Welcome to Oil Country Tubular Limited

OCTL Drill Collars (Slick and Spiral) are manufactured from AISI 4145 H Chromium Molybdenum Alloy Steel and are fully heat treated to a Brinell Hardness range of 285-341 BHN and have a minimum Charpy V-notch Impact strength of 40 ft-lbs. at 70° F and a minimum elongation of 13%. The mechanical properties meet or exceed API Specification 7 requirements. The physical properties are guaranteed one inch below the surface at ambient room temperature.

Mechanical Properties (4145 H Chromium Molybdenum Alloy Steel)

Drill Collar OD(in.)	Minimum Yield Strength (psi)	Minimum Tensile Strength (psi)	Minimum Hardness(BHN)
3 1/8 to 6 7/8	110,000	140,000	285
7 to 11	100,000	135,000	285

Drill Collars are precision trepanned to close bore tolerance and all bores are drifted to API Specification 7. The connections are cut on CNC Machines. All API connections comply with dimensional requirements specified in API Spec 7 and guidelines presented in API RP 7G.

The thread roots as well as elevator and slip recess upper radii are systematically cold rolled to improve fatigue resistance of the connections by minimizing crack initiation. To improve resistance to galling all connections are phosphatized and coated with an API thread compound. The connections are provided with pressed steel or cast steel thread protectors.

Spiral Drill Collars

To avoid differential pressure sticking in the hole, the surface of drill collars can be provided with three spiral grooves reducing the contact area with the wall of the hole. The spiral grooves let mud circulate freely around the Drill Collar to equalize pressure and prevent a seal from forming. Loss of weight is approximately 4%, compared to Slick Drill Collars.

Drill Collar Manufacturing Schedule

Drill Collar Diameter	Bore +1/16" - 0"	Connection	Approximate Weight Drill Collar	Bending Strength Ratio
in.	in.		lb / ft
3 1/8	1 1/4	NC 23 (2 3/8Reg)	22.00	2.57:1
3 1/2	1 1/2	NC 26 (2 3/8 IF)	26.70	2.42:1
4 1/8	2	NC 31 (2 7/8 IF)	33.65	2.43:1
4 3/4	2	NC 35	46.81	2.58:1
5	2 ¼	NC 38 (3 1/2 IF)	53.29	2.38:1
6	2 1/4	NC 44	82.61	2.49:1
6	2 13/16	NC 44	75.90	2.84:1
6 1/4	2 1/4	NC 44	90.52	2.91:1
6 1/4	2 13/16	NC 46 (4 IF)	83.81	2.63:1
6 1/2	2 1/4	NC 46 (4 IF)	99.52	2.76:1
6 1/2	2 13/16	NC 46 (4 IF)	92.81	3.05:1
6 3/4	2 1/4	NC 46 (4 IF)	108.52	3.18:1
7	2 1/4	NC 50 (4 1/2 IF)	117.52	2.54:1
7	2 13/16	NC 50 (4 1/2 IF)	110.77	2.73.1
7 1/4	2 13/16	NC 50 (4 1/2 IF)	119.81	3.12:1
7 3/4	2 13/16	NC 56	139.9	2.70:1
8	2 13/16	NC 56	150.81	3.02:1
8 1/4	2 13/16	6 5/8 API Reg	161.81	2.93:1
9	2 13/16	NC 61	195.81	3.17:1
9 1/2	3	7 5/8 API Reg	217.00	2.81:1
9 3/4	3	NC 70	230.00	2.57:1
10	3	NC 70	242.97	2.81:1
11	3	NC77(8 5/8 API Reg)	299.00	2.84:1

Slip and Elevator Recesses Dimensions

Drill Collar Diameter OD	Elevator Recess Diameter	Slip Recess Diameter	Elevator Recess Radius
	A	B	R
in.	in.	in.	in.
4 1/8	3 11/16	3 3/4	1/8
4 3/4	4 1/4	4 3/8	1/8
5	4 1/2	4 5/8	1/8
6	5 3/8	5 1/2	1/8
6 1/4	5 5/8	5 3/4	1/8
6 1/2	5 7/8	6	1/8
6 3/4	6	6 1/4	3/16
7	6 1/4	6 1/2	3/16
7 1/4	6 1/2	6 3/4	3/16
7 3/4	7	7 1/4	3/16
8	7 1/4	7 1/2	3/16
8 1/4	7 1/2	7 3/4	3/16
9	8 1/8	8 1/2	1/4
9 1/2	8 5/8	9	1/4
9 3/4	8 7/8	9 1/4	1/4
10	9 1/8	9 1/2	1/4
11	10 1/8	10 1/2	1/4

API Stress Relief Features and API Bore Back Box decrease the frequency of fatigue failures by improving the bending strength of pin and box connections, thereby, reducing high stress concentrations. Stress relief features are machined in compliance with API Specification 7. Connections NC23, NC 26 (2 3/8 IF) and NC 31 (2 7/8 IF) do not have sufficient metal to accommodate stress relief features.

Slip and Elevator recesses improve handling efficiency and safety. The upper radius of the elevator recess is cold-rolled. Slip and Elevator recesses can be used together or separately. Slip and Elevator Recesses are machined in compliance with API RP 7G guidelines.

On enquiries and orders, please specify:

Outside Diameter, Bore, Length, Connection Size and Type, API Stress Relief Features on Pin and Box ends, Slick or Spiral,

Hard banding (band location and width), Slip or Elevator Recesses, Pressed or Cast Steel Thread Protectors, and any special features.

Quality Control

OCTL Drill Collars are inspected to comply with API standards. The inspections include visual dimensional checks as well as Ultrasonic Inspection on each bar over its full length and section.

Mechanical properties are verified on samples taken from the end of the bar.

Thread Profile, Lead, Taper, Pitch and Gage Standoff are 100% inspected on each Drill Collar to all applicable API Specifications and recorded as part of the manufacturing records.

Drill Collar product and process traceability is maintained from receipt of mill certified raw material to completion of all the manufacturing. Unique product number is die-stamped on each Drill Collar for traceability.

Complete documentation is provided with each shipment detailing the full Quality Control records.

"Committed to Total Quality and Customer Satisfaction"