Page 96 - Air and gas Drilling Field Guide 3rd Edition

4.5 Safety Equipment 87

DRILL PIPE

(18Jt. OR MORE)
HEVI-WATE ®
DRILL PIPE CROSS-OVER
SUB
ADDITIONAL
DRILL COLLARS INTEGRAL
BLADE
STABILIZER

30 ft
DRILL COLLAR SHOCK SUB ®
VIBRATION
DAMPENER

STRING
RWP
STABILIZER
SHORT
DRILL COLLAR

BOTTOM HOLE
RWP
STABILIZER

6 POINT
REAMER

FIGURE 4-22. Typical tapered drill string using heavyweight drill pipe (courtesy of Smith
International).

4.5.1 Float Valves
Figures 4-23 and 4-24 show the two typical drill string float valves. These are also
known as nonreturn valves. These two types are the dart type and the flapper
type. These are safety valve devices that prevent the back flow or U-tube flow
of liquids or gases from the annulus into the inside of the drill string.