In Situ Launch System for Underground Gas Main Isolation
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Solution Overview
Problem
Existing methods for stopping gas flow in low-pressure underground gas mains require excavation, which is expensive, disruptive, and time-consuming, especially during emergencies or maintenance situations.
Innovation Solution
An in situ launch system that includes an outer launch tube with a transition fitting and a completion plug, allowing for the deployment of inflatable balloon stoppers without excavation by threading the system to the gas main and using a 3" inner launch tube to install and inflate stoppers within the main.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If excavation is performed to expose the gas main pipe for stopping-off gas flow, then access to the gas main is achieved, but the procedure becomes expensive, disruptive, and time-consuming
Solution Approach 1:
The launch tube system is pre-installed on the gas main during initial installation, with the stopper stored within the launch tube. When emergency stoppage is needed, the stopper is simply launched through the launch tube into the gas main without requiring excavation or complex preparation, thus eliminating time loss while maintaining ease of access.
Solution Approach 2:
The launch tube serves as an intermediary device between the accessible launch station and the underground gas main. It provides a direct pathway for deploying the stopper into the gas main without requiring personnel to physically excavate and access the buried pipe, thus resolving the contradiction between easy access and time consumption.
2Ease of operation
If excavation is performed to expose the gas main pipe, then stopping-off access is obtained, but environmental disruption and cost increase
Solution Approach 1:
The launch tube acts as an intermediary that enables stopping-off access through a non-invasive launch station at the surface. This eliminates the need for excavation and associated environmental disruption while maintaining the ability to access and stop gas flow in the underground main.
Solution Approach 2:
The stopping-off function is extracted from the buried gas main and relocated to an accessible launch station at the surface. The launch tube connects these two locations, allowing the stopper to be deployed into the underground main from the surface-level launch station, thus eliminating environmental disruption while preserving stopping-off capability.
3Reliability
If a traditional tap and stopper installation method is used, then gas flow can be stopped, but the procedure is very time-consuming during emergencies
Solution Approach 1:
The stopper is pre-positioned within the launch tube during system installation, and the launch tube is pre-connected to the gas main. During an emergency, the stopper is immediately launched into the gas main through the pre-prepared launch tube, eliminating the time-consuming steps of excavation, tapping, and stopper installation required by traditional methods, thus achieving both reliability and high-speed shutdown.
Solution Approach 2:
The launch tube system uses pneumatic or mechanical launch mechanisms to rapidly propel the stopper into the gas main. This pneumatic/hydraulic launch method enables extremely fast deployment of the stopper compared to manual installation, thereby improving productivity (shutdown speed) while maintaining the reliability of gas flow stoppage.
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 quick isolation of gas distribution system sections without excavation, reducing environmental disruption and time, and is suitable for emergency or maintenance situations in large diameter low-pressure metallic gas mains.
Implementation Method 1
a transition fitting having a proximal end fitted to the distal end of the outer launch tube with a gas tight seal
Implementation Method 2
a completion plug threaded into the internal threads of the transition fitting
Data Source
AI summary
An in situ launch system for an underground gas main stop-off station includes: an outer launch tube having a distal lower end and a proximal upper end; a transition fitting having a proximal end fitted to the distal end of the outer launch tube with a gas tight seal, and a distal end; the distal end of the transition fitting having external threads having a first nominal dimension, and internal threads having a second nominal dimension; and a completion plug threaded into the internal threads of the transition fitting.