GRISLEE: Gasmain Repair and Inspection System for Live Entry Environments

US gas companies spend over $300 million annually detecting and repairing gas leaks in urban and suburban settings. The current approach is one of above-ground leak detection and pinpointing, followed by excavation, repair and restoration. The major cost incurred is typically that of digging and restoring the excavation site. The Gas Research Institute and the National Aeronautics and Space Administration are funding a program at Carnegie Mellon University (CMU) Robotics Institute and Maurer Engineering to reduce the cost of repairing gas distribution mains using advanced remote and robotics technologies to provide up to 50% cost savings over conventional repair methods. Under this program, CMU has developed GRISLEE (Gasline Robotic Inspection System for Live Entry Environments), a coiled-tubing deployed, remotely controllable, modular leak-detection, inspection, surface-preparation and repair robot system for the real-time in situ spot repair of live 4 inch diameter distribution gas mains. The system is capable of repairing two or more leaks per day from a single excavation over a 2000 ft length under live conditions (i.e., without downtime of the gas main and thus no customer service interruption). The prototype system has undergone laboratory testing and proven the feasibility of its modular inspection, sensing, preparation, and repair technologies and systems. Field trials with multiple utilities will be carried out during late 2002.