17
6.3.
MAINTENANCE DURING EACH
DRY-‐DOCKING PERIOD
To continually deliver full heat transfer capacity, both
internal and external heat transfer surfaces must be
maintained clean and free of corrosion.
Inspect, clean and service the tube bundle and the sea
chest every dry-‐docking period.
6.3.1.
Dismounting the tube bundle
For external inspection and cleaning, the tube bundle
needs to be dismounted:
1)
Remove the water cover according to the
instructions of section 6.2.
2)
To dismount the tube bundle, loosen the collar
bolts.
Do not remove the tube bundle or
the collar bolts/Allen head screws
when the vessel is afloat!
3)
Tighten the M16 eyebolts into the tube sheet (see
section 3.2).
4)
Carefully and slowly lift or lower the tube bundle
out of the sea chest.
Mind the weight. Take care not to damage the
coating or the surfaces of flanges.
5)
Move the tube bundle to a place where inspection
and cleaning can take place. Prevent damaging
the tubes and the coating. Put it down on a soft
surface, e.g. a sheet of rubber.
6.3.2.
Cleaning of the tube bundle
§
Internal tube cleaning.
When the tubes are
excessively fouled on the inside or when bends are
clogged (see also section 6.2), the tube bundle can be
cleaned by putting it in a container with water and
cleaning chemicals.
Alternatively, it can be cleaned ultrasonically.
When using this type of cleaning, contact a competent
company that specialises in ultrasonic or chemical
cleaning and/or cleaning agents. Supply the company
with full characteristics of used water, the materials of
the box cooler and its use.
When required, contact Duramax Marine® for advice.
§
External cleaning of the tube bundle.
Excessive
marine fouling will significantly reduce the heat
transfer.
When cleaning is required, proceed as follows:
1)
Scrape off the marine growth at the outside of the
tube bundle with a wooden or plastic scraper or
use a non-‐metallic brush.
Use wooden or plastic scraper with a maximum
thickness of 5 mm to clean between the tubes.
Prevent damaging the coating or the surface of
uncoated tubes. Do NOT use metal scrapers or
metal brushes
.
2)
For coated box coolers: after mechanical cleaning,
clean the tube bundle with a steam cleaner set at
a maximum temperature of 120°C.
Next clean the tube bundle for 15 minutes with a
solution of chloride (5 mg Cl per litre).
3)
Finally, rinse the tube bundle thoroughly with
clean unheated water, using a high pressure
cleaner at a maximum pressure of 100 bar.
When using other cleaning methods contact a
competent company that specialises in chemical
cleaning and/or cleaning agents. Supply the
company with full characteristics of the materials
of the box cooler and its use.
4)
Check if the heat curded duroplast coating of the
tube bundle is damaged (when applicable).
A damaged coating (also small damages) will lead
to accelerated (galvanic) corrosion.
Small coating damages can be touched up by a
special two-‐component repair set, which can be
ordered from Duramax Marine®. When larger
areas are damaged, the complete tube bundle
needs to be re-‐coated. In that case contact
Duramax Marine®.
6.3.3.
Damaged tubes
When the tubes are damaged, contact Duramax
Marine® for advice.
