Inspection of pipelines, pipework and associated plant is usually carried with one or more of the following methods
Radiography Just like a medical X-ray, a beam of X- [or gamma] radiation is passed through the item under test onto a photographic film. Any defects show up as a shadow in the film
Ultrasonic examination Ultrasonics is akin to radar in that a beam of high frequency sound is passd through the component. Defects will refect the beam which is detected and displayed electronically
Magnetic particle inspection Magnetic particle inspection relied on the ability of a magnet to attract a magnetic medium such as fine iron filings. Surface discontinuities,when in a magnetic field, attract the filings and thus outline the defect
Dye penetrant examination Dye penetrant relies on dye sprayed on the surface being trapped in the defect. When the dye is removed from the surface, the dye in the cracks can be seen when a developer coat is sprayed on the surface.
Visual examination Altough last on this list, visual examination should be the first to be carried out. Surface defects, poor profile and incorrect geometry are all checked at this stage.