Subsea Isolation Valve Local Position Indicator
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Solution Overview
Problem
Subsea isolation valves lack a local visual and tactile indication of their position, making it difficult for divers and Remotely Operated Vehicles (ROVs) to operate them effectively, especially under high pressure and large profile conditions.
Innovation Solution
Integration of a local position indicator into the hydraulic actuation system of the subsea isolation valve, using a volumetric displacement device connected to the force closed balance line, which provides a visual and tactile indication of the valve's position without modifying the internal workings of the valve, and is calibrated to be depth-insensitive to seawater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy hydraulic operators are used for subsea isolation valves, then the valve can operate at high pressures, but the valve profile becomes large and weight increases
Solution Approach 1:
The patent uses a subsurface safety valve (SSV) design that replicates the essential function of heavy hydraulic operators but with a compact structure. The SSV copies the pressure-operated opening mechanism while eliminating the need for large external hydraulic components, thus achieving high pressure capability with reduced weight and profile.
Solution Approach 2:
The patent utilizes hydraulic pressure from the control line to directly operate the valve opening mechanism through a piston system. The hydraulic force from the control line pressure opens the valve, eliminating the need for separate heavy hydraulic operators and their associated external mechanisms.
2Reliability
If heavy hydraulic operators are used for subsea isolation valves, then the valve can operate at high pressures, but the valve profile exposed to wave action increases
Solution Approach 1:
The patent uses a subsurface safety valve (SSV) design that replicates the essential function of heavy hydraulic operators but with a compact structure. The SSV copies the pressure-operated opening mechanism while eliminating the need for large external hydraulic components, thus achieving high pressure capability with reduced weight and profile.
Solution Approach 2:
The patent utilizes hydraulic pressure from the control line to directly operate the valve opening mechanism through a piston system. The hydraulic force from the control line pressure opens the valve, eliminating the need for separate heavy hydraulic operators and their associated external mechanisms.
3Weight of stationary object
If subsurface safety valves are used instead of heavy hydraulic operators, then weight and profile are reduced, but local position indication capability is lost
Solution Approach 1:
The patent introduces a position indicator mechanism that acts as an intermediary between the valve's internal piston and the external operator. The indicator piston is connected to the control line piston through hydraulic fluid, transferring position information without requiring direct mechanical connection or modification of the valve internals. This allows divers or ROVs to visually assess valve position.
Solution Approach 2:
The patent replaces direct mechanical position indication mechanisms with a hydraulic fluid-based indication system. The position of the control line piston is transmitted through hydraulic fluid pressure to move an indicator piston, which then provides visual position feedback. This substitution eliminates complex mechanical linkages while providing clear position indication.
4Reliability
If the position indicator is integrated into the force close line, then the indication system can operate at lower pressures, but the system complexity increases
Solution Approach 1:
The patent makes the force close line serve dual functions: its primary function of forcing the valve closed and a secondary function of providing position indication through the indicator piston. By utilizing the existing force close line for both purposes, the patent avoids adding a separate indication system, thereby reducing overall complexity while achieving reliable position feedback.
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
Enables effective local operation of subsea isolation valves by divers and ROVs with a reliable and seawater-insensitive position indication system, meeting API standards without requiring internal valve modifications, and reducing the weight and profile of the valve, thus minimizing drag and resistance from underwater currents.
Implementation Method 1
hydraulic pressure in the operating control line
Implementation Method 2
The position indicator is a volumetric displacement device. The volume displaced by the operating piston is the volume pushed to the position indicator.
Implementation Method 3
The indicator piston can displace trapped fluid against a floating piston to isolate the indicating piston and its seals from seawater.
Data Source
AI summary
A local position indicating device for a subsea isolation valve that has no other visual signals of its position integrates to the hydraulic actuation system for the isolation valve. Three way valves, connected to an operating control line and a force closed balance line leading to opposed ends of an operating piston, are located by the isolation valve and redirected by a diver or ROV, to locally operate the valve. The balance line has a piston that is displaced with fluid pushed by the operating piston when the isolation valve is opened with hydraulic pressure in the operating control line local connection. The piston connected to the balance line moves an indicator out of its housing for the local indication that the isolation valve is open. Displaced fluid from movement of the piston in the position indicator moves a floating piston to keep seawater away from the indicating piston.