Page 202 - Air and Gas Drilling Manual

5-44 Air and Gas Drilling Manual
The inside of the drill string is approximated by the inside diameter of the drill
pipe. The inside diameter of the API 2 7/8 inch, 6.85 lb/ft nominal, EU, NC 31,
Grade E drill pipe is 2.441 inches (see Table B-4).
d = 2 441. inches
i
d
D = i
i
12
D = 0 203. ft
i
Equation 5-10 becomes
  2
 
f =  1 
  0 203  
.
.
 2 log  + 114 
  0 00015 
.
f = 0 018
.
Equations 5-8 and 5-9 become, respectively,
.
a = 10
i
53 36
.
a = 0 019.
i
and
.
1 599)
b = 0 018  53.36  2 (. 2
i
π
0203)
2 322 . ) ( .  10 .    2 4
(
0 203)
  (.
4
b = 9 592
,
i
Equation 5-7 becomes