NCCER Welding key terms

A written authorization issued before welding, cutting, brazing, or grinding in a plant or shop. It confirms fire hazards were assessed, combustibles moved or protected, and a fire watch arranged for the job.

A trained person who stays at the hot-work area watching for sparks and smoldering fires while work proceeds and for a required period afterward, commonly 30 minutes, with authority to stop the job and raise an alarm.

A hood or duct placed close to the arc that pulls welding fume and gases away at the source before they reach the welder's face. It is the preferred engineering control for welding fume.

Painful inflammation of the eye's surface caused by ultraviolet light from an arc, with a gritty feeling, tearing, and dislike of light appearing hours later. It is prevented by wearing a proper filter lens.

The darkened glass or auto-darkening panel in a welding helmet, rated by shade number. The shade must match the process and current so the arc stays visible without letting harmful light through.

The voltage measured at the electrode holder when the machine is running but no arc is burning. It is the shock hazard present whenever a welder touches the holder or a bare electrode.

An area with limited entry and exit that is not meant for continuous occupancy, such as a tank or pit. Welding inside requires testing the atmosphere, forced ventilation, an outside attendant, and a rescue plan.

The cable and clamp connecting the workpiece back to the welding machine, completing the circuit. A loose or dirty connection adds resistance, causes an unstable arc, and can send stray current through equipment.

A safety device fitted at the regulator or torch that stops flame from travelling backward up the hose into the gas supply, using a check valve and a porous metal flame barrier.

A loud pop or momentary flash at the torch tip when the flame retreats into the tip and relights. Common causes are a dirty or overheated tip, wrong gas pressure, or touching the tip to the plate.

An oxyfuel flame burning equal parts oxygen and fuel gas, recognized by a sharp, rounded inner cone. It is the usual flame for cutting steel and for welding mild steel without adding or removing carbon.

An oxyfuel flame with more oxygen than the fuel gas needs, giving a short, pointed inner cone and a hissing sound. It cuts faster but can oxidize steel and burn carbon out of the weld.

An oxyfuel flame with excess fuel gas, showing a hazy feather beyond the inner cone. It adds carbon to the metal and is used for hardfacing and for welding high-carbon steels.

The width of metal removed by the cutting oxygen stream. It is wider than the tip orifice because the jet spreads, and it determines how much material is lost and how much the part shrinks.

The backward lean of the cutting oxygen stream measured on the cut face, from the top edge to where the stream leaves the bottom. Correct drag gives a square, clean cut at the right travel speed.

The ring of flame from the torch's heating orifices that raises the steel to a dull red heat, its ignition temperature, before the cutting oxygen lever is pressed.

An angled face cut or ground on the edge of thick plate so the arc can reach the root. Typical bevels are 30 to 37.5 degrees per side with a root face left at the bottom.

The gap between the two members at the bottom of a joint before welding. It allows the root pass to penetrate fully, and it must stay uniform along the joint.

The flat, unbeveled surface left at the bottom edge of a prepared joint. It prevents the arc from burning through too easily and helps the welder control root penetration.

The positioning of parts before welding, covering gap, alignment, mismatch, and square. Careful fit-up controls distortion and lets the root pass penetrate the same amount all along.

A short weld used to hold parts in alignment until the finished weld is made. Tacks are usually consumed by the root pass, so they must be clean and fully fused.

Bending, twisting, or shrinking of a workpiece caused by uneven heating and by contraction of weld metal as it cools. It is limited by balanced sequences, backstepping, preset gaps, and fixtures.

A groove melted into the base metal beside the weld bead and left unfilled. It thins the section and creates a stress riser; typical causes are too much current, too long an arc, or a wrong work angle.

Gas pockets trapped in the weld as it solidifies, showing as pinholes or a honeycomb pattern. Sources include moisture in electrodes or flux, oil and paint on the metal, and lost gas shielding.

Flux slag trapped inside the weld or between passes because the previous bead was not cleaned. It acts as a notch and is removed by chipping, grinding, and brushing between passes.

A defect in which the weld metal does not melt into the sidewall, the previous bead, or the root. Low heat input, fast travel, wrong angle, and dirty metal are common causes.

Wandering of the arc away from the joint because of magnetic forces around the work. It happens mostly with direct current, especially near the ends of the plate or the ground clamp.

The gap between the tip of a covered electrode and the puddle, normally about equal to the electrode's core diameter. Too long a gap lowers penetration and adds spatter and porosity.

The code printed on a covered electrode, such as E7018. The E marks an electrode, 70 gives minimum tensile strength in thousands of psi, 1 sets position, and 8 identifies coating and current type.

The direction of current flow between electrode and work. Electrode positive concentrates heat in the work for deep penetration; electrode negative heats the electrode more and suits tungsten arc welding on thin metal.

A consumable filler rod coated with a flux mixture. Burning the coating creates shielding gas and slag, steadies the arc, and can add alloys to the weld metal.

The shallow bowl left at the end of a weld where the arc stopped. It is the last metal to solidify and can crack, so it should be filled before breaking the arc.

The copper or copper-alloy tube at the end of a wire-feed gun that feeds the wire and passes welding current into it. It must match the wire size and is replaced when the bore wears.

The length from the end of the contact tip to the surface being welded. It controls current and arc stability; holding it steady matters greatly in self-shielded flux-cored welding.

A wire-feed transfer mode where the wire touches the puddle, the arc goes out, and the wire burns off again many times each second. It runs cool and suits thin sheet.

Gas flowing from the gun or torch to surround the arc and puddle and keep air away. Argon-carbon dioxide blends are common for carbon steel; argon or helium is used for aluminum and stainless steel.

Flux-cored welding that relies on the flux to make its own protective gas, so no cylinder is needed. It tolerates wind and is favored outdoors, and it is run with a drag angle.

The non-consumable rod in gas tungsten arc welding that carries the arc and does not melt into the puddle. It is tungsten alloyed with oxides such as thoria or ceria, and its tip shape matters.

A separate rod of metal fed by hand into a gas tungsten arc weld puddle. It must match or suit the base metal and be free of oil, rust, and moisture.