7.1.2 Pipe
systems carrying sea-water or fresh water are to meet the requirements
of Vol 2, Pt 7, Ch 1 Piping Design Requirements, Vol 2, Pt 7, Ch 2 Ship Piping Systems and Vol 2, Pt 7, Ch 3 Machinery Piping Systems. Where there is a risk of fresh-water or sea-water systems
becoming contaminated with process chemicals, substances or effluent,
pipe systems are to comply with Vol 2, Pt 12, Ch 1, 7.1 General 7.1.1.
7.1.3 Chemical transfer and control arrangements are to be provided with one
stop-valve capable of being manually operated on each tank filling and discharge line,
located near the tank penetration, plus one stop valve at each chemical-hose loading
connection. The stop valve for the chemical tank discharge line is additionally to the
quick closing type and is to meet the requirements of Vol 2, Pt 12, Ch 1, 9.1 General 9.1.6.
7.1.4 Bilge
and effluent pumping and piping systems in the emissions abatement
plant spaces are to be constructed of materials suitable for any chemicals
or substances used by the emissions abatement plant, any effluent
that is produced or any combination of substances on board which might
result from accidental admixture.
7.1.5 Arrangements
are to be provided for the control of the bilge and effluent pumping
and piping system. They are to be installed in the emissions abatement
plant spaces from within these spaces and also from a position outside
the spaces.
7.1.6 Bilge
and effluent pumping and piping systems for hazardous materials should,
wherever possible, be installed in the space associated with the particular
hazard.
7.1.8 Where
filters are used, they are to be capable of being removed for cleaning
and replaced safely without interrupting emissions abatement plant
or combustion machinery operations.
7.1.9 Where
scrubbers are used, the following apply:
-
Closed loop wet
scrubbers are to have natural gravity fall drainage from the wet sump
of the scrubber to the process tank or circulating pump suction, with
the drain line dimensioned to accommodate 125 per cent of the maximum
pumping capacity of the installed water pump(s). No valves are to
be fitted to the drain line from the scrubber sump to the process
tank unless it can be demonstrated that suitable precautions are in
place to prevent the possibility of the scrubber filling with water
and reverse-flowing into the combustion machinery exhaust duct. Where
a valve is fitted to this line, the system is to be protected as for
the overboard discharge valve of an open loop system, in accordance
with Table 1.9.1 Machinery emissions to air
abatement plant: alarms and safeguards.
-
For open loop
wet scrubbers, the overboard discharge valve and any other sea-water
valves downstream of the scrubber are to be protected in accordance
with Table 1.9.1 Machinery emissions to air
abatement plant: alarms and safeguards. The sea
suction valve(s) are also to have position indicators which are to
give remote indication of valve position. The scrubber is to be mounted
above the waterline under all normal ship operating conditions to
prevent sea-water ingress into the scrubber.
-
For wet scrubbing
systems (open loop and closed loop), an overflow line is to be fitted
to prevent the risk of reverse flow of water to combustion machinery.
This overflow is to be dimensioned to accommodate 125 per cent of
maximum capacity of installed water pumps and is to have no impairment
to flow. This overflow line is to be directed to the process tank
in closed loop or hybrid installations. On open loop installations,
it is to be directed overboard. The overboard discharge is to have
an effective means of preventing reverse flow of seawater. Alternative
arrangements to prevent the risk of reverse flow are subject to special
consideration.
-
Overboard discharge
connections from scrubbers are to be positioned below the lowest operating
waterline and are to be internally protected from effluent-induced
corrosion.
7.1.10 Where
applicable, tanks are to be maintained within the temperature limits
of the chemicals and substances they contain so as to avoid risks
of boiling, stress corrosion, freezing and other temperature-sensitive
processes.