Slick drill collars are supplied with the mill as-rolled surface finish. Spiraled drill collars have grooves machined in the outside surface. The spiral grooves promote even flow of drilling fluid around the collar diameter, equalizing pressure and reducing the occurrence of differential sticking.
Grant Prideco Drill Collars are integral heavy-wall joints that are manufactured from a solid bar of modified alloy steel. The solid bars are quenched and tempered to obtain the required mechanical properties, then trepanned, drifted and threaded. Drill collars are furnished as slick or spiraled in 30 or 31 foot lengths.
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