3.15.1 The effluent piping from scrubbers and
deck water seal drain pipes, where fitted, should be of corrosion-resistant
material, or of carbon steel suitably protected internally against
the corrosive nature of the fluid.
3.15.2 The scrubber effluent pipe and deck water
seal drain pipe, where fitted, should not be led to a common drain
pipe and the deck seal drain should be led clear of the engine-room
and any other gas-safe space.
3.15.3 Piping made in glass-reinforced plastics
of acceptable manufacture, substantial thickness, pressure tested
and adequately supported, may be acceptable for effluent piping from
scrubbers under the following conditions:
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.1 The effluent lines should, as far as possible,
be led through cofferdams or ballast tanks and be in accordance with
the load line regulations in force.
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.2 Where effluent lines are led through machinery
spaces the arrangements should include:
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.2.1 a valve fitted to a stub piece at the shell
and actuated both from inside and outside the machinery space by pneumatic
or hydraulic means led through steel piping. The valve should close
automatically in the event of failure of the operating media. The
valve should have a position indicator. This valve is to be closed
at all times when the plant is not in operation as well as in the
event of a fire in the machinery space. Suitable instructions to this
effect are to be given to the master;
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.2.2 a flap nonreturn valve;
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.2.3 a short length of steel pipe, or spool piece,
lined internally and fitted between the valve referred to in .1 above
and the nonreturn valve referred to in .2 above; this is to be fitted
with a 12.5 mm diameter flanged drain branch pipe and valve;
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.2.4 a further spool piece fitted inboard of,
and adjacent to, the nonreturn valve referred to in .2 above, similarly
fitted with a drain.
Note The purpose of this arrangement is to enable the tightness
of the valves and nonreturn valves referred to in .1 and .2 above
to be checked and to facilitate the removal of the nonreturn valve
for examination and replacement);
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.2.5 means should be provided outside the machinery
space for stopping the scrubber pump.
A suitable
arrangement is illustrated in figure 17.
3.15.4 A water seal in the shape of a `U' bend
at least 2 m in depth should be fitted at least 2 m below the equipment
to be drained. Means should be provided for draining the lowest point
of the bend. In addition the seal should be adequately vented to a
point above the water level in the scrubber or deck water seal.
3.15.5 The diameter of the effluent and drain
pipes should be adequate for the duties intended and the pipe run
should be self draining from the water seal referred to in 3.15.4.