End Fitting Additive Manufacturing for Corrosion-Resistant Passageways
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Solution Overview
Problem
Conventional end fittings for flexible pipes, used in deep and ultra-deep water environments, face challenges such as corrosion from acidic gases like H2S, leading to hydrogen cracking and high manufacturing costs due to the need for expensive corrosion-resistant alloys and time-consuming machining processes for complex passageways.
Innovation Solution
The method involves additive manufacturing to create near net shape precursors for end fitting components, integrating corrosion-resistant regions within the base material, allowing for non-linear fluid communication passageways that would be difficult or costly to achieve with traditional techniques, reducing the risk of hydrogen cracking and lowering production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional drilling techniques are used to create passageways through end fitting components, then the manufacturing process is simple and cheap, but the bore surfaces are vulnerable to corrosion from acidic gases like H2S, leading to hydrogen cracking
Solution Approach 1:
The patent applies local quality by creating a dual-material structure where the end fitting has a base material (e.g., steel) for structural integrity and a corrosion-resistant material (e.g., nickel alloy or duplex stainless steel) applied only to the bore surfaces and regions exposed to acidic gases. This localized application of corrosion-resistant material protects vulnerable areas without requiring the entire component to be made from expensive corrosion-resistant alloys, thus improving reliability while managing manufacturing complexity and cost.
Solution Approach 2:
The patent employs composite materials by combining two or more materials with different properties within a single end fitting component. The base material provides mechanical strength and structural support, while the corrosion-resistant material (such as nickel alloy 625, duplex stainless steel, or super duplex stainless steel) provides protection against acidic gas corrosion. This composite approach allows the component to simultaneously achieve high reliability in sour service environments and cost-effectiveness by using materials strategically.
2Reliability
If expensive corrosion-resistant alloys are used to manufacture entire end fitting components, then corrosion resistance is improved, but manufacturing costs increase significantly
Solution Approach 1:
The patent applies local quality by creating a dual-material structure where the end fitting has a base material (e.g., steel) for structural integrity and a corrosion-resistant material (e.g., nickel alloy or duplex stainless steel) applied only to the bore surfaces and regions exposed to acidic gases. This localized application of corrosion-resistant material protects vulnerable areas without requiring the entire component to be made from expensive corrosion-resistant alloys, thus improving reliability while managing manufacturing complexity and cost.
Solution Approach 2:
The patent applies parameter changes by modifying the material composition parameter of the end fitting component. Instead of using a uniform expensive corrosion-resistant alloy throughout the entire component, the invention changes the material parameter locally at critical surfaces (bore surfaces, fluid communication passageways) while using cheaper base materials in non-critical structural regions. This parameter change strategy reduces material cost while maintaining the necessary corrosion resistance for reliable operation in sour service environments.
3Adaptability or versatility
If conventional drilling methods are used for passageways, then manufacturing is straightforward, but complex non-linear passageway designs are difficult or costly to achieve
Solution Approach 1:
The patent applies preliminary action by incorporating fluid communication passageways directly into the mold or tooling used to form the end fitting component during the manufacturing process. This preliminary incorporation of passageways allows for complex non-linear designs to be created as integral features of the component geometry itself, rather than requiring subsequent drilling or machining operations. The passageways are formed simultaneously with the component body, enabling design flexibility while maintaining manufacturing simplicity.
Solution Approach 2:
The patent applies merging by combining the formation of the end fitting component body and the fluid communication passageways into a single manufacturing operation. Instead of separately creating the component and then drilling passageways through it, the invention merges these operations by forming both the external geometry and internal passageway structures in one process step using specialized mold or tooling. This merging enables complex non-linear passageway designs to be achieved without significantly increasing manufacturing complexity.
Data Source
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AI summary
A method, a component part of an end fitting and a preformed member for manufacturing a component part of an end fitting are disclosed. The method comprises the steps of, via an additive process, providing a near net shape (NNS) precursor corresponding to a component part of an end fitting layer-by-layer and subsequently performing at least one post NNS processing operation on the NNS precursor to provide the component part.