Over the past year, Technip completed the qualification of two cost effective products for reeling installation. These are mechanically lined pipes (lined pipes) and optimized wall thickness High Frequency Induction (HFI) pipes. Separate successful qualification programs including numerical analyses, full scale and small scale testing were undertaken.
Mechanically lined pipe is a very cost effective alternative to solid stainless or metallurgically clad pipelines for the transportation of increasingly corrosive fluids, which is a strongly growing trend. Such product was installed by S-lay in the past and there has been an incentive to qualify it for the very efficient reeling installation method. A number of critical control parameters enabling maintenance of liner integrity throughout the reeling process have been identified. A lined pipe design that can be reeled at atmospheric pressure without compromising the integrity of the liner has been qualified.
HFI pipelines are commercially more attractive than the commonly used seamless pipelines. However, some aspects of the HFI pipe technical specifications are not readily adapted to design optimized wall thickness pipelines for reel-lay installation. This paper addresses the resolution of the wall thickness selection of such pipes, for designs governed by reeling. The qualification program provided the justification for using optimized HFI pipe wall thickness for reeling in current projects.
Both HFI and lined pipeline products offer significant procurement cost savings to a project. Each technology has reached a qualification maturity, which has led to project applications for some. These products could be combined within a single very cost effective pipe-in-pipe design for challenging flow assurance conditions, in terms of corrosion resistance and wax/hydrate avoidance.
Many field developments combine the challenges of high passive insulation demands and needs to transport highly corrosive products under high temperature and pressure conditions. A typical solution meeting such technical requirements would be a low Overall Heat Transfer Coefficient (OHTC) reeled pipe-in-pipe (PiP), inclusive of a solid Corrosion Resistant Alloy (CRA) inner pipe. The outer pipe (also called carrier pipe) would typically be a seamless carbon steel pipe, whereas expensive stainless steel materials, such as 13%Cr martensitic steel, 22%Cr Duplex or even 25%Cr Super Duplex would be considered for the CRA inner flowline.
Technip has recently been able to propose a cheaper reeled PiP solution by introducing two cost attractive pipeline products, which have been qualified for reeling. These are optimized wall thickness HFI carbon steel pipes (instead of seamless pipe) for the carrier pipe and mechanically lined pipe for the inner flowline.