Dual Hardness Sealing Elements for Blowout Preventers

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Solution Overview

Problem

Blowout preventers with single durometer polymers face issues of non-uniform compressive forces, leading to either excessive deformation or insufficient sealing due to low hardness polymers extruding under pressure, while high hardness polymers fail to deflect adequately to form a sealing interface.

Innovation Solution

Employing a sealing element with two or more polymers of different Shore A hardnesses, where a softer polymer is used in the sealing interface region and a harder polymer in an adjacent region to concentrate compressive forces and control axial and radial deformation, thereby enhancing sealing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a low hardness polymer is used in the sealing element, then the polymer can deform easily against a mating surface to create a sealing interface, but the polymer extrudes under pressure and provides low sealing force

Engineering Contradiction:

Improvedeformation capabilityVSAvoidsealing force

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The sealing element is divided into multiple regions with different polymer hardnesses. The sealing interface region uses a softer polymer (first hardness) that deforms easily to create sealing contact, while the second region uses a harder polymer (second hardness) that resists extrusion and maintains structural integrity under pressure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the sealing element are assigned different material properties (hardness). The sealing interface region has lower hardness for easy deformation and sealing contact, while the second region has higher hardness for resistance to extrusion and maintenance of sealing force.

Inventive Principle:

Principle #3Local quality

2Reliability

If a high hardness polymer is used in the sealing element, then the polymer has higher modulus and resists extrusion, but the polymer does not sufficiently deflect under low compressive forces to form a sufficient sealing interface

Engineering Contradiction:

Improveresistance to extrusionVSAvoiddeflection capability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The sealing element is segmented into a sealing interface region with softer polymer for easy deflection and sealing contact, and a second region with harder polymer for resistance to extrusion and maintenance of sealing force.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sealing interface region uses softer polymer with lower modulus for sufficient deflection under compressive forces to form sealing interface, while the second region uses harder polymer with higher modulus for resistance to extrusion.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If a single durometer polymer is used in the sealing element, then the manufacturing process is simple, but the compressive forces are not uniform within the sealing element leading to non-uniform sealing performance

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoiduniformity of compressive forces

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The sealing element is divided into multiple regions with different polymer hardnesses to achieve uniform compressive forces. The softer polymer in the sealing interface region deforms to distribute compressive forces evenly, while the harder polymer in the second region maintains structural integrity and prevents non-uniform stress distribution.

Inventive Principle:

Principle #1Segmentation

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 dual hardness approach ensures consistent sealing performance by preventing extrusion of the softer polymer and increasing compressive forces, achieving higher utility in controlling compressive sealing forces within the sealing element, with a yield recovery of 75% to 99% after deformation.

Implementation Method 1

a softer polymer with a compressive modulus that is sufficient to achieve the desired sealing pressure is used within the sealing interface region

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

a harder polymer is used to increase the compressive forces within the first polymer

Methodology Applied

Scientific EffectCompressive strength: Compression

Implementation Method 3

the harder polymer is used to increase the compressive forces within the first polymer

Methodology Applied

Scientific EffectStress concentration:

Implementation Method 4

with a yield recovery of 75% to 99% after deformation

Methodology Applied

Scientific EffectElastic recovery: Elastic Recovery

Data Source

PatentUS11761287B2Dual hardness sealing elements for blowout preventer

Publication Date: 2023.09.19 LANXESS CORPORATION

AI summary

The present invention relates to sealing elements for blowout preventers comprising a sealing interface region, and a second region, wherein said sealing interface region is formed of a first polymer and said second region is formed of a second polymer, the first and second polymers having different Shore A hardnesses, including sealing elements made of dual hardness polyurethane.