Subsea Casing Pressure Equalizing Valve
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Solution Overview
Problem
Subsea arrangements face challenges in balancing the pressure of fluids within casings against ambient sea water pressure, particularly at greater depths, which can lead to casing collapse due to external hydrostatic loads, and existing solutions are not simple or reliable enough for widespread use.
Innovation Solution
A pressure equalizing valve with a valve body that automatically opens under external hydrostatic pressure to allow sea water into the casing, balancing internal fluid pressure, and then closes under gravity to prevent further fluid exchange once installed, ensuring the casing is not subjected to excessive external loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the casing is lowered into the sea to greater depths, then the heat bank can provide thermal insulation for subsea installations, but the external hydrostatic pressure increases causing the casing to collapse
Solution Approach 1:
The patent introduces sea water as an intermediary substance between the external environment and the internal space of the casing. By allowing sea water to enter the internal space through the pressure equalizing valve, the intermediary fluid transmits external hydrostatic pressure uniformly throughout the internal space, preventing the casing from experiencing differential pressure that would cause collapse.
Solution Approach 2:
The pressure equalizing valve enables the system to self-regulate by automatically opening when external pressure exceeds internal pressure, allowing sea water to enter and equalize the pressure. The valve then automatically closes when pressures are equalized, maintaining the balanced state without external intervention throughout the operational depth range.
2Strength
If a pressure balancing device is added to prevent casing collapse, then the casing can withstand greater depths, but the device complexity increases
Solution Approach 1:
The pressure equalizing valve is designed to automatically respond to pressure differential without external control. The valve body with movable base section and valve member with valve seat creates a self-actuating mechanism that opens when external pressure exceeds internal pressure and closes when pressures are equalized, eliminating the need for complex control systems, sensors, or external actuation mechanisms.
Solution Approach 2:
The patent extracts the pressure balancing function from complex active control systems and implements it through a simple passive mechanical valve structure. By removing unnecessary complexity and retaining only the essential pressure-responsive opening and closing mechanism, the solution achieves pressure balancing with minimal device complexity.
3Strength
If the pressure equalizing valve remains open to allow pressure equalization, then the fluid pressure is balanced, but fluid flow into and out of the internal space continues
Solution Approach 1:
The pressure equalizing valve incorporates a feedback mechanism where the valve member's position is directly controlled by the pressure differential across the valve. When internal pressure equals external pressure, the valve member returns to sealing contact with the valve seat, automatically closing the flow path. This feedback control ensures fluid enters only when needed for pressure equalization and stops when the balance is achieved, preventing continuous fluid loss.
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 solution provides a simple and reliable method to balance fluid pressure within subsea casings against sea water pressure, preventing casing collapse and ensuring stable operation at various depths, while maintaining thermal insulation for subsea installations.
Implementation Method 1
The valve body is axially displaceable upwards, under the effect of an external fluid pressure acting on the valve body, from a resting position, in which the valve member is in sealing contact with the valve seat
Implementation Method 2
The valve body is axially displaceable downwards, under the effect of gravity, from the raised position to the resting position
Data Source
AI summary
A subsea arrangement comprising an external casing and a pressure equalizing valve for equalization of the fluid pressure in an internal space of the casing. The pressure equalizing valve is provided with a valve body including a base section displaceably received in an opening provided in the casing; and a valve member secured to the base section and arranged inside the casing, the valve member facing a valve seat surrounding said opening. The valve body is displaceable upwards, under the effect of an external fluid pressure, from a resting position, in which the valve member prevents fluid flow into and out of said internal space, to a raised position, in which the valve member allows fluid flow from the surroundings into said internal space for equalization of the fluid pressure therein when the subsea arrangement is lowered into the sea.