Flexible Riser End Fitting Assembly Without Tensile Armour Bending

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Solution Overview

Problem

Existing end fittings for flexible risers require bending of the tensile armour during assembly, leading to plastic deformation, residual tensions, and microstructural modifications, which accelerates fatigue and increases the risk of failure.

Innovation Solution

The end fitting is designed with a novel configuration that separates the sealing zone of the polymeric pressure layer and the adhesion/anchoring zone of the tensile armour, allowing for assembly without deforming the armour, using a core and outer casing with distinct sealing and anchoring points to eliminate plastic deformation and maintain the original geometry of the tensile armour.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the tensile armour is bent during assembly to achieve adhesion in the wedge region, then the adhesion between the end fitting and riser is improved, but plastic deformation occurs causing residual tensions and microstructural modifications that accelerate fatigue

Engineering Contradiction:

Improveadhesion between end fitting and riserVSAvoidplastic deformation and residual tensions

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The end fitting is divided into distinct functional zones: a sealing zone for the polymeric pressure layer and an adhesion zone for the tensile armour. This segmentation allows the sealing and adhesion functions to be performed at different locations, eliminating the need to bend the tensile armour for adhesion while maintaining effective sealing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A resin is introduced as an intermediary substance in the adhesion zone to bond the tensile armour to the end fitting. This resin-mediated adhesion occurs without requiring mechanical bending of the armour, thus avoiding plastic deformation while achieving reliable attachment.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If the sealing and adhesion zones are combined in the same region (wedge region), then the assembly process is simplified, but the tensile armour must be bent causing plastic deformation and microstructural changes

Engineering Contradiction:

Improveassembly processVSAvoidgeometry of tensile armour

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The end fitting structure is segmented into separate sealing and adhesion zones along the axial direction. The sealing zone is positioned at one location while the adhesion zone with resin is positioned at another location, allowing both functions to be performed without overlapping in space, thus avoiding the need to bend the armour.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The problem is solved by transitioning from a radial approach (bending armour inward to reach sealing layer) to an axial approach (separating sealing and adhesion functions along the length of the end fitting). This dimensional reorganization eliminates the geometric conflict that causes armour deformation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If the end fitting design requires bending of tensile armour to access inner sealing layer, then sealing can be performed, but residual tensions and fatigue risk increase

Engineering Contradiction:

Improvesealing of polymeric pressure layerVSAvoidfatigue life of riser

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The end fitting is designed with segregated functional zones where the sealing zone for the polymeric pressure layer is spatially separated from the adhesion zone for the tensile armour. This allows the sealing operation to be performed without requiring any bending or deformation of the tensile armour, thereby preserving its structural integrity and fatigue life.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The resin acts as a mediator that enables adhesion of the tensile armour to the end fitting structure without requiring mechanical deformation of the armour. This chemical bonding mechanism replaces the need for bending and subsequent adhesion, eliminating the source of residual tensions and microstructural damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach simplifies the assembly process, reduces residual tensions, and enhances the structural performance and fatigue life of flexible risers, enabling their use in deeper waters and improving the precision of adhesion between the end fitting and the riser.

Implementation Method 1

adhesion of the wire of the tensile armour is promoted by a resin in a section inside the end fitting

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentEP2492571B1End fitting for a riser and method

Publication Date: 2019.09.25 PETROLEO BRASILEIRO SA PETROBRAS

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AI summary

The present invention relates to an end fitting of a flexible riser. The device makes it possible to carry out the assembly procedure without the need to bend the tensile armour. By means of the assembly procedure thereof, the technique proposed eliminates residual tension due to plastic deformation of the tensile armour and modifications in the microstructural properties of the steel, imposed by current end fittings and the corresponding techniques for assembling the same.