ROV Gripper Unit for Subsea Riser Repair
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Solution Overview
Problem
The oil and gas industry faces challenges in repairing subsea risers, particularly in deep water where access is limited, and existing methods are not adequately sensitive to the fragile nature of risers or equipped with contingency measures for failed repairs.
Innovation Solution
A method utilizing a gripper unit apparatus and alignment, installation, and activation apparatus, hydraulically controlled from a remotely operated vehicle (ROV), which includes lightweight gripper units with self-activating slips and springs to securely engage and disengage from the riser pipe, ensuring minimal risk of damage and facilitating remote operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional repair methods are used, then repair capability is maintained, but accessibility to deep water risers is lost and diver safety is compromised
Solution Approach 1:
The patent replaces manual diver operations with a remotely operated vehicle (ROV) system. The ROV carries and deploys the gripper unit apparatus, allowing repair operations to be performed remotely from a safe distance. This substitution eliminates diver exposure to hazardous deep water environments while maintaining repair capability.
Solution Approach 2:
The ROV serves as an intermediary between the operators and the deep water environment. It transports the gripper unit apparatus to the riser location and facilitates remote operation, acting as a mediator that enables repair work without requiring direct human presence in hazardous conditions.
2Strength
If heavy-duty gripper units are used to ensure secure engagement, then gripping strength is improved, but deployability from ROV is compromised
Solution Approach 1:
The gripper unit apparatus is divided into multiple functional components: gripper fingers for engagement, slips for clamping action, springs for self-activating force, and hydraulic control elements. This segmentation allows each component to be optimized for its specific function while keeping the overall weight manageable for ROV deployment.
Solution Approach 2:
The gripper unit incorporates self-activating slips with springs that automatically engage and apply clamping force when the gripper fingers contact the riser pipe. This self-service mechanism eliminates the need for heavy external actuation systems, reducing weight while maintaining secure engagement capability.
3Extent of automation
If complex hydraulic control systems are used, then remote operation capability is improved, but system complexity and failure risk increase
Solution Approach 1:
The hydraulic control system is integrated into the ROV's existing hydraulic architecture, allowing the same hydraulic power source to control both the ROV's navigation functions and the gripper unit apparatus. This multi-functionality approach avoids duplicating hydraulic systems, reducing overall complexity while maintaining full remote operation capability.
Solution Approach 2:
The control functions for the gripper unit apparatus are merged with the ROV's existing control systems. Hydraulic lines and control mechanisms are combined into a unified system, reducing the number of separate components and potential failure points while enabling coordinated remote operation.
4Reliability
If self-activating slips with springs are used, then secure engagement is improved, but device complexity increases
Solution Approach 1:
The slips are designed with integrated springs that automatically activate the clamping action when the gripper fingers engage the riser pipe. The springs self-generate the necessary clamping force without requiring external power sources or complex actuation mechanisms, improving reliability while adding minimal complexity.
Solution Approach 2:
The slips transition from a static clamping design to a dynamic self-activating system where springs provide continuous adaptive force. This dynamic mechanism automatically adjusts to maintain secure engagement as the riser pipe moves or deforms, improving reliability through active compensation rather than rigid fixed-position clamps.
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 safe and effective repair of subsea risers in deep water by providing a lightweight, ROV-deployable gripper unit that securely engages and disengages from the riser pipe, reducing the risk of damage and allowing for remote operation, thus addressing the challenges of accessibility and fragility.
Implementation Method 1
lightweight gripper units with self-activating slips and springs to securely engage and disengage from the riser pipe
Implementation Method 2
hydraulically controlled from a remotely operated vehicle (ROV)
Data Source
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AI summary
A method of landing an apparatus onto a shaft, the method comprising: providing an attachment means attached to and protruding from the shaft at a pre-determined location on the shaft; suspending the apparatus from a topside vessel, such that a portion of the apparatus designed to mate with the attachment means is positioned substantially above the attachment means; manoeuvring the apparatus substantially along the axial direction of the shaft until said portion of the apparatus comes into contact with the attachment means; releasing the apparatus from the topside vessel such that the apparatus becomes supported on the shaft by the attachment means.