Pipe End Closure Assembly Hydraulic Sealing
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Solution Overview
Problem
Existing pipe end closure assemblies face challenges in hostile environments, such as underwater pipelines, where high torque is required for sealing, potentially damaging the pipe and lacking multiple redundancy to prevent fluid leakage, and are prone to fatigue stress cracking due to radial forces.
Innovation Solution
A closure assembly comprising a coaxial cylindrical plug and collar that can be configured to grip both the inner and outer faces of the pipe, using hydraulic pressure to engage and disengage without applying excessive torque, providing multiple redundancies and reducing shear stress through aligned radial forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high torque is applied to tighten the closure assembly to grip and seal the pipe end, then the sealing reliability is improved, but the pipe may be damaged or weakened
Solution Approach 1:
The patent replaces the traditional screw-threaded mechanical tightening system with a hydraulic actuation system. A hydraulic piston applies axial force to the plug, which then engages with the pipe end through bearing surfaces. This substitution eliminates the need for high torque application that could damage the pipe, while maintaining reliable sealing through hydraulic pressure control.
Solution Approach 2:
The closure assembly uses a hydraulic piston and fluid pressure system to achieve the gripping and sealing function. Hydraulic fluid is pumped into the piston chamber to generate the necessary axial force, providing controlled, high-force engagement without mechanical threading. This hydraulic mechanism resolves the contradiction by delivering sufficient sealing force without the damaging torque of traditional screw systems.
2Reliability
If multiple redundancies of closure seals are provided to reduce risk of failure, then the sealing reliability is improved, but the device complexity increases
Solution Approach 1:
The closure assembly is divided into functionally independent components: a primary seal system at the plug-pipe interface and a secondary seal system at the collar-pipe interface. Each seal can function independently, providing redundancy without requiring a fully duplicated complex assembly. This segmentation achieves reliability through distributed sealing zones while maintaining manageable device complexity.
Solution Approach 2:
The design incorporates backup sealing mechanisms that are pre-positioned and ready to function if the primary seal fails. The collar seal acts as a predetermined backup that requires no additional activation, providing fail-safe protection. This beforehand cushioning approach ensures redundancy is available without adding complex control systems or activation mechanisms.
3Reliability
If the closure assembly is designed to grip the inner wall of the pipe, then the sealing capability is improved, but radial forces may cause fatigue stress cracking or fracture of the pipe
Solution Approach 1:
The patent replaces the traditional gripping mechanism that applies concentrated radial forces with a distributed bearing surface system. The plug and collar engage the pipe end through extended axial bearing surfaces rather than localized radial gripping. This substitution distributes the mechanical load along the axial direction, eliminating fatigue-inducing cyclic radial stresses while maintaining secure attachment and sealing capability.
Solution Approach 2:
The design transitions from radial force application (perpendicular to pipe axis) to axial force application (parallel to pipe axis). The hydraulic piston applies force along the axial direction, and the bearing surfaces distribute this load axially along the pipe end. This dimensional change in force application eliminates the fatigue stress cracking problem associated with radial gripping forces while maintaining effective sealing.
Data Source
AI summary
A closure assembly for terminating an end of a pipe (4) has an end-cap (4) holding and having fluid-tight connection to a mutually coaxial cylindrical plug (2) and circular collar (3). The plug (2) and the collar (3) are configurable between respective engaged and disengaged configurations and mutually spaced to provide an annular space therebetween when the plug (2) and collar (3) are in their disengaged configurations. The annular space is arranged to receive an end of a pipe (1) arranged coaxially with the plug (2) and collar (3), the plug (2) and collar (3) being respectively slidable into and over the end of the pipe (1). The plug (2), when in its engaged configuration, grips the inner face of said pipe (41) and to provide a fluid tight seal and the collar (3), when in its engaged configuration, grips the outer face of the pipe (1) and to provide a fluid tight seal.