Threadless Fluid End Assembly for Leak-Free High-Pressure Bores
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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, causing retaining nuts to back off and internal threads to crack, leading to erosion and repair needs.
Innovation Solution
The fluid end assembly design eliminates internal threads by using a non-threaded retainer system with a fastening system that secures components without threading into the bore walls, utilizing a retainer element and fastening system to hold components in place, ensuring no external or internal threads are formed, thus preventing leakage and thread failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal threads are used to secure retaining nuts, then components can be held in place, but thread failure and leakage occur under high pressure
Solution Approach 1:
The patent removes the internal threading feature from the bore walls entirely, extracting the problematic element that causes thread failure under high pressure. Instead of threads, a smooth-bore design is used with retaining elements that secure components through alternative mechanisms such as friction fits, clips, or external fastening systems, thereby eliminating the source of thread cracking and leakage.
Solution Approach 2:
The patent replaces the threaded mechanical connection system with an alternative retention mechanism. This substitution eliminates the stress concentration and fatigue issues associated with internal threads while maintaining the ability to securely hold components like plungers and seals under high-pressure conditions through non-threaded fastening methods.
2Ease of operation
If retaining nuts are used with internal threads, then components are secured, but nuts back off and threads crack under high pressure
Solution Approach 1:
The patent eliminates the internal threading feature that causes reliability issues, while maintaining component retention through alternative mechanisms such as smooth-bore friction fits, external fastening systems, or non-threaded retaining elements that do not suffer from back-off or cracking problems under high pressure.
Solution Approach 2:
The patent introduces intermediary retention elements or fastening systems that mediate between the need to secure components and the avoidance of threaded connections. These intermediaries provide reliable component retention without the harmful effects of internal threads, such as stress concentration and thread failure.
3Ease of manufacture
If threading is performed in bore walls, then components can be assembled, but erosion and repair needs increase
Solution Approach 1:
The patent removes internal threading from the bore walls, eliminating the feature that leads to erosion and frequent repairs. The smooth-bore design reduces material removal and stress points, thereby decreasing maintenance frequency and extending component life while still enabling assembly through alternative retention methods.
Solution Approach 2:
The patent employs disposable or easily replaceable non-threaded retaining elements rather than permanent threaded connections. This approach allows for simpler, less invasive maintenance and repair operations, reducing the need for complex thread repair procedures and extending the overall lifespan of the fluid end assembly.
Data Source
AI summary
A fluid end having as 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.