When the dust settles after completion of a facility’s relief system design revalidation, the difficult task of mitigating any identified deficiencies begins. The question inevitably arises as to which deficiencies to address first, and if your facility has recently undergone a unit wide or facility wide relief system revalidation, you may be wondering how to tackle such a monumental task. Well, as the adage says, “The only way to eat an entire elephant is one bite at a time.” Similarly, the best way to tackle a long list of relief system deficiencies is one relief system and one relief device at a time.
While the average oil, gas, and specialty chemical employee may not do much daily computer coding, there are a few things we could learn from those who do. Computers process volumes of information, but before an individual task can be processed and completed, a scheduler must decide which tasks to prioritize and complete first. In fact, there is an entire field of computer science dedicated to task scheduling for computer processors. Below are a few algorithms used by computer scientists to schedule tasks for processors. This is certainly not an inclusive list, but these are ones that I think can provide insight into prioritizing mitigation plans for relief system deficiencies. The best option for you depends on your primary objectives and metrics for closing out deficiencies.
Shortest Job Next Algorithm (The Snowball Method): This algorithm looks at the time required to complete a given process and moves the one with the shortest processing time to the front of the processing queue. This algorithm focuses on getting as many short and easy tasks out of the way before tackling the more difficult tasks or the tasks that will take longer to complete. This algorithm works well for quickly reducing the overall number of tasks to be completed. By working on the relief system deficiencies that are easiest to close, you can quickly reduce the overall number of open deficiencies. Another analogy would be the “The Debt Snowball,” which in personal finance, is a method of debt reduction by working towards paying off the smallest loan first and then devoting those resources to the next largest loan. Using this method, particularly at the beginning of the mitigation process, would reduce the number of deficiencies that are open for the longest period of time. In addition, this method could be utilized to reduce the number of deficiencies in the interim time while waiting for higher risk deficiency mitigations to be implemented in the next turnaround. Set pressure adjustments to account for static head, applying carseals to valves that need to remain open or closed, and instances where sharpening the pencil could result in the elimination of the deficiency altogether are examples of deficiencies that may get prioritized with this method.
Highest Priority First Algorithm: This algorithm assesses the importance of a task, assigns it a priority level, and moves tasks with the highest priority to the front of the processing queue. In the context of relief system deficiency mitigation, this could mean performing a risk assessment to determine the risk gap created by a deficiency (removing credit in the unit PHA for an undersized device, for instance), and then working on the systems with the highest risk gap or highest consequence severity first. The Highest Priority First method is probably the most utilized scheme for relief system mitigation because it quickly reduces the overall risk to the facility. Mitigating deficiencies with the highest risk first eliminates the vulnerabilities with the largest contributions to the facility’s overall risk profile. This is one benefit over the Shortest Job Next algorithm, which prioritizes lower risk deficiencies that are easier to mitigate. Higher risk deficiencies would center on major unit equipment and would include (but not be limited to) items such as undersized devices, unprotected systems, and devices at risk of instability due to high inlet or outlet pressure loss.
Earliest Deadline First Algorithm: As the name suggests, this algorithm prioritizes processing tasks with the earliest due date and schedules them first. This method works well for minimizing the number of overdue items, but can be complicated by turnaround (TAR) schedules. Continuous process units can often go five years between TARs, and if a deficiency has a fixed deadline for mitigation, the deficiency may have to be deferred until the field work can be completed in the next TAR. Even then, a higher risk deficiency may need to be addressed first and the TAR scheduler may not be able to schedule everything into the docket of work to be completed in the TAR. In addition, this algorithm (in the context of relief system deficiency mitigation) is almost a subset of the Highest Priority First Algorithm because most companies develop their due dates for deficiencies based on the risk ranking of deficiency in question.
These are just a few ideas for how to prioritize relief system deficiencies for mitigation. In the field of processor task scheduling there is no best algorithm, and the same is true for relief system mitigation projects. Computer programmers often use a combination of multiple algorithms to tackle scheduling problems and multiple simultaneous approaches to address a long list of relief system deficiencies is also valid, especially when there are multiple personnel and project resources to distribute the workload among. Cognascents stands ready to assist with you with your relief system mitigation needs. Contact us today for more information.
