NEW GUIDELINES FOR CERTIFICATION OF OFFSHORE ACCESS SYSTEMS USING MOTION COMPENSATED GANGWAYS

摘要

Motion compensated Offshore Access Systems (OAS) are emerging technologies offering substantial advantages to offshore support vessels. Improvements in terms of personal safety during transfer from a ship to an offshore asset and extension of operating weather windows compared to conventional methods are examples of these benefits. Indeed, the conventional personal transfer systems (lifted basket, bump-and-jump from a crew boat or helicopter transfer) present some risk regarding safety, limited operating time frame or high cost that the new OAS significantly help to improve. Even though the first models of compensated gangways were installed 10 years ago, neither a design standard nor a certification procedure for these systems has been published at the time this paper was written. In recent years, many different technologies have emerged in the industry, which may nevertheless be divided into two categories: the passive transfer gangways, which are securely connected to the offshore asset and then put in free-flow for personal transfer, and the active transfer gangways, which remain motion compensated during transfer of personal. Undoubtedly the safety issues would substantially differ from one type of system to the other, as well as the critical components. Based on experience accumulated over the past years with the Dutch developers and manufacturers of OAS, major challenges and issues are highlighted in this paper. As several different designs exist, the safety principles and certification framework proposed in this paper are generic and not design-specific. Due to the inherent novelty of motion compensated gangway systems, particular attention is paid to the assessment of new features. Consequently, a risk-based Guidance is provided to describe a method for the qualification of new technology to be used for the most innovative parts of the OAS. This paper presents the main OAS technologies on the market, the related safety issues and the developments made by Bureau Veritas in relation with the publication of the new Guidance Note NI629 Certification of Offshore Access Systems. It develops safety principles for both active and passive OAS, design loading conditions, requirements for structural assessment, machinery and control system design as well as testing procedures.