Hot tapping is the technique used to attach a branch connection to a pipe while the system is in service, and then creating an opening in the said pipe by drilling or cutting. While hot taps are most often done in piping system, they may also be done on pressure vessels and storage tanks to add nozzles. Hot tapping permits additional connections without depressurization or disruption of process operations. They may also be used to make piping connections where it would be inconvenient to prepare the system for hot work. Hot tapping is also used to isolate pipe sections for maintenance by plugging or stop the line either with or without bypass line.

Hot tapping is a dangerous operation. Therefore, hot tapping should generally be used only when it is impractical to take the system out of service. When specifying hot tapping, care and attention is required throughout inspection, design, and testing to ensure that the operation is done in a safe and reliable manner. Therefore, a hot tapping should be considered only after other options are evaluated and rejected. Each hot tapping should be properly designed, the hot tapping location thoroughly inspected, and the installation procedures reviewed.