X-ray Testing (also called Radiographic Testing – RT) is a non-destructive testing (NDT) method that uses X-rays or gamma rays to inspect the internal structure of materials, detecting defects like cracks, voids, inclusions, and weld flaws.
How X-ray Testing Works
- Radiation Source
– X-ray machines (for controlled, high-resolution imaging).
– Gamma-ray sources (e.g., Iridium-192, Cobalt-60 for thicker materials).
- Penetration & Absorption
– High-energy rays pass through the test object.
– Denser areas (like metal) absorb more radiation, while defects (voids, cracks) allow more rays to pass through.
- Detection & Imaging
– Film Radiography – Traditional method using X-ray film.
– Digital Radiography (DR) – Uses detectors for instant images.
– Computed Radiography (CR) – Uses phosphor plates scanned into a digital image.
- Image Interpretation
– A certified RT inspector analyzes shadows/density changes to identify flaws.
Advantages of X-ray Testing
Detects internal defects (cracks, porosity, inclusions).
Works on most materials (metals, composites, ceramics).
Permanent record (film or digital images for documentation).
No surface prep required (unlike UT or PT).
Disadvantages & Safety Risks
Radiation hazard – Requires strict safety protocols (shielding, restricted zones).
Expensive equipment & licensing (gamma sources need regulatory compliance).
Limited portability (X-ray machines are bulky; gamma sources are hazardous).
2D limitations (unless using CT scanning).
Applications of X-ray Testing
– Welding Inspection (pipeline, pressure vessel, aerospace welds).
– Aerospace & Automotive (casting defects, turbine blade inspection).
– Electronics (PCB soldering defects).
– Archaeology & Art Restoration (non-invasive artifact analysis).
Safety & Regulations
– ALARA Principle (As Low As Reasonably Achievable – radiation exposure control).
– OSHA 1910.1096 (Ionizing Radiation Standards).
– ASME BPVC Section V (Radiographic Testing Standards).
– Requires certified Level II/III RT personnel.
Standards for X-ray Testing
– ASTM E94 (Standard Guide for Radiographic Examination)
– ISO 17636 (Radiographic Testing of Welds)
– ASME B31.3 (Process Piping Radiography Requirements)
When to Use X-ray Testing?
– Critical welds in pipelines or pressure vessels.
– Detecting internal casting defects (porosity, shrinkage).
– When a permanent inspection record is needed.
