Subsea Valve Actuator Locking Nut for ROV-Guided Replacement
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Solution Overview
Problem
Existing subsea valve actuators face challenges such as cumbersome clamps that are difficult to position and disengage, especially when using a Remotely Operated Vehicle (ROV), metal actuators prone to rusting, and calcium deposits that complicate disassembly.
Innovation Solution
An actuator assembly with a guide rod and locking nut system that includes a guide passage with tapered contact surfaces, allowing easy assembly and disassembly by an ROV, and an internal passage for anti-calcification fluid, along with an electrical connection for cathodic protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clamps are used to attach the actuator to the valve assembly, then the actuator can be secured in position, but the clamps are cumbersome and difficult to position and disengage, especially when using an ROV
Solution Approach 1:
The attachment system is divided into separate components: a guide rod that is part of the actuator assembly and a guide element with a guide passage that is part of the valve assembly. The guide rod fits into the guide passage, and a locking nut secures it in place. This segmentation allows for easier positioning and disengagement compared to monolithic clamps.
Solution Approach 2:
The guide rod acts as an intermediary component between the actuator and the valve assembly. It provides a standardized interface that fits into the guide passage, facilitating easy attachment and detachment while maintaining secure connection. The locking nut serves as another intermediary that secures the guide rod in place.
2Strength
If metal actuators are used, then structural strength is achieved, but the actuators rust quickly requiring frequent service and replacement
Solution Approach 1:
The patent applies cathodic protection to the metal actuator, which converts the harmful effect of corrosion into a beneficial protective mechanism. By connecting the actuator to a sacrificial anode or impressed current system, the metal surface is protected from rusting while maintaining its structural strength.
3Reliability
If calcium deposits are allowed to form in gaps and passages, then the assembly becomes difficult to disassemble, but preventing them requires additional maintenance operations
Solution Approach 1:
The patent incorporates a flushing passage that allows fluid to be introduced to prevent calcium deposits from forming in the first place. By maintaining continuous or periodic flushing, the passage remains clear and the assembly can be easily disassembled when maintenance is required.
4Reliability
If the guide passage has a tight fit for the guide rod, then secure attachment is achieved, but assembly and disassembly become difficult
Solution Approach 1:
The patent uses a tapered guide passage that provides a dynamic fit for the guide rod. The taper allows the guide rod to be easily inserted and removed while maintaining a secure connection during operation. The locking nut provides additional security when the guide rod needs to remain fixed in position.
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
Facilitates safe and controlled actuator replacement, reduces rusting, and prevents calcium deposits, ensuring reliable operation and reduced maintenance frequency.
Implementation Method 1
the distal opening is provided with an inwardly tapered contact surface
Implementation Method 2
the actuator housing is, while in an installed position, in electric contact with the X-mas tree or manifold of the other subsea structure, and is protected by the cathodic protection system already installed on that subsea structure
Implementation Method 3
The guide rod has an internal passage having an inlet connectable to a source of anti-calcification fluid and at least one outlet on the outer surface of the rod
Data Source
AI summary
A locking nut for locking a subsea unit relative to a guide rod fixed to a subsea installation is described. The locking nut has a body with a bore. The body comprises first and second parts that are detachable from one another. An assembly incorporating the locking nut is also described.