Radiographic Testing(RT)
Definition
An NDE method that uses penetrating radiation (X-rays or gamma rays) to produce an image of the internal structure of a component. The radiation passes through the material and is captured on film or a digital detector. Variations in material thickness, density, or internal flaws appear as contrast differences on the image. RT is effective for detecting volumetric flaws (porosity, inclusions, voids) and some planar flaws (cracks oriented favorably to the beam).
Context
RT has traditionally been the primary weld inspection technique but is increasingly supplemented or replaced by advanced UT techniques (PA-UT, TOFD) which are faster, do not require radiation safety controls, and are more sensitive to planar flaws. RT remains valuable for detecting porosity and for permanent image records.
Examples
- Film radiography of a butt weld reveals scattered porosity and a linear slag inclusion, both requiring assessment against the acceptance criteria of ASME Section VIII.
- Digital radiography (DR) provides immediate feedback during field inspection, reducing turnaround time compared to conventional film radiography.
Applicable Standards
- ASME V Article 2
- ASTM E94
- ISO 17636
Related Terms
A group of analysis techniques used to evaluate the condition of materials, components, and assemblies without causing damage or altering their serviceability. NDE methods detect surface and subsurface flaws, measure wall thickness, characterize material properties, and assess the integrity of welds and joints. Common NDE methods include ultrasonic testing (UT), radiographic testing (RT), magnetic particle inspection (MPI/MT), liquid penetrant testing (PT), visual testing (VT), eddy current testing (ECT), and acoustic emission testing (AE).
Ultrasonic Testing(UT)An NDE method that uses high-frequency sound waves to detect internal flaws and measure wall thickness in materials. A transducer sends ultrasonic pulses into the material; reflections from internal surfaces, flaws, or the back wall are analyzed to determine thickness, flaw size, and flaw location. UT techniques include conventional (A-scan), phased array (PA-UT), time-of-flight diffraction (TOFD), guided wave (GWUT), and automated/semi-automated scanning (AUBT).
Magnetic Particle Inspection(MPI/MT)An NDE method for detecting surface and near-surface discontinuities in ferromagnetic materials. The test surface is magnetized (using a yoke, prods, or coil) and ferromagnetic particles (dry powder or wet suspension) are applied. Particles accumulate at areas of flux leakage caused by discontinuities, forming visible indications. MPI is highly sensitive to surface-breaking cracks, particularly fatigue cracks, stress corrosion cracks, and weld defects.
Inspection EffectivenessA qualitative rating of the probability that an inspection activity will correctly identify and characterize the damage present in the inspected equipment. Inspection effectiveness is categorized from A (Highly Effective — high probability of detecting the damage) through E (Ineffective — virtually no chance of detection). The rating depends on the inspection technique used, the skill of the inspector, the coverage area, and the damage mechanism being sought.
Where this appears in Reliatic
This concept is used in the Inspections module.