Farr HD8625, Technical Manual

Page: 28 / 156

2.12
hD8625 8-
5
/
8
” 35K T
ong
T
echnical
M
anual
MCCOY DRILLING & COMPLETIONS ACCEPTS NO RESPONSIBILITY FOR DESIGNING AND
SELECTING AN ADEQUATE SUSPENSION AND RESTRAINT SYSTEM FOR YOUR DRILLING
EQUIPMENT
ALL SELECTED FASTENERS, SHACKLES, CLAMPS, ETC. USED FOR CONSTRUCTING THE
SUSPENSION AND SNUB LINES MUST BE RATED FOR THE CALCULATED FORCES.
Suspension & Restraint (Cont’d)
If you do not know which specific spring hanger is in use, check the specification page in this manual for information on the recom-
mended spring hanger for this application. McCoy Drilling & Completions will not guarantee or specify spring hangers other than what
has been supplied by McCoy.
Many applications use a lift cylinder for adjusting the height of the tong. Ensure the weight of the lift cylinder is known if it has not
been included in the total weight of the tong.
All forces upon the suspension line must be considered when calculating necessary strength of the suspension line. The weight of
the tong, the weight of the lift cylinder, the weight of the spring hanger, and the force imparted on the suspension line by the spring
hanger must all be added together in order to arrive at the total force supported by the suspension line. Select your suspension
line based upon the total force and the margins of safety dictated by the policies of your company and by established engineering
practices. Ultimately, calculating the force on the suspension line and selection of the suspension line is the complete responsibility
of the customer.
McCoy Drilling & Completions recommends using dual backup (snub) lines of sufficient strength to withstand the force imparted by
the maximum rated torque of the tong in use. Calculate the force on the snub lines by dividing the maximum torque of the tong by
the tong’s torque arm (expressed in feet). For example, a 35,000 lbs.-ft. tong with a 36 inch (3 ft.) torque arm will generate 11667 lbs.
of force against the snub line. Select your snub lines based upon the total force and the margins of safety dictated by the policies of
your company and by established engineering practices. Ultimately, calculating the force on the snub line and selection of the snub
line is the complete responsibility of the customer.
Snub lines must be securely connected to the rear of the tong, and tied off to a suitable anchor. One snub line must be secured to
the load cell, which is then secured to the rear of the tong. The side of the tong the load cell connects to is dependant upon whether
make-up or break-out activities are underway. To ensure accurate torque measurement, the torque measurement line must be con-
nected perpendicular to the lengthwise axis of the tong, and perpendicular to the hang line (see illustrations 2.F.1 and 2.F.2). Connect
the second snub line on the opposite side of the load cell, perpendicular to the lengthwise axis of the tong and perpendicular to the
vertical.
I
llustratIon
2.f.1: t
ong
s
usPensIon
r
elatIve
t
o
a
xIal
C
entre
s
eTup
& o
peraTion
90
o