sentence: Pipelines are made of metal.
sentences_before: A 'pipeline' is a long tube, that is used to transport liquids or gases over long distances.
sentences_after: While the transport of liquids and gases is common, some pipelines are used to transport coal or iron ore, which are mixed with mud. Such pipelines are sometimes called slurry pipelines. Even though a pipeline is very expensive to build, it often is a more economical form of transport that the transport by road.
concept_name: pipeline
headings: Pipeline
categories: Technology