Xylem Heat Exchangers - Manual (Page 7)

13
To locate ruptured or corroded tubes
or leaking joints between tubes and
tubesheets, the following procedure is
recommended:
• Remove tube side channel covers
or bonnets.
• Pressurize the shell side of the
exchanger with a cold fluid,
preferably water.
• Observe tube joints and tube ends for
indication of test fluid leakage.
14
With certain styles of exchangers,
it will be necessary to buy or make a
test ring to seal off the space between
the floating tubesheet and inside shell
diameter to apply the test in paragraph
13. Consult your nearest ITT Heat Transfer
sales representative for reference
drawings showing installation of a test
ring in your heat exchanger.
15
To tighten a leaking tube joint, use a
suitable parallel roller tube expander.
• Do not roll tubes beyond the back face
of the tubesheet. Maximum rolling
depth should be tubesheet thickness
minus 1/8”.
• Do not re-roll tubes that are not leaking
since this needlessly thins the tube
wall.
16
It is recommended that when a heat
exchanger is dismantled, new gaskets be
used in reassembly.
• Composition gaskets become brittle
and dried out in service and do not
provide an effective seal when
reused.
• Metal or metal jacketed gaskets in
initial compression match the contact
surfaces and tend to work-harden and
cannot be recompressed on reuse.
17
Use of new bolting in conformance with
dimension and ASTM specifications of
the original design is recommended where
frequent dismantling is encountered.
cautIon:
Do not remove channel covers, shell
covers, floating head covers or bonnets
until all pressure in the heat exchanger
has been relieved and both shell side and
tube side are completely drained.
cautIon:
Since many of the removable compo­
nents of the heat exchanger, particu­
larly in the larger sizes, are too heavy for
people to handle, care must be used to
take this weight with proper rigging to
avoid injury. Wear hard hats and safety
shoes as required.
cautIon:
Do not thread rods or cables through
tubes of a heat exchanger equipped with
ITT Standard Amatran
® tubes, or any
with internal fins.
cautIon:
When the heat exchanger is cleaned, it is
important that full characteristics of the
fouling material and the cleaning agent
be known and care exercised in handling
them according to instructions. Use eye
protection to prevent damage to your
eyes. Wear a respirator when required.
cautIon:
Do not blow out heat exchangers with
air when the normal process fluids or
the cleaning fluids being handled are
inflammable.
7