Pipeline pigging with nitrogen gas is a process that involves cleaning the interior of a pipeline using nitrogen gas and a device called a “pig”. The pig is a cylindrical object that is inserted into the pipeline and propelled through it using pressurized nitrogen gas. As the pig moves through the pipeline, it removes any impurities, such as rust, scale, or other debris, from the interior walls of the pipeline. 

The nitrogen gas used in pipeline pigging is an inert gas that does not react chemically with the substrates in the pipeline. This makes it an ideal choice for purging pipelines of unwanted gases and impurities without causing any damage to the pipeline itself. 

The process of pipeline pigging with nitrogen gas is critical during natural gas line commissioning for flow lines. This procedure is necessary to eliminate oxygen, water vapor, and other impurities that are retained within a newly laid pipeline network.