) or metal active gas welding (MAG welding), but these terms are nonstandard in the United States.
The use of an abrasive to cut the surface of a part and change its shape. The finish symbol for grinding is "G."
The total included angle of the groove between workpieces being welded together. The size of the groove angle depends on the welding method and requirements.
A weld made in the opening between two parts that provides space to contain weld metal. Groove welds are used on all joints except lap joints.
The process of striking a material with a hammer to reduce stress and flatten it into the desired shape. The finish symbol for hammering is "H."
A controlled heating and cooling process used to change the structure of a material. Heat treatment alters a material's physical and mechanical properties.
The examination of a part during or after its creation to confirm that it adheres to specifications. Inspection allows welders to identify and correct defects.
Welding that produces short, evenly spaced welded sections along one or both sides of a joint. Intermittent welding can be used when applications do not require one continuous weld along the length of the entire joint.
A groove weld made in an opening shaped like the letter "J." J-groove welds use one base metal with a square edge and one base metal with a concave edge.
The meeting point of two materials that are joined together. Welding creates a permanent joint.
The depth to which weld metal extends into a joint. Joint penetration, including any root penetration, is used to determine the size of a groove weld.
The configuration in which two or more workpieces are joined. There are five basic joint types: butt, corner, parallel, lap, and T-joints.
A joint created between the edge of one part and the surface of an overlapping parallel part. Lap joints provide more stress resistance than butt joints.
A nondestructive testing method that involves filling a pipe with air or gas and submerging it in water to detect leaks from holes or flaws. The symbol for leak testing is "LT."
The side of a fillet weld that connects the root to the toe. The length of the legs determines the size of a fillet weld.
The process of removing metal to form or finish a part. The finish symbol for machining is "M."
magnetic particle testing
A nondestructive testing method that involves magnetizing a part and covering it with tiny iron oxide particles that accumulate in any cracks or seams. The symbol for magnetic particle testing is "MT."
A supplementary symbol that tells the welder that one side of the joint requires complete joint penetration. The melt-through symbol is a solid half-circle located on the reference line opposite the weld symbol.
metal classification system
A system that uses unique designations to identify different types of metal. Metal classification system designations consist of numbers and letters.
An atomic particle with no charge. Neutrons are located in the nucleus of an atom.
neutron radiographic testing
A nondestructive testing method that uses a neutron beam to create an image of the interior of a weld. The symbol for neutron radiographic testing is "NRT."
NDT. A form of inspection that tests a part without damaging its integrity. Nondestructive testing symbols may be included in a welding symbol.
An additional instruction or general comment added to a print. Notes contain information about design aspects.
The part of a welding symbol that is above the reference line. Instructions that appear on the other side apply to the side of the joint opposite the arrow side.
Extending in the same direction and equally distant from one another at all points. Parallel lines or objects never intersect.
A joint created between the aligned edges of two parallel parts. Parallel joints, previously known as edge joints, are useful for joining plate metal workpieces.
A nondestructive testing method that uses a fluorescent liquid or dye to detect surface flaws. The symbol for penetrant testing is "PT."
An intersection of two lines or objects that meet at right angles to one another. Perpendicular lines create angles measuring exactly 90 degrees.
The distance from the center of one weld to the center of the next weld. Pitch measurements are included in the welding symbol for intermittent welds.
plain carbon steel
The most basic form of steel that contains less than 3% alloying elements other than iron and carbon. Plain carbon steel is 20% carbon.
A weld made in a circular hole in one part to join it to another part positioned directly beneath it. Multiple plug welds are usually required to form a strong joint.
A closed container designed to hold liquids or gases at high pressures. Welding applications on pressure vessels follow ASME codes.
A document that contains all the requirements necessary to manufacture a quality part. Prints usually include views, dimensions, and notes.
A nondestructive testing method that involves applying pressure to a part. The symbol for proof testing is "PRT."
A nondestructive testing method that uses X-rays and gamma rays to produce an image of the interior of a part. The symbol for radiographic testing is "RT."
The horizontal line around which all other instructions for a weld are grouped. The reference line is a straight line that connects to the arrow element on one end and may have a tail on the other end.
The process of passing metal through rollers to reduce stress and improve surface finish. The finish symbol for rolling is "R."
The point at which the weld intersects the surfaces of the base metals opposite the face of the weld. Some welds have openings located at the root.
The exposed surface at the back of a weld. The root face is exposed by the root opening.
The separation between base metals at the root of a weld. The size of the root opening determines how much weld metal is needed to obtain fusion at the root.
The depth to which weld metal penetrates beyond the root of the weld. Root penetration is measured from the root to the back of the weld.
A continuous weld made on or between the surfaces of overlapping parts. Seam welds are often used for tanks or pipes.
A weld made in an elongated hole in one part to joint it to another part positioned directly beneath it. Slot welds are stronger than plug welds but require more filler metal.
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 with the American Iron and Steel Institute (AISI).
A description of the essential physical and technical properties of a finished part. Specifications outline important information including finished part dimensions and how the part must respond to forces acting upon it.
A small weld made on or between the surfaces of overlapping parts. Multiple spot welds are generally required to join parts.
square groove welds
A groove weld made in a square-shaped opening. Square groove welds use base metals with straight edges that are slightly separated.
An intermittent weld that consists of a sequence of alternating welds on either side of a joint. The welding symbol for a staggered-intermittent weld includes two weld symbols that are off-set from one another on either side of the reference line.
An established policy regarding a particular practice or method. Welding codes are a type of standard.
A metal alloy made of iron and carbon. Steels often contain small amounts of alloying elements such as manganese, phosphorus, sulfur, and silicon.
A symbol that appears within a welding symbol to give further information about the weld. Supplementary symbols are included in the welding symbol only when necessary.
The degree of roughness and variation on the surface of a part after it has been manufactured. The surface finish requirements of a part depend on its intended use.
A sign or mark that represents something else. Symbols are often used to convey production instructions in prints.
An optional part of a welding symbol that is located at the end of the reference line opposite the arrow element. The tail is included only when it is necessary to provide further instructions on specifications, processes, or other information about a weld.
The distance between a weld's root and a line drawn between the weld toes. Theoretical throat, actual throat, and effective throat are all ways of measuring a weld's throat, but the effective throat measurement is most important because it determines weld strength.
The distance between a weld's root and face. The throat usually refers to a weld's effective throat because it helps determine the weld's strength.
A joint created between the edge of one part and the surface of a second, perpendicular part that resembles the letter "T." T-joints are very common joints that are simple to create.
The point at which a weld's face meets the base metal. A line drawn between the toes marks the top of the weld's effective throat.
A groove weld made in an opening shaped like the letter "U." U-groove welds use base metals with concave edges.
A nondestructive testing method that uses high-frequency sound waves to discover surface and interior defects. The symbol for ultrasonic testing is "UT."
Unified Numbering System
UNS. A common metal classification system that is used for both ferrous and nonferrous metals. The Unified Numbering System uses designations that consist of a prefix followed by five digits.
A groove weld made in an opening shaped like the letter "V." V-groove welds use base metals with angled edges.
A drawing that consists of all the lines that illustrate the shape of a part from a specific direction or angle. A print often contains multiple views to convey all of a part's design elements.
A nondestructive testing method that involves using the eyes to perform a close examination of a part for surface defects. The symbol for visual testing is "VT."
A mixture of metals that joins at least two separate parts. Welds can be produced by applying heat, pressure, or both heat and pressure.
A strip of metal located on the side of the joint 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 tells the welder that the joint requires weld backing. The weld backing symbol is a rectangle located on the reference line opposite the weld symbol.
The end product of a joint that has been welded. The weld bead can be flat, convex, or concave in shape.
A numerical value in a welding symbol that indicates the measurement of one or more components of a weld. Weld dimensions appear beside the weld symbol.
The distance along a joint that is covered by a weld. Weld length measurements appear to the right of the weld symbol in the welding symbol.
A weld dimension that indicates the length of the legs for a fillet weld or the depth of joint penetration for a groove weld. Weld size appears to the left of the weld symbol in a welding symbol.
A metal strip that is inserted into the root of a joint to act as weld backing. A weld spacer maintains a joint's root opening during welding.
weld spacer symbol
A supplementary symbol that tells the welder that the joint requires a weld spacer. The weld spacer symbol is a rectangle centered on the reference line with one half on the arrow side and the other half on the other side.
The part of a welding symbol that indicates the type of weld required for the joint. The weld symbol usually resembles the shape of the weld.
The shape of the weld used to join workpieces. There are six main weld types: fillet, groove, plug, slot, spot, and seam welds.
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.
A collection of laws or standards that outline practices for a particular welding application. Welding codes ensure safe welding practices and high-quality welded products.
welding procedure specification
WPS. A written document that contains all the necessary and specific information for creating a qualified weld. Welding procedure specifications must be approved and tested before welding can begin.
A systematic grouping of symbols that denote welding instructions on a print. The welding symbol includes all the necessary information required to create a specific weld.
An electromagnetic wave with a high frequency and low wavelength. X-rays are used to view the interior of solid objects during radiographic testing.