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JA Oilfield Drill Collars are manufactured from 4145H modified quenched and tempered steel. Strict metallurgical specifications are followed to insure that full length heat treating produces a consistent maximum depth of hardness. Standard Features The bores are held to close tolerances by trepanning and are drifted to API specifications. The outside surface is “as-rolled”, which is the original mill finish. Connections are machined to API specifications and monogrammed with the API symbol. Connections are also kemplated to prevent galling. Thread roots are “cold rolled” to provide longer fatigue life. Steel drill collars are offered both in a slick and spiral O.D. Spiraling the collars reduces wall contact between the drill collar and the wall of the hole to prevent differential wall sticking.
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SPECIAL DRILL COLLAR FEATURES Stress Relief Features Stress relief features are recommended for drill collars as well as all downhole drilling tools where cyclic fatigue may occur from bending. The API relief groove on the pin and the boreback on the box remove unengaged threads in highly stressed areas of the drill collar connection. This provides a more flexible connection less likely to crack in fatigue because bending in the connection occurs in areas with smooth surfaces free of stress concentration. Slip and Elevator Recesses Slip and elevator recesses are designed to cut drill collar handling time by elimination lift subs and safety clamps. Extreme care is taken to machine smooth radii free of tool marks. Added fatigue life is obtained by cold rolling radii at the upper shoulders with a specially designed cold rolling tool.
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Hardbanding Hardbanding material consists of granular tungsten carbide that is fed automatically into the molten weld puddle to obtain uniform distribution of the tungsten carbide particles. The resulting deposit of hardbanding is flush to 1/32” above the OD of the collar. Hardbanding on the box end (endless for the special purpose of protecting slip and elevator recesses) is not recommended because the hardbanding covers the normal slip area. Ordering Instructions: When ordering or requesting quotations on drill collars, please specify: 1. Drill collar OD
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