48 | INSTALLATION, OPERATION and MAINTENANCE MANUAL
7) Test the heat exchanger for leaks by using potable water at the desired
pressure but do not exceed the test pressure specified on the customer
drawing. The test may be done on each side separately (unbalanced) or on
both sides (balanced) at once. Ensure the correct test pressure is used for the
unbalanced or balanced tests. Make sure all air is vented from the heat
exchanger before performing the pressure test.
Note: Pneumatic pressure tests using air, helium or nitrogen are not
recommended. Pneumatic tests shall only be used when the APV GPHE cannot
be completely drained of the hydrostatic test water and the remaining traces of
test water are detrimental to the operating fluid(s). The pneumatic pressure
test shall comply with all applicable codes, standards, and regulations,
including those established by OSHA.
8) Leaks presenting as more than a very slow weep at low pressure will require
the heat exchanger to be drained and opened per the guidelines in step 10.
9) If slow weep leaks occur, the heat exchanger may be further tightened and
retested. It is suggested that this be done in increments of approximately
0.025mm (0.001 in.) per plate until the leak stops or the minimum dimension
specified on the customer drawing is reached. The plate pack must not be
compressed below the minimum dimension without written authorization
from SPX FLOW Engineering.
10) If the leaks continue, mark them carefully, drain and open the heat exchanger in
accordance with Section 9.7. Inspect the area of the leaks closely for damaged
gaskets, plates, sealing surfaces or debris. Replace all suspect plates or
gaskets, clean the sealing surface with a lint free cloth, and repeat steps 1
through 7.
9.7. Opening Tie Bar Frames
Tie bar frames may be opened safely by following steps 1 through 6 in Section 9.6 in
reverse order. The tie bars must be loosened in the same sequence and amount as
described in each step.
Never open a GPHE until the equipment is below 38ºC (100ºF).
Never open a GPHE which is under pressure.
Never open a GPHE while piping is connected to the follower or connector
grids.
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