25
2005 Doctor Martin Luther King Jr Street
Indianapolis, IN 46202
Rev 07-2021
TENSIONING THE TUBE NUT
The enclosing tube sags slightly
from its own weight as it is installed, and
must be pulled tight (tensioned) to make
it straight. The tube nut (see Fig. 15)
holds the tube in its straightened
position. This section describes two
methods of tensioning the tube. The
second method (the “wrenching
method”) is given as an alternative for
use with pumps having settings less than
500 feet.
Note: The correct tension is the
weight of the enclosing tube plus 10%.
Weights-per-foot for each tube size
are given in Table 2. Multiply by the
total length of tube to determine the total
weight.
Table 2. Weight per Foot of
Enclosing Tube
Tube size (in.) Weight per foot
(lb.)
1 ¼ 2.99
1 ½ 3.63
2 5.02
2 ½ 7.66
3 10.25
3 ½ 12.50
4 14.98
5 20.78
6 28.57
Apply a generous coating of grease
to both sides of the gasket and place the
gasket on the discharge head. Install the
tube nut, screwing it down manually
until its shoulder rests firmly on the
gasket.
The upper end of the tube may be
pulled by the hoist to obtain the
predetermined tension value. This
requires the use of a dynamometer scale
and a specially-made fitting to grip the
tube. The fitting may be a short tube
with welded-on lugs for gripping with a
sling and an internal thread to mate with
the tube thread.
Figure 17. Typical tube nut assembly.
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