Longitudinal Expansion Joint Locking and Sealing for Subsea Piping
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Solution Overview
Problem
Piping systems for subsea oil wells often have inaccurate dimensions, requiring an expansion joint that can accommodate these inaccuracies without needing new piping components.
Innovation Solution
A longitudinal expansion joint with a telescopically engaged casing system, including a locking mechanism and sealing system, allowing for longitudinal adjustment and sealing between casing members, facilitated by a cam mechanism and support rods, enabling precise adjustment and sealing in subsea environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If prefabricated piping components are used with fixed dimensions, then manufacturing and installation are simplified, but the system cannot accommodate dimensional inaccuracies in the real-world environment
Solution Approach 1:
The expansion joint incorporates a telescopic mechanism with movable inner casing relative to the outer casing, allowing the joint to dynamically adjust its length to accommodate dimensional variations in the piping system without requiring complex reconfiguration
Solution Approach 2:
The expansion joint is divided into separate modular components including inner casing, outer casing, seal units, and adjustment mechanisms that can be independently manufactured and assembled, simplifying the overall piping system while providing adaptability
2Adaptability or versatility
If the expansion joint allows longitudinal adjustment to accommodate dimensional variations, then adaptability improves, but the sealing reliability becomes more difficult to ensure
Solution Approach 1:
The seal energizing mechanism responds to the relative position of the inner and outer casings, automatically adjusting seal pressure to maintain reliable sealing regardless of the longitudinal adjustment position, ensuring consistent sealing performance across the full range of motion
Solution Approach 2:
A push plate is introduced as an intermediary element between the seal unit and the movable casing, transmitting and distributing the sealing force evenly across the seal interface while allowing longitudinal movement, thus maintaining sealing reliability during adjustment
3Measurement precision
If a locking mechanism is added to secure the longitudinal position, then positioning accuracy improves, but the device complexity increases
Solution Approach 1:
The locking mechanism utilizes the existing threaded structures and movable components of the telescopic mechanism itself to provide locking functionality, rather than introducing entirely separate locking components, thus achieving positioning accuracy without proportionally increasing complexity
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 expansion of up to 12 inches or more, accommodating dimension inaccuracies in oil well designs without the need for new piping components, ensuring reliable sealing and adjustment in subsea conditions.
Implementation Method 1
A seal energizing means pushes against the push plate to energize the seal unit to seal between the first casing member and the second casing member
Implementation Method 2
The locking sleeve can be rotated relative to the second casing member to longitudinally adjust a position of the second casing member relative to the first casing member
Data Source
AI summary
A longitudinal expansion joint for piping systems, includes a first casing member and a second casing member telescopically engaged with a second end of the first casing member, the second casing member having a first end adapted to connect to a second pipe and having a second end with a flange portion having a threaded outer surface. A longitudinal adjustment mechanism for longitudinally adjusting a position of the second casing member relative to the first casing member. A locking sleeve for locking a longitudinal position of the second casing member relative to the first casing member. A sealing system including a seal unit disposed between the first casing member, and the second casing member and a push plate disposed against the seal unit. A seal energizing system pushes against the push plate to energize the seal unit to seal between the first casing member and the second casing member.