Thermoplastic Penetrator Isolation for Pressure Vessels

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Solution Overview

Problem

Conventional connectors for undersea pressure vessels face issues with galvanic corrosion, limited robustness, and weight, particularly in deep-sea applications where aluminum connectors are inadequate, and coatings have limited effectiveness and potential sealing issues.

Innovation Solution

A penetrator isolation device made from high-performance thermoplastics with low creep properties, including a central cylindrical portion and a lower flange portion, coupled with a custom nut that secures the penetrator through a tapered through-hole, providing dielectric isolation and reducing stress concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If aluminum connectors are used to mitigate galvanic corrosion, then corrosion resistance is improved, but robustness and lifetime deteriorate

Engineering Contradiction:

Improvegalvanic corrosionVSAvoidconnector robustness and lifetime

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent employs a composite structure consisting of a titanium connector body (providing strength and corrosion resistance) combined with a polymer coating layer (providing dielectric isolation). This composite approach allows the connector to simultaneously achieve robustness from the titanium substrate and galvanic corrosion mitigation from the polymer layer, resolving the contradiction between material strength and corrosion protection.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The polymer coating acts as an intermediary layer between the titanium connector and the aluminum pressure vessel wall. This intermediate layer prevents direct galvanic interaction between dissimilar metals while maintaining the structural integrity of the titanium connector, thus protecting against galvanic corrosion without sacrificing connector robustness.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If coatings are applied to isolate pressure vessel material from connector body material, then galvanic corrosion is reduced, but seal effectiveness deteriorates

Engineering Contradiction:

Improvegalvanic corrosionVSAvoidseal effectiveness

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The polymer coating is applied selectively to specific surfaces of the titanium connector where dielectric isolation is needed, while leaving other surfaces exposed or treated differently to ensure proper sealing. This localized application of the coating allows galvanic corrosion protection at the interface with the pressure vessel wall while maintaining sealing capability at the O-ring contact surfaces.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If conventional connectors with predetermined size are used, then manufacturing is simplified, but pressure vessel wall thickness is increased

Engineering Contradiction:

Improveconnector installationVSAvoidpressure vessel wall thickness

Core Design Contradiction:

Ease of manufactureVSLength of stationary object

Solution Approach 1:

The connector design incorporates a tapered geometry that allows dynamic adaptation to different wall thicknesses. The tapered shape enables the connector to be installed in walls of varying thickness without requiring precise pre-drilling or counter-boring, thus maintaining ease of manufacture while accommodating thinner pressure vessel walls.

Inventive Principle:

Principle #15Dynamics

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 reduces galvanic corrosion and stress concentrations, allowing for thinner pressure vessel walls while maintaining a secure seal, thus extending the lifetime of the pressure vessel and minimizing weight.

Implementation Method 1

A penetrator isolation device made from high-performance thermoplastics with low creep properties... providing dielectric isolation and reducing stress concentrations

Methodology Applied

Scientific EffectDielectric isolation: Dielectric

Implementation Method 2

coupled with a custom nut that secures the penetrator through a tapered through-hole, providing dielectric isolation and reducing stress concentrations

Methodology Applied

Scientific EffectStress distribution:

Data Source

PatentEP3260365B1Pressure vessel penetrator isolation device

Publication Date: 2020.03.25 THE BOEING CO

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AI summary

An isolation device for use with a pressure vessel penetrator. The isolation device is formed from a high performance thermoplastic having low creep properties and includes a central cylindrical portion, a lower inner flange portion and, preferably, an upper outer flange portion. The cylindrical portion has an inner diameter adapted to receive an upper larger diameter portion of the penetrator. The lower inner flange portion is coupled to a lower portion of the central cylindrical portion and forms an aperture for receiving a lower smaller diameter portion of the penetrator. The upper outer flange portion is coupled to an upper portion of the central cylindrical portion and may include clocking apertures. The high performance thermoplastic may be 30% glass-filled PEEK or TORLON®. A custom tapered nut may be provided to secure the penetrator in an internal tapered recess of the pressure vessel.