Evaluation of Emergency Depressurization Valves for LNG Facility Case Study

The Challenge

A global energy infrastructure company, primarily engaged in liquified natural gas (LNG) related businesses and the leading producer of LNG in the U.S., requested an evaluation of the emergency depressurization (EDP) valves at its LNG facility. The scope of work included analyzing the performance and reliability of these critical valves to ensure that they could effectively and safely depressurize the system in an emergency, protecting both personnel and equipment.

NFPA 59A mandates pressure relief valves (PRVs) on Liquefied Natural Gas (LNG) facilities for overpressure protection. These valves, along with Emergency Shutdown Valves (ESVs) and vent systems, are critical safety layers, necessitating regular testing (e.g., annually) to ensure set pressures are correct and performance is maintained, preventing catastrophic failures in cryogenic systems.

Our Approach

The ioMosaic team leveraged Process Safety Office^® SuperChems^®, our proprietary software, to simulate the client's process based on their specific facility data. A rigorous analysis was conducted by modeling two critical overpressure scenarios: cold depressuring and fire depressuring. For each scenario, ioMosaic evaluated the adequacy of the emergency depressurization valves against the stringent requirements of API 521, 6th Edition, providing a comprehensive assessment of the valve performance under extreme conditions.

The standard provides the fundamental framework for ensuring pressure safety in complex LNG facilities by detailing how to design systems to handle extreme events, especially fire, using engineering principles and best practices.

The Benefits

Our evaluation identified a critical safety gap in the client's depressurization valves, finding them to be inadequate for fire depressuring scenarios, specifically failing to meet the requirement to depressurize below 100 psig within 15 minutes. Additionally, a potential risk for flow restriction was identified by our analysis, which could prevent the valves from effectively depressuring the vessel for a portion of the relief segment.

With this vital information, the client was now equipped to make the necessary adjustments to their relief system, ensuring full compliance with industry standards and significantly enhancing safety at their facility.

Learn More

Our mission is to help you protect your people, your plant, your stakeholder value and our planet. To learn more about how we can help you manage risk, call us at 1.844.ioMosaic.