Drill Collar

In drilling, a drill collar consists of a heavy pipe above the drill bit in a drill string. Its main characteristic is big wall thickness (generally is 38 to53 mm, equivalent to the pipe wall thickness of 4 to 6 times), and it has a larger gravity and stiffness.

Parameters of Steel Drill Collars

Drill collar number and connection label	OD(mm)	ID(mm)	Length(m)	BD(mm)	BSR	Weight(lb/ft)
		+1.59 0	±152.4	±0.4
NC23-31	79.4	31.8	9.14	76.2	2.57:1	22
NC26-35	88.9	38.1	9.14	82.9	2.42:1	27
NC31-41	104.8	50.8	9.14 or 9.45	100.4	2.43:1	35
NC35-47	120.7	50.8	9.14 or 9.45	114.7	2.58:1	47
NC38-50	127.0	57.2	9.14 or 9.45	121.0	2.38:1	53
NC44-60	152.4	57.2	9.14 or 9.45	144.5	2.49:1	83
NC44-60	152.4	71.4	9.14 or 9.45	144.5	2.84:1	75
NC44-62	158.8	57.2	9.14 or 9.45	149.2	2.91:1	91
NC46-62	158.8	71.4	9.14 or 9.45	150.0	2.63:1	83
NC46-65	165.1	57.2	9.14 or 9.45	154.8	2.76:1	99
NC46-65	165.1	71.4	9.14 or 9.45	154.8	3.05:1	91
NC46-67	171.4	57.2	9.14 or 9.45	159.5	3.18:1	108
NC50-70	177.8	57.2	9.14 or 9.45	164.7	2.54:1	117
NC50-70	177.8	71.4	9.14 or 9.45	164.7	2.73:1	110
NC50-72	184.2	71.4	9.14 or 9.45	169.5	3.12:1	119
NC56-77	196.8	71.4	9.14 or 9.45	185.3	2.70:1	139
NC56-80	203.2	71.4	9.14 or 9.45	190.1	3.02:1	150
6 5/8 REG	209.6	71.4	9.14 or 9.45	195.6	2.93:1	160
NC91-90	228.6	71.4	9.14 or 9.45	212.7	3.17:1	195
7 2/8 REG	241.3	76.2	9.14 or 9.45	223.8	2.81:1	216
NC70-97	247.6	76.2	9.14 or 9.45	232.6	2.57:1	229
NC70-100	254.0	76.2	9.14 or 9.45	237.3	2.81:1	243
8 5/8 REG	279.4	76.2	9.14 or 9.45	266.7	2.84:1	299
We can apply designated connection and length as per customers' requirement.

Note

1. Put drill bit under pressure
2. Ensure the necessary strength under the condition of the compression
3. To reduce the vibration, swing, and beating, of the drill bit, makes the bit work smoothly.
4. Inclination control

Features

1. Trepanning and Heat Treatment
Drill collars are trepanned and drifted to API Spec 7. Full-length heat-treatment processes ensure that mechanical properties meet or exceed API Spec 7 requirements. A hardness range of 285-341, Connections NC23, NC26 and NC31 (2 3/8 IF and 2 7/8 IF) have a sufficient steel thickness for machining stress-relief grooves.
Steel drill collars material and process traceability are maintained from receipt of mill certified raw material to completion of all the manufacturing. Serial numbers are dying stamped on bar biddies.
2. Phosphate-coated or copper plating
All threads are phosphate-coated or copper plating to improve abrasive resistance and reduce thread fastening.
3. Rigid Inspection Procedures
We inspect all our steel drill collars to comply with API standards. These inspections include visual dimensional checks as well as ultrasonic inspections over the entire body of the drill collar.
4. Slip groove, Elevator groove and its size
Our company offers optional slip and elevator recesses to improve handling efficiency and safety. The upper radius of the elevator recess is cold can be used together or separately. Unless otherwise specified, slip and elevator recesses are machined in compliance with API RP7Gguidelines.
5. Cold Rolling
Steel drill collars thread roots, as well as elevator recess upper radii, are processing cold-rolled. Cold rolling creates a compressive recess upper radii stress condition that increases fatigue life by minimizing crack initiation.
6. Thread protectors
Our company offers cast steel, steel, plastic steel thread protectors for its drill stem.