Non-intrusive inspections can be used to inspect a variety of pressure vessels. Nonetheless, they do require a more sophisticated and considered approach than a normal intrusive inspection. The vessel type, service, geometry, materials, credible damage mechanisms and inspection and maintenance history must all be taken into account and an appropriate technique or combination of techniques identified for each area of the vessel. An air receiver vessel with no credible internal damage mechanisms could be assessed, for example, using ultrasonic testing techniques.
It is important to define the objectives of any NII activity in advance as there are several factors that can impact on its effectiveness and may affect the decision of whether to opt for an NII technique or not.
It is not always possible to utilise NII and the decision depends critically on the vessel itself and the level of degradation expected.