Fluid-End Plug Bore Clearance for Lower Assembly Force
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Solution Overview
Problem
The assembly and disassembly of discharge and suction plugs in high-pressure fracturing pumps are difficult due to small clearances between the plug and bore, requiring high torque and force, especially at operating pressures up to 20,000 psi.
Innovation Solution
The plugs are designed with variable diameters and reduced axial length of the sealing section, allowing for minimal engagement with the bore, and incorporating diametral clearances to facilitate rotation and stepwise insertion/removal, reducing friction and assembly/disassembly effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plug is designed with full engagement to the bore walls, then sealing performance is improved, but assembly and disassembly require high torque and force
Solution Approach 1:
The plug is divided into two distinct zones along its length: a first zone with full diametral engagement to the bore walls for sealing, and a second zone with reduced engagement (clearance) for ease of installation. This segmentation allows each zone to perform its specific function optimally without compromising the other.
Solution Approach 2:
Different regions of the plug have different engagement characteristics with the bore. The first region (adjacent to the seal) has minimal clearance for reliable sealing, while the second region (extending to the external surface) has increased clearance to reduce friction during assembly and disassembly. This local differentiation of engagement quality resolves the contradiction between sealing reliability and operational ease.
2Reliability
If the clearance between plug and bore is reduced, then sealing effectiveness is improved, but friction and assembly difficulty increase
Solution Approach 1:
The plug structure is segmented into zones with different clearance characteristics. The first zone has reduced clearance (minimal diametral clearance) to maximize sealing effectiveness, while the second zone has increased clearance to minimize friction during assembly and disassembly operations.
Solution Approach 2:
The clearance between the plug and bore is locally optimized: minimal clearance in the sealing region (first zone) to ensure reliability, and larger clearance in the non-sealing region (second zone) to reduce friction. This local quality differentiation allows the system to achieve both effective sealing and easy assembly.
3Reliability
If the plug engagement length is increased, then sealing reliability is improved, but installation force and torque requirements increase
Solution Approach 1:
The plug is segmented into a first zone with full engagement length for sealing reliability and a second zone with reduced engagement (clearance) that extends to the external surface. This segmentation allows the sealing function to be achieved with minimal engagement length while the remaining length provides clearance to reduce installation force requirements.
Data Source
AI summary
A closure for a fluid end having a middle sealing section which engages a seal. The sealing section either has a larger outer diameter than adjacent sections or contacts a bore with a smaller inner diameter than adjacent sections. In either case, the clearance formed on either side of the sealing section reduces friction and allows the closure to be rocked back and forth to insert and remove the closure from the fluid end bore.