Drill collar

number

and

connection

label

Outside

diameter

D

in

Bore

d

in

+1/16

0

Length

L

Ft

+6

0

Bevel

diameter

DF

in

±1/64 in

Reference

bending strength

ratio

BSR

NC23-31

3 1/8

1 1/4

30

3

2.57:1

NC26-35

3 1/2

1 1/2

30

3 17/64

2.42:1

NC31-41

4 1/8

2

30 or 31

3 61/64

2.43:1

NC35-47

4 3/4

2

30 or 31

4 33/64

2.58:1

NC38-50

5

2 1/4

30 or 31

4 49/64

2.38:1

NC44-60

6

2 1/4

30 or 31

5 11/16

2.49:1

NC44-60

6

2 13/16

30 or 31

5 11/16

2.84:1

NC44-62

6 1/4

2 1/4

30 or 31

5 7/8

2.91:1

NC46-62

6 1/4

2 13/16

30 or 31

5 29/32

2.63:1

NC46-65

6 1/2

2 1/4

30 or 31

6 3/32

2.76:1

NC46-65

6 1/2

2 13/16

30 or 31

6 3/32

3.05:1

NC46-67

6 3/4

2 1/4

30 or 31

6 9/32

3.18:1

NC50-70

7

2 1/4

30 or 31

6 31/64

2.54:1

NC50-70

7

2 13/16

30 or 31

6 31/64

2.73:1

NC50-72

7 1/4

2 13/16

30 or 31

6 43/64

3.12:1

NC56-77

7 3/4

2 13/16

30 or 31

7 19/64

2.70:1

NC56-80

8

2 13/16

30 or 31

7 31/64

3.02:1

6 5/8 REG

8 1/4

2 13/16

30 or 31

7 45/64

2.93:1

NC61-90

9

2 13/16

30 or 31

8 3/8

3.17:1

7 5/8 REG

9 1/2

3

30 or 31

8 13/16

2.81:1

NC70-97

9 3/4

3

30 or 31

9 5/32

2.57:1

NC70-100

10

3

30 or 31

9 11/32

2.81:1

8 5/8 REG

11

3

30 or 31

10 1/2

2.84:1