Inglenook Engineers are often faced with questions that do not always have clear answers in the available industry guidance documents. In an effort to improve Inglenook’s practice and provide clarity on issues common to many facilities, Inglenook’s Engineers write white papers to document different approaches to solving both general and unique challenges faced in the industry today.
- May, 2017
Pressure Relief Design Basis Revalidation (426 KB)
Summary: The periodic verification of the relief system design and design basis is good practice, but does not mean an operator must re-perform the Pressure Relief Analysis (PRA) at each cycle. Similar to the verification of Process Hazard Analyses, a streamlined approach to verification of the PRA is advocated when an operator has put processes in place to maintain the relief system design basis in response both to changes within the facility as well as to internal and external learnings. This Revalidation encompasses three main elements of evaluation: Baseline, Capability, and Effectiveness. The objective of the baseline assessment is to identify the potential for systemic weaknesses in the PRA that may pose significant risks to operations yet may not be revealed as part of the evergreening process evaluation, while the capability and effectiveness assessments are geared towards evaluating those evergreening processes. By having an appropriate program in place, the PRA Revalidation can be a cost effective solution to the periodic verification of the relief system design and design basis, while still driving continual improvement in both the relief system design itself and the processes used to maintain that design basis.
- July, 2016
Detailed Thermal Inbreathing Analysis for API 12-F Tanks (606 KB)
Summary: The API Standard 2000, 7th Edition thermal inbreathing calculation has conservative assumptions regarding the rainfall rate and fluid properties within the tank that can result in excessive venting requirements for small tanks, such as those constructed to API Standard 12-F. Using local rainfall rates and thermophysical properties of actual tank vapor contents can yield venting requirements that allow a properly sized vent to fit on existing standardized tank-vent connections.
- October, 2014
Mixing of Hot and Volatile Fluids (523 KB)
Summary: An inadvertent mixing of hot and volatile fluids can result in overpressure if the volatile fluid is vaporized and sufficient volumetric accumulation occurs. Hot fluid temperatures exceeding the bubblepoint temperature of the volatile fluid is the common criterion for establishing applicability of the scenario, and cases in which that hot fluid temperature exceeds what is known as the superheat limit of the volatile fluid are usually identified as requiring a refocus of engineering effort to prevention rather than mitigation. For cases involving distillation systems immediately downstream, an additional screening for the scenario applicability can be made based on the capacity of the cooling system.