Hydraulically Balanced Collapsible Sealing Elements for Multi-Diameter Pipeline Pigs
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Solution Overview
Problem
Existing pipeline pigs are limited in their ability to traverse pipelines with varying diameters, as they require different sizes for different diameter sections, restricting their operational envelope and efficiency in dual- and multiple-diameter pipelines.
Innovation Solution
The development of a pipeline pig equipped with collapsible and expandable sealing elements, each having an internal cavity and reservoir in communication to maintain fluid pressure, allowing the same set of sealing elements to provide sliding seal engagement and drive/cleaning functions across different diameters through a hydraulic accumulator system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sealing elements are sized for a constant internal diameter section of pipeline, then sealing engagement with the inner wall surface is maintained, but the pig cannot traverse pipelines with different diameter sections
Solution Approach 1:
The sealing elements are designed to dynamically change their outer diameter by collapsing or expanding, allowing them to adapt to different pipeline diameters while maintaining sealing engagement. The elements transition between expanded state (for larger diameter pipes) and collapsed state (for smaller diameter pipes), enabling the pig to traverse multiple diameter sections with a single pig design.
Solution Approach 2:
The sealing elements utilize hydraulic pressure to change their physical parameters (outer diameter) by moving fluid between an internal cavity and a reservoir. By controlling the fluid volume and pressure, the elements can expand to match larger pipe diameters or collapse to fit smaller diameters, while the accumulator maintains pressure to ensure continuous sealing contact with the pipe wall.
2Adaptability or versatility
If tight clearances are required for sealing engagement, then sealing is improved, but the pig cannot adapt to varying pipeline diameters
Solution Approach 1:
The pig is designed with universal sealing elements that can perform sealing and driving functions across multiple pipeline diameters. The same set of sealing elements, through hydraulic expansion and collapse, replaces the need for multiple specialized pigs for different diameter sections, simplifying the overall system while maintaining tight clearance sealing capability.
Solution Approach 2:
The pig incorporates a hydraulic system with accumulators, internal cavities, and reservoirs to control the expansion and collapse of sealing elements. Hydraulic pressure from the accumulators maintains the necessary force for sealing engagement while allowing the elements to adapt their diameter, eliminating the need for complex mechanical adjustment mechanisms.
3Adaptability or versatility
If dual diameter capability is provided by foam pigs, then versatility is improved, but the operating envelope and pipe diameters the pigs can function in are limited
Solution Approach 1:
The hydraulic system incorporates feedback through the accumulator, which automatically maintains pressure within the sealing elements regardless of their expansion or collapse state. The accumulator responds to pressure changes and fluid volume shifts, ensuring continuous sealing force is applied to the pipe wall, thereby maintaining reliable sealing across the full range of diameter transitions.
4Adaptability or versatility
If the sealing elements collapse into smaller diameter line by rotation or spring-loaded arms, then adaptability is improved, but the same set of sealing elements cannot maintain consistent sealing pressure
Solution Approach 1:
The invention replaces mechanical rotation or spring-loaded mechanisms with a hydraulic system. The accumulators maintain consistent sealing pressure by hydraulically balancing the collapsing and expanding sealing elements. This ensures that regardless of the element's current size or transition state, the sealing pressure remains consistent and reliable throughout the diameter transition process.
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 the pipeline pig to traverse dual- or multiple-diameter pipelines with consistent sliding seal engagement and primary function performance, minimizing stress on elastomeric materials and maintaining balanced pipe-wall force through adjustable fluid volume and pressure, thus overcoming the limitations of prior art pigs.
Implementation Method 1
An accumulator maintains a pressure of the first and second volumes of the fluid so that regardless of a sealing element's current size, or whether the element is transitioning between sizes, the element can perform its primary function of driving or cleaning
Implementation Method 2
The sealing elements, which are typically made of an elastomeric material, use product flow to drive the pig forward under differential pressure while maintaining sealing engagement with an inner wall surface of the pipe
Data Source
AI summary
A pipeline pig that can traverse dual- or multiple-diameter pipes or pipelines has collapsible and expandable sealing elements that support the pig, provide a sliding (dynamic) seal with the pipe wall, and maintain the necessary pressure for driving or cleaning as the elements collapse and expand. The sealing elements each have an internal cavity sized to house a first volume of a fluid and a reservoir sized to house a second volume of the fluid. The cavity and reservoir are arranged so that a portion of the volumes of the fluid can move between each. An accumulator maintains a pressure of the first and second volumes of the fluid so that regardless of the sealing element's current size, or whether the element is transitioning between sizes, the element can maintain a sliding seal engagement with the pipe wall and perform the primary function of driving or cleaning (or both).