Ball Valve With Crenulate Seats for Cold Fluids
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Solution Overview
Problem
Conventional ball valves face issues with high operating torque due to friction, leakage, and heat transfer, especially in low-temperature applications, requiring excessive torque for manual operation and oversized motors for motorized operation, and struggle with accommodating hydrostatic expansion and preventing damage from trapped liquids.
Innovation Solution
The ball valve design incorporates upstream and downstream seats with crenulate configurations, a corrugated stem housing, and a unique ball seal washer seat to reduce friction and leakage, allowing for low-friction operation, near-zero shut-off, and safe accommodation of trapped liquids, with a convertible handle and actuator system and a stem seal design that can be replaced under pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional stem packing is excessively tightened to achieve leak tightness, then stem leakage is prevented, but friction against the valve stem increases and higher torque is required to rotate the stem
Solution Approach 1:
The stem packing is divided into multiple segments or layers, allowing differential compression across the packing depth. This segmentation enables the packing to maintain leak tightness at the sealing surfaces while reducing overall friction, as not all packing material is compressed to the same degree.
Solution Approach 2:
The packing material properties are modified by changing parameters such as material composition, density, or cross-sectional area along the stem length. This allows the packing to provide adequate sealing force where needed while reducing friction in other regions, optimizing both leakage prevention and operational torque.
2Reliability
If ball seal washers are held against the ball surface with substantial force to prevent leakage, then shut-off tightness is achieved, but friction increases and more torque is required to turn the valve stem
Solution Approach 1:
The ball seal washers are designed with curved or spherical sealing surfaces that match the ball's geometry. This curvature allows for point or line contact rather than broad surface contact, reducing the friction area while maintaining effective sealing force where the surfaces intersect.
Solution Approach 2:
The ball seal washers are positioned asymmetrically or have asymmetric pressure distribution, concentrating the sealing force at specific critical locations on the ball surface rather than distributing it uniformly. This reduces overall friction while maintaining leak tightness at the most critical sealing points.
3Productivity
If conventional ball valves are used in low-temperature applications, then fluid control is achieved, but heat transfer to the stem and stem housing causes frosting or moisture condensation on the exterior surfaces
Solution Approach 1:
The stem and stem housing are designed with thermal expansion compensation features or materials that accommodate temperature variations. This reduces thermal stress and minimizes heat transfer pathways, helping to prevent exterior frosting while maintaining functional performance in low-temperature applications.
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 significantly reduces operating torque, achieves near-zero shut-off leakage, and prevents damage from hydrostatic expansion, allowing for efficient operation in low-temperature applications with reduced heat transfer and frost prevention, enabling smaller motor actuators and easier maintenance.
Implementation Method 1
upstream and downstream seats with crenulate configurations... to reduce friction and leakage
Implementation Method 2
safe accommodation for hydrostatic expansion... upstream seat intermittently disengages from the ball to relieve hydrostatic expansion of a liquid within the ball
Data Source
AI summary
A ball valve including upstream and downstream seats and a ball having a flow opening disposed between the upstream and downstream seats. A flow path is defined through the valve only when the ball is disposed in an open position. In one embodiment, when the ball is disposed in a closed position the upstream seat may intermittently disengage from the ball to relieve hydrostatic expansion of a liquid within the ball resulting an increased pressure that is greater than a pressure within a body cavity of the valve outside the ball. In another embodiment, a distance between the upstream and downstream seats is greater than an outer diameter of the ball and the ball engages only one of the upstream and downstream seats when disposed in the closed position and a pressure differential is defined between the upstream and downstream seats. The upstream and downstream seats may each include a partially spherical sealing surface that may have a crenulate configuration.