A View of the Evolving LNG Regulations and Associated Exclusion Zones from an Industry Perspective

Recent growth in availability of domestic natural gas has led to a shift in the U.S. gas industry from being a net LNG importer to the prospect of becoming a net LNG exporter.  As a consequence, many industry players are actively pursuing natural gas liquefaction projects at existing LNG import terminals.  In concert with this growth in proposed construction projects, the LNG facility permitting process driven by Federal Energy Regulatory Commission (FERC) has changed dramatically over the past few years.   Although the requirements for LNG facility siting and design are codified in the CFR 193 and NFPA 59A, many of the exclusion zone analysis requirements are stated broadly and involve some level of expert interpretation.  FERC has in the past clarified their interpretation of the federal requirements by means of formal letters and less formal precedent-setting memoranda.  These interpretations continue to evolve over time and drive new tools and considerations.

This paper examines the ramifications of consequence-based accidental release scenarios that have been historically required, describes the latest requirements imposed by FERC and explains how these came into existence.  The changing requirements have ostensibly been driven toward better definition of release sources; however, FERC’s requirements have challenged the available and approved analytical tools.  Also with this evolution, new types of scenarios coupled with new models have heavily influenced piping and equipment design, unit layout, unit siting, and mitigation strategies.  This paper will discuss the evolution and the now dominant considerations for facility siting and unit design that drive the safety aspects of LNG facility permitting process from the industry’s perspective.

Specific examples of scenarios will be provided as well as their consequences in terms of the resulting ½-LFL vapor clouds as well as the distance to the 1 psi boundary for the corresponding vapor cloud explosions.  This paper will also provide a summary of the effectiveness of mitigation techniques, including the use of vapor fences based on numerous case studies.