Safety and Regulatory Perspective for Floating LNG plant Offshore (FLNG)
Authors: Patel Harish N. , Rynn Philip Gerard , Wang Xiaozhi , Das Bibek , Pham Man 
Published: October 2011

Growing interest in the commercialization of stranded offshore gas fields coupled with industry forecasts indicating that worldwide demand for natural gas will increase is leading to significant interest in the development of offshore liquefied natural gas (LNG) production plants or floating LNG (FLNG). Offshore LNG production is an emerging technology; therefore, there is a lack of in-service experience and a need for a sound regulatory framework for safety requirements. This paper will explain the approach that ABS has taken in establishing classification rules for FLNG that are contained in two (2) new ABS Guides for FLNG concepts.

As an emerging technology, there is an increased need to develop safety regulations to allow investors, regulators and the public to gain confidence in this emerging field. From a classification society perspective, ABS has developed Rules and standards for the design, construction and operational maintenance of gas carriers and the new emerging floating gas transportation concepts such as FLNG, including transfer and storage based on our working experience with various FLNG projects. This paper also identifies tools and software developed by ABS to address novel features and their application to FLNG structures that are significantly larger in size than conventional carriers and have cargo tanks in a two-row configuration that can be extremely difficult to analyze.

ABS has provided Approval in Principle (AiP) and Front-End Engineering Design (FEED) approval to designers for various FLNG concepts. Based on experience gained from these projects, ABS has developed safety requirements to class FLNG structures, process and related safety systems that will enhance the overall safety aspect of this novel concept. These safety requirements provided the foundation for two (2) new ABS Guides.

This paper identifies the principal safety considerations and hazards that must be assessed and mitigated when developing FLNG concepts. Safety requirements for the hull, cargo storage, transfer, process facility, mooring system and various safety systems will also be discussed. Guidance from ABS was developed with cooperation from the industry and through experience gained by working on various LNG and offshore floating production projects.

Introduction

With the growing focus on environmental issues and society and government pressure to reduce ‘green house’ gases, there has been increasing focus on natural gas as a cleaner energy source. Over the last ten years ABS has seen increasing focus on natural gas and LNG production by oil and gas producers. Most of this LNG is supplied to the consumers by converting the gas to LNG, transporting it by ship, regasifying the LNG at a terminal and then distributing it to the consumer through a pipeline networks.

However, a considerable portion of the world's natural gas reserves fall into the category termed ‘offshore stranded’, where the conventional means of production and transportation is not practical or economical to produce these reserves. As demand for cleaner energy increases, these offshore stranded gas fields look more attractive to energy companies and they have been actively looking for new technologies to provide solutions to commercialize these ‘offshore stranded’ gas fields.

This has led to the development of Floating Liquefied Natural Gas (FLNG) plants for the production, storage and transfer of LNG to vessels. At present, FLNG appears to offer the best alternative for the development of stranded gas assets.