Nested Pig Assembly for Subsea Pipeline Diameter Transitions
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Solution Overview
Problem
Subsea pipeline systems face challenges with increased complexity and depth, requiring flexible and lighter weight pipes to manage varying diameters and traverse difficult terrain, while current technologies limit piggability across different pipe sizes and types.
Innovation Solution
A pig assembly with a larger diameter pig having an internal compartment for a smaller diameter pig, allowing passage through larger and smaller diameter functional lines with differing diameters, enabling fluid communication and pipeline maintenance across varying diameters and types of pipes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pipeline systems use greater flexibility and various sizes of subsea pipeline to traverse difficult terrain and deeper waters, then the ability to adapt to complex geographical formations is improved, but the piggability of the lines deteriorates
Solution Approach 1:
The patent implements a nested pig assembly where a first pig with larger outer diameter is configured to contain a second pig with smaller outer diameter within its interior compartment. This nesting arrangement allows the combined assembly to pass through pipeline diameter transitions from larger to smaller diameters, maintaining piggability across varying pipeline sizes while enabling the system to use flexible pipes of various diameters to adapt to complex terrain and deeper waters
2Adaptability or versatility
If pipeline systems use transitions between various types of pipe and various pipe diameters to meet system requirements, then the flexibility of pipeline design is improved, but the ability to effectively pig the lines deteriorates
Solution Approach 1:
The nested pig configuration allows the first pig to traverse the larger diameter pipeline section while containing the second pig, which is then released to continue through the smaller diameter pipeline section. This resolves the contradiction by maintaining continuous piggability through diameter transitions, enabling designers to use various pipe types and diameters for optimal system configuration without sacrificing maintenance capability
Solution Approach 2:
The pigging system is segmented into multiple pigs of different diameters that can be deployed sequentially through the same pipeline. The first pig handles the larger diameter section and releases the second pig for the smaller diameter section, allowing the pipeline system to incorporate various pipe types and diameters while maintaining effective pigging capability throughout the entire system
Data Source
AI summary
Disclosed is a pig assembly for maintaining a functional line for conveying fluid. In one aspect, the pig assembly includes a larger diameter pig having an internal compartment and at least one smaller diameter pig adapted to fit therein. The larger diameter pig is capable of passing through a larger diameter functional line and the smaller diameter pig is capable of passing through a smaller diameter functional line. In another aspect, a method for maintaining a functional line for conveying fluid is provided which includes pigging a subsea line having at least a larger diameter functional line and a smaller diameter functional line in fluid communication with one another using a pig assembly as described herein.