What NDT contributes
Non-destructive testing examines characteristics or discontinuities without making the component unusable through the test itself. It can look for damage from manufacturing or in service. Its findings depend on the technique, accessible surface, material and flaw being sought; they are not an absolute guarantee that every possible defect is absent.
Related concept: Pressure equipment.
Choose the method for the damage mechanism
Visual inspection, liquid penetrant testing, magnetic particle testing, ultrasonics and radiography have different capabilities. A method suitable for detecting a surface discontinuity may not detect an internal one. Before commissioning testing, define the expected damage, where it may occur and what size is significant.
Procedure and competence
Testing requires instructions specifying preparation, equipment, parameters, coverage and recording criteria. Personnel qualifications must match the method and task. Asking only for “ultrasonic testing” leaves unresolved what will be examined, the detection capability required and how the findings will inform decisions about the equipment.
How to read the report
The report must identify the areas examined, inaccessible areas, indications found and limitations. An indication is not automatically a rejectable defect: assessment requires criteria applicable to the component. Conversely, “no indications” describes only what was detectable within the scope and sensitivity of the test actually performed.
Risks of the inspection itself
Testing may require work at height, vessel entry, removal of insulation or chemical use. Industrial radiography introduces ionising radiation risks and specialised controls. The programme must establish safe conditions for inspectors, without treating maintenance urgency as a reason to omit isolation or exclusion zones.
Hypothetical example
A report records thickness measurements at several points on a pipe, but the most likely localised corrosion lies outside that grid. Acceptable measurements do not prove that the entire pipe is sound. The responsible person must review whether the coverage and method address the expected damage before accepting continued service.
