Jump menu

Main content |  back to top

Pipelines Terminology

Barrel: 42 U.S. gallons.

Batch: A quantity of petroleum product of like specifications moved through the pipeline as an identifiable, individual unit. A batch is measured in barrels.

Block Valve: A type of valve that can block oil flow in both directions. Block valves include manual gate valves, remote gate valves and station block valves (suction valves and discharge valves).

Booster Station: A pump station used to increase the pressure of oil received through a main pipeline to pump it to the next station or terminal.

Breakout Tank: A tank used to relieve surges in a hazardous liquid pipeline system, or to receive and store hazardous liquid transported by a pipeline for re-injection and continued transportation by pipeline. (definition by D.O.T)

Check Valve: A type of valve that allows one-way flow only and prevents the reverse flow of oil. Check valves are designed to be held open by flowing oil and to drop closed automatically when oil flow stops or is reversed.

Cold Zone: Area free of hydrocarbon vapors and safe for necessary personnel.

Common Carrier: Any transportation system available for use by the public for transporting oil. Almost all interstate pipelines are common carriers.

Control Center: Pipeline systems are operated from highly computerized control centers which coordinate operations throughout the system - everything from rate of flow, to pressure, to opening and closing valves. The control centers also monitor devices that can alert operators to abrupt changes in operating parameters, providing a detection mechanism for fast response to emergency conditions. Satellite and telecommunications links connect control centers with facilities along pipelines to assure rapid response and constant monitoring of pipeline conditions.

Crude Oil: The basic raw material pumped from the earth. There are many different grades of crude, each containing various vapors, liquids and solids. This crude is changed at a refinery into products.

Discharge Pressure: Pressure of the oil in the pipeline as it exits a pump station.

Gathering Lines: A small diameter pipeline used in gathering crude oil from the oil field to a common point for further movement to a trunk line.

High Pressure Pipelines : Pipeline systems that operate at over 600 psi.

Hot Zone: Area where hazardous vapors and liquids are present. Working in a hot zone requires a special permit and personal protective equipment.

Interface: The mixture which occurs during normal pipeline operations between adjacent batches of petroleum products or crude having different specifications. Also called "slop" or "transmix."

Linefill: The volume of oil, usually measured in barrels, in the pipeline from the origin to the terminus. Linefill can also refer to the volume of oil contained in a given segment of the pipeline.

Manifold: An arrangement of connected piping and valves used to provide links between a number of pumps, tanks, and/or pipelines.

Manual Block Valve: Block valves that are operated manually.

Maximum Allowable Operating Pressure (MAOP): A rating indicating the maximum pressure at which a pipeline or segment of a pipeline may be operated under the D.O.T. regulations in normal conditions. Also called pressure rating.

Pig: A device placed inside a pipeline that is used to clean or scrape residues from the inner wall of the pipe. A pig is pushed through the pipeline by the oil flowing in the pipeline. See also “smart pig” and “pig traps.”

Pig Trap: A type of pipeline equipment used to launch and receive pigs and smart pigs. Also called “pig launchers” and “pig receivers.”

Pipeline System: All parts of the physical facilities through which oil is transported, including line pipe, valves, pumping units, metering stations and tanks.

Pressure Relief Valve: A valve designed to open automatically to relieve pressure and keep it below a specified level.

Pressure Spike: A sudden, brief rise in pressure.

Pressure Surge: A pressure spike produced by a sudden change in velocity of the moving stream that results from shutting down a pump station or pumping unit, closure of a valve or any other blockage of the moving stream. The pressure surge moves through the pipeline at sonic velocity and stops and reverses direction when it hits a closure in the pipeline such as a closed valve.

Products: Refined hydrocarbons made from crude oil. Gasoline, fuel oil, jet fuel, diesel fuel are typical petroleum products that are transported in pipelines.

Remote Block Valve: A block valve that can be remotely controlled, as in from a pipeline control center, for the primary purpose of directing pipeline flow and isolating the pipeline into segments in the event of a pipeline break.

SCADA (Supervisory Control and Data Acquisition System): A comprehensive electronic surveillance system used to monitor and control an entire pipeline system and its operations from a pipeline control center. Pipeline operating data is remotely collected from transmitting devices located along the pipeline system. The data typically includes the pressures, volume and flow rate of each pipeline, and the operating status of all pumping equipment and remotely operated valves on each pipeline. This data is sent to the control center’s SCADA system and is used by the pipeline controller for the proper operation and control of each pipeline.

Smart Pig: An electronic internal inspection device placed inside the pipeline to provide data about the condition of the pipeline, such as measuring dents or locating corrosion.

Station Block Valve : A gate valve installed at the inlet (suction) side and the outlet (discharge) side of the pump station to isolate the pump station from the pipeline in the event of an emergency.

Suction Pressure: The pressure of the oil in the pipeline as it enters a pump station.

Tank Farm: A pipeline facility that contains a group of tanks connected to a pipeline or pipelines through which oil is moved.

Trunk Line: A main pipeline.

Yield Strength: The stress level above which the pipe will yield/bend/stretch. The yield strength of the steel is determined by testing during the manufacture of the pipe. Yield strength is a parameter used in determining a pipeline’s maximum allowable operating pressure.