A process of filling an underground natural gas pipeline and similar pipelines with an inert foam to render the pipeline unusable. Pipelines which are no longer in service must be properly be abandoned in a manner acceptable to the United States Environmental Protection Agency. The pipeline is cut at periodic intervals to create a shorter pipe and small sections of pipe are removed. An electrical or plumber's snake or similar device is passed through the pipe between the cuts to ensure that a clear path exists. A dual hose is then pulled through the pipe from a first opening to a second opening and a mixing device having a mixing head and a static mixing tube is then attached to the hoses. The chemicals needed to produce the foam are then pumped through the hoses. The hoses are then pulled back to the first opening as the mixed chemicals are pumped through the mixing head. The mixed chemicals react with each other to create an inert foam. Sufficient chemicals are pumped into the pipeline and reacted to fill the pipeline to more than 50% of the pipeline volume with the inert foam to a density of about 2 pounds per cubic foot.
