Qualification of Composite Armor Materials for Unbonded Flexible Pipe

Abstract

Abstract This paper presents the plan and execution of a comprehensive test program toqualify composite tensile and pressure armor materials for application inunbonded flexible pipe for deep and ultradeep water, high temperature andpressure production and high pressure injection service. Due to lighter weightand resistance to corrosion and fatigue, composite materials are beingimplemented for the pressure and tensile armor in unbonded flexible pipe. Amaterial qualification program is necessary to define material properties thatare used in design and to assure that the materials will meet performancerequirements over the service life. The material qualification testing programpresented in this paper can also be used as a model for other compositematerial qualification programs for offshore applications. The qualification test program was developed based on the design of thepressure and tensile armor layers, and a comprehensive evaluation of thepotential failure modes and associated failure mechanisms associated with theapplication of composite armor materials for the layers. The materialqualification program was developed based on the guidelines presented inDNV-OS-C501 Offshore Standard for Composite Components. Since compositematerials are anisotropic, material properties in the principal directionsneeded for analysis, and how these properties vary with time as a result of theloads and environments experienced over the service life are evaluated. Thematerial qualification requirements have been agreed by members of the flexiblepipe technical community and are being published in Draft InternationalStandard API 17J/ISO 13628-11 as Annex H. This paper summarizes therequirements and presents one manufacturer's initial work to qualify bothfiberglass and carbon fiber based composite armor materials for the pressureand tensile armor layers in unbonded flexible pipe. Introduction The advantages of replacing the metallic pressure and tensile armor of unbondedflexible pipe, with fiber reinforced polymer (FRP) materials, or compositearmor, have been known for many years.