On the Specifications of Flexible Composite Ball Socket Joint Pipe Characterized by Barrel Shell Model

Abstract

Abstract Pipelines for deep-water application should be designed to be extremely flexible to ease the installation procedures. Such flexibility will improve the bending instabilities of reeled pipelines during spooling of initially straight or laying of initially bent pipe. Also during construction, pipeline flexibility could be exploited to connect pipelines and risers to floaters, manifolds, wellheads, buoys, and platforms. Therefore, the proposed flexible pipe is designed to be positionable and bendable enough to fit the above requirements. The pipe is comprises a series of interconnected ball-and-socket sections forming a liner and a fluid-tight cover, one or more helical wounding layers applied to the internal liner for absorbing tension loads, and one or more additional helical wounding layers applied for absorbing bending loads. In order to form a liner, the ball-and-socket segment will passes through a die, while a thread guide applies a plurality of reinforcing threads in a particular pattern to the exterior surface thereof to keep the segments to be snappingly engageable and maintain the pipe flexibility without significantly increasing in the thickness of the pipe wall or weight. The ball and socket segments are assumed manufactured from a lightweight composite material consisting of epoxied matrix reinforced by long continuous fibers. The socket segment was assumed a stiffer ring. Therefore, this paper will emphases on the design parameters of the ball joint that form the pipe by modeling it as laminated composite barrel shell and examining its elastic deformations capacity under pure bending conditions (e.g., typical reeling installation condition). To this aim, a straightforward treatment of the problem is presented via using Hamilton's principle and based on the first order shear deformation theories. The solution of the laminated composite barrel shell was formulated to follow exactly a simply supported boundary condition. Finally, the in-plane stresses and inter-laminar stresses were evaluated for wide range of loading conditions. Introduction The so called; a flexible ball socket joint, thread flexible round, or ball joint pipe is anticipated to be used in particular, although not exclusive, as utility in offshore or onshore for the transportation of petroleum oil and gas or other fluids. Such pipes are made up of a number of substantially rigid composite ball and socket segments, each segment combine the low weight and high strength properties. Thereby the pipe becomes extremely bendable and sufficiently flexible to spool onto reel for the purpose of reeling installation. Although flexible pipes are well known in the art and are for example they described in the standards; ANSI/API 17 B; Recommended Practice for Flexible Pipe, and ANSI/API 17J; Specification for Unbonded Flexible Pipe, the ball joint pipes haven't modeled yet. In this paper the proposed flexible ball socket joint pipe was invented to fulfill a number of requirements:First of all the pipe was designed to have a very high mechanical strength to withstand the forces it will be subjected to during transportation, deploying and in operation.The ball segments was designed to withstand the internal pressure that are usually considered very high and may vary considerably along the length of the pipe, in particular when applied at varying water depths. Therefore, the ball segments will be stiffer enough to resist the different in pressure, result in preventing the pipeline damage such as burst and collapse.The flexible pipe was designed from specific composite materials to be highly non-corrosive and chemical resistance.The proposed ball joint pipe was designed to keep the weight of the pipe relatively low, both in order to reduce transportation cost and deployment cost but also in order to reduce risk of damaging the pipe during deployment.