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2.18 CLEANING PUMPROOM BILGES
Because of their special location and function, tanker pumprooms are
particularly hazardous and require special care and precautions. Over
time, even small leakages of cargo into the pumproom bilges can produce
dangerous levels of hydrocarbon vapours. Pumproom bilges should be pumped
out to the slop tank after each cargo discharge and the pumproom should
be washed periodically to remove any accumulated residues. The pumproom
bilges must be washed before any repairs which would require maintenance
personnel to enter the bilges.
If the pumps, valves and other pumproom connections are properly maintained,
leakage will be minimal and cleaning may be required only after every
second or third cargo. Whatever the frequency, it is vitally important
that the pumproom bilges be maintained clear of hydrocarbons.
When cleaning is required, the bilges should be pumped dry, then flushed
with water and pumped dry again. A washing team should be set up with
two men at the pumproom lower level doing the washing and a support
team at the top of the pumproom. Both men in the washing team must wear
hydrocarbon detector alarms. If the bilges are especially dirty and
therefore liable to generate significant quantities of gas while washing,
then the washing team must wear breathing apparatus. If one man must
enter the bilges to complete part or all of the washing, then he must
wear breathing apparatus and a tended lifeline secured to his safety
harness.
A work permit should be issued for the pumproom washing operation. Additional
ventilation, using portable fans, should be provided to introduce fresh
air into the bilges and the pumproom exhaust fan(s) should be run on
high speed. The deck support team should have all necessary rescue equipment
ready. Before washing begins, pumproom equipment which is likely to
be damaged by water spray should be covered and sealed with plastic
film.
With the ship listed appropriately and the pumproom bilge pump running,
the washing team begins washing with the hand hose, working from the
far corner of the pumproom toward the bilge suction. The hose size and
flow rate should not exceed the capacity of the pumproom bilge pump/eductor
and the hose should be fitted with a valve so that the flow can be controlled,
or shut off by the nozzleman.
When the washing operation is completed, the hose team withdraws and
the pumproom is ventilated for several hours (overnight if possible),
to remove all hydrocarbon vapours. The chief officer should then test
the pumproom with the combustible gas indicator at all levels, including
the bilges (using the extension sampling hose).
With ventilation maintained as before, and with all of the tank entry
precautions in place as for cleaning cargo tanks, the crew can enter
the bilges and remove any sediment or scale remaining.
2.18.1 Pumproom bilge inspection
The time immediately after the pumproom bilges have been cleaned provides
the best opportunity for a thorough inspection. The inspection should
include (without being limited to):
Verify correct operation of the pumproom bilge alarm(s).
Check all valve, strainer and pump casing drain plugs are tight.
Check condition of all cargo piping drain valves and reach-rod connections.
Perform preventive maintenance thickness checks (if due), on cargo piping,
sea-chests, lower sections of bulkheads and bottom plate pitting.
Examine and record the condition of coatings in bilges.
Replace any permanent electrical lamps which are only accessible from
the bilges.
Check the condition of the gaskets and glands on all explosion-proof electrical
fixtures.
Perform the sea valve integrity test using the following procedure:
Use the test fittings installed according to the illustration on this
page. The test should be conducted in calm weather alongside a dock,
or at anchor.
1 Close the sea chest valve and block valve No.2.
2 Drain water from the pipe section between the sea
chest valve and block valve No.2.
3 Close block valve No.1.
4 Pressurise the pipe to about 50 psig (3.5 kg/cm2).
5 Watch the pressure gauge for a pressure drop over
15 minutes.
6 If a pressure drop is noted, check alongside the
ship for bubbles and at test fitting 'B' for leakage. A balloon fitted
over test fitting 'B' will indicate slow leaks. This will identify which
valve is leaking.
7 If the sea valve and block valve No.l are tight,
block valve No.2 may be tested by opening block valve No.l and closing
fitting 'B'. Re-pressurise the pipe to about 50 psig and watch for a
pressure drop over 15 minutes.
Immediately after pumproom cleaning, it may be desirable to complete
any other pumproom preventive maintenance scheduled for in the near
future.
Refer to text for detailed instructions.
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