Hot tapping, or pressure tapping, is the method of making a connection to existing piping or pressure vessels without the interruption of emptying that section of pipe or vessel. This means that a pipe or tank can continue to be in operation whilst maintenance or modifications are being done to it. The process is also used to drain off pressurised casing fluids.

Hot tapping is used to make repairs where corrosion or other types of physical damage have occurred to a particular system, but it can also be applied for modification or upgrade work.

Hot tapping allows a new pipeline connection to be made while the network remains in service.

The procedure for performing a shutdown interconnect can differ for each set of circumstances and specific application, but essentially in a high-pressure system the surrounding valves need to be closed in order to isolate the pipeline segment. A number of inserted plugs are subsequently placed next to the valves in a procedure which is designed to stop pipeline leakage.

Criteria which must be met to satisfy the Lockout / Tagout exemption for performing Hot Taps are:

If all four criteria cannot be met, then the Hot Tap should NOT be performed and the Lockout / Tagout Procedure should be followed for performing the work.

This Hot Tap Procedure is applicable to piping and equipment manufactured from ferrous (iron) and austenitic steel. Other materials – cast iron (Mondi pipe), aluminum, copper, etc. – are NOT covered in this procedure and may be unsuitable for Hot Tapping or may require special procedures.

Installation of hot tap subsea pipeline can be seen in this video below: