Many systems found in industrial environments contain gases and liquids at high temperatures or pressures, or fluids that are otherwise inherently dangerous, such as ammonia. Within these systems are components that break the boundaries of the system with moving parts, like the stem of a valve or the shaft of a pump. In order to prevent the fluid within these systems from escaping to the atmosphere, packing is installed that can seal the component yet still allow relative motion between its parts. It is important to understand how this packing works, how it is installed, and what must be done to maintain it in a proper working condition.
