Pressure Sensor Unit With Segmented Shaft And Thin-Walled Design
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Solution Overview
Problem
Existing pressure sensor units for measuring hydrocarbon stream pressures in underwater plants are expensive due to the high cost of materials like 'Inconel 625' and require thick walls to withstand pressure differences, making them costly to produce and machine.
Innovation Solution
The pressure sensor unit design incorporates a shaft part with perforations to allow process fluid into the inner room, reducing the need for thick walls and using a separating membrane on a block within the shaft part, enabling the shaft part to be made of thin-walled material while maintaining structural integrity and sealing effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick walls are used to withstand pressure differences, then structural integrity is improved, but material consumption and production costs increase
Solution Approach 1:
The shaft part is divided into a outer shaft wall and an inner partition wall, creating separate pressure zones. The partition wall separates the process fluid pressure from the sensor chamber, allowing the outer shaft wall to be thin-walled while still maintaining structural integrity through the segmented design.
Solution Approach 2:
Different parts of the structure have different wall thicknesses optimized for their specific functions. The partition wall is thin since it only needs to separate pressures, while the flange and sensor housing have sufficient thickness for sealing and housing components. This local optimization reduces overall material consumption while maintaining strength where needed.
2Reliability
If expensive materials like Inconel 625 are used, then corrosion resistance and structural integrity are improved, but production costs increase
Solution Approach 1:
The expensive Inconel 625 material is used only in the flange and sensor housing where corrosion resistance and sealing are critical. The shaft part, which is less critical and more exposed to process fluid, uses cheaper stainless steel. This selective material application maintains reliability where needed while significantly reducing overall production costs.
3Measurement precision
If the sensor element is mounted face-mounted in the shaft part, then measurement precision is improved, but the shaft part requires thick walls to protect the sensor, increasing material consumption
Solution Approach 1:
The sensor element is mounted in a separate sensor chamber formed by the partition wall, rather than being face-mounted in the main shaft. This segmentation allows the sensor to be protected in its own chamber while the main shaft wall remains thin, resolving the contradiction between measurement precision and material consumption.
4Adaptability or versatility
If a hydraulic pipe is used to transfer pressure from the membrane to the sensor element, then the sensor element can be positioned away from the process fluid, but the hydraulic pipe requires thick walls to withstand pressure differences, increasing material consumption
Solution Approach 1:
The hydraulic pipe is contained within the sensor chamber formed by the partition wall, creating a separate pressure transfer path. This allows the hydraulic pipe to be thin-walled since it only needs to withstand the pressure difference across the membrane, not the full process fluid pressure. The segmentation isolates the hydraulic system from the high-pressure process fluid environment.
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
This design significantly reduces material consumption and production costs while maintaining technical performance, allowing for cost-effective production without compromising the sensor's ability to measure pressures accurately in harsh environments.
Implementation Method 1
a separating membrane arranged in the inner end 6 of the shaft part
Implementation Method 2
a hydraulic oil between the separating membrane and the pressure sensor element itself
Data Source
AI summary
A pressure sensor unit (1) consists of a shaft part (2) adapted to be introduced in an opening (24) through a pipe wall (14) or chamber wall, and a flange part (17) fastened on the outer end (18) of the shaft part for providing sealing around the outer end (19) of the opening. The shaft part inner end (6) reaches in to engagement with a process fluid (16) which pressure is to be measured. The inner end (6) is provided with perforations (22) for admitting process fluid into the inner room of the shaft part. In the inner room and straight behind the inner end (6) it is arranged a block (8) which constitute a base for a separating membrane (7) for transferral of the process fluid pressure via a hydraulic pipe (10) to a pressure sensor element (4) in the flange part (17). The flange part (2) is constructed as a thin walled pipe, which is enabled because of internal pressure equalisation. Thus great savings is achieved by production of the pressure sensor unit.