NDT Practice Test PDF (Free Printable 2026)

NDT Practice Test PDF – Free Download (2026)

Preparing for your non destructive examination requires more than skimming a textbook. The ASNT NDT Level II certification is one of the most technically demanding credentials in industrial inspection, and the written exam tests your understanding of physical principles, equipment calibration, procedural steps, and code-based acceptance criteria across six primary methods. This page gives you a free printable PDF you can carry to the job site, study on a lunch break, or use in a group review session — no internet required.

What the ASNT NDT Level II Written Exam Covers

The ASNT SNT-TC-1A qualification framework structures the written exam into three components for each method: a General section covering the physical principles and theory behind the technique, a Specific section covering equipment, procedures, and calibration steps for the particular method, and a Practical component where you actually apply the method under supervision. Before you sit the written portions, you need documented hours of on-the-job experience under a certified Level II or Level III — the exact hours vary by method and employer written practice.

Level I technicians can apply a specific method under close supervision but cannot independently interpret results or write procedures. Level II technicians are qualified to set up equipment, calibrate, perform the examination, interpret results against the applicable code or standard, and document findings. Level III technicians develop written procedures, establish acceptance criteria, train and certify Level I and Level II personnel, and approve procedures for use. Most boilermaker NDT roles and industrial inspection positions require at least Level II qualification in one or more methods.

Visual Testing (VT) — The Foundation of All NDT

Visual Testing is the oldest and most frequently used method in the NDT toolkit. Every other inspection method supplements VT rather than replacing it. Direct VT means the inspector's eye is within 24 inches of the surface being examined, with the line of sight no more than 30 degrees from the surface. Remote VT uses mirrors, borescopes, cameras, or robotic crawlers when direct access is physically impossible — inside a pipe, inside a pressure vessel, or on an elevated weld seam.

VT requires adequate illumination. Most codes specify a minimum of 50 foot-candles (500 lux) at the examination surface. Inspectors must check their visual acuity annually using a Jaeger Number 1 chart at 12 inches or a Snellen chart at 20 feet. Color contrast vision is tested as well, because VT depends on seeing color differences in weld toes, heat-affected zones, and surface oxidation.

Acceptance criteria for VT are always defined by the applicable code or standard — ASME Section V for pressure vessels and piping, AWS D1.1 for structural steel, API 1104 for pipelines. Before performing a visual examination, the inspector must know which document governs the work, what discontinuity types are rejectable, and at what size or frequency they become cause for rejection or repair.

Liquid Penetrant Testing (PT) — Surface Defect Detection on Non-Porous Materials

PT works by capillary action: a liquid penetrant seeps into surface-open discontinuities, excess penetrant is removed from the surface, and a developer draws the trapped penetrant back out to form a visible indication. The five steps must be performed in order and within the time windows specified in the procedure.

Step one is precleaning. The surface must be free of scale, paint, oil, grease, and any other contaminant that could block penetrant entry or cause a false indication. Acceptable cleaning methods include solvent wipe, vapor degreasing, ultrasonic cleaning, and chemical etching — never wire brushing, which can mechanically close surface cracks and mask real defects. Step two is penetrant application by spray, brush, or immersion. Step three is the dwell time — the minimum time the penetrant must remain wet on the surface. Dwell times range from 5 minutes for very fine cracks in aluminum to 30 minutes or more for tight fatigue cracks in high-strength steel. Step four is removal of excess penetrant. Water-washable penetrants are removed with a coarse water spray; solvent-removable penetrants are wiped with a solvent-dampened cloth (never flood the surface with solvent). Post-emulsifiable penetrants require an emulsifier applied after the dwell time before washing. Step five is developer application, which draws the penetrant out of the defect and spreads it to form a readable indication.

Fluorescent penetrants (Type 1) are more sensitive than visible-light penetrants (Type 2) because human eyes are far more sensitive to the yellow-green fluorescence under UV-A (black) light than to red indications against a white developer background. Fluorescent PT must be performed in a darkened area with UV-A intensity of at least 1,000 microwatts per square centimeter measured at the examination surface. PT cannot be used on porous materials (cast iron, thermal spray coatings, unimpregnated powder-metal parts) because the penetrant cannot be removed from the pores, producing a blizzard of false indications.

Magnetic Particle Testing (MT) — Ferromagnetic Materials Only

MT detects surface and slightly subsurface discontinuities in ferromagnetic metals by inducing a magnetic field in the part. Where a discontinuity interrupts the flux path, flux leaks out of the surface and attracts magnetic particles to form a visible indication. MT cannot be used on austenitic stainless steel, aluminum, copper, titanium, or any other non-ferromagnetic material.

Magnetization can be circular (current flows through the part or through a central conductor passing through a hole in the part) or longitudinal (current flows through a coil wrapped around the part, or through yoke legs). Circular magnetization is most effective at detecting longitudinal cracks (cracks running parallel to the long axis of the part). Longitudinal magnetization is most effective at detecting transverse cracks. For complete coverage, most procedures require magnetizing the part in at least two directions at roughly 90 degrees to each other.

Wet fluorescent magnetic particle (WFMT) using a UV-A light source provides the highest sensitivity for fine fatigue cracks and is standard practice in aerospace and power generation. Dry magnetic particles are used on rough surfaces, on parts that cannot be wetted, and in the field where UV-A lights are impractical. The continuous method — applying particles while the magnetizing current is flowing — is more sensitive than the residual method because the flux density is at its peak during particle application. Yokes, prods, coils, and central conductors are all acceptable magnetizing techniques; the choice depends on part geometry and the orientation of suspected discontinuities.

Radiographic Testing (RT) — Volumetric Inspection

RT sends ionizing radiation (X-rays from an X-ray tube or gamma rays from a radioactive isotope such as Ir-192, Se-75, or Co-60) through the part. Areas of lower density or reduced thickness absorb less radiation and appear darker on the radiographic film or detector. RT is the primary volumetric method for weld inspection because it detects internal porosity, slag inclusions, lack of fusion, and cracks that are not visible from the surface.

Film radiography uses sensitized film in a light-tight cassette. Digital radiography (DR) and computed radiography (CR) use flat-panel detectors or phosphor imaging plates that are read out electronically. Image quality is verified using image quality indicators (IQIs), also called penetrameters. Wire-type IQIs consist of a series of wires of decreasing diameter; the thinnest wire that is visible on the radiograph defines the sensitivity achieved. Plaque-type IQIs consist of a block of the same material as the part with drilled holes; the smallest hole visible defines sensitivity.

Source-to-object distance (SOD) and object-to-film distance (OFD) control geometric unsharpness. The single-wall single-image (SWSI) technique is preferred; the double-wall double-image (DWDI) technique is used on small-diameter pipe that cannot be accessed from the inside. Film density must fall within the range specified by the applicable code — typically 1.8 to 4.0 for X-ray and 2.0 to 4.0 for gamma ray when measured with a calibrated densitometer.

Radiation safety is a mandatory exam topic. The inverse square law states that radiation intensity decreases with the square of the distance from the source — double the distance reduces intensity to one-quarter. Dosimetry badges and pocket dosimeters measure accumulated dose. Exclusion zones must be established during every exposure. All radiographers must hold an active radiation safety card issued through their employer's radiation safety program and in compliance with applicable NRC or Agreement State regulations.

Ultrasonic Testing (UT) — High-Sensitivity Volumetric and Thickness Inspection

UT uses high-frequency sound waves (typically 1 to 25 MHz) transmitted into the material through a transducer coupled to the surface with a liquid couplant (water, glycerin, or gel). Reflections (echoes) from the back wall of the part and from internal discontinuities are displayed on an A-scan screen as peaks at positions corresponding to their depth. UT can measure wall thickness, locate internal flaws with high precision, and characterize flaw geometry better than any other portable method.

Straight-beam (normal-incidence, longitudinal wave) UT is used for thickness measurement and for detecting planar reflectors perpendicular to the beam. Angle-beam (shear wave) UT is used for weld inspection, where the beam must travel at an angle to intercept vertical planar flaws such as lack of fusion and cracks at the weld fusion line. Common refracted angles are 45°, 60°, and 70° — the choice depends on the weld geometry and the thickness of the material. Transducer frequency selection balances resolution (higher frequency = better resolution) against penetration (lower frequency = greater penetration in attenuating materials like austenitic welds or castings).

Calibration is performed using reference blocks before and after each examination and at regular intervals during the examination. The IIW (International Institute of Welding) block and the distance-amplitude correction (DAC) block are the two most common reference blocks. A DAC curve plots the amplitude response from a series of reference reflectors at increasing depths; all indications exceeding the DAC curve by a specified percentage must be evaluated and recorded. Phased-array UT (PAUT) uses multiple elements that can be electronically focused and steered to produce sectorial (S-scan) images and encoded linear scans, significantly reducing inspection time on complex geometries.

Eddy Current Testing (ET) — Surface and Near-Surface Inspection of Conductors

ET works only on electrically conductive materials. An alternating current through the probe coil induces eddy currents in the part. Discontinuities or property changes disturb the eddy current pattern, and that disturbance is measured as a change in the coil's impedance displayed on the ET instrument screen. ET is highly sensitive to surface and near-surface cracks, is fast (tubes in heat exchangers can be scanned at several feet per second), and requires no couplant and no direct contact beyond the probe.

Frequency selection controls penetration depth — lower frequency means greater depth of penetration but lower surface sensitivity. The lift-off effect (probe wobbling off the surface) creates a signal similar to a conductivity change; technique must minimize lift-off variation or compensate for it in the signal processing. ET cannot size the depth of a crack reliably without reference standards and is not used for volumetric inspection. Phase analysis on the impedance plane display is used to distinguish surface cracks from subsurface flaws and to separate cracks from geometry changes such as edges and fastener holes.

How to Use the NDT Practice Test PDF

Print the PDF double-sided and punch holes for a three-ring binder. Work through each question before checking the answer. When you get a question wrong, do not just move on — write the correct principle in your own words. The ASNT written exam rewards understanding over memorization. If you can explain why a fluorescent penetrant requires a UV-A light source with a minimum intensity of 1,000 microwatts per square centimeter rather than just knowing that number, you will handle rephrased questions on the actual exam with confidence.

Group questions by method. Spend extra time on RT — radiation safety questions appear on every exam, are safety-critical in real work environments, and are often the deciding factor between a pass and a fail. Pay close attention to code references. The applicable document (ASME Section V, AWS D1.1, API 1104) determines the acceptance criteria, the IQI type, and the density requirements for any given examination. The exam will expect you to know which document applies to which type of work.

For UT angle-beam questions, sketch the beam path on paper. Understanding the geometry of the sound path through the base metal, heat-affected zone, and weld fusion line is essential for correctly identifying where a reflector is located relative to the weld centerline. For MT questions, remember that circular magnetization detects longitudinal flaws and longitudinal magnetization detects transverse flaws — if you mix those up, every related question on the exam will go wrong.

Common NDT Exam Mistakes and How to Avoid Them

Many candidates lose points on RT questions because they confuse SWSI and DWDI technique geometry. Draw both setups before your exam: SWSI places the source on one side of the pipe and the film on the other, capturing one wall in each exposure. DWDI is used on small-diameter pipe where the source is placed outside the pipe and the film is also outside, capturing both walls in a single exposure with the indication from the near wall superimposed on the far wall image. Knowing when each technique is required — and how to calculate the required source-to-film distance — is worth multiple points.

On PT questions, candidates frequently confuse water-washable, solvent-removable, and post-emulsifiable systems. The key distinction is that solvent-removable penetrants must never be flooded with solvent during removal because over-removal washes the penetrant out of fine discontinuities, destroying the indication. Post-emulsifiable penetrants are used when the highest sensitivity is required on smooth machined surfaces, because they resist washing better than water-washable systems.

On UT questions, many candidates struggle with the difference between longitudinal waves (compression waves, used in straight-beam contact testing and most immersion testing) and shear waves (transverse waves, produced in the part by mode conversion at a wedge, used in angle-beam weld inspection). The two wave types travel at different velocities in the same material, so the calibrated distance scale on the instrument changes when you switch from straight to angle beam. Always recalibrate when changing transducer or wedge.

NDT in the Boilermaker Trade

Boilermakers fabricate, install, and maintain pressure vessels, boilers, heat exchangers, storage tanks, and process piping. NDT is not optional in this trade — it is required by the codes that govern every pressure boundary weld. A boilermaker NDT technician typically qualifies in RT and UT as the primary volumetric methods, with PT or MT for surface examination. Understanding code requirements under ASME Section I (power boilers), Section VIII (pressure vessels), and Section IX (welding qualifications) is as important as understanding the physics of the inspection methods themselves. The PDF below gives you the practice questions you need to build that knowledge base before your certification exam.