Line pipe is a type of pipe that is manufactured from high strength carbon steel. It is typically made according to metallurgical specifications that were developed by the American Petroleum Institute (API). Line pipe can be used to build pipelines that transport a variety of resources including natural gas, oil, petroleum, and water. This pipe is available in a variety of diameters ranging from 2 inches to 48 inches. Line pipe can include either seamless or welded carbon steel or stainless steel piping. Because line pipe needs to withstand high pressures, there are important tests done on line pipe to ensure it meets all of the requirements of steel chemistry, strength, toughness, and dimensional characteristics. Using line pipe that meets the set criteria will ensure safe and reliable pipeline service.

The size and diameter of line pipe that is required for a pipeline can vary based on the amount of gas or liquid that a pipe is intended to carry as well as the pressures that a line pipe must withstand. For example, in most cases a mainline, the principal pipeline that delivers natural gas, will require line pipe that is around 16 to 48 inches in diameter. Smaller pipelines that deliver gas to the mainline or take gas from a mainline can be constructed of 6 to 16 inch diameter line pipe. One can determine the necessary diameter required for a pipeline by considering the volume of gas or liquid that the line pipe will be carrying as well as the pressure at which this will be transported.

The thickness requirements for line pipe are determined by the maximum operating pressure required for a pipeline. This is based on published standards and federal regulations. Following proper safety regulations when selecting and installing line pipe, will ensure proper pipeline operation and prevent dangerous or hazardous situations.