Radiographic Testing Level 2 Plus RT Safety Vaal

Radiographic Testing (RT) is a non-destructive testing (NDT) method that uses penetrating radiation (X-rays or gamma rays) to create an image of the internal structure of an object on a radiographic film, digital detector, or fluorescent screen. It reveals internal defects such as cracks, voids, inclusions, porosity, or lack of fusion in welds and castings.

How It Works:

1. Radiation Source
   1. X-ray tube (electricity-generated, adjustable energy).
   2. Gamma source (radioisotopes like Ir-192, Co-60, Se-75 – portable, constant energy).
2. Radiation Penetration
   1. Beam passes through the test object.
   2. Dense areas (e.g., metal) absorb more radiation → appear lighter on the image.
   3. Less dense areas (e.g., voids, cracks) allow more radiation → appear darker.
3. Image Capture
   1. Film Radiography: Radiation exposes photographic film → developed into a negative.
   2. Digital Radiography (DR/CR): Uses imaging plates or flat-panel detectors → instant digital image.
4. Image Interpretation
   1. Qualified radiographer evaluates contrast, density, and defect indications.

Applications:

• Weld inspection (pipelines, pressure vessels, structural steel).
• Casting inspection (porosity, shrinkage in engine blocks, valves).
• Aerospace (turbine blades, composite bonding).
• Corrosion under insulation (CUI) via profile radiography.

Advantages:

• Permanent visual record.
• Detects volumetric defects (porosity, slag) and planar defects (cracks).
• No surface preparation needed (unlike UT/MT).
• Suitable for thick materials.

Limitations:

• Radiation hazard – requires safety controls (ALARP, dosimetry).
• Access to both sides needed (source & detector).
• Orientation-sensitive – defects must be aligned with beam.