Risk-Based Inspection (RBI) is used in a wide range of industries to help assess the probability of failure and manage the risk of failure. The RBI assessment identifies the type of potential damage, possible areas where such damage might occur, the rate of such damage, and assesses the impact of such failure. RBI inspection is particularly prevalent in the power and petrochemical sectors. While RBI services contribute to improved safety, they also offer economic benefit by using resources more effectively in the areas of highest risk.

There are four stages of asset/equipment life, with each having its own characteristics and behavior, requiring different management strategies. The four stages include:

1. Post commissioning
2. Risk-based
3. Deterministic
4. Monitored (old age)

At What Stage Should You Consider RBI Implementation?

Ideally, RBI should be implemented as early as possible in the life-cycle until the asset reaches the Terminal stage since the time between inspections becomes shorter as assets grow older and need more attention.

Can RBI be implemented even before the Post Commission stage, i.e. during a “Stage 0”? Yes, RBI implementation is possible at the design/construction stage, i.e., before you start operating. Implementing RBI at the very beginning of an asset’s life cycle helps minimize potential risks.

Stage 1: The potential for damage is higher because service conditions in the equipment could reveal faults and weaknesses. For instance, fabrication defects, installation stresses, faulty material could surface and require attention.

Stage 2: The asset is at its peak operational life during the second stage. Ideally, at this early stage, there should be few operational issues rates and a stable rate of damage accumulation, however, examinations, inspections, and maintenance will still be required during this stage to make sure equipment is operating as required.

Stage 3: The 3rd stage or the deterministic stage is where equipment has been operational for a substantial time. Equipment is ageing and beginning to show the signs of ageing. You must determine the extent of any damage. At this stage, RBI helps determine the extent and rate of damage, and to estimate the remaining life through Fitness for Service or FFS assessment. The assets have been operating for a while so the damage has been accumulating.

Stage 4: This is the Terminal stage, where assets are approaching their end of life. The equipment will have to be repaired, refurbished, decommissioned, or replaced. Damages are being accumulated, leading to increasing repair. The rate of degradation increases rapidly and could even be difficult to predict. At this stage, RBI assessment helps guarantee adequate safety between examinations and get the best performance out of the equipment. You cannot guarantee future service of the equipment beyond the next examination.

RBI Implementation at The End of Life Stage

RBI inspection services at this stage help gain the most remaining economic benefit from the asset, without causing environmental, personal, or financial risks. But the focus should be on high-risk areas where inspections can reduce risks for the remaining life of the asset. Activities that do not impact risk are usually eliminated or reduced.