26. Verify that the oil pressure gauge indicates
zero (0) psi/bar. If any pressure is indicated,
release the hydraulic pressure SLOWLY by
opening the pump pressure release (return
to tank) valve.
27.
Turn down the threaded pullers until the
pistons are fully retracted. Disconnect
hydraulic hoses and install a dust cap (not
shown) over each disconnected coupler.
Remove tensioners from the studs.
7.3 De-tensioning Instructions - 100%
Coverage (tensioner installed on each
stud)
IMPORTANT:
Read precautions and instructions
at beginning of Section 7.0 before beginning
the following steps. Also refer to safety
information contained in sections 2.1.
Note:
For improved illustration clarity, only
one hydraulic hose is shown connected to the
tensioner in figures 15-18.
1. Assemble the tensioner(s) to the stud(s) to
be de-tensioned and connect the hydraulic
hoses. Refer to sections 6.1 and 6.2 for
additional tensioner installation and hose
connection instructions.
2. BEFORE applying any hydraulic pressure;
examine the puller on each tensioner,
the puller should be seated on the ram.
Unscrew the puller by 1/2 turn. This will
raise the puller above the top washer,
preventing the puller becoming locked
on to the ram when the bolt tension is
released. See Figure 15.
3.
Operate the pump to pressurize the
tensioners up to approximately 1000 psi
[70 bar]. Check for oil leaks.
In the following de-tensioning
steps, be certain that the hydraulic pressure
remains below the maximum allowable
hydraulic pressure of 21,750 psi [1500 bar],
and that the load applied does not exceed the
tensile strength of the stud.
4. If no leaks are found, continue operating
the pump. Slowly raise the pressure until
the “break loose” hydraulic pressure value
is reached. This is the pressure at which
a nut on one of the tensioners just begins
to loosen and can be turned by hand with
the tommy bar. Record this pressure for
reference. See Figure 16.
WARNING
a.
Assemble tensioners on any two
“first pass” bolts (labeled “1”) located
diametrically opposite of each other. See
Figure 14.
b. Connect hydraulic hoses.
c. Apply the “second pass” pressure “B”.
d.
Using the tommy bar, attempt to
tighten the nuts on these bolts by hand.
• If the nuts cannot be turned, then
tensioning is complete. Relieve
hydraulic pressure. Go to Step 26.
• If the nuts can be turned, then re-install
the tensioners to the remainder of the
“first pass” bolts (numbered “1”), apply
the “second pass” pressure “B” and
turn-down the nuts one more time as
described in steps 16 through 22.
FIGURE 17, TURNING UP THE NUT
B1 B2
0
FIGURE 18, PRESSURE RELEASED - NUT
DETENSIONED
B2= Break Loose Pressure (B1) + 5%
PRESSURE
RELEASE
CLOSED
PRESSURE
RELEASE
OPEN
1/8 inch
[3-4mm]
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