Submerged Flexible Pipe Buffer Space Corrosion Control
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Solution Overview
Problem
Flexible underwater pipes face corrosion issues due to diffusion of substances like water, chlorides, and hydrogen sulphide into the annular space, leading to weakening and potential rupture, especially under varying pressure and water movements.
Innovation Solution
The pipe design includes a buffer space that floods with water from the body of water, reducing oxygen levels and using a tubular winding to consume oxygen, thereby minimizing corrosion of armor elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the annular space is flooded with water to improve corrosion resistance, then corrosion resistance improves under static conditions, but corrosion persists during vertical movements and pressure variations due to water renewal
Solution Approach 1:
The patent introduces a buffer space that is pre-filled with water before the pipe is deployed or before pressure variations occur. This buffer space acts as a reservoir that maintains water in the annular space even during vertical movements and pressure changes, preventing air ingress and maintaining the corrosive environment that protects the armor layers from oxidation-based corrosion.
Solution Approach 2:
The buffer space serves as an intermediary element between the external environment and the annular space containing the armor layers. It mediates the pressure and volume variations by absorbing expansions and compensating for contractions, thereby maintaining stable water presence in the annular space without direct connection to the external water body that would cause harmful water renewal.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design significantly extends the service life of the flexible pipe by limiting corrosion, even under variations in height and internal fluid pressure, by maintaining low oxygen levels and controlled water renewal in the annular space.
Implementation Method 1
compounds present in the fluid flowing through the pipe pressure sheath diffuse outward to the annular space. These compounds include, for example, water, chlorides, carbon dioxide, and hydrogen sulphide.
Implementation Method 2
The metal armor then undergoes a phenomenon of corrosion which has the consequence, in the more or less long term depending on the severity of the environment, of their weakening, or even their rupture
Implementation Method 3
the consumption of hydrogen sulphide becomes homogeneous when the oxygen content is low and the corrosion of metallic reinforcing elements decreases sharply
Data Source
Figure 1
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Figure 4~6
AI summary
The invention relates to a line comprising: an outer sleeve (22) defining an inner space; - at least one tensile reinforcement layer (34, 36) arranged in as annular space (26) defined within the inner space (15), the annular space (26) being suitable for being flooded with a liquid, in particular water from the body of water. The line defines a buffer space (29) separated from the annular space (26), the buffer space (29) having at least one outlet (62) connected to the annular space (26), to receive liquid from the annular space (26) or dispense liquid to the annular space (26) during variations in the volume of the annular space (26).