Best Practice for Risk Based Inspection

The introduction of the Pressure Equipment Regulations (PER) in 1999 (3.3),
allows manufacturers to construct certain pressure plant without any specific design
or constructional verification by a third party. This may raise issues with respect to
the quality of the information relevant to integrity of new equipment. Duty Holders
and Competent Persons will need to take this into account when formulating a risk
based in-service inspection strategy for CE marked equipment under the PER.
Where there is doubt about the effectiveness or performance of previous
inspections, such that the condition of the equipment inspected is uncertain, risk
based inspection is difficult to apply. RBI must be able to address all relevant
factors have to be taken into account in specifying the inspection strategy. These
factors will vary depending on the type and complexity of the system and it is likely
that they would vary between individual items within the system. By careful
consideration of the way the system operates and the processes used, the relevant
factors can be identified.
It should be recognised that the ‘inspection strategy’ encompasses:
• The type of the inspection, e.g. full internal, non-invasive, continuous
monitoring.
• The nature of the inspection techniques applied, e.g. visual, non-destructive
testing (NDT), or metallurgical analysis.
• The scope of the inspection, i.e. the specific material targeted.
• The inspection interval.
The resulting inspection strategy from a RBI assessment would be a combination of
those aspects considered to be the most safe yet cost effective. The development of
the inspection strategy is discussed in more detail in Chapter 8.
A number of other potential limitations in the application of the RBI approach
include:
• Reliance on the Duty Holder for accuracy of operational parameters.
• Lack of experience in identifying relevant failure modes and damage
mechanisms.
• Reliability and accuracy of the available inspection technique.
• Lack of construction and usage history.
• The possibility of the unexpected failure.
To avoid these issues it is of the utmost importance that the RBI team should be
composed of individuals having the necessary competence and knowledge of all
aspects of the plant.
25