Fluid End Bore Sealing Without Internal Retaining Threads
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Solution Overview
Problem
Fluid end assemblies in oil and gas operations face issues with retaining nuts backing off due to high pressure, leading to fluid leakage and internal thread failures, which require frequent repair or replacement.
Innovation Solution
The design eliminates internal threads in the bores by using a retainer element and fastening system with externally threaded studs and washers to secure components within the fluid end body, preventing longitudinal movement and fluid leakage without forming external or internal threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retaining nuts are threaded into internal threads in bore walls to secure components, then components are held in place, but the internal threads are susceptible to failure and cracking under high pressure
Solution Approach 1:
The invention removes the internal threads from the bore walls entirely, extracting the problematic feature that causes failures. Instead of having threads within the bore, the retaining nut is repositioned to thread into the fluid end body at locations away from the bores, eliminating the source of thread cracking and failure while maintaining component retention functionality.
Solution Approach 2:
The fastening function is segmented into separate locations. The retaining nut threads into the fluid end body at positions away from the bores, separating the fastening mechanism from the bore structure. This allows the bore walls to remain intact without threaded holes, preventing stress concentration and crack initiation at critical locations.
2Reliability
If retaining nuts are used to secure components in bores, then components are retained, but the retaining nuts may back off due to high pressure causing fluid leakage
Solution Approach 1:
The invention incorporates a locking mechanism that prevents backward movement of the retaining nut before pressure can cause it to back off. The locking feature engages with the component or fluid end body to physically block reverse rotation, eliminating the risk of pressure-induced backoff and subsequent fluid leakage.
3Ease of manufacture
If internal threads are formed in bore walls for retaining nut engagement, then components can be secured, but frequent repair or replacement is required due to thread failures
Solution Approach 1:
The invention extracts the internal threads from the bore walls, removing the feature that leads to frequent failures and repairs. By relocating the threading to the fluid end body away from the bores, the bore structure remains intact and durable, significantly extending the service life of the fluid end assembly.
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.