Flexible Armoured Pipe With Metallic Retaining Layer for Hydrolysis Resistance
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Solution Overview
Problem
Existing flexible pipes for marine applications are costly to produce, inflexible in construction, and prone to hydrolysis, requiring numerous variants to accommodate various diameters and pressure loads, with traditional outer armouring tapes being expensive and susceptible to degradation.
Innovation Solution
A flexible pipe design featuring an elongate metallic strip as a retaining layer wound at a high angle around tensile armouring layers, providing radial protection without resisting external pressure, thus reducing material costs and improving durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional tape-based outer armouring layers are used, then radial deformations are limited, but the pipe becomes expensive and susceptible to hydrolysis degradation
Solution Approach 1:
The patent changes the material parameter from polymeric tape to metallic strip (stainless steel or duplex steel), which fundamentally alters the chemical resistance properties by eliminating susceptibility to hydrolysis while maintaining the mechanical function of limiting radial deformations.
Solution Approach 2:
The patent employs a simpler metallic strip design that can be manufactured more economically than complex polymeric tapes, reducing production costs while achieving the same functional outcome of radial deformation control.
2Adaptability or versatility
If multiple variants of tapes are used to accommodate various diameters and pressure loads, then the pipe can be adapted to different applications, but the construction becomes inflexible and costly
Solution Approach 1:
The metallic strip design serves multiple functions: it limits radial deformations, provides corrosion resistance, and can be adapted to different pipe specifications through variations in strip dimensions and winding parameters, eliminating the need for multiple specialized tape variants.
Solution Approach 2:
The patent achieves adaptability by changing physical parameters of the metallic strip (width, thickness, winding angle, winding tension) rather than requiring different material compositions, allowing a single material type to serve multiple application requirements.
3Strength
If the retaining layer is made to resist external pressure, then the pipe structure becomes stronger, but the material costs and weight increase
Solution Approach 1:
The patent applies local quality by designing the metallic strip retaining layer to perform its specific function of limiting radial deformations without requiring it to resist external pressure, allowing other layers (such as the outer sheath or additional armouring) to handle external pressure resistance.
Solution Approach 2:
The patent extracts the function of external pressure resistance from the retaining layer, assigning it solely to limit radial deformations, while separating this function from external pressure resistance to reduce unnecessary material usage and weight.
Data Source
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AI summary
The present invention relates to a flexible armoured pipe having a centre axis and comprising an internal pressure sheath and an outer sheath, where the radial distance between the internal pressure sheath and the outer sheath defines an annulus. The annulus comprises at least one tensile armour layer surrounded by at least one retaining layer constituted by an elongate metallic strip wound around the at least one tensile armour with an winding angle of at least 65° in respect of the centre axis.