PEEK-Graphite Thread Coating for Seizure-Resistant OCTG Joints
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Solution Overview
Problem
Existing technologies for lubricating connections for oil country tubular goods using solid lubricating coating films face challenges in achieving stable lubrication and corrosion resistance under severe conditions of large and unbalanced loads, leading to seizure issues.
Innovation Solution
A solid lubricating coating film is developed using graphite as the main solid lubricant and PEEK resin as the main binder resin, with specific optimization of graphite content, particle size, and blending ratio to prevent the formation of harmful black tape-shaped secondary products and enhance film durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a solid lubricating coating film is formed using graphite as the main solid lubricant, then lubricity is improved, but harmful black tape-shaped secondary products are generated causing seizure
Solution Approach 1:
The invention converts the harmful black tape-shaped secondary products generated by graphite into beneficial fine powder secondary products by adding PTFE as a solid lubricant. The PTFE modifies the decomposition behavior of graphite under thermal stress, transforming the harmful tape-shaped debris into fine powdery debris that does not cause seizure, thereby converting a harmful effect into a beneficial one.
Solution Approach 2:
The invention uses a composite material system consisting of graphite (50-90 wt%) as the main solid lubricant and PTFE (10-50 wt%) as an auxiliary solid lubricant. This composite approach combines the high lubricity of graphite with the seizure-preventing properties of PTFE, achieving both excellent lubrication performance and resistance to seizure under severe loading conditions.
2Ease of operation
If graphite content is increased to improve lubrication, then lubricity is enhanced, but the formation of harmful secondary products increases
Solution Approach 1:
The invention optimizes the compositional parameter of the solid lubricating coating film by specifying that graphite content should be 50-90 wt% and PTFE content should be 10-50 wt%. This parameter optimization ensures sufficient graphite content for high lubricity while limiting the formation of harmful secondary products through the presence of PTFE, which modifies the secondary product morphology.
3Ease of operation
If conventional solid lubricating coating films are used, then lubrication is achieved, but corrosion resistance is insufficient under severe conditions
Solution Approach 1:
The invention creates a composite solid lubricating coating film system that provides both lubrication and corrosion resistance. The combination of graphite and PTFE in specific proportions (graphite 50-90 wt%, PTFE 10-50 wt%) forms a synergistic system that maintains lubrication performance while improving resistance to corrosion under severe conditions including large and unbalanced loads.
4Ease of operation
If a solid lubricating coating film is applied to achieve dry dope-free lubrication, then lubrication without heavy metals is achieved, but seizure occurs under large and unbalanced loads
Solution Approach 1:
The invention develops a dry dope-free lubricating system using a composite of graphite and PTFE that maintains environmental friendliness (no heavy metals) while achieving seizure resistance under severe conditions. The composite structure allows the material to withstand large and unbalanced loads without seizure, overcoming the limitation of conventional dry dope-free lubrication.
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 optimized solid lubricating coating film achieves improved lubricity and corrosion resistance, effectively preventing seizure and maintaining performance under severe make-up and break-out conditions in actual well environments.
Implementation Method 1
a solid lubricating coating film which is composed of a binder resin as a matrix component, a solid lubricant dispersed and distributed in the binder resin
Implementation Method 2
the phenomena described by the terms 'lubricity' and 'high lubricity' mean low friction and slippery phenomena
Implementation Method 3
a solid lubricant dispersed and distributed in the binder resin
Implementation Method 4
a coating film composed of a binder resin as a matrix component
Implementation Method 5
The present disclosure is intended to provide corrosion resistance while improving lubrication by a solid lubricating coating film
Data Source
AI summary
A solid lubricating coating film capable of imparting favorable lubricity and corrosion resistance to a connection for oil country tubular goods. Two or more solid lubricants are dispersed in a binder resin. Graphite is contained in an amount of 50% or more and 90% or less of a total weight of the solid lubricants, and the graphite has a scaly shape and an average particle diameter of 10.0 μm or less. A solid lubricant made of one or more materials selected from BN, mica, talc, MCA, MoS2, PTFE, PFA, and FEP is further contained as other solid lubricants of the two or more types of solid lubricants. The binder resin contains a PEEK resin having an average particle diameter of 20 μm or less as a main component, and the PEEK resin is contained in an amount of 70% or more of a total weight of the binder resin.