GMAW NC II key terms

The set of wearable items required for GMAW work, including welding helmet with proper shade lens, flame-resistant clothing, leather gloves, safety boots, and hearing or respiratory protection where assessed as necessary.

A scale value indicating the darkness of the filter lens in a welding helmet; higher numbers block more light and are selected according to welding current to protect the eyes from arc radiation.

Local exhaust ventilation or on-torch extraction that captures metal oxide fumes and shielding gas decomposition products at the arc before they enter the welder's breathing zone.

A workplace organization method using five steps: sort, set in order, shine, standardize, and sustain, applied to keep welding stations clean, tools locatable, and hazards visible.

A written authorization confirming that fire watches, combustible clearance, and extinguishing equipment are in place before welding, cutting, or grinding is started in a designated area.

A person assigned to monitor sparks, slag, and heat conduction around hot work for a specified period, with authority to stop work and sound an alarm if fire risk appears.

A controlled procedure for entering tanks, vessels, or pits with limited access and poor ventilation, requiring atmosphere testing, a standby attendant, and an approved entry permit before welding begins.

The attachment of the work lead clamp to clean metal on the workpiece so welding current returns safely to the power source, preventing stray current paths and electric shock.

A qualified document that states the ranges of variables, such as current, voltage, travel speed, gas flow, and joint preparation, that must be followed to produce a compliant weld.

The record of the actual variables and destructive test results used to prove that a welding procedure produces joints meeting the required mechanical properties.

A welding parameter, such as filler metal classification, shielding gas composition, or current mode, that cannot be changed outside the qualified range without requalifying the procedure.

A drawing notation consisting of a reference line, arrow, and optional tail that conveys joint type, weld size, length, spacing, groove preparation, and process to be used.

The horizontal line in a welding symbol to which the arrow, tail, and weld symbols are attached; symbols below it indicate the arrow side and above it the other side.

Conventions that locate a weld relative to the joint: a symbol under the reference line means the side the arrow points to, and above the line means the opposite side.

A drawing symbol showing the shape of a prepared joint, such as V, bevel, U, or square, together with groove depth, root opening, and included angle details placed on the reference line.

Dimensions placed to the left and right of a fillet symbol giving the leg length in millimeters and, where shown, the weld length and pitch spacing along the joint.

A small circle placed at the junction of the arrow and reference line indicating that the weld is to be applied continuously around the entire joint perimeter.

Removal of mill scale, rust, oil, paint, and moisture from the joint area before welding, since contamination causes porosity, incomplete fusion, and unstable arcs in GMAW.

The alignment and spacing of parts before welding, controlling root gap, mismatch, bevel angle, and tack placement so the finished joint meets dimensional and strength requirements.

The clearance left between the two members at the joint root, allowing arc penetration to the root and influencing bead shape, fusion, and distortion.

A short temporary weld used to hold parts in alignment during fit-up; in GMAW tacks should be of sufficient size and cleaned so they fuse fully into the final weld.

Tooling that locates and holds workpieces during welding; jigs guide the tool or part, while fixtures clamp the assembly to maintain alignment and reduce movement and distortion.

The distance from the end of the contact tip to the workpiece surface; excessive distance increases resistance heating and spatter, while too short a distance risks tip damage and poor visibility.

The length of electrode wire extending beyond the contact tip before the arc; it affects current density, deposition rate, and arc stability and must be kept within the WPS range.

The rate at which filler wire is pushed through the torch, usually in meters per minute; it primarily controls welding current and deposition rate in constant-voltage GMAW.

The electrical potential across the arc, controlled on the machine and mainly determining arc length; it affects bead width, penetration profile, and spatter level.

The physical gap between the electrode wire tip and the molten weld pool, which is maintained by matching voltage setting to wire feed speed and torch height.

A gas or gas mixture, commonly argon, carbon dioxide, or argon-carbon dioxide blends, supplied around the arc to exclude air and prevent oxidation and nitrogen porosity.

The volume of shielding gas delivered per unit time, usually liters per minute; too low allows atmospheric contamination and too high causes turbulence and porosity.

A GMAW metal transfer mode at low current where the wire repeatedly contacts the pool and pinches off; suitable for thin sheet and out-of-position work but prone to spatter.

A high-current GMAW transfer mode, typically with argon-rich gas, in which fine droplets are projected axially across the arc, giving deep penetration and high deposition with little spatter.

The orientation of the gun relative to the joint and the direction of movement; a push angle improves visibility and penetration control, while a drag angle increases penetration.

A controlled side-to-side oscillation of the torch used to widen the bead and ensure fusion into both sidewalls, with dwell at the edges to prevent undercut.

Techniques such as balanced welding sequence, backstep welding, pre-setting, and clamping that limit shrinkage stresses and dimensional change in welded assemblies.

A sequence in which short bead segments are deposited opposite to the overall direction of progress so shrinkage is distributed and distortion is reduced.

Examination of the finished weld by eye and with aids such as a magnifier and weld gauge to detect surface defects, profile errors, spatter, and dimensional nonconformance before other testing.

Cavities formed by gas trapped in the solidifying weld metal, commonly caused by moisture, oil, drafts, or insufficient shielding gas flow.

A groove melted into the base metal along the weld toe that remains unfilled, reducing cross-section and acting as a stress concentration; often caused by excessive current or travel speed.

A discontinuity where weld metal fails to bond to the base metal or to a previous pass, frequently caused by low heat input, wrong torch angle, or contamination.

The depth of weld metal extending into the joint root; insufficient penetration leaves a notch at the root, while excessive penetration produces a heavy root bead or burn-through.

A set of calibrated blades and scales used to measure fillet leg length, throat thickness, weld reinforcement, undercut depth, and root gap against drawing requirements.

Removal of spatter, slag islands, and discoloration after welding by chipping, brushing, or grinding, followed by inspection of the cleaned surface for defects.

A record documenting joint identification, WPS used, welder, parameters, inspection results, defects found, and corrective action taken, providing traceability for the completed work.

The consumable copper component in the GMAW gun that transmits welding current to the wire and guides it toward the joint; wear enlarges the bore and causes erratic arcs.

The replaceable tube inside the gun cable that guides the electrode wire from the feeder to the torch; kinks or debris in the liner cause wire feeding hesitation and burnbacks.

The clamp connecting the work return cable to the workpiece; it must grip clean bare metal firmly to complete the circuit and avoid arcing, heating, or erratic welding current.