DRILL PIPE WITH LIGHTENING OUTER COATING Russian patent published in 1997 - IPC

FIELD: mining industry. SUBSTANCE: drilling of prospecting and production oil and gas wells can be performed by drilling tool represented by drill pipe with lightening outer coating made in the form of integral sheathing located on pipe surface and which is in the form of circular float- like member made of material with density less than density of bore-hole filling liquid. Installed at end faces of sheathing coaxially to load-bearing pipe body are metal washers connected with metal T-section ring which embraces entire coating through its length over spiral line. EFFECT: high efficiency. 3 dwg