Pressure-Compensated Feedthrough Assembly for PEEK Creep Prevention
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Solution Overview
Problem
Poly-ether-ether-ketone (PEEK) materials used in feedthrough connectors for subsea wellhead systems are susceptible to creep due to differential pressures and temperatures, risking failure of the pressure containment and potential catastrophic blowouts.
Innovation Solution
Incorporating a pressure compensation chamber with a metallic bellows to equalize the pressure on both sides of the PEEK material, using a dielectric fluid to balance the chamber pressure with the gallery pressure, preventing creep and maintaining the integrity of the feedthrough assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PEEK material is used in feedthrough connectors for electrical communication and pressure barrier, then chemical resistance and broad temperature range operation are improved, but creep susceptibility under differential pressure and extreme temperatures worsens
Solution Approach 1:
A pressure compensation chamber filled with dielectric fluid is introduced as an intermediary between the gallery pressure environment and the downhole pressure environment. This chamber mediates the pressure differential by allowing the dielectric fluid to transmit gallery pressure to the PEEK material, thereby compensating for the downhole pressure and preventing creep while maintaining electrical insulation.
Solution Approach 2:
The pressure compensation chamber changes the pressure parameter experienced by the PEEK material. By equalizing pressures on both sides of the PEEK material through the dielectric fluid in the compensation chamber, the net pressure differential is reduced to near zero, eliminating the creep-inducing stress while maintaining the material's structural integrity.
2Reliability
If transmission pin passes through pressure seal to provide electrical communication, then electrical connectivity is improved, but pressure containment integrity worsens due to penetration point
Solution Approach 1:
The dielectric fluid in the pressure compensation chamber acts as an intermediary that allows the transmission pin to pass through the pressure seal without compromising containment. The fluid transmits pressure evenly around the pin, and the bellows mechanism compensates for volume changes, maintaining pressure integrity despite the penetration.
Solution Approach 2:
A flexible bellows structure is used to seal around the transmission pin while accommodating its presence. The bellows can flex and deform to maintain the pressure barrier around the pin penetration, preventing leakage while allowing electrical communication to pass through.
3Reliability
If pressure compensation chamber with dielectric fluid is added to prevent PEEK creep, then pressure containment reliability is improved, but device complexity increases
Solution Approach 1:
The pressure compensation chamber serves multiple functions simultaneously: it provides pressure compensation to prevent PEEK creep, maintains electrical insulation through the dielectric fluid, and accommodates the transmission pin penetration. This multi-functionality reduces the need for separate components and justifies the added complexity by delivering multiple benefits from a single integrated structure.
Solution Approach 2:
The pressure compensation chamber merges several functions into one component: pressure equalization, electrical insulation, and mechanical support for the transmission pin. By combining these functions, the overall device complexity is minimized while achieving the desired reliability improvements.
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 pressure compensation chamber effectively prevents creep in PEEK materials by equalizing pressures, ensuring the feedthrough assembly maintains its structural integrity and contains downhole fluids, reducing the risk of failures and leaks.
Implementation Method 1
at least one metallic bellows is positioned in the pressure compensation chamber for equalizing the chamber pressure with the gallery pressure
Implementation Method 2
using a dielectric fluid to balance the chamber pressure with the gallery pressure
Data Source
AI summary
A receptacle for a downhole system includes a pressure seal for isolating a first pressure and a second pressure, and a transmission pin passes through the pressure seal. A pressure compensation chamber is positioned within the receptacle between the first pressure and the second pressure and has a chamber pressure sealed from the first pressure and the second pressure. The transmission pin is partially positioned in the pressure compensation chamber, and a pressure compensation device is positioned in the pressure compensation chamber for equalizing the chamber pressure with the first pressure.