STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

Hoisting System 543
75, 562.50 lb, divided by 2 since this load is shared by legs C and D) and the
dead-line load at leg A (i.e., 75,562.50 lb).
The actual load on the derrick is the sum of the bottom row in Table 4-4.
The equivalent load is four times the force in leg A, which is the largest load
of all four legs.
Thus,
764,625.00
DEF =
4( 228,937.50)
= 83.50%
HOISTING SYSTEM
A hoisting system, as shown in Figure 4-8, is composed of the drawworks,
traveling block, crown block, extra line storage spool, various clamps, hooks,
and wire rope.
Normally, a hoisting system has an even number of working lines between
the traveling block and the crown block. The fast line is spooled onto the
drawworks’ hoisting drum. The dead line is anchored to the rig floor across
from the drawworks. The weight indicator is a load cell incorporated in the dead
line anchor.
Dead
line anchor
Figure 4-8. Schematic of simplified hoisting system on rotary drilling rig [9].