It could be said that petroleum products keep America running. Petroleum products like oil and natural gas are the principal sources of energy in the United States and are used in many manufacturing and chemical processes. Petroleum products are primarily transported by pipeline. There are more than a million miles of liquid and natural gas pipeline in this country, ranging in diameter from two inches to four feet. These pipelines bring crude oil and natural gas from production fields to processing plants and refineries – and ultimately to the consumer. The Pipeline Mechanical three-level curriculum is a part of NCCER’s Pipeliner Training and Assessment Program (PTAP) and covers topics such as Piping and Mechanical Blueprint Reading, Inspect and Repair Valves, and Unit Alignment.