Page 148 - Drilling Technology in Nontechnical Language

Chapter 5 – RIG SELECTION AND RIG EQUIPMENT 139

specified torque range. Drillpipe will normally be torqued up to around
24,000 foot-pounds (ft-lb); large drillcollar torques may be in the range of
65,000 ft-lb to 75,000 ft-lb.

Two tongs are used; one is placed on the box OD and the other on the
pin. The box end tong (called the backup tong because it backs up the box
while the pin moves) is fastened with a length of wire rope to a strong

point on the rig floor. The pin end tong (called the makeup tong because it
is the one that makes up the connection) has a tension sensator attached to
it, which measures the pull on a chain that the driller uses to exert a large
force on the end of the tong. This chain, the makeup chain, is powered by
the same electric motor that powers the drawworks.
Torque is expressed as a force multiplied by the length of a lever or
arm, hence the term foot-pounds. A normal rig tong has a 4 ft arm, and to
exert a torque of 24,000 ft-lb requires a pull of 6,000 lb.

Fig. 5–23. A 5" drillpipe elevator, open

_Devereux_Book.indb 139 1/16/12 2:09 PM