Pipe-in-Pipe Hole Sealing With Pressure-Controlled Friction Welding
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Solution Overview
Problem
Existing methods for sealing holes in pipe-in-pipe structures, particularly in subsea pipelines, are time-consuming and prone to leakage, as they require force-fitting and welding of plugs, which can be inefficient and risk air leakage before the plug is securely welded.
Innovation Solution
A method involving a sealed chamber that adjusts pressure and composition within the annulus, allowing for friction-welding of a spinning plug into the hole, ensuring a secure seal while maintaining alignment and managing thermal management effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If force-fitting and welding of plugs is used to seal holes in pipe-in-pipe structures, then sealing reliability is improved, but the process time and risk of leakage during the process increase
Solution Approach 1:
The patent applies preliminary action by first lowering the pressure in the annulus through the drawdown port before sealing it. This creates a pressure differential that facilitates the sealing process and reduces the risk of leakage during plug installation. The pressure is reduced to below atmospheric level, then the plug is installed, and finally the pressure is restored, ensuring a secure seal throughout the process.
2Reliability
If force-fitting and welding of plugs is used to seal holes, then sealing reliability is improved, but the complexity of the sealing process increases
Solution Approach 1:
The patent replaces the complex mechanical process of force-fitting and welding plugs with a pressure-controlled sealing method. By using pressure differential control, the system achieves reliable sealing without requiring mechanical force-fitting or welding operations, thereby reducing process complexity while maintaining or improving sealing reliability.
3Adaptability or versatility
If drawdown ports with isolation valves are used to modify annulus pressure, then pressure control flexibility is improved, but the risk of leakage increases
Solution Approach 1:
The patent introduces a sealed chamber as an intermediary between the drawdown port and the annulus. This chamber allows pressure control operations to be performed safely while isolating potential leakage paths. The chamber acts as a buffer zone that maintains pressure differential control without directly exposing the annulus to leakage risks associated with port operations.
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
This approach significantly reduces the time and risk of leakage by maintaining pressure and composition control during the sealing process, ensuring a reliable and efficient sealing of the annulus in pipe-in-pipe structures.
Implementation Method 1
friction-welding a spinning plug into the hole
Data Source
AI summary
A method of sealing a hole in a wall of a hollow structure comprises providing a sealed chamber that is external to the structure and that is in fluid communication with an internal space of the structure via the hole. The structure may be a pipe-in-pipe structure and the internal space may be an annulus between outer and inner pipes. Fluid flows through the hole into or out of the chamber as the pressure and/or composition of fluid in the internal space is adjusted. Then, a plug is spun and friction-welded into the hole. The plug is inserted into the hole from within the chamber.