CSWIP 3.0 Visual Welding Inspector Practice Questions — 10 Free (2026)

A hole is found where the root run of a thin walled pipe collapsed locally during welding. What is this imperfection, and what causes it?

• A. Root concavity, pulled inward by an internal purge pressure that was set far too high
• B. A wormhole, grown from gas boiling out of a crevice underneath the root run
• C. Burn through, from too much heat acting on a root too thin to support the pool ✓
• D. A crater pipe, left where the welder broke the arc without any slope out
• E. Excess penetration, sagging through evenly along the whole of the root run

Burn through, also called melt through, happens when the arc delivers more heat than the root can withstand: the pool loses support, collapses, and leaves a hole or a deeply sunken window in the root. Thin walls, wide gaps, knife edge root faces and excessive current all push in this direction. Root concavity is a smooth continuous groove rather than a local collapse, excess penetration is a protruding bead that is still intact, a crater pipe is a small shrinkage hollow at a stop, and a wormhole is a buried tubular gas cavity. CSWIP 3.0 course material (TWI WIS1), 3.6

Which two of the common examination methods are essentially surface inspection techniques?

• A. Radiographic and ultrasonic testing
• B. Ultrasonic and magnetic particle testing
• C. Radiographic and dye penetrant testing
• D. Ultrasonic testing and dye penetrant testing
• E. Magnetic particle and dye penetrant testing ✓

Magnetic particle testing depends on flux leaking from flaws at or just under the surface, and penetrant testing depends on liquid entering openings in the surface, so both are surface techniques. Radiography and ultrasonics form the volumetric pair, interrogating the full thickness of the joint. Any pairing that mixes a volumetric method with a surface method does not answer the question, because only one member of such a pair works at the surface. CSWIP 3.0 course material (TWI WIS1), 8.1

In arc welding, the electrical energy supplied to the arc is converted mainly into which two forms of energy that create health hazards?

• A. Sound and chemical energy
• B. Heat energy and light energy ✓
• C. Nuclear energy and magnetic energy
• D. Kinetic energy and potential energy
• E. Pressure energy and vibration energy

The arc turns electrical energy into intense heat, which melts the joint but also creates sparks, burns and fire risk, and into light spanning the ultraviolet, visible and infrared ranges, which threatens the eyes and skin. Both of these outputs have direct health consequences and are treated together as one of the four safety headings. Sound is a minor by product of most arc processes, and the arc produces no nuclear energy, while the mechanical forms of energy listed are not what the arc conversion produces. CSWIP 3.0 course material (TWI WIS1), 11.3

How is the design throat thickness of a mitre fillet weld defined?

• A. The longest straight line that can be drawn anywhere inside the weld
• B. The distance measured along the vertical plate from the weld root up to the toe
• C. The height of any weld metal standing proud of a flat mitre face line
• D. The shortest distance from the root to the straight line joining the toes ✓
• E. The width of the face divided by the number of runs used to deposit it

The design throat is the perpendicular, and therefore shortest, distance from the root of the weld to the straight line running between the two toes, which for a mitre profile lies on the face itself. The distance from the root up the plate to a toe is a leg length, not the throat. Metal standing above the mitre line is convexity, which design calculations ignore. The longest line inside the weld would overstate the section, and dividing face width by run count is not a recognised dimension at all. CSWIP 3.0 course material (TWI WIS1), 1.5

Why must the welder remove the slag completely from each MMA run before depositing the next run on top of it?

• A. Because the slag would stop the next electrode from striking an arc anywhere
• B. Because slag left in place would make the finished weld far too heavy overall
• C. Because slag gives off dangerous fumes only when it is covered by weld metal
• D. Because the colour of the slag must be logged before the next run begins
• E. Because any slag left behind can become trapped as inclusions in the weld ✓

Slag that remains on a run can be melted over rather than floated out when the next pass is deposited, leaving solid non-metallic inclusions inside the joint. These slag inclusions are a common welding defect and the reason inter-run cleaning is a hold point in many procedures. The arc will still strike with slag nearby, the weight of residual slag is trivial, fume comes from the arc while welding rather than from buried slag, and no code asks for slag colour to be logged. CSWIP 3.0 course material (TWI WIS1), 5.2

When the dimensions of pipe are checked, which two measurements are needed in addition to those that would be taken on plate?

• A. Length and wall thickness
• B. Width and its flatness
• C. Diameter and ovality ✓
• D. Camber and its sweep
• E. Hardness and toughness

Pipe checks cover length and wall thickness just as plate checks cover length, width and thickness, but pipe additionally needs its diameter and ovality inspected because an out-of-round pipe causes fit-up problems at the weld preparation. Length and wall thickness are therefore common to both product forms rather than extra. Hardness and toughness are mechanical properties, and camber and sweep are straightness terms that the notes do not list here. CSWIP 3.0 course material (TWI WIS1), 6.4

Solid MAG wires for steel are deoxidised to avoid porosity. Which two elements are the usual deoxidants?

• A. Copper and zinc
• B. Chromium and nickel
• C. Manganese and silicon ✓
• D. Sulphur and phosphorus
• E. Carbon and boron

Because the shielding gas for steel is deliberately slightly oxidising, the wire must carry elements that combine with oxygen before it can form porosity, and manganese and silicon are the standard pair, sometimes reinforced with titanium and aluminium in multiply deoxidised grades. Copper appears only as a surface coating, chromium and nickel are alloying elements for corrosion and toughness, sulphur and phosphorus are impurities to be minimised, and carbon with boron is a hardenability combination, not a deoxidising one. CSWIP 3.0 course material (TWI WIS1), 7.6

On a welding procedure specification, the interpass temperature is normally stated as:

• A. a minimum which the joint must always be kept above
• B. a maximum that must not be exceeded during welding ✓
• C. a range that carries no practical importance at all
• D. an optional note provided for general information
• E. a value that applies only to single run weld work

The interpass figure caps how hot the joint may be when the next run is deposited, so it is written as a maximum. There is separately a floor, because the joint should not fall below the minimum preheat between runs, but that floor is not what the stated interpass value expresses. It is an essential control rather than an optional note, and by its nature it concerns welds built up from more than one run. CSWIP 3.0 course material (TWI WIS1), 10.2

A welder is seen using welding conditions different from those on the applicable WPS. In terms of the purpose of procedure control, what is the main risk?

• A. The joint may not achieve the properties needed for its application ✓
• B. The weld will certainly be rejected at the visual inspection stage
• C. The production schedule will overrun and the contract will lose money
• D. The consumable certificates will no longer be traceable to the joints
• E. The calibration of the welding machines will be considered invalid

The specified conditions are the ones proved by testing to give adequate properties, so departing from them removes that assurance and the joint may be unfit for service even if it looks perfect. Visual inspection cannot see mechanical properties, so rejection at that stage is far from certain, which is precisely why the risk matters. Schedule and cost consequences are possible but secondary, consumable traceability is a separate record keeping matter, and machine calibration is unaffected by how the welder sets the machine. CSWIP 3.0 course material (TWI WIS1), 9.1

Excavation of a defect is complete. Why is NDT applied to the empty excavation before any new weld metal goes in?

• A. To show the defect has been completely taken out of the area ✓
• B. To measure how much weld metal the excavation is going to need
• C. To qualify the gouging operator ready for the following repair
• D. To check that preheat has soaked through to the far side of it
• E. To produce a permanent record of the shape of the excavation

Welding over the remains of a defect buries it under new metal, where finding it again is harder and removing it means doing the whole repair twice, so the cavity is examined to confirm the flaw is entirely gone before filling starts. Estimating consumables is done from the cavity size but needs no NDT. Preheat is verified with temperature measurement rather than flaw detection, operators are qualified through their own separate approval route, and record keeping is a by-product rather than the purpose. CSWIP 3.0 course material (TWI WIS1), 12.2