(41av) Summation of Causes: Inappropriate Use of Layer of Protection Analysis
AIChE Spring Meeting and Global Congress on Process Safety
2023
2023 Spring Meeting and 19th Global Congress on Process Safety
Global Congress on Process Safety
GCPS Alternate Presentations
Hazards associated with thermal expansion or contraction of liquids in fixed volume systems without an associated phase change will be examined. Specific scenarios will be presented to illustrate the phenomena and underlying thermodynamic considerations. These scenarios will then be further developed to demonstrate key factors that can influence the risk of a loss of containment event. Guidance in industry standards, as well as existing gaps, will also be discussed. Finally, tools and techniques will be presented for risk-based analysis to evaluate systems and identify areas or components that are potentially vulnerable to this often-overlooked hazard.
Specific scenarios will be analyzed for thermal expansion mitigation, including liquid-full piping between two block valves, liquid-full piping between a block valve and check valve, and liquid-full vessels. To understand and address the potential risks of each scenario, the following questions will be addressed:
- How does a volume of liquid become trapped?
- What is the fluid and its potential trapped volume?
- What factors influence the thermal expansion hazard?
- How do the design and operation of the system correlate with the risk?
Potential engineering and administrative controls for managing thermal expansion hazards will be discussed that depend on the answers to the above questions. Case studies from the literature and the authorsâ experience will be introduced to support the concepts.