What is the name of dust inside the old isolated pipeline, that line is not in operation or pieces of pipes ?

The dust found inside old isolated pipelines that are no longer in operation or inside pieces of pipes is called as black powder. It is consists of a mixture of iron sulfide, iron oxide, iron carbonate, and other materials like sand, dust, and organic matter. It is hazardous to health if inhaled and can present safety risks during pipeline maintenance and cleaning operations.