Umbilical Cable Tube Wall Hydrogen Embrittlement Resistance
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Solution Overview
Problem
Current subsea umbilical cables face challenges in maintaining mechanical strength and resistance to hydrogen embrittlement, especially when transporting hydrogen gas, due to the brittleness caused by hydrogen absorption in high-strength steel materials under mechanical loading and hydrogen exposure.
Innovation Solution
The umbilical cable features a tube wall made of materials resistant to hydrogen embrittlement, such as 25Cr-6Mo-5Ni duplex stainless steel, austenitic stainless steel, aluminum alloys, or copper alloys like CuNiSi, which are resistant to hydrogen-induced degradation, and optionally reinforced with stainless steel armouring to enhance mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-strength steel is used in the umbilical cable to maintain mechanical strength under loading, then the mechanical strength is improved, but hydrogen embrittlement occurs reducing ductility and making the metal more brittle
Solution Approach 1:
The patent employs a composite structure with an inner tube made of hydrogen-embrittlement-resistant material (such as copper alloy, aluminum alloy, or stainless steel) and an outer reinforcement layer made of high-strength steel. This composite design allows the inner tube to protect against hydrogen embrittlement while the outer layer provides the necessary mechanical strength to withstand hydrostatic pressure, tension, and bending loads during installation and operation.
2Strength
If high-strength steel is used to withstand hydrostatic water pressure and mechanical loading, then the mechanical strength is improved, but the material becomes more susceptible to hydrogen-induced degradation
Solution Approach 1:
The umbilical cable is segmented into distinct functional layers: an inner tube specifically designed to resist hydrogen embrittlement and an outer reinforcement layer designed to withstand mechanical loads. This segmentation allows each layer to be optimized for its specific function, with the inner tube material (copper alloy, aluminum alloy, or stainless steel) providing hydrogen resistance and the outer steel layer providing structural strength against hydrostatic pressure and mechanical loading.
3Strength
If conventional steel conduits are used in the umbilical cable, then the mechanical strength is improved, but the ductility is reduced due to hydrogen absorption
Solution Approach 1:
The patent uses a composite construction where the inner tube is made of materials that maintain ductility in hydrogen environments (such as copper alloys, aluminum alloys, or austenitic stainless steels), while the outer reinforcement provides additional mechanical strength. This composite approach ensures the cable maintains both strength and ductility, preventing the loss of formability and flexibility that would occur with conventional steel conduits exposed to hydrogen.
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 cable with improved mechanical strength and resistance to hydrogen embrittlement, ensuring the umbilical cable's durability and reliability in transporting hydrogen and electric power, particularly in offshore and marine environments, by using materials that maintain ductility and fatigue resistance even under dynamic conditions.
Implementation Method 1
a tube (3) for transporting hydrogen having a tube wall (4) made of a material resistant to hydrogen embrittlement
Data Source
Figure 1a~1b
Figure 2
AI summary
The present invention relates to an umbilical cable suited for transporting hydrogen gas, comprising an electric conductor (2), and a tube (3) for transporting hydrogen having a tube wall (4) made of a material resistant to hydrogen embrittlement.