Flush Threaded Connection for Tubular Conduits

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Solution Overview

Problem

Existing threaded connections in tubular conduits face issues with galling, stripping, and cross-threading due to high torque requirements, which can compromise fluid-tight integrity and prevent reuse, especially under lateral or bending forces encountered in directional boreholes.

Innovation Solution

A flush threaded connection design featuring parallel threads on male and female connectors with symmetrical shoulders and corresponding faces, allowing for metal-to-metal seals and elastic deformation to maintain contact under tension or bending, preventing damage and enhancing reusability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If significant torque is applied to form a fluid-tight seal between threaded members, then the connection integrity is improved, but the threads become damaged through galling, stripping, or cross-threading

Engineering Contradiction:

Improvefluid-tight seal integrityVSAvoidthread integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The connection interface is divided into two separate sealing mechanisms: a primary seal at the interface between mating surfaces and a secondary seal within the threaded engagement. This segmentation allows the primary seal to bear the bulk of the sealing requirement, enabling the threaded connection to be made with lower torque and preventing thread damage while maintaining fluid-tight integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A sealing element (such as an O-ring or gasket) is introduced as an intermediary between the mating surfaces to create the primary seal. This intermediary component assumes the function of sealing, allowing the threaded connection to focus on mechanical fastening with reduced torque requirements, thereby preventing galling and stripping.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If multiple redundant seals are used to ensure fluid-tight integrity, then the connection reliability is improved, but the device complexity increases

Engineering Contradiction:

Improvefluid-tight seal integrityVSAvoidconnection structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sealing function and the connection function are merged into a single integrated interface design. The mating surfaces are configured to provide both mechanical engagement and sealing simultaneously, eliminating the need for separate redundant seal components while maintaining fluid-tight integrity under high pressure and lateral forces.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If thread coatings or treatments are applied to prevent galling, then the ease of operation is improved, but the manufacturing complexity and cost increase

Engineering Contradiction:

Improvethread engagement easeVSAvoidthread treatment process complexity

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The design converts the potentially harmful high-torque requirement into a benefit by using the torque to compress a sealing element that creates a primary seal. This allows the threaded connection to be made with controlled, lower torque that prevents galling and stripping, while the sealing element provides the necessary fluid-tight seal without requiring complex coatings or treatments.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 solution provides a stable, fluid-tight connection that withstands high pressures and lateral or bending forces without galling, allowing for efficient handling and reuse of tubular segments, with mechanical efficiency and strength properties exceeding 70% of the unaltered conduit wall structure.

Implementation Method 1

allowing for metal-to-metal seals and elastic deformation to maintain contact under tension or bending

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS10281066B2Flush threaded connection and method of forming and using the flush threaded connection

Publication Date: 2019.05.07 HOUSTON INT SPECIALTY

AI summary

Embodiments provide a flush fluid connection having a first fluid connector having a male connector end including an elongated nose section having a front surface and a first external sealing surface. The male connector end includes an external shoulder extending outwardly relative to a longitudinal axis and a second external sealing surface adjacent the external shoulder, and external threads between the first external sealing surface and the second external sealing surface. The flush fluid connection includes a second fluid connector that has a female connector end having an elongated nose section comprising a front surface and a first internal sealing surface. The female connector end includes an internal shoulder extending inwardly relative to the longitudinal axis and a second internal sealing surface adjacent the internal shoulder, and internal threads between the first internal sealing surface and the second internal sealing surface.