Dual-Piston Ball Valve Seat Boosting for Pressure-Reversal Sealing
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Solution Overview
Problem
Ball valves used in subterranean production wells face seal integrity issues due to distortion under extreme pressures, as the large surface area exposed to pressure differentials causes loss of seal integrity, particularly when pressure is applied from below.
Innovation Solution
A dual piston arrangement with two floating pistons positioned diametrically above the metal-to-metal (m-t-m) seal diameter, allowing the m-t-m seal diameter to be moved closer to the inside diameter of the seating member, minimizing exposed ball surface area and reducing distortion, while providing customizable piston areas for optimal contact stress and reducing swaging forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single piston arrangement is used, then the device complexity is reduced, but the seal integrity deteriorates under extreme pressures due to ball distortion
Solution Approach 1:
The single piston is divided into two separate pistons (first piston and second piston) positioned at different locations. The first piston responds to pressure from below the ball, while the second piston responds to pressure from above the ball. This segmentation allows independent control of boost forces applied to the seating member, enabling compensation for ball distortion under extreme pressures while maintaining manageable device complexity.
2Strength
If the m-t-m seal diameter is positioned farther from the inside diameter, then the structural strength is improved, but the exposed ball surface area increases causing greater distortion and seal failure
Solution Approach 1:
The solution positions the metal-to-metal seal diameter closer to the inside diameter of the seating member, thereby reducing the exposed ball surface area and minimizing distortion. Simultaneously, the dual piston arrangement with customizable areas provides localized compensatory forces that maintain adequate contact stress and seal integrity, allowing the seal to function reliably despite the reduced structural margin.
3Force
If pressure differential is increased to improve seal contact stress, then the seal force is improved, but the ball distortion increases causing loss of seal integrity
Solution Approach 1:
The dual piston arrangement creates counterbalancing forces that compensate for ball distortion. When pressure differential increases and causes ball distortion, the pistons generate opposing boost forces on the seating member that maintain proper seal contact. The first piston compensates for distortion from below-pressure, while the second piston compensates for distortion from above-pressure, effectively counteracting the harmful shape changes.
4Manufacturing precision
If piston area is fixed, then the manufacturing precision is improved, but the adaptability to different pressure conditions deteriorates
Solution Approach 1:
The patent enables customization of piston areas (first piston area and second piston area) to optimize performance under different pressure conditions. By varying the area parameters of the two pistons, the system can be tailored to achieve equal net boost effect from both above and below pressures, adapting to specific application requirements while maintaining manufacturing precision through standardized piston design approaches.
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 configuration enhances seal integrity by minimizing ball distortion and maintaining consistent net boost area regardless of pressure direction, allowing for tailored diameters to achieve equal net boost effect from both above and below, thereby improving the reliability of the seal under varying pressure conditions.
Implementation Method 1
the first piston area and the second piston area are sized such that, when a pressure differential is applied across the ball valve member, the boost forces generated by the first and second pistons provide equal net boost effect
Implementation Method 2
A valve assembly comprises... a first piston... and a second piston... positioned diametrically above a metal-to-metal (m-t-m) seal diameter... allowing fluid to flow into a fluid chamber within the ball housing
Data Source
AI summary
A valve assembly, is presented that has a seating member is slidably coupled to a valve body adjacent a valve body bore and has a metal seat located on a seating end thereof that is engagable against a ball valve member. The seating member has a vent port located there through to allow fluid to flow into a fluid chamber within the ball housing. A first piston is slidably located between the seating member and the ball housing and located over the vent port, and a second piston is slidably located between the seating member and the ball housing and is located downhole from the first piston. Sealing members are located between the first and second pistons and engaged against the seating member.