Sri Lanka NVQ Level 3 Welder Written Examination common mistakes
Sri Lanka NVQ Level 3 Welder Written Examination · Understand the traps and how to avoid them.
When asked to select an electrode for a given steel and position, the candidate names an electrode from memory by its trade nickname, then cannot state the current type, polarity, or positional capability it implies.
Electrode classification codes (such as E6013 or E7018 under AWS, or the equivalent ISO 2560 designations) are memorised as isolated strings rather than decoded as a set of properties: tensile strength, position, coating type, and current. Candidates who learned by copying a shop's usual rod never built the decoding habit, so any unfamiliar steel or position exposes the gap.
What to do instead
Practise decoding codes field by field on paper: write the standard, the strength digits, the position digit, the coating/current digit, and the hydrogen level, then state one sentence for each field. Do this for at least six codes spanning cellulosic, rutile, and basic coatings, and for each one write which position and polarity it suits and why. Attach each code to a real job (root pass on pipe, vertical fillet, repair of cast iron) so the code is retrieved with its application.
The candidate reads a drawing and reports a dimension or weld symbol without first establishing the scale, the projection method (first angle versus third angle), and which view is the front view, so the answer is taken from the wrong view or a scaled measurement is treated as true size.
Candidates learn symbol shapes but not drawing conventions, and drawings in the exam are often reduced. They measure with a rule on a reduced print, or they interpret a first-angle layout as third-angle and place a feature on the wrong side. Under time pressure they skip the title block entirely.
What to do instead
Adopt a fixed reading order and rehearse it: title block (scale, projection symbol, units, material), then views to identify front/top/side, then dimensions, then symbols, then notes. Do worked examples where the same part is drawn in both first and third angle and identify which is which from the symbol alone. For any dimension not given numerically, state that it cannot be scaled and say what information is missing.
When a question describes a defect, the candidate names the defect correctly but gives a generic cause ('wrong current') instead of the specific process variable, and cannot link the defect to the parameter that controls it or to the inspection method that would detect it.
Defect knowledge is often learned as a picture-matching exercise. Candidates recognise lack of fusion or porosity visually but never built the causal chain from parameter to defect, so they cannot answer the 'why' or 'how would you detect it' part that carries the marks.
What to do instead
Build a three-column table for each defect: appearance and location, the two or three process variables that cause it (current, travel speed, arc length, gas flow, moisture, fit-up gap), and the detection method (visual, dye penetrant, magnetic particle, radiography, ultrasonic). Write the causal sentence in full, for example: low current plus fast travel gives insufficient heat input, so the sidewall does not melt and lack of fusion remains; it is planar and oriented vertically, so ultrasonic testing is preferred over radiography. Cover at least ten defects this way.
The candidate answers distortion and residual stress questions by listing remedies (backstep, balanced sequence, pre-set, stress relief) without saying which distortion type each remedy addresses, what the mechanism is, or what the trade-off is.
Distortion is taught as a list of tricks in the workshop. Candidates never connect non-uniform heating and cooling, restraint, and the position of the neutral axis to the resulting angular, longitudinal, or transverse movement, so any question phrased around mechanism or a specific joint defeats them.
What to do instead
For each remedy write: the distortion type it controls, the mechanism (for example, balancing shrinkage about the neutral axis by placing welds symmetrically), and the cost (extra handling, added restraint stress, loss of productivity). Work numerical examples of angular distortion from a V-groove and of shrinkage allowance for a butt joint. Practise explaining why stress relief reduces residual stress but does not remove distortion already locked in.
On calculation items the candidate substitutes numbers into a formula without checking unit consistency, so a heat input answer comes out in the wrong unit, or a deposition or consumption figure is off by a factor of ten because millimetres and metres were mixed.
Formulas are memorised without their units. Heat input (kJ/mm) requires voltage, current, and travel speed in compatible units; electrode consumption requires deposit efficiency and joint volume. Candidates also omit the efficiency factor or the groove cross-section area, and they do not sanity-check the magnitude of the answer.
What to do instead
Write every formula with its units attached and carry units through the arithmetic as if they were algebraic quantities. Do a set of drill problems where the travel speed is given in mm/min and must be converted to mm/s, and where heat input is requested in kJ/mm from amps and volts. After each answer, ask whether the magnitude is plausible (a manual arc weld is typically of the order of 0.5 to 3 kJ/mm) and adjust or flag the error.
The candidate treats welding safety as a list of personal protective equipment and misses the hierarchy of hazard control, the specific hazard of the process (fume from a particular consumable, radiation from a particular arc, fire risk from a particular surroundings), and the correct emergency or permit action.
Safety is revised last and from a PPE poster. Candidates can name a helmet and gloves but cannot state why extraction is preferred to a respirator, which gases are produced by which process, or what to do before hot work in a confined space or near flammables. Questions that test reasoning rather than recall then fail.
What to do instead
Reorganise safety revision by hazard rather than by equipment: fume and gases (process and consumable specific), arc radiation and eye damage, electric shock and the significance of open-circuit voltage and wet conditions, fire and explosion, confined space, and manual handling. For each, state the control in hierarchy order (eliminate, substitute, engineer, administrate, PPE) and the reason PPE is last. Learn the permit and fire-watch sequence for hot work and the action for a person in contact with a live electrode.
When asked about weldability or preparation of a material, the candidate answers for mild steel regardless of the material named, ignoring carbon equivalent, preheat, hydrogen control, or the special problems of stainless steel, aluminium, or cast iron.
Most workshop experience is on mild steel, so the candidate generalises. They do not know that carbon equivalent predicts hardenability and cracking risk, that stainless steel needs low heat input and separate tools to avoid contamination, or that aluminium needs oxide removal and different current.
What to do instead
Make a material-by-material card: carbon equivalent and what it implies for preheat, the main cracking risk, the preparation and cleaning requirement, the consumable and shielding choice, and one characteristic defect. Include mild steel, higher-carbon and low-alloy steels, austenitic stainless, aluminium, and cast iron. Learn to calculate carbon equivalent from a composition and to state the preheat decision it drives. Practise answering the same question for three materials in turn.
The candidate confuses welding position and progression terminology, mixing flat, horizontal, vertical, and overhead, and mixing vertical-up with vertical-down, so answers on parameter selection, electrode choice, and technique are applied to the wrong position.
Positions are learned in the booth by feel rather than by definition, and the exam uses the standard designation letters and descriptions. Candidates also assume one set of parameters works everywhere, so they cannot explain why vertical-up needs lower current and a different manipulation from flat.
What to do instead
Learn the standard position designations and their definitions, including the difference between a fillet and a groove in the same position, and the plate and pipe rotation conventions. For each position write the current range direction (lower for vertical and overhead), the arc length control, the manipulation, and the electrode coating that suits it. Draw the four positions from memory and label them.
The candidate describes inspection and quality control as 'check it visually and if it looks fine it passes', without naming the inspection stage, the applicable acceptance basis, the method's limitation, or the documentation that records the result.
Inspection is seen as someone else's job. Candidates do not distinguish before, during, and after welding checks, do not know that surface methods cannot find internal planar defects, and have not seen a weld procedure specification or a welder qualification record, so documentation questions are answered vaguely.
What to do instead
Learn the inspection sequence: procedure and consumable verification, joint preparation and fit-up check, in-process checks (current, preheat, interpass temperature, pass sequence), and post-weld examination. For each method state what it detects, what it cannot detect, and the safety or surface preparation requirement. Learn the purpose of the weld procedure specification, procedure qualification, and welder qualification, and who is responsible for each record.
The candidate answers fabrication and fit-up questions by describing the finished weld rather than the preparation sequence, omitting root gap, root face, included angle, alignment, and cleaning, and so cannot explain how poor fit-up produces a specific defect.
Fit-up is treated as unskilled preparation and skipped in revision. Candidates do not know typical edge preparation dimensions or how gap and root face interact with current and travel to control root penetration, so they cannot reason about burn-through, lack of penetration, or excessive reinforcement.
What to do instead
For single-V, double-V, square, and U preparations, learn the typical root gap, root face, and included angle ranges and the reason for each. Then write the failure chain: too large a gap with high current gives burn-through; too small a gap or too large a root face with low current gives lack of root penetration. Practise stating a fit-up check sequence (alignment, gap, bevel angle, cleanliness, tack placement) before any arc is struck.