Dry Coated Tubular Threaded Elements for Hydrocarbon Wells
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Solution Overview
Problem
Existing threaded elements for hydrocarbon wells face issues with galling and corrosion during makeup and breakout operations, particularly under high axial loads and misalignment, and current coatings are either ineffective or environmentally harmful, requiring complex production cycles and additional protective layers.
Innovation Solution
A solid thin coating with a viscoplastic matrix containing specific solid lubricant particles, such as graphite fluoride, boron nitride, and polytetrafluoroethylene, which adheres to the substrate and provides anti-galling and corrosion protection, applied in a single layer before machining, enhancing durability and reducing environmental pollution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional protective grease or oil coating is applied to threaded elements, then corrosion protection during transport and storage is improved, but galling risk increases during makeup operations under high axial load
Solution Approach 1:
The patent changes the physical state parameter of the protective coating from liquid/grease to solid, specifically using a dry free-flowing powder coating. This parameter change allows the coating to provide both corrosion protection and anti-galling properties, as the solid powder can withstand high axial loads without causing galling while maintaining protective barriers against corrosion.
Solution Approach 2:
The patent uses composite material composition by combining multiple functional components in the dry coating: corrosion inhibitors for corrosion protection, solid lubricants for reducing friction and preventing galling, and binders for adhesion. This composite approach simultaneously addresses both corrosion protection and galling prevention that were conflicting in traditional single-material coatings.
2Ease of operation
If threaded elements undergo makeup-breakout cycles under high axial load and misalignment, then assembly and disassembly are achieved, but galling and coating particle tear-off occur
Solution Approach 1:
The patent modifies the mechanical strength and toughness parameters of the coating by using a flexible binder system that allows the coating to deform elastically under high axial loads and misalignment conditions. This enables the coating to maintain integrity during makeup-breakout cycles rather than flaking or tearing off, while still providing lubrication and anti-galling protection.
3Object-affected harmful factors
If solid lubricant particles are dispersed in a solid matrix coating, then anti-galling properties are improved, but the coating requires hardening by heating in a furnace which adds complexity to the production cycle
Solution Approach 1:
The patent replaces the thermal hardening process with a chemical or physical setting mechanism. The coating composition uses binders that set at ambient or elevated temperatures through chemical reactions (such as moisture-curing or two-component polymerization) rather than requiring high-temperature furnace hardening. This substitution eliminates the complex thermal processing equipment and energy requirements while maintaining coating integrity and performance.
4Reliability
If existing solid coatings are applied to threaded elements, then some protection is provided, but they frequently flake off and particles are torn from the rubbed surface under drill site conditions
Solution Approach 1:
The patent optimizes the adhesion parameters by using binders with appropriate tack and bonding characteristics that create strong chemical or physical bonds with the metal substrate. The coating formulation includes adhesion promoters and uses surface preparation requirements that enhance mechanical interlocking. These parameter changes prevent flaking and particle tear-off during makeup-breakout operations, reducing harmful particle dispersion into the environment.
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 coating significantly increases the number of makeup-breakout cycles by 50% while preventing galling and corrosion, maintaining performance under extreme pressures and reducing debris dispersion, thus improving productivity and environmental safety.
Implementation Method 1
a solid thin coating which is not sticky to the touch and adheres to the substrate, which comprises a solid matrix in which particles of solid lubricant are suspended
Implementation Method 2
the solid matrix is lubricating and exhibits plastic or viscoplastic type rheological behaviour
Implementation Method 3
a solid thin coating which is not sticky to the touch and adheres to the substrate
Implementation Method 4
which comprises a solid matrix in which particles of solid lubricant are suspended... provides anti-galling and corrosion protection
Data Source
Figure 1~5
Figure 3~4
AI summary
The coating (11) comprises a solid matrix adhering to the substrate (13) in which are dispersed particles of solid lubricants from at least two classes which are selected to exert a synergistic effect between themselves and with the constituents of the matrix. Protection against corrosion and against galling of the threadings of threaded elements used in hydrocarbon wells.