Corrosion Resistant Pressure Module Using Dissimilar Metal Segmentation
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Solution Overview
Problem
Existing process pressure transmitters face challenges in providing a cost-effective solution for prolonged exposure to seawater due to the corrosive effects, as materials like titanium are difficult to weld with other alloys and result in high costs.
Innovation Solution
A pressure sensor module with a two-part housing, where one member is made of a seawater-resistant material like titanium and the other of a lower-cost metal such as stainless steel, mechanically coupled with a tantalum seal to ensure reliable welding and prevent fluid leakage, allowing for a robust and cost-effective design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium is used for the housing to provide complete imperviousness to seawater corrosion, then corrosion resistance is improved, but manufacturing difficulty and cost increase due to inability to weld with other alloys
Solution Approach 1:
The housing is divided into two separate members: a first member made of titanium or titanium alloy that contacts seawater, and a second member made of stainless steel or other alloy that houses the pressure sensor. This segmentation allows each material to be optimized for its specific function while avoiding the need to weld dissimilar metals together.
Solution Approach 2:
An intermediary coupling mechanism is introduced between the titanium member and stainless steel member, eliminating the need for direct welding between dissimilar metals. The coupling allows mechanical connection while maintaining the corrosion resistance of titanium and the manufacturability of stainless steel.
2Reliability
If titanium is used throughout the entire pressure transmitter, then corrosion resistance is improved, but cost effectiveness deteriorates
Solution Approach 1:
Different materials are applied to different parts of the housing based on their specific functional requirements. The titanium member is used only where corrosion resistance is critical (seawater exposure), while the stainless steel member is used where it provides sufficient corrosion resistance and better cost-effectiveness for housing the pressure sensor.
Solution Approach 2:
The housing is constructed as a composite structure combining titanium and stainless steel members. This composite approach leverages the superior corrosion resistance of titanium in the seawater-exposed portion while utilizing the cost-effective and easily manufacturable stainless steel for the internal housing portion.
3Reliability
If titanium is used for the housing, then corrosion resistance is improved, but device complexity increases due to difficulty in joining with other materials
Solution Approach 1:
The housing is segmented into separate titanium and stainless steel members that are coupled together, simplifying the joining process by avoiding direct welding of dissimilar metals. Each member can be manufactured and prepared independently, then assembled using appropriate coupling mechanisms.
Solution Approach 2:
A coupling mechanism serves as an intermediary between the titanium member and stainless steel member, simplifying the overall assembly process. The coupling allows for straightforward mechanical connection without requiring complex welding procedures for dissimilar metals.
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 robust and cost-effective pressure sensor module suitable for long-term seawater exposure, ensuring reliable operation and reducing material costs by using dissimilar metals with a suitable seal to prevent corrosion and facilitate welding.
Implementation Method 1
A seal is coupled to the first and second members to seal an interface between the first and second members
Implementation Method 2
Pressure is transferred from the isolation diaphragm to the pressure sensor using a substantially incompressible, inert fill fluid
Implementation Method 3
The pressure sensor itself has a physical structure such as a sensing diaphragm that reacts to the pressure, such as by deforming
Data Source
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AI summary
A pressure sensor module for a process pressure transmitter is provided. The pressure sensor module includes a first member formed of a metal suitable for exposure to seawater. The first member has a passageway extending therethrough. An isolation diaphragm (50) is coupled to the first member and has a first side configured to contact a process fluid and an opposite side in fluidic communication with the passageway of the first member. A second member is formed of a different metal than the first member and is mechanically coupled to the first member to define a chamber that is fluidically coupled to the passageway. A pressure sensor )40) is disposed to sense a pressure within the chamber. A seal is coupled to the first and second members to seal an interface between the first and second members.