12
4.4.2.
Safety devices to be installed
Overpressure or overheating may cause the box
cooler to leak, rupture or burst.
1)
Fit a suitably sized and rated pressure limiting
device (e.g. a pressure safety relief valve).
The set pressure must ensure that no part of the
box cooler will experience pressure above the
design pressure (see section 2.4).
2)
Ensure suitable controls to prevent the maximum
allowable temperature from being exceeded
(if required by the process).
4.4.3.
Connecting the piping to the box cooler
1.
Make sure that the piping is clean before it is fixed
to the nozzles so that no dirt or (metal) particles
can enter the box cooler.
2.
Remove all protective caps, plugs, shipping covers,
etc., from the box cooler.
3.
Make sure that all gasket faces of the flanges and
all nozzle openings are clean and free of defects
(burrs, pits, dents, etc.).
4.
Do not force the piping into alignment
.
Make sure that the mating faces of the flanges of
the box coolers and the piping are parallel to each
other.
5.
Use properly sized gaskets with the correct
pressure class, suitable for the working
temperatures and for all used fluids.
Recommended are reinforced graphite ring
gaskets.
6.
Make sure the gaskets are properly centred and
tighten up the stud bolts of the flanges alternate
and crosswise to guarantee an even setting of the
gaskets (see section 4.4.4).
4.4.4.
Tightening torques
The bolts and nuts of the water covers and flanges
need to be tightened during installation and
maintenance or when joints are leaking.
Lubricate the threads of the bolt or stud, and the
surface of the nut face adjacent to the flange or
washer. Tightening of the bolts must be done
“diagonally” with a torque wrench in at least four
steps, see table 1 and fig. 12a, b, c and d.
In the case of leaking, the tightening torques may be
increased by approximately 15%.
Figure 12a. Order of tightening of the collar bolts.
Figure 12b. Order of tightening of the bolts of the water
cover of a single section box cooler.
Start from the center.
Figure 12c. Order of tightening of the bolts of the water
cover of a double or triple section box cooler.
Start from the (central) partition.
Figure 12d. Order of tightening of the bolts of the water
covers and the flanges.
Tightening torque [Nm]
Size
Carbon steel, class 8.8 / ASTM A193 B7
Step 1
Step 2
Step 3
Step 4
M 12
25
45
65
85
M 16
60
110
165
215
M 20
130
230
330
430
M 24
200
400
575
740
Table 1. Recommended tightening torques (the values are
base on "lightly lubricated bolts".
