دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: drill pipe that is manufactured with walls that are thicker than those in standard drill pipe. Special extnilength tool joints are attached to the heavier-walled tube. lYPically, 5-inch heavy wall ,.drill pipe weighs50 pounds per foot (75 kilograms per metre);5-inch conventional drill pipe weighs 19.5 pounds per foot (29 kilograms per metre). Also attached to the tube is a centre wear pad that protects the outside diameter of the pipe from abrasion. Heavy wall pipe is often used in the drill stem just above the drill coilars, in the transition zone between the stiffer collars and the more limber drill string, and in place of some drill collars to apply weight on the drill bit in smalliameter and horizontal holes. Sometimes erroneously called heavyweight drill pipe. Compare heavy- weight drill pipe.

n: drill pipe that is like conventional drill pipe except that it is manufactured with a thicker wall, which increases its weight and tensile strength. For example. five-inch lEU grade E75 standardweight drill pipe weighs 19.5 pounds per foot (29 kilograms per metre). while five- inch lEU grade E75 heavyweight drill pipe weighs 25.ro pounds per foot (38.4 kilograms per metre). Heavyweight drill pipe is placed in the top of the string to support a very long string of pipe. Heavyweight drill pipe may be used in the drill stem when high-tensile strength drill pipe is required hit high-grade steel cannot be used because of the highgrade steels susceptibility to hydrogen embrittlernent, which is a form of corrosion caused by hydrogen sulphide. Compare heavy- walled drill pipe.

n: thick -walled drill pipe used in directional drilling and placed between the drill collar and drill pipe.