Polymer Subsea Hatch Hinge for Lightweight Corrosion-Free Installation

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Solution Overview

Problem

Existing subsea structures face challenges in achieving lightweight, cost-effective, and corrosion-resistant hinge solutions that meet the requirements for withstanding impact and allowing overtrawling, while also providing easy access and versatile installation.

Innovation Solution

A one-piece hinge with flexible portions made of polymer material, such as polyurethane, is installed using protrusions that fit into prearranged or on-site created holes in the subsea structure and hatch, allowing for a pivot connection without welding or bolting, and enabling easy installation and adaptation to various configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a metallic hinge is used for connecting hatches to subsea structures, then the hinge provides high strength and durability, but the overall weight of the subsea structure increases and corrosion protection requirements are imposed

Engineering Contradiction:
Improvehinge strengthVSAvoidhinge weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent changes the material parameter from metallic to polymer, fundamentally altering the density and weight characteristics while maintaining functional performance. The polymer hinge achieves sufficient strength through material selection and structural design rather than relying on high-density metallic materials, thereby reducing weight without sacrificing essential mechanical properties.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite polymer materials that combine multiple properties (strength, flexibility, corrosion resistance) into a single material system. This composite approach allows the hinge to achieve the necessary mechanical strength while avoiding the weight and corrosion issues associated with metallic materials, as the composite structure can be optimized for both strength-to-weight ratio and environmental resistance.

Inventive Principle:
Principle #40Composite materials

2Strength

If a metallic hinge is used for connecting hatches to subsea structures, then the hinge provides high strength, but cathodic protection is required to prevent corrosion

Engineering Contradiction:
Improvehinge strengthVSAvoidcorrosion protection complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent replaces expensive, maintenance-intensive metallic hinges with polymer hinges that inherently resist corrosion. The polymer material eliminates the need for cathodic protection systems, sacrificial anodes, and regular corrosion monitoring, effectively treating the hinge as a maintenance-free component that does not require additional protective infrastructure or ongoing corrosion management.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Weight of moving object

If a GRP hinge is used as an alternative to steel hinge, then the weight is reduced, but the hinge requires bolting with corrosion resistant bolts which increases cost and complexity

Engineering Contradiction:
Improvehinge weightVSAvoidhinge assembly complexity
Core Design Contradiction:
Weight of moving objectVSDevice complexity

Solution Approach 1:

The patent merges the hinge body and mounting features into a single integrated polymer component. The mounting portions are formed as integral parts of the hinge body, eliminating the need for separate bolts, nuts, and fastening hardware. This integration simplifies the assembly process and reduces the number of corrosion-prone metallic components that would otherwise be required for attachment.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The polymer hinge performs multiple functions through its own structure: it provides the hinge axis, the mounting attachments, and the corrosion resistance, all within a single material system. The self-tapping or self-anchoring features of the polymer mounting portions allow the hinge to install itself without requiring separate fastening operations or additional corrosion-protected hardware.

Inventive Principle:
Principle #25Self-service

4Strength

If conventional metallic hinges are used, then the connection is strong, but the installation process is complex and time-consuming

Engineering Contradiction:
Improveconnection strengthVSAvoidinstallation time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The polymer hinge is pre-formed with integrated mounting portions that are ready for immediate installation. The mounting features are built into the hinge body during manufacturing, eliminating the need for on-site welding, bolting, or assembly operations. This preliminary preparation of the hinge structure allows for rapid installation by simply positioning and securing the pre-integrated component.

Inventive Principle:
Principle #10Preliminary action

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 solution provides a lightweight, cost-effective, and corrosion-resistant hinge system that simplifies installation, reduces material costs, and ensures structural integrity while allowing for easy access and compliance with overtrawling regulations.

Implementation Method 1

The flexible portion allows for a pivot connection between the first and second mounting portion

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3452692B1Method for installing a hatch to a subsea structure, hinge and assembly for subsea use
Publication Date: 2026.03.11 FMC KONGSBERG SUBSEA AS
  • EP3452692B1 patent drawingFigure 1
  • EP3452692B1 patent drawingFigure 2
  • EP3452692B1 patent drawingFigure 3

AI summary

The invention concerns a method for installing a hatch (34) to a subsea structure (10) by connecting the hatch to the subsea structure by at least one hinge (20) having a first mounting portion (21), a second mounting portion (22), a flexible portion (23) interconnecting the first and second mounting portion allowing a pivot connection between the first and second mounting portion. The installation steps comprise • - inserting a protrusion (23) of the first mounting portion (21) into an installation hole arranged in the subsea structure (10), • -inserting a protrusion (24) of the second mounting portion (22) into an installation hole arranged in the hatch (34), thereby • -engaging the first mounting portion (21) of the hinge (20) for anchorage with the subsea structure (10) and engaging the second mounting portion (22) for anchorage with the hatch (34) thereby arranging for the hatch to pivot between a closed and an open position about a pivot axis provided by the flexible portion of the hinge. The invention also concerns a hinge and an assembly for subsea use.