Zinc Coated Threaded Tubular Element for Corrosion and Galling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing threaded connections for hydrocarbon well drilling and operation face challenges with corrosion, galling, and environmental concerns due to the use of conventional greases, which are not long-term solutions and can lead to environmental blockages.
Innovation Solution
A threaded tubular connection coated with a metallic anti-corrosion and anti-galling layer primarily composed of zinc, deposited electrolytically, combined with a lubricant layer and passivation layers to provide enhanced corrosion resistance, galling prevention, and environmental compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional greases are used on threaded zones and sealing surfaces, then corrosion resistance and galling prevention are improved, but environmental harm increases due to grease extrusion and blockages
Solution Approach 1:
The patent changes the fundamental parameter of the coating material from organic grease to inorganic metallic coating (zinc, zinc-aluminum, or zinc-magnesium alloy). This parameter change eliminates the environmental harm of grease extrusion while maintaining corrosion resistance and galling prevention through the metallic coating's inherent properties and sacrificial protection mechanism
Solution Approach 2:
The metallic coating acts as a sacrificial layer that can be consumed or degraded to protect the underlying steel substrate. This disposable coating approach replaces the need for long-term grease maintenance, providing initial protection that depletes over time rather than requiring ongoing grease application that eventually extrudes harmfully
2Reliability
If metallic coatings are applied to threaded zones and sealing surfaces, then corrosion resistance is improved, but manufacturing complexity increases due to additional coating steps
Solution Approach 1:
The patent employs composite metallic coating systems combining zinc with aluminum or magnesium alloys. These composite materials provide enhanced corrosion resistance and galling prevention properties compared to pure zinc, while the coating process remains a standard industrial operation that integrates into existing manufacturing workflows
Solution Approach 2:
The coating parameters such as thickness (5-20 micrometers) and composition (zinc-aluminum or zinc-magnesium ratios) are optimized to achieve the required performance with minimal additional manufacturing steps. The electrolytic deposition process parameters are controlled to ensure consistent quality without requiring complex multi-step procedures
3Strength
If high axial loads are applied during makeup operations, then connection strength is improved, but galling risk increases in threaded zones and sealing surfaces
Solution Approach 1:
The metallic coating serves as an intermediary layer between the steel threaded zones and sealing surfaces. This intermediate coating reduces direct metal-to-metal contact and friction during high-load makeup operations, preventing galling while allowing the full axial load to be transmitted through the threaded connection
Solution Approach 2:
The coating's physical parameters such as surface hardness, friction coefficient, and thickness are optimized to withstand high axial loads during makeup. The zinc-based coating provides a softer surface that deforms plastically under load to distribute contact pressures, preventing the localized stress concentrations that cause galling
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 solution effectively addresses corrosion and galling issues while ensuring long-term performance and environmental safety by using a zinc-based metallic layer with a lubricant and passivation coating, improving the durability and reliability of threaded connections in harsh environments.
Implementation Method 1
said threaded portion and said sealing surface being coated with a metallic anti-corrosion and anti-galling layer wherein zinc (Zn) is the major element by weight, said layer being deposited electrolytically
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The invention concerns a threaded portion of a tubular element for a threaded tubular connection hiving an axis of revolution, the portion comprising a threading extending over its outer or inner peripheral surface, and a first sealing surface on the peripheral surface, the first sealing surface being capable of producing metal-metal interference with a corresponding second sealing surface belonging to a complementary threaded portion of a tube. The threading and the first sealing surface are coated with a metallic anti-corrosion and anti-galling layer wherein zinc (Zn) is tie major element by weight.