• Arc Plasma – A gas that has been heated by an electric arc to at least partially ionized condition, enabling it to conduct electric current.
  • Back Gouging – The removal of weld metal and base metal from the Root side of a partially welded joint to facilitate complete fusion and complete joint penetration upon subsequent welding from that side.
  • Base Metal – The metal to be/that is welded or cut.
  • Basic Electrode – An electrode that has coating high in limestone and other ingredients low in hydrogen content that form a basic slag.
  • Bevel – An angular type of edge preparation.
  • Butt Joint – A Joint between two members aligned approximately in the same plane.
  • Butt Weld – A Nonstandard term for a weld in a butt joint.
  • Chamfer – A nonstandard term for Bevel.
  • Complete Fusion – Fusion over the entire base metal surfaces intended for welding and between all adjoining weld beads.
  • Complete Penetration – A nonstandard term for Complete Joint Penetration.
  • Contact Tip – A device that transfers current to a continuous electrode.
  • Continuous Weld – A weld that extends continuously from one end of a joint to the other. Where the joint is essentially circular, it extends completely around the joint.
  • CO2  Welding – A nonstandard term for Gas Metal Arc Welding.
  • Cutting Torch (arc) – A device used in air carbon arc cutting, gas tungsten arc cutting, and plasma arc cutting to control the position of the electrode, to transfer current, and to control the flow of gases.
  • Cutting Torch (oxy fuel gas) – A device used for directing the preheating flame produced by the controlled combustion of fuel gases and to  direct and control the cutting oxygen.
  • Defective Weld – A weld containing one or more defects.
  • Deposited Metal – Filler metal that has been added during welding.
  • Deposition Rate – The mass of material deposited in a unit of time.
  • Depth of Fusion – The distance that fusion extends into the base metal or previous pass from the surface melted during welding.
  • Dilution – The change in chemical composition of a welding filler material caused by the admixture of the base metal or previous weld metal in the weld bead. It is measured by the percentage of base metal or precious metal in the weld bead.
  • Edge Joint – A joint between the edges of two or more parallel or nearly parallel members.
  • Edge Preparation – The preparation of the edges of the joint members, by cutting, machining, cleaning, or other means. A nonstandard term when used for Edge Shape.
  • Filler Metal – The metal to be added in making a joint, see Welding Electrode and Welding Rod.
  • Fillet Weld – A weld of approximately triangular cross section joining two surfaces approximately at right angles to each other in a lap joint, T-joint, or corner joint.
  • Flash – The material that is expelled or squeezed out of the weld joint and is formed between around the weld.
  • Flat Position – The welding position used to weld from the upper side of the joint; the face of the weld is approximately horizontal.
  • Flux – A material used to hinder or prevent the formation of oxides and other undesirable substances in molten metal and on solid surfaces, and to dissolve or otherwise facilitate the removal of such substances.
  • Fusion Face – A surface of the base metal that is melted during welding.
  • Fusion Welding – Any welding process that uses fusion of the base metal to make the weld.
  • Gas Cutting – A nonstandard term for Oxygen Cutting.
  • Gas Pockets – A nonstandard term for Porosity.
  • Groove – An opening or channel between two components or in the surface of a part that provides space to contain weld metal.
  • Groove Angle – The included angle between the weld groove faces.
  • Groove Face – Any surface in a weld groove prior to welding.
  • Groove Radius – The radius used to form the shape of a J- or U-groove weld joint.
  • Groove Type – The geometric configuration of a groove.
  • Groove Weld – A weld made in the groove between two members. The standard types of groove welds are as follows:
    • double bevel-groove weld;
    • double flare-bevel-groove weld;
    • double flare V-groove weld;
    • double J-groove weld;
    • double U-groove weld;
    • double V-groove weld;
    • single bevel-groove weld;
    • single flare-bevel-groove weld;
    • single flare-V-groove weld;
    • single J-groove weld;
    • single U-groove weld;
    • single V-groove weld; and
    • square-groove weld.
  • Half Skip – The distance the shear wave travels in a straight line before being reflected by the surface of the material being tested.
  • Heat-affected Zone – The portion of the base metal whose mechanical properties or microstructure have been altered by the heat of welding cutting.
  • Inadequate Joint Penetration – Joint penetration that is less than that specified.
  • Inclined Position – The position of a pipe joint in which the axis of the pipe is approximately at an angle of 45° to the horizontal and the pipe is not rotated during welding.
  • Included Angle – A nonstandard term when used for Groove Angle
  • Incomplete Fusion – A weld discontinuity in which fusion did not occur between weld metal and fusion faces or adjoining weld beads.
  • Index Point – The point on an angle beam transducer at which the sound beam enters the material.
  • Indication – A response or evidence of a response that requires interpretation to determine its significance.
  • Indication Level – A decibel reading from a discontinuity as indicated on a calibration gain or attenuation control.
  • Indication Rating – The decibel reading from a discontinuity in relation to the zero reference level after being corrected for attenuation.
  • Joint – The junction of members or the edges of members that are to be joined or have been joined
  • Joint Penetration – The distance the weld metal extends from the weld face into a joint, exclusive of weld reinforcement.
  • Joint Root – That portion of a joint to be welded where the members approach closest to each other. In cross section, the joint may be either a point, a line, or an area.
  • Lack of Fusion – A nonstandard term for Incomplete Fusion
  • Lap Joint – A joint between two overlapping members in parallel planes.
  • Local Preheating – Preheating of a specific portion of a structure.
  • Local Stress-Relief Heat Treatment – Stress Relief heat treatment of a specific portion of a structure.
  • Longitudinal Discontinuity – A weld discontinuity whose major dimension is in a direction parallel to the weld axis “X”.
  • Manual Welding – A welding operation performed and controlled completely by hand.
  • MIG Welding – A nonstandard term for Gas metal arc welding, Metal-cored arc welding and Flux-cored arc welding.
  • Molten Weld Pool – A nonstandard term for Weld Pool
  • Nozzle – A device that directs shielding media
  • Overhead Position – The position in which welding is performed from the underside of the joint.
  • Overlap – The protrusion of weld metal beyond the toe or weld root.
  • Parent Metal – A nonstandard term for Base Metal.
  • Peening – The mechanical working of metals using impact blows.
  • Penetration – A nonstandard term when used for Joint Penetration and Root Penetration
  • Plasma – See Arc Plasma
  • Plug Weld – A weld made in a circular hole in one member of a joint fusing that member to another member. A fillet welded hole should not be construed as conforming to this definition.
  • Post Heating – The application of heat to an assembly after welding or thermal cutting.
  • Post Weld Heat Treatment – Any heat treatment after welding.
  • Preheat – Application of heat to the base metal to attain and maintain preheat temperature. A nonstandard term when used for Preheat Temperature.
  • Preheat Temperature – A specified temperature that the base metal must attain in the welding or cutting area immediately before these operations are performed.
  • Procedure Qualification – The demonstration that welds made by a specific procedure meet prescribed standards.
  • Puddle – A nonstandard term for Weld Pool
  • Residual Stress – Stress present in a member that is free of external force or thermal gradients.
  • Root Bead – A weld that extends into or includes part or all of the joint root.
  • Root Gap – A nonstandard term for Root Opening.
  • Root Opening – The separation between the work pieces at the joint root.
  • Root Penetration – The distance the weld metal extends into the joint root.
  • Tack Weld – A weld made to hold parts of a weldment in a proper alignment until the final welds are made.
  • Temporary Weld – A weld made to attach a piece or pieces to a weldment for temporary use in handling, shipping, or working on the weldment.
  • Undercut – A groove melted into the base metal adjacent to the weld toe or weld root and left unfilled by weld metal.
  • Vertical Position – The position of welding in which the weld axis is approximately vertical.
  • Weld – A localized coalescence of metals or nonmetals produced either by heating the materials to welding temperatures, with or without the application of pressure, or by the application of pressure alone and with or without the use of filler material.
  • Weldability – The capacity of a material to be welded under the imposed fabrication conditions into a specific, suitability designed structure and to perform satisfactory in the intended service.
  • Weld Axis – A line through the length of a weld, perpendicular to and at the geometric centre of its cross section.
  • Weld Bead – A weld resulting from a pass
  • Welder – One who performs a manual or semiautomatic welding.
  • Welder Performance Qualification – The demonstration of a welder’s ability to produce welds meeting prescribed standards.
  • Welder Qualification – Documentation attesting that a welder has produced welds meeting prescribed standards.
  • Weld Face – The exposed surface of a weld on the side from which welding was done.
  • Welding Electrode – A component of the welding circuit through which current is conducted and that is terminated at the arc, molten conductive slag, or base metal.
    • Arc Welding Electrode – A component of the welding circuit through which current is conducted and that is terminated at the arc.
    • Bare Electrode – A filler metal electrode that has been produced as a wire, strip or bar form and that has had no coating or covering other than that which was incidental to its manufacture or preservation.
    • Carbon Electrode – A non filler electrode used in arc welding or cutting, consisting of a carbon or graphite rod, which may be coated with copper or other materials.
    • Flux-cored Electrode – A composite filler metal electrode consisting of a metal tube or other hollow configuration containing ingredients to provide such functions as shielding from the atmosphere, deoxidation, arc stabilization, and slag formation. Minor amounts of alloying materials may be included in the core. External shielding may or may not be used.
    • Metal Electrode – A filler or non filler metal electrode used in the arc welding or cutting that consists of a metal wire or rod that has been manufactured by any method and that is either bare or covered.
    • Stranded Electrode – A composite filler metal electrode consisting of stranded wires that may mechanically enclose materials to improve properties, stabilize the arc, or provide shielding.
    • Tungsten Electrode – A non filler metal electrode used in arc welding or cutting, made principally of tungsten.
  • Welder Procedure Specification – A document providing in detail the required welding variables for a specific application to assure repeatability by properly trained welders and welding operators.