Bi-Directional Annular Seal With Pressure-Energized Lips

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Solution Overview

Problem

Existing annular seal elements, such as the Straight Bore Metal Seal (SBMS), are ineffective in sealing against high external pressures commonly encountered in ultra-deep water subsea installations, leading to potential leaks, and bi-directional seals like BX and RX gaskets are difficult to mechanically energize due to their stiff cross-sectional shapes.

Innovation Solution

A bi-directional annular seal element with radially and axially oriented sealing lips, featuring flanges that define an outwardly opening cavity, allowing internal pressure to energize one set of lips and external pressure to energize another set, thereby sealing both directions effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional SBMS seal element is used, then internal pressure sealing is effective, but external pressure sealing fails under high pressure conditions

Engineering Contradiction:
Improvesealing effectivenessVSAvoidbi-directional sealing capability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The seal element is divided into multiple functional segments: a body portion with radially outwardly directed sealing lips for internal pressure sealing, and axially outwardly directed sealing lips on flanges for external pressure sealing. This segmentation allows each portion to specialize in one sealing direction, resolving the contradiction between internal and external pressure sealing effectiveness.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The seal element is designed to perform multiple sealing functions in both directions (internal and external pressure) through its multi-lip configuration. The combination of radial sealing lips and axial sealing lips on flanges enables the single seal element to provide bi-directional sealing capability, making it universally applicable for both pressure conditions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If bi-directional seals like BX and RX gaskets are used, then sealing capability in both directions is achieved, but mechanical energization becomes difficult due to stiff cross-sectional shapes

Engineering Contradiction:
Improvebi-directional sealing capabilityVSAvoidmechanical energization
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The seal element employs different lip configurations in different locations: radially directed lips on the body portion and axially directed lips on the flanges. This local differentiation allows each region to be optimized for its specific sealing function while maintaining overall flexibility for mechanical energization, avoiding the uniform stiffness problem of traditional bi-directional seals.

Inventive Principle:
Principle #3Local quality

3Reliability

If traditional seal elements are used, then sealing function is provided, but equipment size and weight increase

Engineering Contradiction:
Improvesealing functionVSAvoidequipment weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The seal element merges multiple sealing functions into a single integrated component. The body portion with radial lips and the flanges with axial lips work together as one unified seal element, eliminating the need for separate seal components and reducing overall equipment weight while maintaining bi-directional sealing capability.

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 seal element provides effective bi-directional sealing with reduced mechanical energization force requirements, allowing for smaller and lighter equipment with enhanced sealing capabilities against both internal and external pressures.

Implementation Method 1

the seal element is configured to seal the external environment from pressure in the enclosure and to seal the enclosure from pressure in the external environment

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentEP4374043B1Bi-directional seal element and sealing system
Publication Date: 2026.01.07 FMC TECH DO BRASIL
  • EP4374043B1 patent drawingFigure 1
  • EP4374043B1 patent drawingFigure 2
  • EP4374043B1 patent drawingFigure 3~4

AI summary

An annular seal element which includes a cylindrical seal body; first and second axially spaced sealing lips which are located on the seal body and are directed generally radially outwardly; first and second spaced-apart sealing flanges which extend radially outwardly from the seal body; and third and fourth sealing lips which are located on the first and second sealing flanges, respectively.