Helical Sensor Cable Routing on Flexible Tubes
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Solution Overview
Problem
Flexible tubes used in offshore oil exploitation, such as those described in API RP 17B and API RP 17E, face challenges in minimizing stress on connection cables when subjected to bending, which can lead to cable breakage or weld failure, and require precise sensor placement to ensure accurate data collection, especially when sensor dimensions are significant compared to the tube diameter.
Innovation Solution
A flexible cylindrical tube design featuring a chain of sensor boxes connected by cables that follow helical paths, with each sensor box placed between upstream and downstream cables oriented parallel to the tube axis, and housed in recesses on the tube periphery, while cables are routed in grooves, allowing for flexible deformation without excessive stress and ensuring accurate sensor orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If connection cables are fixed to the tube in the direction of the axis with length equal to the distance between sensor boxes, then the cable arrangement is simple, but a curvature of the flexible tube exerts strong tensile stress on the cables located on the convex part of the curvature, risking cable breakage or weld failure
Solution Approach 1:
The patent applies helical routing of connection cables around the tube instead of straight axial routing. This curved path allows the cable to accommodate tube bending by distributing stress along the helical path, preventing excessive tensile stress on cables during convex curvature while maintaining a relatively simple overall cable arrangement structure.
2Reliability
If cables are wrapped in a helix around the tube to compensate elongation, then cable stress during curvature is reduced, but the overall length of the cable between two sensors increases and the arrangement becomes more complex
Solution Approach 1:
The helical cable routing serves multiple functions simultaneously: it compensates for cable elongation during tube curvature, maintains consistent effective cable length between sensors, and provides a regular repeating pattern that simplifies installation and manufacturing. This multi-functional approach justifies the increased cable length by delivering multiple benefits in a single routing configuration.
3Ease of manufacture
If sensor dimensions are significant compared to the tube diameter, then the sensor can be more robust and easier to install, but the sensor orientation and position relative to the tube periphery become harder to control precisely
Solution Approach 1:
The patent divides the sensor into multiple components: the sensing element, the circuit board, and the mounting structure. This segmentation allows the sensor to be assembled in stages, with each component positioned and oriented precisely relative to the others, and then the entire assembly mounted to the tube. This modular approach enables robust sensor construction while maintaining precise orientation control.
Solution Approach 2:
The sensor components are pre-assembled and pre-oriented to the correct angular position and orientation relative to the tube periphery before final installation. This preliminary positioning ensures that when the complete sensor assembly is mounted to the tube, the sensing elements are already correctly oriented, achieving precise manufacturing positioning while allowing for robust sensor construction.
Data Source
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AI summary
The invention relates to the installation of chains of measurement sensors on a flexible cylindrical tube (TB). The chains comprise multiple elongate sensor housings, electrically connected to one another by connecting cables. Each housing has two ends, in the elongation direction, connected to an upstream connecting cable and a downstream connecting cable, respectively, the upstream cable and the downstream cable mainly following two parallel helical paths (Ha1, Hb1), separated at the points of connection to the housing by a distance D other than zero in the direction of the axis of the tube. The housing is placed between the two cables and arranged with the elongation direction thereof parallel to the axis of the helical paths, which is the axis of the tube. The sensors of one chain are located on a single generatrix of the cylindrical tube and, if there are a plurality of chains, said sensors are positioned on a plurality of generatrices (G1, G2, G3). The sensor housings and the cables are placed in recesses and grooves provided in the periphery of the tube.