Examples provided here are purely for illustrating software features and functionality.

Example 2 – Risk Based Inspection Analysis of a Reactor Casing

Download Example File for Version 10 (*.rsgz10) or Version 9 (*.rsr9)

Background

This example demonstrates how to perform a risk based inspection analysis using the RBI software.

For this example, you will be analyzing a reactor casing that was installed on March 13, 2006 with a planned replacement date of March 13, 2023. The reactor is subject to general thinning corrosion and possible amine cracking. On average, the reactor contains 15 tons of liquid ammonia with the upstream connected equipment containing another 35 tons of liquid ammonia. Management estimates that the loss of production due to reactor downtime is $100,000 per day. The acceptable safety risk is 2,500m² and the acceptable financial risk is $3 million. You must determine if the reactor requires any further inspections before the planned replacement date.

Analysis

Step 1: Create the system hierarchy.

Step 2: Enter the general properties.

Step 3: Select the applicable damage factors that apply to the component.

Step 4: Enter the damage factor properties.

Step 5: Enter the consequence properties.

Step 6: Calculate the component results and review the values shown next. (Note that most of the dates shown in the following pictures are based on the date when the analysis was performed in the sample project. If you repeat the analysis from scratch, or if you recalculate, the specific dates in your results will be different.)

As shown above, the Area Based Risk exceeds the risk target on November 10, 2018. And, as shown in the Recommended Inspection(s)node, on that date you must perform two inspections: one for the thinning damage and one for amine cracking damage. These must be at least poorly effective (a class “D” inspection). If the inspections do not find anything out of the ordinary (i.e., everything is found to be as currently predicted), then the potential risk is lowered to an acceptable level by the time the reactor is due to be replaced.

The following plot shows these dates graphically.

Note that while the financial risk will not have exceeded its risk target limit on November 10, 2018, it will exceed that limit sometime in 2019 if you do nothing. By performing the recommended inspections on November 10, 2018 (and assuming that nothing out of the ordinary is found during those inspections) you also ensure that the financial risk will not exceed its limit before the planned replacement date. The Financial Risk plot shows this.

Discussion

Based on the analysis the reactor will require additional inspections before the planned replacement date, but as long as they are at least poorly effective, and nothing out of the ordinary is found, then the area and financial risks will likely remain within the limits determined by the management.