Sri Lanka NVQ Level 3 Welder Written Examination study plan

Match each of the five main arc welding processes (SMAW, GMAW, FCAW, GTAW, SAW) to its power source type, current characteristic and typical duty cycle, writing the comparison from memory.

Explain the internal electrical path of a welding set from mains supply through transformer or inverter to the electrode holder, and state why the work return cable must be clamped directly to the workpiece.

List the personal protective equipment required for arc welding and justify each item by the specific hazard it controls (arc radiation, spatter, fume, electric shock).

Demonstrate and describe the correct procedure for isolating and locking off a welding set before changing electrodes or cables.

Identify the fire and fume hazards of welding in a confined workshop space and state the ventilation and fire-watch controls required before striking an arc.

Set and record welding current, voltage and polarity for at least three electrode sizes on a practice plate, and note how arc stability changes across the range.

Explain the AWS/ISO electrode classification system for covered electrodes and decode the meaning of each digit in a code such as E6013 or E7018.

Describe the function of each ingredient in electrode coating (cellulose, rutile, basic, iron powder) and the current type and position each electrode class suits.

Adjust wire feed speed, voltage and shielding gas flow for GMAW short-circuit and spray transfer, and record the sound and bead appearance at each setting.

Store and redry electrodes correctly, and explain why hydrogen-controlled electrodes need baking and holding ovens.

Classify plain carbon steels by carbon content and state the weldability problems (hardenability, cold cracking risk) of each group.

Read the chemical composition and mechanical property tables of a mill certificate and identify the carbon equivalent, explaining what it predicts about preheat need.

Describe the effect of sulphur, phosphorus, hydrogen and nitrogen on weld quality, and state one control measure for each.

Interpret a fillet and butt weld symbol from a drawing, including arrow side, other side, tail, size, length and pitch, and draw the symbol for a stated joint from a written description.

Identify the main views on an engineering drawing (plan, elevation, section, detail) and extract plate thicknesses, edge preparations and weld lengths from a simple fabrication drawing.

Prepare plate edges for single-V, double-V and square butt joints by cutting, grinding and bevelling to a stated angle, and check root gap and root face with a gauge.

Explain how joint design choice (thickness, access, position, distortion risk) drives the selection between butt, fillet, T, corner and edge joints.

Demonstrate and describe correct fit-up sequence for a T-joint and a butt joint, including tacking position, tack size and checking squareness before welding.

Describe preheat and interpass temperature control for a medium-carbon or thick-section steel, and state how to measure both with a contact thermometer or temperature crayon.

Identify common metal preparation faults (mill scale, rust, oil, wrong bevel angle, uneven root gap) and explain the weld defect each one causes.

Identify each of the main weld defects (porosity, slag inclusion, lack of fusion, lack of penetration, undercut, overlap, spatter, crater crack, toe crack) from a specimen or photograph and state its most likely cause.

Explain the difference between visual inspection, dye penetrant, magnetic particle, ultrasonic and radiographic testing, and state which defect type and which material each method suits.

Describe acceptance criteria for a fillet weld (leg length, throat thickness, undercut limit) and measure leg length and throat with a weld gauge.

Explain how welding position, travel angle, arc length and current setting produce undercut and lack of fusion, and demonstrate one corrective adjustment for each.

Describe the purpose and timing of a visual inspection before welding, during welding and after welding, and list what is checked at each stage.

Explain the three causes of welding distortion (longitudinal shrinkage, transverse shrinkage, angular distortion) and describe how each appears in a finished fabrication.

Apply at least four distortion control techniques (balanced welding sequence, back-step welding, pre-setting, restraint, minimum passes) to a practice joint and record the measured result.

Describe stress relief heat treatment: why it is done, the temperature range for carbon steel, soaking time and controlled cooling, and the risks of getting it wrong.

Explain post-weld operations including cleaning, grinding, chipping, descaling and pickling of stainless steel, and state why each matters to quality and corrosion resistance.

Describe how hydrogen can be removed by post-heat and why delayed cracking can appear hours after welding is complete.

Calculate welding current settings, electrode consumption, arc time and deposit efficiency for a given joint, and show each step of the working.

Calculate the length of weld and filler metal mass required for a stated fillet weld size and run length, and estimate the labour time at a stated deposition rate.

Complete a job card or weld procedure record with all required fields: material, thickness, joint type, process, consumable, parameters, welder ID and inspection result.

Explain the purpose of a Welding Procedure Specification and how a procedure qualification record supports it, without claiming to write a qualified procedure.

Describe the workshop housekeeping, waste segregation and environmental controls (fume extraction, scrap metal, gas cylinder storage) expected at the end of a shift.

Complete a full timed mock examination under exam conditions and score it against the answer key, recording the score per domain.

Re-study the two weakest domains identified in the mock and write a corrected summary of each weak area in your own words.

Re-derive from memory the electrode classification codes, weld symbol conventions and the main defect causes without reference material.

Recite the safety controls for electric shock, fire, fume and arc eye, and confirm each against your own workshop practice.

Review your practice weld samples against acceptance criteria and write a short self-assessment of which skills need further bench time after the exam.