In-service inspection; training and certification aspects


A wide range of engineering plant is subject to periodic in-service inspection in order to ensure continuous, safe and cost-effective operation by using fracture mechanics and risk-based assessments. Non-destructive testing (NDT) is an integral part of this critical assessment process and as a result, the demand for reliable in-service NDT inspections in terms of detectability and sizing accuracy is continuously increasing. The most conventional degradation mechanisms such as corrosion, stress corrosion cracking, thermal or fatigue cracking differ significantly from manufacturing flaws; their detection, quantification and accurate sizing by NDT methods require different techniques, equipment and sensitivity settings. ISO 9712 specifies in-service inspection as one of the certification sectors; however, effectiveness of the NDT inspectors on utilising the required techniques and detecting the service-induced flaws is often debatable.

In this paper, the cause for this ineffectiveness is being identified by looking at the standard route to NDT certification according to ISO 9712. Focusing on how and at which level the necessary sector specific competencies are embedded in the training and examination processes the conclusion reached is that in-service inspection sector is not sufficiently covered. To address this problem many certification bodies have introduced sector specific training courses as endorsement courses to existing ones, consequently increasing the number of training hours. An alternative solution proposed in this paper is the introduction of ISO 9712 compliant, employer specific schemes governed by accredited third party certification bodies in order to achieve specific competence assurance requirements, which are related to in-service inspections.