Threaded Pipe Connection with Coined Metal Seal Against High-Pressure Leaks
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Solution Overview
Problem
Leakage in threaded pipe connections used in high-pressure fluid applications, such as hydraulic fracturing, occurs due to extreme shear and tensile stresses, leading to damage and interruption of the fracturing process.
Innovation Solution
A leak-resistant threaded pipe connection design featuring a pin end with an annular seal bulge and a box end with a tapered seal area, where initial make-up to a recommended torque causes plastic deformation, creating a metal-to-metal seal resistant to elevated fluid pressures and stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional threaded connections are used in high-pressure hydraulic fracturing applications, then the connection structure is simple and easy to manufacture, but the connection leaks under extreme shear and tensile stresses at elevated fluid pressures
Solution Approach 1:
The patent applies local quality by creating a seal bulge with specific geometric features (apex, tapered seal area) at the critical sealing location on the pin end. This localized geometric modification concentrates the sealing function at the precise area where metal-to-metal contact is needed, while the rest of the connection structure remains relatively simple. The seal bulge's apex diameter is specifically designed to be smaller than the box end's internal diameter to ensure proper engagement and sealing under stress.
Solution Approach 2:
The patent employs preliminary action through the make-up torque application process. During initial assembly, a recommended make-up torque is applied to the threaded connection, which causes the seal bulge to plastically deform and engage the tapered seal area in advance. This preliminary deformation creates the leak-resistant seal before the connection is subjected to operational shear and tensile stresses, ensuring reliability is established beforehand rather than relying on the connection to remain intact under extreme conditions.
2Length of moving object
If threaded connections are subjected to high shear and tensile stresses during lateral well bore operations, then the connection can accommodate long drilling reach, but the connection begins to leak at elevated fluid pressures
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the pin end, specifically creating a seal bulge with a controlled apex diameter that is smaller than the box end's internal diameter. This geometric parameter change ensures that during make-up, the seal bulge engages the tapered seal area with sufficient interference to create a metal-to-metal seal. The plastic deformation resulting from this parameter mismatch creates a permanent seal that maintains connection integrity even when the connection is subjected to the shear and tensile stresses encountered in long lateral well bore operations.
3Reliability
If a metal-to-metal seal is created through plastic deformation, then the seal is highly resistant to leakage at elevated pressures, but the manufacturing process becomes more complex
Solution Approach 1:
The patent employs preliminary action by designing the seal bulge geometry and make-up torque parameters such that the plastic deformation and seal formation occur automatically during the standard assembly process. The recommended make-up torque is calibrated to cause the seal bulge to plastically deform and engage the tapered seal area, creating the metal-to-metal seal as an inherent part of the connection make-up process rather than requiring a separate manufacturing step. This approach maintains ease of manufacture while achieving high seal resistance.
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 connection provides a reliable, leak-resistant seal even under extreme conditions, maintaining integrity during hydraulic fracturing operations and resisting leakage at pressures up to 15,000 psi with minimal fluid loss.
Implementation Method 1
initial make-up of the leak-resistant threaded pipe connection to a recommended make-up torque causes a plastic deformation of the annular seal bulge against the tapered seal area of the box end to provide a leak-resistant metal-to-metal seal
Data Source
AI summary
A leak-resistant pipe connection has an annular seal bulge on a pin end of the connection and a tapered seal area adjacent a secondary box shoulder of a box end of the connection. The annular seal bulge is coined on contact with the tapered seal area on initial make-up of the connection which provides a metal-to-metal seal that is very resistant to high-pressure fluid leakage even after the connection is subjected to extreme shear and tensile stresses.