Flexible Pipe Annulus Venting With Flushable Redundant Valves
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Solution Overview
Problem
Flexible pipes used in deep and ultra-deep water environments face issues with gas build-up in the annulus, leading to potential blockages in vent valves, which can result in excessive pressure and catastrophic failure, especially due to debris accumulation and limited access for maintenance in sub-sea locations.
Innovation Solution
A vent arrangement comprising multiple vent valves and an annular region flushing valve, connected through a manifold and isolation valves, allows for efficient gas venting and flushing of the annulus, reducing the risk of blockages and pressure buildup by enabling independent operation of each vent valve and internal flushing without external access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single vent valve is used to vent gas from the annulus, then the device complexity is reduced, but the reliability decreases due to blockage risk from debris accumulation
Solution Approach 1:
The single vent valve is divided into multiple vent valves (first vent valve, second vent valve, etc.) that operate independently. Each vent valve has its own venting pathway to the annulus, so if one valve becomes blocked by debris, the other valves can still function to vent gas from the annulus, thereby maintaining system reliability without requiring a complex centralized control mechanism
Solution Approach 2:
Each vent valve is equipped with its own local flushing mechanism that can be activated independently. The flushing pathways are localized to each vent valve assembly, allowing debris to be cleared from specific valves without affecting the entire venting system. This localized approach maintains simplicity while improving reliability through redundancy
2Reliability
If multiple vent valves are installed to reduce blockage risk, then the reliability improves, but the device complexity increases
Solution Approach 1:
Multiple vent valves are merged into a single integrated venting system with common external outlet connections. The vent valves share common flushing pathways and are controlled through a unified manifold structure, reducing the complexity of external piping and control systems while maintaining the reliability benefits of multiple independent venting paths to the annulus
3Ease of repair
If external access is provided for vent valve maintenance, then the ease of repair improves, but the contamination risk increases
Solution Approach 1:
The vent valves and their flushing mechanisms are extracted from the internal annulus space and positioned in accessible locations outside the pipe body or in dedicated maintenance chambers. This allows maintenance personnel to access, inspect, and service the vent valves without cutting into or opening the pipe structure, thereby eliminating the risk of contaminating the annulus or pipe interior during maintenance operations
Solution Approach 2:
A sealed maintenance chamber or isolation manifold is introduced as an intermediary between the vent valves and the external environment. This intermediary structure allows vent valves to be accessed and serviced through sealed ports and connections, preventing direct exposure of the annulus to external contaminants while maintaining ease of repair through dedicated maintenance access points
4Reliability
If flushing capability is added to the vent arrangement, then the reliability improves by preventing blockages, but the device complexity increases
Solution Approach 1:
The vent valves are designed with dual functionality: they serve both as venting valves for gas removal from the annulus and as flushing valves for debris removal. The same valve mechanism and pathway are used for both venting operations and flushing operations, eliminating the need for separate flushing valves and reducing overall system complexity while maintaining high reliability through self-cleaning capability
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 solution effectively reduces the risk of venting arrangement blockages and pressure development in flexible pipes by allowing for reliable gas venting from annular regions, extending the lifespan of the pipes and preventing catastrophic failures, while minimizing the need for external maintenance and reducing contamination risks.
Implementation Method 1
an annular region flushing valve in fluid communication with the vent valve and the annular region access port, the annular region flushing valve being arranged to inject fluid into the vent arrangement for flushing the vent valve, the annular region access port or the pipe body annular region
Data Source
AI summary
A vent arrangement for a flexible pipe body. The vent arrangement comprises a vent valve and an annular region flushing valve. The vent valve is arranged to couple to an annular region access port of a flexible pipe end fitting such that the vent valve can vent fluid from the pipe body annular region. The annular region flushing valve is in fluid communication with the vent valve and the annular region access port. The annular region flushing valve is arranged to inject fluid into the vent arrangement for flushing the vent valve, the annular region access port or the pipe body annular region. An end fitting incorporating the vent arrangement, a flexible pipe comprising the end fitting and a flexible pipe body coupled to the end fitting, and a method of manufacturing a flexible pipe are also disclosed.