Drill Collar

Drill collars put weight on the bit. They are thick-walled tubulars machined from solid bars of modified AISI 4145H chromium-molybdenum alloy steel, full-length heat treated and water quenched to API Spec 7-1 mechanical properties; non-magnetic alloys are also available. Bars are trepanned and drifted to API specification for close-tolerance bores.

Full mechanical and chemical mill test certificates are supplied, guaranteeing a hardness of 285–341 BHN and an impact value of 40 ft-lbs at room temperature one inch below the surface.

Functions

• Weight-on-bit (WOB) and BHA directional control
• Hole size integrity and stiffness to keep the hole straight
• Compressive and torsional load capacity
• Spiral grooves reduce wall contact and differential sticking

Standard features

• OD from 2-7/8" to 11", Range 2 and 3, slick or spiral, to API 7-1 and 7-2
• API and high-performance double-shoulder connections, precision-machined to API Spec 7-2
• Cold-worked thread roots, pin stress-relief groove and box bore-back for fatigue resistance
• Phosphate-coated threads, thread compound and thread protectors fitted for shipment
• Slip and elevator recesses to API RP 7G (five configurations available)
• Steel grades: API, sour service, NS-1, low temperature, non-magnetic

Options

• Hardbanding (type A, B or C; flush or raised)
• Internal plastic coating for OD below 6-1/2"
• Custom slip and elevator recess; NS-1, DS-1 or customer specifications; make and break

Drill collar specifications

* The first two digits of a numbered connection (NC) refer to the pitch diameter; the numbers after the hyphen refer to the drill collar OD in inches and tenths of an inch.

Slip and elevator recess dimensions