Fluid End Bore Sealing Without Threaded Retaining Nuts
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Solution Overview
Problem
Fluid end assemblies in oil and gas operations face issues with fluid leakage and internal thread failure due to high pressure, leading to erosion and cracking, which requires frequent repair or replacement.
Innovation Solution
The fluid end assembly employs a non-threaded fastening system using retainer elements and packing seals to securely hold components in place without forming external or internal threads in the bores, preventing fluid leakage and reducing the risk of thread failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded fastening systems are used to secure components in fluid end assemblies, then the components can be held in place, but the threads are susceptible to failure under high pressure causing leakage and erosion
Solution Approach 1:
The patent removes the threaded connection element entirely from the fluid end assembly. Instead of using bolts or screws with threads that are susceptible to failure, the invention uses a smooth-bore construction with mechanical retention elements (such as clips or retainers) that engage with the component without requiring threaded engagement. This extraction of the problematic threading mechanism eliminates the source of thread failure while maintaining secure component retention.
Solution Approach 2:
The patent employs replaceable retention elements (such as clips or retainers) that can be easily replaced when worn or damaged, rather than replacing the entire fluid end assembly. These retention elements are designed to be sacrificial components that protect the main assembly structure, allowing for maintenance without extensive disassembly or replacement of critical high-pressure components.
2Ease of manufacture
If traditional threaded connections are used in high-pressure fluid end assemblies, then components can be assembled, but internal threads crack and fail under high pressure
Solution Approach 1:
The patent replaces the threaded mechanical connection system with an alternative retention mechanism. Instead of relying on threaded engagement between male and female threads, the invention uses mechanical retention elements such as clips, retainers, or interference-fit components that secure the assembly without creating stress concentration points. This substitution eliminates the cracking and failure modes associated with threaded connections under cyclic high-pressure loading.
3Ease of operation
If threaded bores are formed in the housing, then fastening components can be installed, but the threaded areas are prone to erosion and cracking
Solution Approach 1:
The patent eliminates threaded bores from the housing structure entirely. The design uses smooth-walled bore passages for fluid flow and alternative retention methods for component fastening. By removing the threaded bore features, the invention eliminates the stress concentration zones and erosion-prone areas that would otherwise exist at thread roots and crevices, while maintaining component installation capability through alternative retention mechanisms.
Data Source
AI summary
A fluid end having its fluid flow bores sealed without threading a retaining nut into the walls of each bore. The fluid ends may be assembled using a plurality of different kits, each kit comprising a fluid end body, a component, a retainer element, and a fastening system. The retainer element holds the component within each of the bores formed in the fluid end body and the fastening system secures the retainer element to the body. The fastening system comprises a plurality of externally threaded studs, washers and nuts in some embodiments. In other embodiments, the fastening system comprises a plurality of screws.