Oil and Gas: Terms & Glossary (3)

Davit	Crane-like device made of steel pipe or structural steel that allows replacement parts, tools, and small machinery to be raised and lowered from the top of vertical vessels.
Diameter, inside	The circumference measured around the interior wall of a pipe.
Diameter, nominal	The name given to a particular size of pipe.
Diameter, outside	The circumference measured around the outer wall of pipe.
Dike	Typically an earthen dam or wall surrounding tanks creating a containment area in case of accidental discharge or rupture.
Discharge	Outgoing flow, typically with increased pres sure as in the case of pumps or compressors.
Distillation	The process of extracting and separating molecular compounds from a supply product.
Double extra strong	Category of thick-walled pipe.
Double line	Drawings used to represent piping systems 14" in diameter and larger.
Double pipe exchanger	Exchanger having a small diameter pipe inserted into a large diameter pipe.
Double random length	Length of manufactured pipe, typically 35' to 40' long.
Down comer	Opening adjacent to a tray that allows over flowing liquids to fall to the tray below and begin refractionation.
Drain	Typically an underground piping system that transfers water runoff or waste materials to a processing facility for disposal or treatment. See O.W.S.
Drain funnel	Often a reducer fitting placed at the opening of a drainage pipe that aids in the collection of disposable materials.
Drift	The amount of water lost during the aeration and evaporation sequence in a cooling tower.
Dummy leg	A length of pipe or structural steel welded to the outside of a pipe that provides support for the line.
Eccentric	Reducer or swage having offset center-lines.
Elbow	Fitting used to make changes in direction of pipe line.
Elbow long radius	Ninety degree elbow having a radius equal to one and one-half times the pipe's nominal size.
Elbow short radius	Ninety degree elbow having a radius equal to the pipe's nominal size.
Electric traced	Electric leads coiled around a pipe to maintain a desired temperature.
Elevation	Sectional view of a facility showing vertical height dimensions.
Extra strong	Pipe and fittings having measurements equivalent to schedule 80.

Nontechnical Guide to Petroleum Geology, Exploration, Drilling and Production (2nd Edition)