Fluid End Bore Sealing Using External Stud Retention
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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.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal threads are formed in the bores to secure retaining nuts, then components can be held in place, but the internal threads are susceptible to failure and cracking under high pressure
Solution Approach 1:
The invention extracts the threading function from the bore itself and relocates it to separate studs that are either externally threaded or inserted into the bore. This removes the internal threads from the high-pressure fluid end body, eliminating the weakness point while maintaining the securing function through the studs and retaining nuts assembly.
Solution Approach 2:
The studs serve as intermediary elements between the bore and the retaining nut. Instead of directly threading the nut into the bore, the stud acts as a mediator that provides the threading function externally or in a separate location, protecting the main body from thread-related failures.
2Reliability
If retaining nuts are threaded into internal threads in the bores, then components are secured, but the nuts can back off under high pressure causing leakage
Solution Approach 1:
The invention segments the retention system into multiple independent elements: studs (providing threading), retaining nuts (providing clamping force), and washers (providing distribution and protection). This segmentation allows each element to perform its specific function optimally and makes the system more reliable under high pressure.
Solution Approach 2:
The invention moves the threading function from the internal dimension (inside the bore) to the external dimension (outside the bore on studs), changing the spatial arrangement to eliminate the weakness of internal threads while maintaining the retention function.
3Ease of manufacture
If internal threads are formed in the bores, then retaining nuts can be installed, but frequent repair or replacement is required due to thread failure
Solution Approach 1:
The studs are designed as replaceable elements that can be easily swapped out if damaged, rather than requiring repair of the main bore structure. This approach uses simpler, cheaper components that can be quickly replaced, reducing maintenance time and cost.
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.