Flexible Pipe End-Fitting With Isolated Electric Zones
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Solution Overview
Problem
Electrical heated unbonded flexible pipes in offshore and subsea oil and gas transportation face safety risks due to unintended electrical polarization and potential leak currents, especially during electrical failures, which can lead to hazardous situations and pipe blockages.
Innovation Solution
The assembly includes an end-fitting with three electric zones, where the first and second zones are electrically connected to the pipe's conductive layers and insulated from each other, while the third zone is connected to ground, providing an additional safety measure by ensuring the system operates with an electrically floating power supply and grounding, thus preventing unintended current paths and potential shifts in electrical potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electric heating is applied to prevent fluid cooling and blockage, then fluid flow reliability is improved, but electrical safety hazards increase due to unintended polarization and leak currents
Solution Approach 1:
The end-fitting is segmented into three electrically isolated zones: a first electric zone connected to the inner sheath, a second electric zone connected to the outer sheath, and a third electric zone connected to ground. These zones are electrically insulated from each other, preventing unintended current paths and electrical hazards while maintaining the electric heating function for fluid flow reliability
Solution Approach 2:
An electrically insulating material is introduced as an intermediary between the first and second electric zones, and between these zones and the third ground-connected zone. This intermediary prevents direct electrical contact and potential hazardous current paths while allowing the electric heating system to operate safely
2Power
If high current at high voltage is used for electric heating, then heating effectiveness is improved, but electrical failure risks increase leading to hazardous situations
Solution Approach 1:
The electrical system is divided into three separate zones with distinct electrical connections: the first zone connects to the inner sheath for current return path, the second zone connects to the outer sheath for current supply path, and the third zone provides ground connection. This segmentation allows high power operation while preventing electrical failures from propagating system-wide
Solution Approach 2:
The third electric zone connected to ground provides a reference potential and safety mechanism that monitors and controls the electrical potential in the first and second zones, preventing unintended polarization and providing a safe discharge path for any accumulated electrical energy
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 configuration enhances safety by preventing hazardous electrical potential shifts and reducing the risk of pipe blockages, ensuring reliable operation and reducing the risk of electrical failures leading to unintended leak currents.
Implementation Method 1
rather high currents fed at a high voltage are frequently used to heat the pipe
Implementation Method 2
The end-fitting comprises an electrically insulating material between the first and second electric zones and between these zones and the third electric zone
Data Source
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AI summary
The present invention relates to an assembly comprising an end-fitting and an unbonded flexible pipe comprising several layers. The unbonded flexible pipe has an end-part entering the end-fitting at the front end and the layers of the unbonded flexible pipe being terminated in the end-fitting. The unbonded flexible pipe further comprises a first electrically conductive layer and a second electrically conductive layer, where the first electrically conductive layer is electrically insulated from the second electrically conductive layer. The end-fitting comprises a first electric zone electrically connected with the first electrically conductive layer, and a second electric zone electrically connected with the second electrically conductive layer, the first electric zone is electrically separated from the second electric zone, and the end-fitting comprises a third electric zone, said third electric zone being electrically separated from first electric zone and the second electric zone.