What is Non-destructive Testing (NDT)?
Non Destructive Testing (NDT), also known as Non Destructive Examination (NDE), consists of all the methods and techniques used to acquire information on the integrity and the state of health of a material or a part, without damaging or destroying it.
NDT is to materials what medical imaging is to the human body.
The applications of NDT
All sectors of industry use NDT (aeronautics, aerospace, nuclear, petrochemicals, railways, automotive, metallurgy, foundries, etc.) on parts that are critical to the safety of a piece of equipment or a system. NDT must be capable of detecting any defects that could affect the availability, safety of use and/or, more generally, the conformity of a part with its intended use.
NDT is applied to forged, rolled, die-cast, welded, etc., parts in three cases:
- Inspections during production, which usually result in the defective parts being separated
- Acceptance tests of parts or systems that detect defects and define their nature and characteristics
- In-service inspections to detect, define and size defects that appear during the lifetime of a part or system and monitor them over time
NDT methods
The main NDT methods are:
The types of defects to be detected
NDT searches for two types of defects:
- surface defects, such as holes, cracks, pitting...
- Internal defects, such as porosities, blow holes, inclusions, sub-surface cracks or variations in thickness due to wear or corrosion.
The procedures
NDT processes are used according to procedures that guarantee the objectivity, reproducibility and reliability of the techniques and processes. These procedures are based on standards (usually CEN or ISO standards), codes and specifications that are specific to certain industrial manufacturers
The certification of test agents
In France, the levels of knowledge and skills of the personnel are guaranteed by a certification awarded by the COFREND , the French NDT confederation, on the basis of the results of theoretical and practical exams. There are about 13 000 COFREND certified agents in France.
