Threaded Coupling Sealing Design for High Torque Integrity
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Solution Overview
Problem
Conventional threaded connections in the oilfield industry face issues with galling, deformation, and loss of integrity under high torque and fluid pressures, requiring significant torque for sealing and often resulting in damaged components that cannot be reused.
Innovation Solution
A coupling design featuring a female component with shoulders and a sealing surface, and a male component with complementary shoulders and a sealing surface, forming radial and axial seals that can withstand high torque and pressures without galling, using deformation to enhance the seal and prevent thread damage, and incorporating negative angled load flanks for improved engagement and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If significant torque is applied to form a fluid-tight seal between threaded connections, then sealing integrity is improved, but thread damage such as galling and stripping occurs
Solution Approach 1:
The sealing function is segmented from the threading function. Multiple sealing surfaces (first sealing surface on male component, second sealing surface on female component, and intermediate sealing surface) are provided independently from the threaded engagement surfaces, allowing sealing to occur without requiring excessive torque that would damage the threads.
Solution Approach 2:
An intermediate sealing surface is introduced between the male and female components that engages before the primary sealing surfaces. This intermediate surface acts as a mediator that initiates sealing at lower torque levels, preventing direct high-stress contact between the primary sealing surfaces and threaded portions.
2Reliability
If multiple redundant seals are used to ensure integrity under fluid pressure, then sealing reliability is improved, but device complexity increases
Solution Approach 1:
Multiple sealing functions are merged into a single threaded connection interface. The first sealing surface, second sealing surface, and intermediate sealing surface all engage simultaneously within one connection, providing redundant sealing without requiring separate seal components or multiple connection stages.
Solution Approach 2:
The threaded connection structure serves multiple functions simultaneously: it provides mechanical fastening, creates a first seal, creates a second seal, and includes an intermediate seal. This multi-functionality eliminates the need for separate sealing components, reducing overall device complexity while maintaining high sealing reliability.
3Strength
If thread coatings or sugar blasting are applied to reduce galling, then thread durability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The galling prevention function is extracted from the thread surfaces themselves and relocated to the sealing surfaces. By providing dedicated sealing surfaces that engage at lower stress levels, the need for protective thread coatings or surface treatments is eliminated, simplifying manufacturing while maintaining thread durability.
Solution Approach 2:
The sealing action occurs preliminarily at lower torque levels through the intermediate sealing surface and primary sealing surfaces before high torque is applied. This preliminary sealing prevents high-stress contact between threaded portions, inherently preventing galling without requiring subsequent protective treatments.
4Strength
If specialized thread configurations with specific flank angles are used to reduce galling, then thread durability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The galling prevention function is extracted from the thread geometry and relocated to the sealing surface configuration. By providing dedicated sealing surfaces with appropriate geometry, the thread portions can use standard, easier-to-manufacture thread forms without requiring specialized flank angles or precise geometric tolerances.
Solution Approach 2:
The specialized geometry is applied locally only to the sealing surfaces where it is needed for sealing and galling prevention, while the threaded portions can use standard, simpler geometry. This localized application of complex geometry reduces overall manufacturing precision requirements compared to applying specialized geometry to the entire thread structure.
Data Source
AI summary
Couplings and/or connections include a female component engaged with a male component. A first shoulder of the female component abuts a first complementary shoulder of the male component to form a first radial seal. A second shoulder of the female component abuts a second complementary shoulder of the male component to form a second radial seal. A sealing surface of the female component abuts a complementary sealing surface of the male component to form an axial seal disposed between the first and second radial seals. Plastic and/or elastic deformation of the complementary sealing surface of the male component forms an axial seal between the female component and the male component.