Large-Bore Plug Valve Insert Locking for Sealing and Low Friction
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Solution Overview
Problem
Large bore plug valves in oil or gas operations face issues such as misalignment, wear, erosion, and increased friction due to shifting of the insert relative to the valve body during rotation, which complicates fluid flow control and maintenance of contact pressure.
Innovation Solution
The design incorporates an insert with sealing surfaces that engage the plug to prevent fluid migration into the annular region and a boot that interlocks with the insert to prevent rotation relative to the valve body, reducing friction and maintaining alignment, thereby addressing the issues of misalignment and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact pressure between the insert and the plug is increased to maintain sealing, then sealing reliability is improved, but friction between the insert and the plug increases excessively
Solution Approach 1:
The insert is divided into multiple segments (first insert segment, second insert segment, third insert segment) that can independently engage with the plug. This segmentation allows each segment to contribute to sealing while distributing the contact pressure, thereby maintaining sealing reliability without requiring excessively high overall contact pressure that would generate harmful friction.
2Ease of operation
If the insert is allowed to rotate or shift relative to the valve body during plug rotation, then ease of operation is improved, but misalignment between fluid passages occurs causing wear and erosion
Solution Approach 1:
The insert segments are designed with rotational engagement features that allow them to rotate synchronously with the plug while maintaining their relative positions. The first, second, and third insert segments each engage with corresponding features on the plug, enabling the entire assembly to rotate together as a unified dynamic system, preventing misalignment while facilitating smooth operation.
3Ease of manufacture
If the insert structure is simplified to reduce device complexity, then manufacturing ease is improved, but the ability to prevent fluid migration into the annular region is reduced
Solution Approach 1:
The insert is segmented into multiple independent parts (first, second, and third insert segments) that can be manufactured separately using standard machining processes, maintaining ease of manufacture. Each segment contains sealing surfaces that independently prevent fluid migration at different locations where the plug contacts the insert assembly, collectively providing comprehensive sealing without requiring a complex monolithic structure.
Data Source
AI summary
A plug valve including a valve body defining an internal cavity, a first passage, and a second passage, a plug defining a third passage and being rotatable within the internal cavity, and an insert extending within the internal cavity between the valve body and the plug. The insert defines an interior surface and an opening aligned with the first passage of the valve body. The insert may also define a sealing surface extending around the opening and standing in relief against the interior surface to sealingly engage the plug. In addition to, or instead of, the sealing surface, the insert may define a projection at least partially defining the interior surface. In addition, a boot may be connected to the valve body and interlocked with the projection to prevent, or at least reduce, rotation of the insert relative to the valve body when the plug rotates within the internal cavity.