Sealing Cap With Metal C-Ring Seal For Subsea Pressure Relief

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Solution Overview

Problem

Subsea devices require a reliable sealing mechanism to prevent seawater ingress and oil leakage while ensuring overpressure protection, as existing solutions do not adequately address the high-pressure and corrosive subsea environment.

Innovation Solution

A valve arrangement featuring a seat valve, a spring, and a sealing cap with a metal C-ring seal and an elastomeric O-ring seal, held in place by a weak link, providing multiple barriers against seawater and internal pressure, manufactured using additive manufacturing for enhanced durability and corrosion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sealing cap with metal C-ring seal is used to seal the opening, then sealing reliability is improved, but the risk of overpressure buildup increases

Engineering Contradiction:
Improvesealing reliabilityVSAvoidoverpressure risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The sealing cap is divided into two functional parts: a permanent metal C-ring seal for reliable sealing, and a removable weak link component for pressure relief. This segmentation allows the system to simultaneously achieve both sealing reliability and overpressure protection by separating the sealing function from the pressure relief function.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If a weak link is used for overpressure protection, then safety is improved, but sealing reliability may be compromised

Engineering Contradiction:
Improveoverpressure protectionVSAvoidsealing reliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The weak link is designed as a sacrificial component that is intentionally made to fail at a predetermined pressure threshold. This disposable element provides overpressure protection by breaking or detaching when excessive pressure occurs, while the main sealing system remains intact and reusable.

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

3Reliability

If multiple barriers are implemented, then sealing reliability is improved, but device complexity increases

Engineering Contradiction:
Improvesealing reliabilityVSAvoidsealing structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sealing cap combines multiple sealing mechanisms (metal C-ring seal, elastomeric O-ring seal, and weak link barrier) into a single integrated component that attaches to the filling channel. This merging approach provides multiple barriers against seawater ingress while maintaining relatively simple installation and structure compared to separate multi-component systems.

Inventive Principle:
Principle #5Merging (Combining)

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 effectively seals the opening of subsea devices, preventing seawater ingress and oil leakage, while allowing controlled pressure relief to prevent explosive scenarios during retrieval, ensuring both safety and reliability in harsh subsea conditions.

Implementation Method 1

a metal C-ring seal of the axial seal type arranged in said first groove which, when the sealing cap is applied to an opening to be sealed, is in contact with an inner circumference of a first cylindrical section of said opening thereby radially sealing the opening

Methodology Applied
Scientific EffectRadial sealing contact:

Implementation Method 2

a spring exerting a valve shutting force on the seat valve

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 3

The sealing cap is held in position by a weak link the durability of which is smaller than the valve shutting force of the spring thereby providing overpressure protection by allowing gasses or fluids from within the subsea device having a pressure greater than the shutting force to force the cap out of position and dissipate

Methodology Applied
Scientific EffectOverpressure failure: Fracture Mechanics

Implementation Method 4

an elastomeric O-ring seal arranged in said second groove which, when the sealing cap is applied to said opening, is in contact with a second inner circumference of the first or a second cylindrical section of said opening thereby providing a second sealing of the opening

Methodology Applied
Scientific EffectElastomeric sealing: Elasticity

Data Source

PatentEP3428492B1Sealing cap
Publication Date: 2020.01.15 SIEMENS AG
  • EP3428492B1 patent drawingFigure 1

AI summary

The present invention relates generally to a sealing cap and particularly to a sealing cap for subsea devices. A sealing cap (10) in accordance with the invention comprises a cap body (11a, 11b) which comprises a first cylindrical cap section, a first annular groove (12) in said first cylindrical cap section, and a metal C-ring seal of the axial seal type (13) arranged in said first groove which, when the sealing cap is applied to an opening to be sealed, is in contact with an inner circumference of a first cylindrical section of said opening thereby radially sealing the opening.