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Drill Collar

Product:Drill Collar
Standard: API SPEC 7-1
Steel grade:AISI 4145H
Sizes:3 1/8" -- 11"
Connected Type: NC, IF, REG

Drill collar is thick-wall tubular machined from solid steel bars and manufactured to meet and exceed API specifications. Drill collar, a major component of bottom hole assembly, is in the lowest part of the drill string. The main characteristic of drill collars with large wall thickness (generally is 38 to 53mm that is equivalent to the pipe wall thickness of 4-6 times), has much larger gravity and stiffness.

Drill collars can be divided into spiral drill collar, non-magnetic drill collar and integral drill collar.

The integral drill collar is smooth thick wall round pipe with threads on both ends.

The spiral drill collar is processed 3 right lateral spiral grooves on the surface of circular cylinder in order to reduce the contact area with borehole wall. This can effectively prevent the differential pressure sticking. The non-magnetic drill collar is mainly used in the process of oil drilling monitoring. The standard is N1310 low carbon alloy steel with good low permeability and machining performance.

Drill Collar Production Processes:

drill-collar-process

drill-collar-process-2


Mechanical Properties

OD (inch)

Tensile (Mpa)

Yield Strength (Mpa)

Elongation (L=4D)(%)

Impact AKV (J)

Hardness (HB)

3 1/8~6 3/4

≥965

≥758

≥13

≥54

≥285

7~11

≥930

≥689

≥13

≥54

≥285


Typically Size of Spiral Grooving

OD(In.)

Screw depth(In.)

Screw Leadin

4~4 3/8

6/32±1/32

36±1

4 1/2~5 1/8

7/32±1/32

38±1

5 1/4~5 3/4

1/4±1/32

42±1

5 7/8~6 3/8

9/32±1/16

42±1

6 1/2~7

5/16±1/16

46±1

7 1/8~7 7/8

11/32±1/16

64±1

8~8 7/8

3/8±1/16

68±1

9~9 7/8

13/32±3/32

72±1


Drill Collor
(Number)

Outside Diameter
(In.)

Inside Diameter
(In.)

Length
(ft)

Approximate Weight
(lb/ft)

Typical Bending
Strength Ratio

NC 23-31

3-1/8

1-1/4

30

22

2.57:1

NC 26-35 (2-3/8 IF)

3-1/2

1-1/2

30

27

2.42:1

NC 31-41 (2-7/8 IF)

4-1/8

2

30 or 31

34

2.43:1

NC 35-47

4-3 /4

2

30 or 31

47

2.58:1

NC 38-50 (3-1/2 IF)

5

2-1/4

30 or 31

54

2.38:1

NC 44-60

6

2-1/4

30 or 31

83

2.49:1

NC 44-60

6

2-13 /16

30 or 31

76

2.84:1

NC 44-62

6-1/4

2-1/4

30 or 31

91

2.91:1

NC 46-62 (4 IF)

6-1/4

2-13 /16

30 or 31

84

2.63:1

NC 46-65 (4 IF)

6-1/2

2-1/4

30 or 31

100

2.76:1

NC 46-65 (4 IF)

6-1/2

2-13 /16

30 or 31

93

3.05:1

NC 46-67 (4 IF)

6-3 /4

2-1/4

30 or 31

109

3.18:1

NC 50-70 (4-1/2 IF)

7

2-1/4

30 or 31

118

2.54:1

NC 50-70 (4-1/2 IF)

7

2-13 /16

30 or 31

111

2.73:1

NC 50-72 (4-1/2 IF)

7-1/4

2-13 /16

30 or 31

120

3.12:1

NC 56-77

7-3 /4

2-13 /16

30 or 31

140

2.70:1

NC 56-80

8

2-13 /16

30 or 31

151

3.02:1

6-5/8 API Reg

8-1/4

2-13 /16

30 or 31

162

2.93:1

NC 61-90

9

2-13 /16

30 or 31

196

3.17:1

7-5/8 API Reg

9-1/2

3

30 or 31

217

2.81:1

NC 70-97

9-3 /4

3

30 or 31

230

2.57:1

NC 70-100

10

3

30 or 31

243

2.81:1

8-5/8 API Reg

11

3

30 or 31

300

2.84:1

*The number connection (NC ) is an API connection with the V- .065 thread form with a V- .038R thread root radius. The first two digits are the pitch diameter of the thread and the last two digits are the outside diameter of the drill collar. 

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