In the advanced development of technology, oil and gas industry explores further from shore and deeper to the basin. It is inevitable that the deeper it goes, more pressure it receives. This become a concern in planning a safe pipeline system. For that reason, a new kind of offshore pipeline is invented, the flexible pipe.
A flexible pipe is made up of several different layers. The main components are leak-proof thermoplastic barrier and corrosion-resistant steel wires. The helically steel wires give the structure its high pressure-resistant and excellent bending characteristic, so it provides flexibility.
A figure of typical flexible pipe.
MAIN COMPONENTS
Figure below identifies the main components of flexible pipe cross section:
- Interlocked stainless steel carcass
- Internal pressure sheath, made from nylon, poly vinylidene flouride (PVDF) and high density polyethylene (HDPE)
- Zeta spiral (pressure armour), made from rolled carbon steel
- Tensile armour (double cross wound armours), made from flat rectangular wires
- Outer thermoplastic sheath, made from non-metallic materials
MAIN CHARACTERISTICS
- Flexible. Makes it possible to spool the pipe on a reel or in a carousel for efficient and quick transportation and installation.
- Easy to install. Since the flexible pipe is in continuous form, laying speed will be much faster than laying ordinary rigid carbon steel pipeline.
- Modularity. The independent layers of a flexible structure enable it to be tailored to the precise needs of a specific development.
- Corrosion resistant. Since the steel wires are not in direct contact with the conveyed fluid, they do not require the same corrosion resistance as steel pipe.
- High pressure resistant. Flexible pipes resist all fluid pressures encountered in the most complex subsea application. Besides, the modularity of the flexible pipe manufacturing process enables to adjust pipe thickness, shape, and number of steel wire layers to satisfy a specific requirement.
The image above shows the physical form of flexible pipe.
source :
- http://www.technip.com/sites/default/files/technip/publications/attachments/Flexible_pipe_Web.pdf
- http://www.outokumpu.com/en/CustomerIndustries/Project-and-Process-Industries/Oil-And-Gas/Flexible-Pipe/Pages/Flexible-Pipe.aspx
- Chen, Minghao. Fatigue Analysis of Flexible Pipes Using Alternative Element Types and Bend Stiffener Data. Norwegian University of Science and Technology (NTNU). Norway. 2011.
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