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		RISK BASED INSPECTION

When to Inspect?

The need for inspection is obvious and the reasons manifold.

Very often the need is obligatory based upon the need to demonstrate quality and integrity. Sometimes it is a sensible precautionary measure which helps mitigate risk and underwrite integrity.

When used pro-actively, as an integrated source of plant condition information, it is a powerful management tool which enables more effective commercial management of vital assets, facilitates cost efficient production and maintenance scheduling and mitigates the probability and impact of failure.

At the point of manufacture, fabrication or construction all components and assemblies requires inspection to ensure 'as made' quality compliance with the regulations pertaining to safe and reliable use. Once in service these same products need periodic assessment to ensure that they continue to be fit for safe and reliable purpose.

But not everything can be inspected 100% on a regular basis …….and not everything needs to be!

Those parts which are not critical can be tested less frequently - particularly those which are not exposed to conditions which are likely to incur serious problems, those which have minimal impact in terms of safety and productivity and those which are routinely serviceable or replaceable.

More significantly, most defects are predictable in terms of their probable cause, nature, location and integrity impact.

This risk & probability based assessment approach helps determine what should be inspected, where the focus of attention should be and what to look for - but the question remains when and at what frequency should inspection be performed.

By definition, statutory inspection must be done at the ordained points in time.

Where no such mandatory obligations exist, the question of when (or how frequently) is open to judgement based on a number of key parameters which can best be described as sensible, safe and affordable.

On the question of affordability a further consideration has to be made to establish the differential between getting it right and the consequential cost of getting it wrong.

Exercising this judgement requires a good understanding of the factors affecting condition, actual condition and the probability and consequence of failure.

NDT provides answers to these questions

For more information on Risk based Inspection, please see:-

- Risk Based Inspection
- Why shut down?
- What to Inspect?
- Which Technique?

If you have any further questions or require more detailed answers relating to the above, contact Colin Mortimer