Flexible Pipe Sacrificial Layer for Strain Mitigation

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Solution Overview

Problem

Conventional flexible pipes face issues with polymer layer strain and microcrazing due to non-uniform surface profiles and high pressures, leading to potential failure and reduced service life, especially in deep-water environments where extreme conditions increase the risk of blockages and pressure-related damage.

Innovation Solution

Incorporating a sacrificial layer that is soluble or dispersible in a solvent medium, such as water, which can be removed during manufacturing or testing, reducing strain on polymer layers and preventing microcrazing by providing a smooth surface for barrier layers and accommodating creep without compromising the pipe's structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If a polymer layer is extruded to conform to the outer shape of the carcass layer, then the pipe body can be formed with a pressure-containing conduit, but the polymer layer develops irregularities (nubs or cusps) that act as stress concentration areas

Engineering Contradiction:

Improveconformation to carcass layer shapeVSAvoidstress concentration in polymer layer

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

A sacrificial layer is applied to the carcass layer before extruding the polymer layer. This preliminary layer provides a smooth, uniform surface that prevents stress concentration irregularities in the final polymer layer, while being removable afterward to leave a clean interface.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The sacrificial layer acts as an intermediary between the irregular carcass layer surface and the polymer layer. It mediates the interface by providing a smooth surface for polymer extrusion, preventing direct contact between the polymer and the stress-concentrating irregularities of the carcass layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the pipe operates in deep water environments with high external pressure, then the pipe can transport fluids from sub-sea locations, but the polymer layers are subjected to severe non-uniform strain that causes deformation and creep into armour layer gaps

Engineering Contradiction:

Improvedeep water operation capabilityVSAvoidpolymer layer strain resistance

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The sacrificial layer is positioned between the polymer layer and the armour layer to provide beforehand cushioning. When external pressure causes the polymer to deform and creep, the sacrificial layer absorbs these deformations and prevents direct stress transmission to the armour layer gaps, cushioning the polymer from severe strain.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The sacrificial layer serves as a mediator between the polymer layer and the armour layer during deep water operation. It transfers and distributes the non-uniform strain caused by external pressure, preventing concentrated stress at the armour layer gaps and reducing polymer deformation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If a sacrificial layer is added to provide a smooth surface and accommodate creep, then the polymer layer strain is reduced, but the pipe body structure becomes more complex with additional layers

Engineering Contradiction:

Improvepolymer layer strain reductionVSAvoidnumber of pipe body layers

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sacrificial layer is designed as a temporary, disposable component that serves its protective function during manufacturing and initial operation, then is removed when no longer needed. This allows the pipe structure to gain the benefits of strain reduction during critical phases without permanently increasing complexity.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The sacrificial layer is discarded after serving its protective purpose. It is removed from the pipe body once the polymer layer has been properly formed and the pipe is ready for service, recovering the simplified structure while having provided necessary protection during manufacturing and initial operation.

Inventive Principle:

Principle #34Discarding and recovering

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

The sacrificial layer effectively mitigates strain and microcrazing issues, enhancing the flexible pipe's durability and longevity by allowing for the removal of stress-concentrating irregularities and maintaining the pipe's structural integrity under high pressures and extreme conditions.

Implementation Method 1

the sacrificial layer is soluble or dispersible on contact with a solvent medium, in particular an aqueous medium

Methodology Applied

Scientific EffectSolubility: Solvation

Implementation Method 2

the sacrificial layer is soluble or dispersible on contact with a solvent medium

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Data Source

PatentEP3003715B1Flexible pipe body layer and method of producing same

Publication Date: 2019.05.15 BAKER HUGHES ENERGY TECHNOLOGY UK LTD

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AI summary

A flexible pipe body (300) configured for offshore use or a flexible pipe precursor, and a method of preparing a flexible pipe are disclosed. The pipe body or precursor includes a sacrificial layer (310) which is, at least partially, removable on contact with a solvent medium such as an aqueous solvent, in particular water