Oil-Well Pipe Zn-Ni Thread Plating for Galling Resistance
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Solution Overview
Problem
Existing oil-well metal pipes with Zn--Ni alloy plating layers experience peeling during repeated fastening and loosening, leading to decreased galling resistance due to insufficient adhesion of the plating layer.
Innovation Solution
The oil-well metal pipe incorporates a Zn--Ni alloy plating layer on the pin and/or box contact surfaces, with controlled X-ray diffraction intensities satisfying the condition I18/(I18+I36+I54) ≥ 0.6 to enhance adhesion, and optionally includes a lubricant coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Zn-Ni alloy plating layer is formed on the pin contact surface or box contact surface to enhance corrosion resistance and wear resistance, then the corrosion resistance and wear resistance are improved, but the plating layer may peel off during repeated fastening and loosening, causing the coefficient of friction to increase and galling resistance to decrease
Solution Approach 1:
The patent applies parameter changes by controlling the crystallographic orientation of the Zn-Ni alloy plating layer through specific plating conditions. By adjusting the plating parameters to achieve a preferred orientation where the (111) crystal plane is parallel to the contact surface, the patent improves adhesion while maintaining corrosion and wear resistance. This resolves the contradiction by changing the physical parameter of crystal orientation rather than altering the material composition.
2Reliability
If heavy metal-containing compound greases (dopes) are applied to improve galling resistance, then the galling resistance is improved, but heavy metals such as Pb, Zn, and Cu may affect the environment
Solution Approach 1:
The patent extracts and eliminates the harmful heavy metal components from the lubrication system by replacing compound greases with a Zn-Ni alloy plating layer. The plating layer itself provides the necessary friction modification and galling resistance without introducing environmental contaminants. This extraction principle removes the harmful substances while preserving the beneficial functional properties.
Solution Approach 2:
The patent replaces the mechanical lubrication system (compound greases with heavy metals) with a surface engineering solution (Zn-Ni alloy plating layer). Instead of using external lubricants, the solution creates a protective surface layer that inherently provides low friction and high adhesion, substituting a chemical lubrication approach with a structural surface modification approach.
3Duration of action of moving object
If the Zn-Ni alloy plating layer repeatedly experiences strong friction during fastening and loosening, then the contact surfaces maintain low coefficient of friction, but the plating layer may peel off and the galling resistance will rapidly decrease
Solution Approach 1:
The patent applies preliminary action by pre-forming the Zn-Ni alloy plating layer with optimized crystal orientation before the pipe undergoes repeated fastening and loosening operations. The plating layer is prepared in advance with the (111) plane parallel to the contact surface, which provides enhanced adhesion and prevents peeling during subsequent friction cycles. This preliminary structural preparation ensures long-term durability and maintains galling resistance throughout the service life.
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 enhanced adhesion of the Zn--Ni alloy plating layer improves the galling resistance and durability of the oil-well metal pipe by reducing peeling and maintaining frictional stability.
Implementation Method 1
The Zn contained in the Zn—Ni alloy plating layer formed on a contact surface of the oil-well metal pipe enhances the corrosion resistance of the oil-well metal pipe by sacrificial protection
Implementation Method 2
X-ray diffraction intensities of the Zn—Ni alloy plating layer satisfy Formula (1)
Implementation Method 3
The pin contact surface and the box contact surface repeatedly experience strong friction during fastening and loosening of the oil-well metal pipe
Data Source
AI summary
An oil-well metal pipe according to the present disclosure includes: a pipe main body that includes a pin which includes a pin contact surface including an external thread part and which is formed at a first end portion, and a box which includes a box contact surface including an internal thread part and which is formed at a second end portion; and a Zn—Ni alloy plating layer which is formed on at least one of the pin contact surface and the box contact surface. The X-ray diffraction intensities of the Zn—Ni alloy plating layer satisfy Formula (1).I18/(I18+I36+I54)≥0.6(1)Here, in Formula (1), in units of cps, an X-ray diffraction intensity of {411} and {330} is substituted for I18, an X-ray diffraction intensity of {442} and {600} is substituted for I36, and an X-ray diffraction intensity of {552} is substituted for I54.