Copper-Nickel-Tin Rod Coupling for Galling-Resistant Service
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Solution Overview
Problem
Conventional sucker rod couplings made from steel or nickel alloys suffer from galling (wear due to adhesion) issues, leading to mechanical integrity failures and costly remediation in hydrocarbon extraction systems, as they lack intrinsic galling resistance and require frequent surface treatments.
Innovation Solution
Spinodally-hardened copper-nickel-tin alloys with specific weight percentages and properties, such as high tensile strength, fatigue strength, fracture toughness, and corrosion resistance, are used to create couplings with integrated grooves for improved galling resistance and fluid flow, reducing wear and extending equipment life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional steel or nickel alloy couplings are used, then high tensile strength is achieved, but galling resistance deteriorates leading to mechanical integrity failures
Solution Approach 1:
The patent applies spinodal hardening treatment to copper-nickel-tin alloy couplings, transforming the material's microstructure to achieve both high tensile strength (≥75 ksi yield strength) and inherent galling resistance. This heat treatment process changes the physical parameters of the alloy at the microscopic level, creating a fine-grained structure that simultaneously enhances strength and reduces adhesive wear between sliding surfaces
Solution Approach 2:
The invention uses a multi-element copper-based alloy system (copper-nickel-tin) that combines the advantages of different metals. The base copper provides excellent corrosion resistance and inherent galling resistance, while nickel and tin additions enhance tensile strength and mechanical properties. This composite alloy approach achieves both high strength and reliability without requiring surface treatments
2Reliability
If surface treatments are applied to increase galling resistance, then galling resistance improves temporarily, but the treatments wear off requiring periodic re-application
Solution Approach 1:
The spinodally-hardened copper alloy coupling provides self-service by inherently resisting galling through its material properties and microstructure. The spinodal decomposition creates a fine-grained, heterogeneous structure that prevents adhesive wear without requiring external surface treatments. The coupling maintains its galling resistance throughout its service life without needing maintenance or re-treatment
Solution Approach 2:
The spinodal hardening treatment permanently alters the material's microstructural parameters, creating a stable, fine-grained structure that maintains consistent galling resistance throughout the coupling's entire service life. This one-time heat treatment process achieves long-term reliability without the need for periodic re-application of surface treatments
3Ease of manufacture
If couplings are made with smooth exterior surfaces, then manufacturing is simplified, but fluid flow is impeded in the conduit
Solution Approach 1:
The coupling's exterior surface is segmented into multiple longitudinal grooves that divide the surface into channels. This segmentation allows fluid to flow through multiple pathways around the coupling, reducing flow resistance and energy loss while maintaining a relatively simple manufacturing process using standard machining operations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The spinodally-hardened copper-nickel-tin alloy couplings provide enhanced mechanical integrity and corrosion resistance, delaying destructive damage and reducing maintenance costs by improving galling resistance and fluid flow, thus extending the service life of hydrocarbon recovery components.
Implementation Method 1
couplings made from a spinodally-hardened copper alloy
Data Source
AI summary
A cold worked and spinodally-hardened copper alloy comprising from about 8 to about 20 wt % nickel, and from about 5 to about 11 wt % tin, the remaining balance being copper, and having a 0.2% offset yield strength of at least 75 ksi, is used to form a sucker rod coupling or subcoupling. Each coupling is formed from a core having two ends, each end having an internal thread. These box ends engage the pin of a sucker rod or other rod. The exterior surface of the core includes grooves running between the two ends.