Vacuum Insulated Tubing Cladding for Corrosion-Prone Fillet Welds
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Solution Overview
Problem
Existing vacuum insulated tubing for oil and gas wells fails to withstand high pressure and temperature conditions due to corrosion of fillet welds, leading to potential collapse and loss of vacuum, with existing protective methods like High-Velocity Oxygen Fuel coating and laser cladding being inadequate.
Innovation Solution
A tubing component with a frustoconical fillet weld and a protective metallic layer extending over the weld, made from a corrosion-resistant alloy like Inconel 625, using Gas Tungsten Arc Welding for cladding, ensuring leak-tightness and resistance to corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a fillet weld is used to join the inner and outer tubes, then the assembly is structurally connected, but the fillet weld becomes highly prone to corrosion from oil and H2S
Solution Approach 1:
A protective metallic layer is introduced as an intermediary between the fillet weld and the corrosive environment (oil and H2S). This protective layer acts as a barrier that prevents direct contact between the weld material and corrosive substances, thereby maintaining the structural integrity of the fillet weld while providing corrosion resistance.
Solution Approach 2:
The solution combines multiple materials with different properties: the base metal tubes, the fillet weld material providing structural strength, and a protective metallic layer providing corrosion resistance. This composite structure allows each material to perform its specialized function, resolving the contradiction between structural connection and corrosion resistance.
2Object-affected harmful factors
If High-Velocity Oxygen Fuel coating is applied to protect the fillet weld, then corrosion protection is provided, but the solution does not meet design requirements for high pressure and high temperature wells
Solution Approach 1:
The protective coating material parameters are changed from standard High-Velocity Oxygen Fuel coating materials to a protective metallic layer material specifically selected for high pressure and high temperature resistance. This parameter change in material properties allows the coating to withstand the extreme well conditions while maintaining its corrosion protection function.
3Object-affected harmful factors
If laser cladding is used to protect the fillet weld, then corrosion resistance is improved, but tight machining tolerance on the surface is required which is not compatible with current vacuum insulated tubing assembly techniques
Solution Approach 1:
The protective metallic layer is applied after the fillet weld is formed, rather than requiring pre-preparation of the surface before welding. This sequence of operations eliminates the need for tight machining tolerances on the surface before cladding, as the protective layer is deposited on the as-welded surface geometry.
4Temperature
If the vacuum space is formed with fillet welding, then the space is created for thermal isolation, but the fillet weld is highly prone to corrosion leading to loss of vacuum
Solution Approach 1:
The protective metallic layer serves as an intermediary barrier that protects the fillet weld from corrosion, thereby preventing pinhole formation and maintaining vacuum integrity in the space between the inner and outer tubes, while the fillet weld continues to provide the structural connection necessary for thermal isolation.
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 provides a vacuum insulated tubing capable of withstanding high pressures and temperatures without collapsing and maintains vacuum integrity, resisting corrosion from oil and H2S, while allowing for precise production and assembly.
Implementation Method 1
using Gas Tungsten Arc Welding for cladding
Implementation Method 2
The vacuum insulated tubing has a vacuum space between the inner and the outer tubes to improve the thermic isolation
Implementation Method 3
to improve the thermic isolation between the inside of the inner tube and the outside of the outer tube
Implementation Method 4
The vacuum space is formed with a fillet welding between the end of the inner tube and the outer tubes
Data Source
AI summary
Disclosed is a tubing component for the oil and gas industry. The tubing component includes an outer tube and an inner tube within the outer tube, said tubes being so configured to create a space between each other over a specified length. Each end of the inner tube is secured to the internal surface of the outer tube by a frustoconical fillet weld so that said space is leak-tight. The inner tube has a first internal diameter ID along a first length starting from each end of said tube, and a second, smaller internal diameter ID′ along a second length beyond the first length. The tubing component further includes a protective metallic layer extending at least over the fillet weld. Also disclosed is a method for producing this tubing component.