Subsea Pig Launcher Gripper Mechanism for Sequential Multi-Pig Release
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Solution Overview
Problem
Existing subsea pig launchers are impractical for storing and successively launching multiple pigs due to reliability issues with retaining multiple pigs, complex reinstallation processes, and the need for multiple pressure lines, which increases costs and complexity.
Innovation Solution
A multiple pig launcher with a tubular structure featuring a launching station, a holding station, and a pig stopper mechanism with radially-movable gripper elements and cam formations to selectively hold and release pigs, allowing for sequential launch using a single valve and minimizing the risk of uncontrolled launches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple pigs are stored in a horizontal or vertical tube ready to be launched, then the launcher can contain multiple pigs for successive launches, but the reliability of retaining multiple pigs is compromised and the system becomes more complex
Solution Approach 1:
The launcher is divided into separate compartments or sections, each capable of holding individual pigs. This segmentation allows each pig to be retained independently, improving reliability while maintaining the ability to store multiple pigs. The modular structure enables controlled release of individual pigs without affecting the retention of others.
Solution Approach 2:
Retention mechanisms such as stops, latches, or gating structures are introduced as intermediary elements between the pigs and the launcher walls. These intermediaries provide reliable retention by mechanically preventing unintended movement or release of pigs, while allowing controlled discharge when needed.
2Productivity
If multiple kick lines are provided to launch pigs successively, then multiple pigs can be launched in sequence, but the device complexity and cost increase
Solution Approach 1:
Multiple kick lines are merged into a single shared pressure supply system. A common high-pressure fluid source serves all launch compartments through a manifold or distribution system, eliminating the need for separate pressure lines to each pig. This reduces device complexity and cost while maintaining the ability to launch multiple pigs successively.
Solution Approach 2:
A single kick line or pressure supply system is designed to serve multiple functions by providing pressure to different compartments at different times. The universal pressure system can be directed to any required compartment through valve control, enabling successive pig launches without requiring dedicated pressure lines for each pig.
3Duration of action of moving object
If the pig launcher is removed from the pipeline periodically for reloading and maintenance, then the pigs can be replaced and the launcher maintained, but the process becomes complicated, time-consuming and expensive
Solution Approach 1:
The launcher is pre-loaded with multiple pigs during manufacturing or initial installation, eliminating the need for frequent reloading operations. This preliminary action extends the operational duration between maintenance intervals and simplifies the reloading process by reducing its frequency.
Solution Approach 2:
Instead of removing the entire launcher for reloading, the design allows for in-situ reloading through access ports or removable sections. The reloading process is inverted from a complex removal-reinstallation operation to a simpler insertion-through-opening operation, reducing time and cost while maintaining launcher service life.
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 efficient and reliable sequential launch of multiple pigs using a single valve, reducing the complexity and cost of reinstallation and operation by ensuring secure retention and controlled release of pigs within the launcher.
Implementation Method 1
a pig stopper mechanism that is operable selectively to hold a second pig at the holding station when launching the first pig... The pig stopper mechanism comprises at least one radially-movable gripper element that is arranged to apply radially-inward gripping force to a pig held at the holding station
Implementation Method 2
a pig is driven along a pipeline from a pig launcher, or trap, to a pig receiver by a pressure differential in the pipeline between upstream and downstream sides of the pig... introducing high-pressure fluid through a pressure inlet into a volume behind the pig
Implementation Method 3
a pig has a series of annular or disc-shaped circumferential seals that separate the volume within the pipeline ahead of the pig from the volume within the pipeline behind the pig
Data Source
AI summary
A multiple pig launcher includes a tubular structure along which a series of pipeline pigs may be advanced in stepwise fashion to be launched into a pipeline in succession. A launching station holds a first pig at a downstream end of the series in readiness for launch. A pig stopper mechanism is operable selectively to hold a second pig at a holding station upstream of the launching station when launching the first pig and to release the second pig from the holding station to be advanced into the launching station after the first pig has been launched. The pig stopper mechanism comprises at least one radially movable gripper element that can apply radially inward gripping force to a pig held at the holding station.