Hydraulic Line Pressure Compensation Against Subsea Collapse
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Solution Overview
Problem
Hydraulic lines in subsea umbilicals face collapse due to external pressure differentials exceeding their collapse pressure rating, particularly in deep water environments, where the hydrostatic pressure of the marine riser fluid is greater than the internal fluid pressure, leading to potential collapse and operational challenges.
Innovation Solution
A hydraulic protection system that includes a pressure sensing assembly and a pressure compensation assembly, which automatically increases the internal pressure of the hydraulic line by communicating external fluid pressure when a predetermined differential is reached, preventing collapse by maintaining the pressure below the collapse rating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If umbilical lines are designed with higher collapse pressure rating to withstand deep water pressure, then the line can resist external pressure differential, but the umbilical becomes very heavy, expensive and difficult to handle
Solution Approach 1:
The system proactively pressurizes the umbilical line before collapse occurs by detecting pressure differential trends and activating the HPU in advance. The collapse prevention system monitors the pressure differential across the umbilical wall and triggers pressurization when approaching critical thresholds, preventing collapse rather than reacting after it occurs.
Solution Approach 2:
The patent introduces a collapse prevention system as an intermediary between the external pressure environment and the umbilical line. This system includes pressure sensors, control logic, and a HPU that act as a buffer, translating external pressure conditions into appropriate internal pressurization responses without requiring the umbilical itself to be inherently collapse-resistant.
2Reliability
If conventional collapse protection methods are used with heavy umbilicals, then the umbilical can withstand collapse pressure, but the system becomes expensive and difficult to handle
Solution Approach 1:
The system dynamically adjusts the pressurization level based on real-time pressure differential measurements. Rather than maintaining constant high pressure or using static heavy construction, the HPU activates and modulates pressure output according to the actual external pressure conditions and umbilical vulnerability, optimizing protection while minimizing operational complexity.
Solution Approach 2:
The collapse prevention system incorporates continuous feedback through pressure sensors that monitor the pressure differential across the umbilical wall. This feedback loop provides real-time information to the control system, which adjusts HPU output accordingly, creating a self-regulating protection mechanism that responds precisely to actual collapse risks.
3Ease of operation
If the umbilical line is vented to equalize pressure, then the internal pressure equals hydrostatic head, but the external pressure differential causes collapse when marine riser pressure is higher
Solution Approach 1:
The umbilical protection system is self-activating, requiring no external intervention. When the pressure sensor detects that the pressure differential is approaching collapse thresholds, the system automatically triggers the HPU to pressurize the umbilical line, making the protection mechanism autonomous and responsive to actual conditions.
Solution Approach 2:
The system uses hydraulic principles by employing a HPU to generate and deliver pressurized fluid into the umbilical line. This hydraulic pressurization creates internal pressure that counteracts the external collapse pressure differential, utilizing fluid mechanics to achieve structural protection without mechanical reinforcement.
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 system effectively prevents hydraulic line collapse by compensating for pressure losses, ensuring the internal pressure remains above the external pressure, thus avoiding breach of the collapse pressure rating and maintaining operational safety.
Implementation Method 1
a pressure sensing assembly (50) arranged to monitor a pressure differential between the fluid external to the hydraulic line and the fluid contained within the hydraulic line
Implementation Method 2
a pressure compensation assembly (52) coupled to the hydraulic line and exposed to the fluid external to the hydraulic line. The pressure compensation assembly (52) is operable, when the pressure differential monitored by the pressure sensing assembly (50) reaches a predetermined level, to employ the pressure of the fluid external to the hydraulic line to increase the pressure of the fluid contained within the hydraulic line
Implementation Method 3
The present invention provides a hydraulic protection system for preventing collapse of a hydraulic line, in the event of a loss of pressure occurring in the hydraulic line
Data Source
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AI summary
A hydraulic protection system (46) for preventing collapse of a hydraulic line (38). The system comprises a pressure sensing assembly (50) which is arranged to monitor a pressure differential between fluid external to the hydraulic line and fluid contained within the hydraulic line; and a pressure compensation assembly (52) which is adapted to be coupled to the hydraulic line and which is exposed to the fluid external to the hydraulic line. The pressure compensation assembly (52) is operable to employ the pressure of the fluid external to the hydraulic line to increase the pressure of the fluid contained within the hydraulic line and thereby compensate for the loss. The system is arranged so that the pressure compensation assembly (52) is operated when the pressure differential monitored by the pressure sensing assembly (50) reaches a predetermined level, which is below a collapse pressure of the hydraulic line.