Flexible Stem Bellow Assembly High-Pressure Torque Reduction
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Solution Overview
Problem
High fluid pressures in valve assemblies, such as those used in subterranean well control, increase friction between the stem, stem bellow, and gland, resulting in high actuation torque, which is difficult to manage effectively with existing technologies.
Innovation Solution
A stem bellow assembly featuring a flexible stem bellow with parallel ribs, a low-friction spacer ring, and a thrust washer, which reduces frictional forces by distributing the load and allowing the valve to operate at high pressures without excessive torque through the use of a spacer ring that contacts the gland at high pressures and a low-friction thrust washer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional stem bellow assembly is used in high pressure valve assemblies, then the valve can maintain a seal at high pressures, but the friction between the stem, stem bellow, and gland increases resulting in high actuation torque
Solution Approach 1:
A thrust washer is introduced as an intermediary component between the stem bellow assembly and the gland. This thrust washer bears the axial thrust loads generated by high fluid pressure, preventing these loads from being transmitted to the stem bellow and gland interfaces. Consequently, the friction and actuation torque are significantly reduced while the sealing capability is maintained.
Solution Approach 2:
The stem bellow assembly is divided into multiple segments or bellows elements that can independently compress and expand. This segmentation allows each segment to accommodate pressure changes more efficiently, reducing the overall frictional resistance during actuation while maintaining the sealing function across the entire assembly.
2Stress or pressure
If the stem bellow is designed to withstand high pressures, then the valve can operate at high fluid pressures, but the friction and wear between components increase
Solution Approach 1:
The thrust washer serves as a mediator that intercepts and carries the high pressure loads, preventing direct contact and friction between the stem bellow and gland under high pressure conditions. This intermediary component protects the other surfaces from wear while allowing the valve to operate at high pressures.
Solution Approach 2:
The design changes the load distribution parameters by introducing the thrust washer, which alters how pressure forces are transmitted through the assembly. Instead of the pressure loads being distributed across multiple friction-prone interfaces, the thrust washer concentrates and carries these loads, reducing friction and wear at critical interfaces.
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 the actuation torque required to operate the valve at high pressures, achieving efficient control of fluid flow while maintaining a seal, with a reduction in 'break to open' torque of over 60% compared to traditional stem bellows.
Implementation Method 1
A flexible stem bellow assembly disposed between the stem and the gland that includes a flexible stem bellow with parallel ribs
Implementation Method 2
an increased amount of friction between a stem, a stem bellow, and a gland may result in a large amount of torque to actuate the valve
Data Source
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AI summary
A bellows assembly is configured to mount between a movable valve structure and a stationary valve structure of a valve assembly. The bellows assembly comprises a bellows and a spacer. The bellows is configured to compress until a gap is closed relative to the spacer. The bellows assembly is configured to bear a load through the bellows before the gap is closed, and the bellows assembly is configured to bear the load through the bellows and the spacer after the gap is closed.