Qualification of Flexible Fiber Reinforced Pipe Downline for Pipeline Commissioning Applications
Authors: Joshi Rohit , Dhagat Alok , Yu Yong , Yu Liang 
Published: May 2013

This paper presents a comprehensive approach to development and qualification of flexible fiber reinforced pipe (FFRP®) for deep water pipeline commissioning applications. Flexible fiber reinforced pipe is a light weight, high strength, high fatigue resistance unbonded flexible pipe structure employing composite materials for the pressure and tensile armor layers. Lightweight downlines enable smaller service vessels to conduct pipeline commissioning operations in deep and ultradeep water, improving the overall pipeline commissioning economics relative to steel armored flexible pipe or steel coil tubing. FFRP's robust design and good fatigue resistance enable it to be used in multiple similar commissioning projects with different vessels.

The development and qualification summary presented in the paper is also relevant to the application of FFRP for dynamic risers permanent oil and gas production and water and gas injection applications. Work in progress towards achieving the permanent application qualification is presented in the paper. Lighter weight flexible pipe structures simplify riser configurations and enable smaller installation and operation vessels in ultradeep water, reducing overall installed cost.

The following aspects are addressed in the paper:Pipe and end fitting design requirements and design elementsFailure Mode Identification and Risk Ranking in accordance with DNV RP A203Qualification of the materials used in the pipe structure, including the confirmation of characteristic properties for design purposesSmall scale tests to evaluate pipe layer performance, and interaction with other layers, and tensile armor anchoring in the end fittingFull scale tests to qualify the pipe structure. The results of tests on two pipe structures, 3.5-inch ID, 280 barg (4065 psig) design pressure for 1600 meters water depth, and 4-inch ID, 294 barg (4265 psig) design pressure for 1500 meters water depth are presented.Independent verification of the design methodology and qualification test program

The qualification program confirmed the suitability of the materials and pipe structure for the pipeline commissioning application, and built a foundation for qualification of the pipe structure for ultradeep water permanent riser applications.

Introduction

As offshore field development moves into deeper water, commissioning of the newly installed subsea pipelines calls for a downline pipe with features including sufficient flow capacity, low flow resistance, lightweight, high strength, reelable, good flexibility and fatigue resistance. Such downline will enable the installation contractor to conduct the commissioning work with smaller, lower day rate vessels and cut down total operation time. Typical pipeline commissioning work includes flooding, pigging, hydrostatic testing, dewatering and MEG swabbing operations. For each project, the downline may be deployed and retrieved up to 50 times. It is also highly preferred that the downline will be suitable for redeployment for similar applications in multiple fields.