Risk-based inspection

Risk Based Inspection (RBI) is a risk based approach to prioritizing and planning inspection used in engineering industries, and predominant in the oil and gas industries. This type of inspection planning analyses the probability (or likelihood) and consequence of failure of an asset to calculate its risk of failure. The level of risk is used to develop a prioritised inspection plan for the asset. It is related to (or sometimes a part of) Risk Based Asset Management (RBAM), Risk Based Integrity Management (RBIM) and Risk Based Management (RBM).

It is used to prioritise inspection, usually by means of non-destructive testing (NDT), requirements for major oil platforms, refineries and chemical installations around the world. The resulting inspection plan outlines the type and frequency of inspection for the asset. It is used for industrial pipework, process systems, pipelines, structures and many other types of assets in these industries.

Items with high probability and high consequence (i.e. high risk) are given a higher priority for inspection than items that are high probability but for which failure has low consequences. This strategy allows for a rational investment of inspection resources.

Following an explosion in April 2001, the ConocoPhillips-owned Humber Refinery in the United Kingdom was found guilty of failing to appropriately monitor the deterioration of its pipework. An RBI programme has since been employed by the company.^[1]

Risk Based Inspection is an inspection planning tool rated under Risk and Reliability Management (RRM).

Objectives

RBI will assist a company to select cost effective and appropriate maintenance and inspection tasks and techniques, to optimize such efforts and cost, to shift from a reactive to a proactive maintenance regime, to produce an auditable system, to give an agreed “operating window”, and to implement a risk management tool.

Risk Based Inspection (RBI) is a proven method used to optimize inspection activities based on risk analysis. RBI improves plant reliability and safety whilst reducing unplanned outages and repair costs. Once the RBI program is operational inspection learning is fed back to help lower the risk profile of an asset’s equipment.

Purposes

The purposes of RBI include:

1. To move away from time based inspection often governed by minimum compliance with rules, regulations and standards for inspection.
2. To apply a strategy of doing what is needed for safeguarding integrity and improving reliability and availability of the asset by planning and executing those inspections that are needed.
3. To provide economic benefits such as fewer inspections, fewer or shorter shutdowns and longer run length.
4. To safeguard integrity.
5. To reduce the risk of failure.
6. To Increase plant availability and reduce unplanned outages.
7. To Reduce inspection and maintenance costs without compromising safety or reliability.
8. To provide a flexible technique able to continuously improve and adopt to changing risk environment.
9. To ensure Inspection techniques and methods are clearly defined based on thorough understanding of potential failure modes

Standards

There are many international engineering standards and recommended practices that outline requirements, methodologies and the implementation of RBI. Included in these are API RP 580^[2] & 581.

References

External links

• Health and Safety Executive: Best practice for risk based inspection as a part of plant integrity management