Sri Lanka NVQ Level 3 Welder Written Examination key terms

Wearable gear such as a welding helmet with filter lens, leather gloves, apron, safety boots and respirator that shields the welder from arc radiation, spatter, fumes and electric shock.

Painful inflammation of the cornea and conjunctiva caused by unprotected exposure to ultraviolet radiation from a welding arc, felt as gritting pain and light sensitivity some hours after exposure.

Numerical rating of a filter lens that states how much arc light and UV radiation it blocks; the correct number rises as welding current and arc brightness increase.

Local exhaust ventilation that captures welding smoke at the arc before it reaches the welder's breathing zone, reducing exposure to metal oxide and gas hazards.

Written authorisation required before welding, cutting or grinding outside a designated area, confirming fire precautions, removal of combustibles and a fire watch are in place.

A person assigned to watch for ignition during hot work and for a set period afterwards, with extinguishing equipment ready, so smouldering fires are caught before they spread.

Drawing method that shows a three-dimensional object as separate front, top and side views arranged on one sheet, each view giving true shape in one plane.

Drawing layout in which each view is placed on the far side of the object from the observer, so the view seen from the left appears on the right of the front view.

Drawing layout in which each view is placed on the near side of the object, so the view seen from the left appears on the left of the front view; common in ISO and American practice.

Ratio stating how a drawn length relates to the real object, written such as 1:2 for half size or 1:50 for a large fabrication; dimensions always state real size, not drawn size.

Standard drawing notation made of a reference line, arrow, and icons that specify the joint type, weld size, length, spacing and any finish or process notes.

The horizontal line of a welding symbol on which weld icons and dimensions are placed; the arrow line points from it to the joint and the tail carries process notes.

Optional forked end of a welding symbol reference line where the process, electrode specification or other reference information is written for the fabricator.

Total included angle between the prepared faces of a single-V or single-U joint, chosen to allow electrode access to the root while limiting fill volume.

Deliberate space left between the two parts at the bottom of a joint before welding, allowing full penetration of the root pass.

The flat, un-beveled portion of a joint edge at the root, which supports the molten pool and prevents burn-through while the root pass is made.

The ease with which a metal can be welded into a sound joint under normal workshop conditions, judged by cracking risk, porosity and the properties of the finished weld.

A calculated number that combines carbon with other alloying elements to express how readily a steel hardens and cracks during welding; higher values demand more preheat.

Heating the base metal to a controlled temperature before welding so it cools more slowly, limiting hardening and helping hydrogen escape from the joint.

Delayed cold cracking that appears hours or days after welding when hydrogen trapped in hardened weld metal builds pressure; prevented by low-hydrogen electrodes, preheat and dry consumables.

Chromium-nickel steel with a non-magnetic face-centred structure, highly corrosion resistant but prone to distortion and hot cracking because it expands and conducts heat poorly.

Loss of corrosion resistance in stainless steel when chromium carbide forms at grain boundaries in the heat-affected zone, leaving chromium-depleted zones that rust.

The band of base metal next to the weld that was heated but not melted, where microstructure and properties change and where many cracks and failures begin.

Shaping of joint faces by grinding, machining or thermal cutting to the specified bevel angle, root face and cleanliness before fit-up and welding.

Aligning and holding parts in correct position with the specified gap, root face, alignment and tack welds before final welding begins.

A short weld used only to hold parts in alignment until the final weld is made; it must be sound enough to survive and is usually fused into the finished joint.

Manual arc process in which a flux-coated consumable electrode melts to form the weld while its coating produces shielding gas and slag over the molten pool.

Process using a continuous bare wire electrode fed through a torch with an externally supplied shielding gas, giving high deposition with little slag.

Process using a non-consumable tungsten electrode and separate filler rod under inert gas shielding, giving precise control for thin sections and root passes.

Gas or gas mixture fed around the arc to exclude air and prevent oxidation and nitrogen pickup in the molten weld pool.

Way molten metal crosses the arc in GMAW, described as short-circuiting, globular or spray, each giving different penetration, spatter and positional behaviour.

Baking or storing covered electrodes in heated ovens and keeping them dry so the coating absorbs no moisture that would introduce hydrogen into the weld.

The wire, rod or electrode added to a joint to form the weld metal; its composition is chosen to match or improve the properties of the base metal.

Welding current divided by the cross-sectional area of the electrode or wire, controlling melting rate, penetration and the arc's stability.

The amperage flowing through the arc, which mainly controls penetration depth, deposition rate and heat input; set higher for thicker metal and larger electrodes.

Energy delivered per unit length of weld, calculated from voltage, current and travel speed; too high input weakens the joint and increases distortion.

Rate at which the arc moves along the joint; slow travel deepens penetration and widens the bead, while fast travel risks lack of fusion.

Unwanted change of shape in a welded part caused by uneven heating, cooling and shrinkage of the weld metal and surrounding plate.

Technique in which short weld runs are made in the opposite direction to the general progress, so each run ends against cold metal and shrinkage is spread out.

Pattern of welding alternately on opposite sides of a joint or about the neutral axis so shrinkage forces cancel and the part stays straight.

Controlled heating of a completed weldment to a set temperature, holding and slow cooling to relieve residual stress, soften the HAZ or restore properties.

Heating the base metal to a controlled temperature before welding so it cools more slowly, limiting hardening and helping hydrogen escape from the joint.

Trapped non-metallic slag or flux within the weld, usually caused by poor inter-run cleaning, low current or wrong electrode angle, and detected by radiography or ultrasonics.

Gas bubbles trapped in solidified weld metal, appearing as internal or surface holes, caused by moisture, dirt, oil or lost shielding gas.

A planar defect where weld metal fails to melt into the base metal or previous pass, often from low current, fast travel or wrong electrode angle.

Inspection methods such as visual, dye penetrant, magnetic particle, ultrasonic and radiographic testing that reveal defects without damaging the welded part.

Set of folding templates used to check fillet leg length, throat thickness, crown height, misalignment and undercut against the specified dimensions.