Qualification Program for End Fittings of Flexible Pipes

Abstract

Flexible pipes and their accessories are a pillar in the ultra-deep water oil and gas exploration, making them the focal points of analyses for integrity management, risk reduction and performance of the entire system. Responsible for the connection between two flexible pipes or between pipes and equipment, the end fittings are considered, in certain applications, a critical point of the system, requiring special attention to its design in order to ensure the highest reliability and minimize its impacts on flexible pipe design. Every end fitting must, in its interface with the flexible pipe, provide internal and external sealing capacity as well as tensile strength when under various operational conditions. Additionally, the end fitting design should aim to reduce as much as possible the impact on the performance of the flexible pipe. The qualification tests are divided into 3 levels – small, mid, and full-scale – representing, respectively, the characterization of interfaces and materials, individual systems and the product as a whole. In addition to this division, the tests are also divided based on their load cases as static, such as burst, axial tension, external and internal pressure, and dynamic, such as cyclic tensile tests combined with internal pressure. All test results are related with predictions of design methodologies and application scenarios, thus validating the respective methodologies and categorizing the end fitting for an operational envelope. This article details a qualification program of a new model of end fitting for offshore flexible pipes evidencing the strategy adopted and applicability in shallow to ultra-deep water fields, under static or dynamic loads.