Asymmetrical Threaded Coupling With Deflection Relief Grooves
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for an inexpensive, load-transferring threaded coupling that provides metal-to-metal seals capable of withstanding pipe burst pressures without deforming, while also offering high torque capacity and requiring no additional seal parts.
Innovation Solution
A threaded coupling design featuring asymmetrical tapered edges, deflection relief grooves, and metal-to-metal seals that absorb torque forces, allowing for efficient torque transfer and maintaining high contact pressure without localized peaks, using coatings like zinc, copper, and tin to prevent galling and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional threaded couplings are used, then manufacturing cost is reduced, but seal reliability deteriorates due to inability to withstand burst pressure
Solution Approach 1:
The patent changes the geometric parameters of the threaded coupling, specifically introducing asymmetrical tapered edges with specific angle ranges (10-40 degrees) and deflection relief grooves with controlled radial depths (up to 30% of threaded relief groove depth). These parameter changes enable the coupling to withstand burst pressures while maintaining manufacturability from standard pipe stock.
Solution Approach 2:
The patent applies metallic coatings (zinc, copper, or tin alloys) to the threaded coupling surface, creating a composite structure that combines the base metal with protective coating layers. This composite approach provides both mechanical strength for burst pressure resistance and corrosion/galling protection, improving seal reliability without significantly increasing manufacturing cost.
2Strength
If metal to metal seals are designed to withstand burst pressure, then seal capacity is improved, but risk of deformation increases under high stress
Solution Approach 1:
The patent incorporates deflection relief grooves that create controlled deformation zones before the metal-to-metal seal surfaces. These grooves absorb and distribute stress concentrations, preventing unpredictable deformation of the seal surfaces under burst pressure conditions. The grooves have radial depths limited to 30% of the threaded relief groove depth to control the cushioning effect.
Solution Approach 2:
The patent creates localized zones with different mechanical properties: the metal-to-metal seal surfaces are designed for high contact pressure and sealing, while the deflection relief groove regions are designed to accommodate controlled deformation. This local differentiation allows the seal surfaces to maintain structural stability while the groove regions provide stress relief.
3Force
If asymmetrical tapered edges are implemented, then torque capacity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent implements asymmetrical tapered edges on the threaded coupling with outer taper angles between 10-40 degrees, creating an asymmetric geometry that optimizes torque transfer from the external thread to the internal thread. This asymmetric design provides superior torque capacity compared to symmetric designs while still being manufacturable using standard machining processes.
Solution Approach 2:
The asymmetrical tapered edges serve multiple functions: they provide torque transfer capability, create the metal-to-metal seal geometry, and define the engagement characteristics of the threaded connection. By combining multiple functions into a single geometric feature, the patent reduces overall structural complexity despite the asymmetric design.
4Reliability
If coatings are applied to prevent galling, then reliability is improved, but manufacturing steps increase
Solution Approach 1:
The patent applies metallic coatings (zinc, copper, or tin alloys) to the threaded coupling surface, creating a composite structure that combines the base metal with protective coating layers. This composite approach provides both mechanical strength for burst pressure resistance and corrosion/galling protection.
Solution Approach 2:
The patent specifies precise parameter ranges for the coatings including material composition (zinc, copper, or tin alloys) and thickness control to ensure optimal performance. These parameter specifications enable standardized manufacturing processes that balance protection effectiveness with manufacturing efficiency.
Data Source
AI summary
A threaded coupling for joining tubulars for oil and gas field operations forming connected tubulars. The threaded coupling has a body with an outer surface, an inner surface and a central axis, a first tapered edge, a second tapered, and a first coupling bearing face and second coupling bearing faces for supporting load, weight, or both on the connected tubulars. As the inner surface of the body is swaged onto each tubular, the inner surface of the body deflects away from the central axis, providing a plurality of bands of high contact pressure for each metal to metal seal between the inner surface of the body and each connected tubular to sustain seal pressures between the threaded coupling.