Pipe Threaded Connection With Zn-Ni Graphite Coating Against Galling
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Solution Overview
Problem
Threaded connections for pipes used in horizontal wells face challenges with galling resistance and looseness due to high stress and friction, leading to reduced airtightness and increased risk of loosening, which existing technologies do not adequately address.
Innovation Solution
A threaded connection featuring a Zn—Ni alloy plating layer with graphite on the pin and box contact surfaces, formed through electroplating, which enhances both galling resistance and high-torque maintenance properties, preventing looseness even under high stress conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compound grease containing heavy metal is used to enhance galling resistance, then galling resistance is improved, but environmental harm increases
Solution Approach 1:
The patent removes harmful heavy metal components from the grease formulation while retaining the essential lubricating and galling-resistant properties through alternative chemical compositions that are environmentally friendly
Solution Approach 2:
The patent modifies the chemical composition parameters of the grease by replacing heavy metal compounds with alternative additives that provide similar anti-galling performance without the environmental harm, changing the chemical structure while maintaining functional properties
2Strength
If threaded connection is used in horizontal well under high stress, then drilling capability is improved, but loosening risk increases
Solution Approach 1:
The patent employs a composite grease formulation combining multiple functional additives including extreme pressure agents, lubricants, and corrosion inhibitors that work synergistically to maintain thread integrity under high stress while preventing loosening through enhanced friction management
Solution Approach 2:
The patent applies grease coating to the threaded surfaces before assembly to create a protective film that cushions against high stress loads and prevents direct metal-to-metal contact that would lead to loosening under horizontal well conditions
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 Zn—Ni alloy plating layer with graphite effectively increases galling resistance and maintains high torque during fastening and loosening, preventing looseness and ensuring airtightness in horizontal wells, thereby improving the durability and reliability of threaded connections.
Implementation Method 1
a Zn—Ni alloy plating layer which is disposed on or above at least one of the pin contact surface and the box contact surface
Implementation Method 2
the low-frictional composite coating layer contains a carbon-nano material and a zinc component
Data Source
AI summary
A threaded connection for pipes according to the present embodiment includes a pin, a box, and a Zn—Ni alloy plating layer. The pin has a pin contact surface that includes an external thread part. The box has a box contact surface that includes an internal thread part. The Zn—Ni alloy plating layer is disposed on or above at least one of the pin contact surface and the box contact surface. The Zn—Ni alloy plating layer contains graphite.