Fluid End Bore Sealing Without Internal Retaining Threads
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Solution Overview
Problem
Existing fluid end assemblies in oil and gas operations face issues with retaining nuts backing off due to high fluid pressures, leading to leaks and erosion of bore walls, as well as cracking of internal threads.
Innovation Solution
The fluid end assembly design eliminates internal threads in the bores, using a retainer element and fastening system to securely hold components in place without threading, thereby preventing the issues associated with internal thread failures and retaining nut unthreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal threads are formed in the bores for retaining nuts, then components can be secured in place, but the internal threads crack under high fluid pressure and retaining nuts back off
Solution Approach 1:
The patent removes the internal threads from the bore structure entirely, extracting the problematic element that caused cracking and failure. Instead of having threads within the bore wall, the design uses a retainer element with external threads that engages with the component from the inside, eliminating the weak internal thread structure while maintaining secure component retention.
2Reliability
If retaining nuts are threaded into internal threads, then components are held in place, but high fluid pressure causes nuts to back off and leaks to occur
Solution Approach 1:
The patent introduces a retainer element as an intermediary component between the bore wall and the component. This retainer element has external threads that engage with the component and is secured to the bore wall through other means (such as interference fit or mechanical engagement), acting as a mediator that prevents direct threading into the bore wall and eliminates the back-off problem under pressure.
3Ease of manufacture
If internal threads are formed in the bore walls, then retaining nuts can be installed, but erosion of bore walls occurs due to high pressure and unthreaded nuts
Solution Approach 1:
The patent extracts the internal threading from the bore wall structure, removing the source of erosion. By using a retainer element with external threads that does not require threading into the bore wall, the design eliminates the mechanical wear and erosion that occurs at the thread-bore interface while maintaining ease of assembly through the retainer element's engagement mechanism.
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 that each comprise 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.