Abstract

DNV has developed a new recommended practice for risers fabricated from composites (fiber reinforced plastics) within a joint industry project. This RP is closely linked to the offshore standard DNV-OS-F201 for dynamic risers. This paper gives a brief overview of the content of the RP, its safety philosophy, materials description, calculation methods and test requirements.

Introduction

Composite risers have been considered as promising concept for offshore applications for many years. Various composite riser developments are pursued by the industry, e.g. [1-4]. While the technology has progressed considerably over the last years, acceptance of composite risers has been difficult. One major reason for the resistance to use such risers has been the lack of industry standards. As a response to this a Recommended Practice RP for composite risers has been developed by DNV in close co-operation with the industry. The following companies have been participants in the Joint Industry Project: ABB, Conoco, FMC Kongsberg Offshore, Kværner Oilfield Products, Norsk Hydro, Statoil, Sulzer and Timet.

Subsequent to the termination of the Joint Industry Project, it has been agreed upon by the project partners that DNV shall transform this project RP into a DNV Recommended Practice, DNV RP-F202, which will be linked to the newly developed DNV Offshore Standard for Dynamic Risers DNV-OS-F201 [5]. The RP for composite risers is also closely linked to the DNV offshore standard for composite components DNV-OSC501 [6]. The connection between the various documents is shown in Figure 1.

The offshore standards and recommended practices in this series are purely technical documents, they are not linked to any kind of services. The offshore standards are governing documents for the more specific recommended practices. Figure 1. Link between standards and practices related to risers(Available in full paper)

Scope and Application

The Composite Riser RP provides the design philosophy, loads and global analysis aspects valid for risers made of composite materials. The RP applies to all new built riser systems and may also be applied to modification, operation and upgrading of existing risers.

The risers covered in the RP can be jointed or continuous. Bonded rubber risers and risers with un-bonded load bearing structures are not included. Applications are production, drilling and injection risers, as well as choke and kill lines. The scope covers design, materials, fabrication, testing, operation, maintenance and re-assessment of riser systems. Aspects related to documentation, verification and quality control are also addressed. The main purpose is to cover design and analysis of top tensioned and compliant composite riser systems operated from floaters and fixed platforms. The RP applies for permanent operation (e.g. production and export/import of hydrocarbons and injection of fluids), as well as for temporary operation (e.g. drilling and completion/workover activities). The RP is applicable to structural design of all pressure containing components that comprise the riser system.

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