Fluid End Bore Sealing Without Internal Retaining Threads
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Solution Overview
Problem
Existing fluid end assemblies in oil and gas operations experience leakage and erosion due to high-pressure fluid pumping, caused by retaining nuts unthreading from internal threads in the bores, leading to frequent repairs and replacements.
Innovation Solution
The fluid end assemblies eliminate internal threads in the bores by using a fastening system with studs and retainer elements to secure components without threading, ensuring a secure seal through seals and packing nuts, preventing longitudinal movement and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retaining nuts are threaded into internal threads in the bores to secure components, then the components are held in place, but the retaining nuts unthread over time due to high-pressure fluid pumping, causing leakage and erosion
Solution Approach 1:
The patent removes the threaded retaining nuts and internal threads from the bore structure entirely. Instead, a threaded component is inserted into the bore, and a retainer element is placed over the bore to secure the threaded component without requiring internal threading in the bore itself. This extraction of the problematic threading mechanism eliminates the unthreading issue while maintaining component retention.
Solution Approach 2:
The patent divides the retention system into separate functional elements: a threaded component that provides the threading interface, and a retainer element that provides the securing function. This segmentation allows the threading to be isolated to a replaceable component rather than being integral to the bore structure, preventing the unthreading problem from affecting the entire assembly.
2Ease of operation
If internal threads are formed in the bores to accommodate retaining nuts, then components can be secured, but erosion occurs at the threaded regions due to high-pressure fluid flow
Solution Approach 1:
The patent extracts the internal threading from the bore structure and relocates it to a separate threaded component. This removes the erosion-prone threaded regions from the high-velocity fluid flow path in the bores, eliminating the erosion problem while preserving the threading function in a protected location.
Solution Approach 2:
The threaded component acts as an intermediary element that provides the threading interface between the retainer and the bore without being directly exposed to the erosive fluid flow. This mediator protects the threaded regions from erosion while still enabling secure component retention.
3Strength
If traditional threaded fastening systems are used to secure plugs and components in the bores, then components are held securely, but frequent repairs and replacements are needed due to unthreading and erosion
Solution Approach 1:
The patent removes the vulnerable threaded fastening system from the bore structure and replaces it with a non-threaded retainer-based system. This eliminates the unthreading failure mode that caused frequent repairs, thereby improving operational continuity while maintaining fastening strength through the retainer element.
Solution Approach 2:
The patent segments the fastening system into a threaded component (which remains secure in the bore) and a retainer element (which provides the fastening function). This segmentation prevents the unthreading problem from disrupting operational continuity, as the threaded component cannot unthread from the retainer.
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.