Nondestructive

Nondestructive refers to methods and practices that assess the properties, integrity, or performance of a material, component, or structure without causing damage that would render it unusable. In engineering and manufacturing, the terms nondestructive testing (NDT), nondestructive evaluation (NDE), and nondestructive inspection (NDI) are used to describe approaches that seek information while preserving the item for its intended use.

Common nondestructive methods include radiography (x-ray or gamma imaging), ultrasonics, eddy current testing, magnetic particle inspection, liquid penetrant testing, infrared thermography, and acoustic emission. Some techniques inspect surfaces, others probe internal features, and many rely on interpreting signals or images by trained personnel. Equipment ranges from simple visual inspection tools to sophisticated imaging and data-analysis systems.

NDT/NDE/NDI are widely applied in aerospace, automotive, energy, construction, oil and gas, and infrastructure to support quality control, safety assessment, and maintenance planning. They help detect cracks, corrosion, wear, or other flaws, and can be used for monitoring deterioration over time or verifying production integrity. Standards and qualification programs are maintained by organizations such as ASTM International, ISO, and the American Society for Nondestructive Testing (ASNT). Personnel may hold certifications at levels I, II, or III, reflecting their training and supervisory capabilities.

Limitations include the potential for missed defects, false indications, or interpretation errors; some methods require access to specific surfaces or equipment; and nondestructive results may be less definitive for certain material properties compared with destructive testing. The term contrasts with destructive testing, where the specimen is altered or consumed to obtain data.