Pipe Threaded Connection Coating for Over-Torque and Galling Resistance
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Solution Overview
Problem
Existing threaded connections for pipes or tubes lack high over-torque performance, leading to difficulties in adjusting fastening torque due to insufficient torque on shoulder resistance, despite having good galling resistance.
Innovation Solution
A threaded connection with a solid lubricant coating layer containing a resin, solid lubricant powder, and Cr2O3 on at least one contact surface of the pin and box, which enhances both over-torque performance and galling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy metal-containing compound greases are used to improve galling resistance, then galling resistance is improved, but environmental harm increases due to heavy metal contamination
Solution Approach 1:
The invention extracts and removes the harmful heavy metal components (Pb, Zn, Cu) from the compound grease formulation while retaining the essential lubricating and galling-resistant properties through alternative solid lubricant materials and coating technologies
Solution Approach 2:
The invention changes the chemical composition parameters of the lubricant by substituting heavy metal compounds with environmentally friendly solid lubricants such as molybdenum disulfide, graphite, and polytetrafluoroethylene, thereby maintaining performance while eliminating environmental harm
2Ease of operation
If the difference between shouldering torque and yield torque (torque on shoulder resistance) is insufficient, then fastening torque adjustment becomes difficult, but increasing this difference may compromise other performance characteristics
Solution Approach 1:
The invention optimizes the friction characteristics and torque distribution parameters through selective application of solid lubricant coatings on specific contact surfaces, thereby adjusting the torque on shoulder resistance to an optimal range that enables easy fastening torque adjustment while maintaining reliability
Solution Approach 2:
The invention applies solid lubricant coatings selectively to specific local areas (contact surfaces) rather than uniformly across all surfaces, creating local variations in friction properties that optimize torque distribution and improve fastening operation ease
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 use of Cr2O3 in the solid lubricant coating layer significantly increases torque on shoulder resistance and galling resistance, allowing for more reliable and repeatable fastening and loosening operations without galling.
Implementation Method 1
The threaded connection for pipes or tubes includes a solid lubricant coating layer on at least one of the contact surfaces of the pin and the box
Implementation Method 2
The solid lubricant coating layer contains a resin, a solid lubricant powder and Cr2O3
Data Source
AI summary
This invention provides a threaded connection for pipes or tubes having high over-torque performance, and a method for producing the threaded connection for pipes or tubes. A threaded connection for pipes or tubes according to the present embodiment includes a pin and a box. The pin and the box include a contact surface including a threaded portion and a metal contact portion. The threaded connection for pipes or tubes includes a solid lubricant coating layer on at least one of the contact surfaces of the pin and the box, the solid lubricant coating layer including a resin, a solid lubricant powder, and Cr2O3.