| 摘要 |
A tool and method for plugging a service connection to a gas main in preparation for removal of the service tee removes the perforator, mills the hole in the main to provide a smooth seat for a sealing plug, and inserts a gas-tight sealing plug into the hole. The tool of the invention is operable through a narrow "keyhole" excavation, which decreases the risk to service personnel and significantly reduces costs of repairing the excavation. In the preferred embodiment the tool is loaded with a milling bit and a sealing plug before attachment to the service tee. The tool head is engaged to the service tee in a gas-tight fit to prevent the escape of gas during the procedure, and an adapter plate is pivoted between three working positions to perform the three steps of the service connection plugging method. In the preferred embodiment a pneumatic gear motor drives a hexagonal driver bit actuated by a linear actuator located in the shaft of the tool, the driving bit providing the required mechanical interface with each of the accessories involved in each step of the procedure. A separate pneumatic motor pivots the adapter plate between working positions, and specialized adapter is provided at each working position of the adapter plate allowing the same actuators to be used for the perforator removal, milling and plugging operations.
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