1. n. [Production]

A procedure used in the repair of a pipeline to isolate a section of line in the absence of a shutoff valve. After welding a flanged saddle to the pipe, the line is hot tapped—a method of making a connection to existing piping or pressure vessels without the interruption of emptying that section of pipe or vessel—and an expanding resilient plug is inserted into the pipe bore. When the repair is completed, the plug is withdrawn and a valve, installed on the saddle flange, is closed.