Introduction To Tubulars Page 08 Of 10

TUBULARS The Heavy Weight While being similar in appearance to drill pipe, heavy weight has the following different dimensional characteristics.

Heavy weight drill pipe was developed in the mid 1960's as an intermediate weight drill string member. It was originally developed for several reasons:.

As a transition member to be run between drill pipe and drill collars.

The tube wall is heavier, about 1" thick in most sizes.

As a flexible weight member to be run in directional drilling.

The tool joint(s) are longer. Some manufacturers provide spiral grooving in this larger section. It is said that this promotes hole cleaning and, resistance to differential wall sticking, among other advantages.

As a weight member on small rigs, drilling small diameter holes. More recently with the advent of horizontal drilling, it has found a new application, being used in the curved portion of the hole below the drill collars.

Hardbanding is normally standard on both box and pin tool joints with additional hardbanding on the center wear section.

It is manufactured primarily in three sizes: 3-1/2'', 41/2'', and 5". Most manufacturers also make 4" size, with some 5-1/2" and even 6-5/8" size.

API pin stress relief features and API boreback box stress relief features are normally standard on sizes above 3-1/2".

Dimensional Data and Performance Properties The Heavy Weight