Hong Kong Regulations

MERCHANT SHIPPING (PREVENTION OF OIL POLLUTION) REGULATIONS - SCHEDULE 4

GUIDELINES AND SPECIFICATIONS FOR OIL DISCHARGE MONITORING AND CONTROL SYSTEMS FOR OIL TANKERS

[regulation 15(3)]

1 PURPOSE

1.1 The purpose of these Guidelines and Specifications is- .1 to provide a
uniform interpretation of the requirements of regulation 15(3)(a) of these
Regulations; and .2 to assist in determining appropriate design, construction
and operational parameters for oil discharge monitoring and control systems
when such systems are fitted in ships.

2 BACKGROUND

2.1 The requirements relating to oil content monitoring of oil  tanker ballast
and tank washing water are contained in regulation 15(3)(a) of these
Regulations which stipulates that oil tankers of 150 gross registered tonnage
and above shall be equipped with an approved oil discharge monitoring and
control system and that the system shall record continuously- .1 the discharge
of oil in litres per mile and total quantity of oil discharged; or .2 in lieu
of the total quantity of oil discharged, the oil content of the effluent and
rate of discharge. In both cases the record shall be "identifiable as to the
time and date" and shall be kept for at least three years.

2.2 Regulation 15 also provides that the system shall come into operation when
there is any discharge of effluent into the sea and shall be such as will
ensure that any discharge of oily mixture is automatically stopped when the
instantancous rate of discharge of oil exceeds 30 litres per mile. In
existing oil tankers the stopping of the discharge may be performed manually
and the rate of discharge may be estimated from the pump characteristics.
(L.N. 641 of 1994)

2.3 A test and performance specification for the basic oil content meter
indicating oil content in ppm, is specified in Schedule 3 hereto.

3 APPLICATION

3.1 An oil discharge monitoring and control system of an approved design shall
be fitted in every oil tanker of 150 gross registered tonnage and above, and
shall be fitted in- .1 new tanker; .2 existing tankers, on or before 2 October
1986.

3.2 Existing tankers operating with dedicated clean ballast tanks in
accordance with regulation 18(9) must fit an oil content meter not later than
the first scheduled shipyard visit after the commencement of these
Regulations.

4 DEFINITIONS

In this Schedule-

4.1 "Oil discharge monitoring and control system"
(油類排放監察及控制系統) means an oil discharge monitoring and
control system covering any one of the units referred to in paragraphs 4.2,
4.3 and 4.4.

4.2 "Control unit"

4.2.1 "Control unit" (控制部件) means a control unit which receives
automatic signals of- .1 oil content; .2 flow rate of discharge; .3 ship's
speed in knots; .4 date and time (GMT); and .5 discharge valve position (open
or closed).

4.2.2 The unit shall make automatic recording of- .1 instantaneous rate of
discharge of oil; .2 total quantity of oil discharged; .3 date and time (GMT);
.4 discharge valve position (open or closed); .5 alarm condition; .6 failure
(i.e. no flow, fault etc.); and .7 override action (i.e. manual override,
flushing, calibration etc.).

4.2.3 The unit shall be fitted with a staring interlock and discharge valve
control capability. The unit shall meet the specifications contained in the
relevant paragraphs of section 6.

4.3 Computing unit

4.3.1 "Computing unit" (運算部件) means a computing unit which receives
automatic signals of- .1 oil content; .2 date and time (GMT); .3 discharge
valve activation; .4 flow rate of discharge; and .5 ship's speed in knots. The
flow rate and ship's speed may be manually inserted into the unit.

4.3.2 The unit shall make automatic recordings of- .1 instantaneous rate of
discharge of oil; .2 total quantity of oil discharged; .3 date and time (GMT);
.4 discharge valve position (open or closed); .5 alarm condition; .6 failure
(i.e. no flow, fault etc.); .7 override action; .8 manual input (i.e. speed,
flow); and .9 oil content if the flow rate has been manually inserted.

4.3.3 Unless explicitly stated in paragraph 5 the unit need not be fitted with
a starting interlock or discharge valve control capability.

4.3.4 The unit shall meet the specifications contained in the relevant
paragraphs of section 6.

4.4 Calculating unit

4.4.1 "Calculating unit" (計算部件) means a calculating unit which
receives automatic signals of- .1 oil content; .2 flow rate of discharge; .3
ship's speed. The flow rate and ship's speed may be manually inserted into the
unit.

4.4.2 The unit shall make an automatic recording of- .1 oil content, unless
the oil content meter is provided with a recorder.

4.4.3 The unit shall display- .1 instantaneous rate of discharge of oil; .2
total quantity of oil discharged, unless permitted to be calculated manually.

4.4.4 The time and date, instantaneous rate of discharge of oil and the total
quantity of oil discharged, unless permitted to be calculated manually.

4.4.5 The unit need not be fitted with a starting interlock nor discharge
valve control capability.

4.4.6 The unit shall meet the specifications contained in the relevant
paragraphs of section 6.

4.5 "Starting interlock" (起動連鎖) is an automatic device which prevents
the initiation of the opening of the discharge valve before the monitoring and
control system is fully operational when use of this system is required by
these Regulations.

4.6 The "discharge valve control" (排放閥門控制器) is an automatic
device which initiates the sequence to stop the overboard discharge.

5 IMPLEMENTATION REQUIREMENTS

5.1 The implementation scheme set out below provides different requirements
for oil discharge monitoring and control systems depending on size and
building date of the oil tanker. The scheme also allows for different
requirements, depending on the installation date of the system.

5.2 Under the implementation scheme contained in paragraph 5.4 oil  tankers of
150 gross registered tonnage and above have been arranged into five
categories. Each category of oil tanker shall be fitted with an oil discharge
monitoring and control system as set out below.

5.3 The implementation scheme set out in paragraph 5.4 gives details, with
reference to paragraph 4, of the minimum equipment required to comply with
this scheme. Where equipment of a higher category than required is fitted the
requirements of paragraph 5.4 shall be deemed to be complied with.

5.4 Implementation scheme

5.4.1 Category I .1 An oil tanker is in this category when it is of 4000 tons
deadweight and above and is a "new ship" as defined in regulation 1(2) of
these Regulations and the oil discharge monitoring and control system is
installed on or after 1 June 1982. .2 This category of ship shall be fitted
with a control unit as defined under paragraph 4.2.

5.4.2 Category II .1 An oil tanker is in this category when it is of 4000 tons
deadweight and above and is a "new ship" as defined in regulation 1(2) of
these Regulations and the oil discharge monitoring and control system is
installed before 1 June 1982. .2 This category of ship shall be fitted with a
computing unit as defined under paragraph 4.3. .3 The system shall also be
fitted with a starting interlock and a discharge valve control preventing the
discharge of effluent before the oil content meter is fully operative; in
addition the system shall be fitted with automatic devices to activate
overboard discharge valve closure.

5.4.3 Category III .1 An oil tanker is in this category when it is of 150
gross registered tonnage and above, but less than 4000 tons deadweight and is
a "new ship" as defined in regulation 1(2) of these Regulations. .2 This
category of ship shall be fitted with a computing unit as defined under
paragraph 4.3. .3 No automatic devices are required to activate overboard
discharge valve closure, neither is a starting interlock required.

5.4.4 Category IV(a) .1 An oil tanker is in this category when it is of 20000
tons deadweight and above and is an "existing ship" as defined in regulation
1(2) of these Regulations and the oil discharge monitoring and control system
is installed between 2 October 1984 and 2 October 1986. .2 This category of
ship shall be fitted with a computing unit as defined under paragraph 4.3. .3
The system shall also be fitted with a starting interlock but need not be
fitted with a discharge valve control preventing the discharge of effluent
before the oil content meter is fully operative but no automatic devices are
required to activate overboard discharge closure. .4 For oil tankers within
this category up to and including 100000 tons deadweight, where the overboard
discharge has local manual control or where control is provided by means of
extension rods, the Director may grant exemption from the requirement to fit a
starting interlock system.

5.4.5 Category IV(b) .1 An oil tanker is in this category when it is of 20000
tons deadweight and above and is an "existing ship" as defined in regulation
1(2) of these Regulations and the oil discharge monitoring and control system
is installed before 2 October 1984. .2 This category of ship shall be fitted
with a computing unit as defined under paragraph 4.3. .3 No automatic devices
are required to activate overboard discharge valve closure, neither is a
starting interlock required.

5.4.6 Category V(a) .1 An oil tanker is in this category when it is of 150
gross registered tonnage and above but less than 20000 tons deadweight and is
an "existing ship" as defined in regulation 1(2) of these Regulations and the
oil discharge monitoring and control system is installed between 2 October
1984 and 2 October 1986. .2 This category of ship shall be fitted with a
calculating unit as defined under paragraph 4.4. .3 No automatic devices are
required to activate overboard discharge valve closure, neither is a starting
interlock required.

5.4.7 Category V(b) .1 An oil tanker is in this category when it is of 150
gross registered tonnage and above but less than 20000 tons deadweight and is
an "existing ship" as defined in regulation 1(2) of these Regulations and the
oil discharge monitoring and control system is installed before 2 October
1984. .2 This category of ship shall be fitted with a calculating unit as
defined under paragraph 4.4. However, the total quantity of oil discharged may
be computed manually. .3 No automatic devices are required to activate
overboard discharge valve closure, neither is a starting interlock required.

5.5 The Appendix to this Schedule is a summary, in tabular form, of the above
implementation requirements.

6 TECHNICAL SPECIFICATIONS

6.1 Oil discharge monitoring and control system

6.1.1 The oil discharge monitoring and control system shall be so fitted that
it can effectively monitor and control the discharge of any effluent into the
sea through those overboard discharge outlets permitted by regulation 26(2)
which in the opinion of the Director are necessary to fulfil the operational
requirements of the tanker. The system may additionally cover- .1 the
gravitational discharge of ballast water from cargo tanks; and .2 the midship
cargo manifold arrangement when used to meet the requirements of regulation
26.

6.1.2 Dirty ballast water or oil contaminated water shall not be discharged
into the sea through outlets which are not controlled by the monitoring and
control system.

6.1.3 The system shall function effectively, according to the criteria shown
below, under all environmental conditions which vessels are normally assumed
to encounter, and shall be designed and constructed to withstand the
environmental conditions as specified in paragraph 6.1.6 of these Guidelines
and Specifications- .1 Except where manual operation of the system is
permitted the system shall be so designed that no ballast discharge can take
place unless the monitor is in the normal operating mode and the relevant
sampling point has been connected to the monitor. .2 Preferably the system
should have a minimum number of discharge outlets and sampling points so
arranged that discharge can take place via only one sampling point at a time.
.3 Where it is intended that more than one line shall be used for simultancous
discharge purposes, one oil content meter, together with a flow meter, shall
be installed per discharge line. These instruments shall be connected to a
common processing unit. .4 In order to avoid alarms due to short term high oil
concentration signals (spikes) causing indications of high instantaneous rates
of discharge, the short term high ppm signal may be suppressed for a maximum
of 10 seconds by employing a delay relay. Alternatively, the instantaneous
rate of discharge may be the average during the preceding 20 seconds or less
as computed from instantaneous ppm values produced by the oil content meter
with intervals of a maximum 5 seconds.

6.1.4 The system shall comprise the following- .1 an oil content meter to
measure the oil content of the effluent in parts per million. This meter shall
be approved in accordance with the provisions contained in Schedule 4 hereto
and to take into account the range of cargoes carried; .2 a flow rate system
to indicate the quantity of effluent being discharged in a unit of time (see
also paragraphs 6.3.7 and 6.3.8); .3 a vessel speed indicating device; to give
the vessel's speed in knots (see also paragraphs 6.4.2 and 6.4.3); .4 a
sampling system, to convey a representative sample of the effluent to the oil
content meter; .5 a control section which includes- .1 a processor, which
accepts signals of oil content, flow rate and the vessel's speed and converts
them into litres per mile and the total quantity of oil discharged (see also
paragraph 6.5.3); .2 a transmitting device to provide alarms and, where
required command signals to the discharge control arrangement; .3 a recording
device to provide, where required, a continuous record of the effluent
discharged; .4 a manual override system to be used in the event of failure of
the monitoring and control system; and .5 where required a transmitting device
to provide signals to a starting interlock preventing the discharge of
effluent before the oil content meter is fully operative.

6.1.5 The electrical components of the system installed in a hazardous area of
a vessel shall meet the appropriate safety requirements provided for these
areas.

6.1.6 The control section of an oil discharge monitoring and control system
shall be capable of operating satisfactorily under the following environmental
conditions- .1 Ambient air temperature: 0℃ to 55℃ in enclosed spaces:
-25℃ to 55℃ on open decks .2 Vibration: 2.0 to 13.2 Hz, with displacement
amplitude of ±1.0 mm
13.2 to 80.0 Hz with an acceleration amplitude of ±0.7 g .3 Voltage
variations for alternating current: permanent variation of ±10% .4
Inclination: inclination at angles of up to 22.5o in any plane from the normal
operational position

6.2 Sampling system

6.2.1 Sampling points shall be so located that relevant samples can be
obtained from those out- lets that are used for operational discharges in
accordance with paragraph 6.1.1. The sampling probes located in the overboard
discharge lines and the piping system connecting the sampling probes to the
oil content meter shall meet the following requirements- .1 the piping and
probe shall be of corrosion-resistant and oil-resistant material, of adequate
strength, properly jointed and supported; .2 the system shall have a stop
valve fitted adjacent to each probe, except that where the probe is mounted in
a cargo line, that is to the midship cargo manifold arrangement, two stop
valves shall be fitted, in series in the sample line; .3 sampling probes shall
be arranged for easy withdrawal and shall be mounted as far as practicable at
an accessible location in a vertical section of the discharge line. If a
sampling point has to be made in a horizontal section then suitable
arrangements shall be made to obtain representative samples. Sampling probes
shall normally penetrate inside the discharge pipe to a distance of one
quarter the diameter of that pipe; .4 means shall be provided for cleaning the
probes and piping system by the provision of permanent clean water flushing
arrangements or some other equivalent method, especially in the case of probes
mounted in a cargo line. The design of the probes and piping shall be such as
to minimize their clogging by oil, oily residue and other matter; .5 the
velocity of the fluid in the piping shall be such that, taking into
consideration the length of the piping, the overall response time shall be as
short as possible between an alteration in the mixture being pumped and the
alteration in the meter reading and in any case not more than 40 seconds; .6
the location of sampling probes in relation to any point of flow diversion to
a slop tank shall be selected with regard to the need for sampling the oily
water during the recirculation mode; .7 the arrangements for driving the
sampling pump or any other pumps such as those provided for washing windows
shall have regard to the safety requirements of the space in which the pump is
located; .8 the flushing arrangements shall be such that where necessary they
can be utilized for stabilizing the oil content meter and correcting for zero
settings; and .9 sample water when returned to the slop tank shall not be
allowed to free fall into the tank.

6.3 Flow rate indicating system

6.3.1 A flow meter for measuring the rate of discharge shall be installed in a
vertical section of a discharge line or in any other section of discharge line
as appropriate, so as to be always filled with the liquid.

6.3.2 A flow meter shall employ an operating principle which is suitable for
shipboard use and, where relevant, can be used in large diameter pipes.

6.3.3 A flow meter shall be suitable for the full range of flow rates that may
be encountered during normal operation. Alternatively, arrangements such as
the use of two flow meters of different ranges or a restriction of the
operational flow rate range may be employed to meet this requirement.

6.3.4 The flow meter, as installed, shall have an accuracy of ±15 per cent,
or better, of the instantaneous rate throughout the operating range.

6.3.5 Any component part of the flow meter in contact with the effluent
discharge including associated piping, if fitted, shall be of
corrosion-resistant and oil-resistant material of adequate strength.

6.3.6 The design of the flow metering arrangements shall have regard to the
safety requirements of the space in which it is located.

6.3.7 In ships fitted with a computing unit the flow rate may be determined
from the pump characteristics and the data manually inserted into the unit.

6.3.8 In ships fitted with a calculating unit the flow rate may be manually
inserted into the unit. The flow rate shall be estimated from the best
available source e.g. pump characteristics, speed of pump(s), ullages or
knowledge of pumping rates for particular tanks on the ship.

6.3.9 In oil tankers where the gravitational discharge of ballast water from
the cargo tanks in accordance with regulation 26(6)(d) is permitted means,
such as calibration curves, shall be provided to estimate the flow rate of
discharge.

6.4 Vessel's speed indicating system

6.4.1 The automatic speed signal required for the control unit shall be
obtained from the vessel's speed indicating device by means of a repeater
signal. This information shall be readily available in a form that can be
accepted by a processor. The speed information used may be either speed over
the ground or speed through the water depending upon the speed measuring
equipment installed on board.

6.4.2 In ships where a computing unit is required the vessel's speed may be
manually inserted into the unit. This data shall be obtained from the ship's
log or from an indicating device which transmits signals which need not be in
a form which can be accepted by a computer system.

6.4.3 The vessel's speed on ships required to install a calculating unit may
be obtained from the ship's log or from the navigation charts and shall be
estimated from the most reliable source.

6.5 Processor and transmitting device

6.5.1 The processor shall receive, at time intervals not exceeding 5 seconds,
signals from the oil content meter, the flow rate measuring system and the
vessel's speed indicator and automatically compute the following- .1
instantaneous rate of discharge of oil in litres/mile; and .2 total quantity
of oil discharged per voyage in m 3 or litres.

6.5.2 When the rates of discharge calculated by the processor exceed the
limits imposed by regulation 13(2)(d) and (e) the transmitting device shall
provide alarms and, in new ships, it shall also provide command signals to the
discharge valve control which will cause the discharge of effluent into the
sea to stop.

6.5.3 In existing ships fitted with a calculating unit where the unit is
installed on 2 October 1984 the total quantity of oil discharged may be
computed manually.

6.6 Recording Devices

6.6.1 Control Unit .1 The recording device for a control unit shall include a
digital printer or an analogue recorder or a combination of both or a recorded
visible display. The record shall be identifiable as to time and date and
shall be kept for at least 3 years. .2 The data to be automatically recorded
shall include at least the following items- .1 instantaneous rate of discharge
of oil (litres per mile); .2 the total quantity of oil discharged (litres); .3
time and date (GMT); .4 the discharge valve position (open or closed); .5
alarm condition; .6 failure (i.e. no flow, fault, etc.); and .7 override
action (i.e. manual override, flushing, calibrating, etc.).

6.6.2 Computing Unit .1 The recording device for a computing unit shall
include a digital printer or an analogue recorder or a combination of both or
a recorded visible display. The record shall be identifiable as to time and
date and shall be kept for at least 3 years. Manual input information shall be
identifiable on the record. .2 The data to be automatically recorded shall
include at least the following items- .1 instantaneous rate of discharge of
oil (litres per mile); .2 the total quantity of oil discharged (litres); .3
time and date (GMT); .4 manual input information; .5 the valve position (open
or closed); .6 alarm condition; .7 failure (i.e. no flow, fault, etc.); .8
override action (i.e. manual override, flushing, calibration, etc.); and .9
oil content if flow rate is manually inserted.

6.6.3 Calculating Unit .1 An automatic recording device is not required for a
calculating unit, but, where fitted, the recording device shall include a
digital printer or an analogue recorder or a combination of both or a recorded
acceptable visible display. The record shall be identifiable as to time and
date, which may be entered manually, and shall be kept for at least 3 years.
.2 The data to be automatically recorded on the above-mentioned recording
device shall include at least the following item- .1 oil content in ppm,
unless the oil content meter is provided with a recorder.

6.6.4 Recording for digital printers Occasions of recordings. Data required by
paragraphs 6.6.1.2, 6.6.2.2 and 6.6.3.2 of these Specifications shall be
printed out with the following minimum frequency- .1 when the discharge is
started; .2 when the discharge is stopped; .3 at intervals of not more than
every 10 minutes; .4 when an alarm condition is developed; .5 when normal
conditions are restored; .6 at the change of valve order or valve position; .7
when introducing input data; .8 at not more than every 10 litre/mile change in
computed rate of discharge, unless an equivalent trend indicating arrangement
is provided; .9 when selecting zero setting or calibration mode; and .10 on
manual command.

6.6.5 Recording for analogue recorders Data required by paragraphs 6.6.1.2,
6.6.2.2 and 6.6.3.2 of these Specifications shall be continuously recorded in
such a way as would satisfy the following requirements- .1 the chart speed
shall be indicated. If the speed is controllable, the recorder shall be
provided with a marker to identify the speed of the chart paper; and .2 means
shall be provided to enable the chart paper to be interpreted as to time, date
and readings after it has been removed from the recorder.

6.7 Data display

6.7.1 The current data shall be visibly displayed.

6.7.2 The recording device and data display shall be located in a position
easily accessible to the person in charge of the operation of discharging the
effluent overboard.

6.8 Manually operated alternatives

6.8.1 The alternative means and information for use in case of any one failure
in the system shall be as follows- .1 oil content meter: visual observation of
the surface of the water; .2 sampling pump: visual observation of the surface
of the water; .3 flow meter: pump characteristics, etc.; .4 vessel's speed
indicating device: main engine rpm etc.; .5 processor: manual calculation and
manual recording; and .6 discharge valve control: manual operation of pumps
and valves.

6.9 Alarm conditions resulting in the stopping of discharge.

6.9.1 Audio-visual alarms shall be initiated for any of the following
conditions- .1 whenever the instantaneous rate of discharge of oil exceeds 60
litres per mile; .2 when the total quantity of oil discharged reaches the
allowable limit prescribed by the provisions of the relevant Regulations; .3
failure of the system's operation, such as- .1 power failure; .2 loss of
sample; .3 failure of the measuring or recording system, and .4 when the input
signal of the sensors exceeds the effective capacity of the system.

6.10 Location of alarm indicator

6.10.1 The alarm indicator of the system shall be installed in the cargo
control room where provided and/or other places where it will attract
immediate attention and action.

7 EQUIPMENT, OPERATION AND MAINTENANCE MANUALS

7.1 The owner shall ensure that approved equipment, operational and/or
maintenance manuals for the various items comprising the oil discharge
monitoring and control systems are on board the vessel. These manuals shall
cover the oil content meter, control, computing or calculating unit, flow
meter and ship's speed indicator, where required.

APPENDIX

OIL DISCHARGE MONITORING AND CONTROL SYSTEM FOR OIL TANKERS-SUMMARY OF
IMPLEMENTATION REQUIREMENTS

CATEGORY TYPE
Feature I II III IV(a) IV(b) V(a) V(b)
Applicability New≧4K New≧4K New <4K						Existing≧20K						Existing<20K

Compliance Late Early Late or early Late Early Late Early

A
A
A
A
A
A
A
A M M M M E E
A M M M M E E
Input information
Ppm
Flow rate
Speed
Time and date A A A A A M M
Starting interlock A A A*
Discharge valve
control A A

A A A A A A M* A M*
A A A A A A M* M*
A A A A A M* M*
Output information 1/mile Total quantity Time and date Ppm A A A A A A

System format Control unit Computing unit Calculating unit

Key to Table: NEW -New oil tanker according to regulation 1(2) of these
Regulations EXISTING -Existing tanker according to regulation 1(2) of these
Regulations K -1000 tons deadweight EARLY-NEW -Before 1 June 1982
EARLY-EXISTING -Before 2 October 1984 LATE-NEW -On or after 1 June 1982
LATE-EXISTING -Between 2 October 1984 and 2 October 1986 A -Automatic function
M -Manually inserted data from installed source E -Manually inserted data
estimated from best available source A* -Automatic function, but waivers may
be granted for oil tankers≦ 100K where the overboard
discharge valve control system is manual M* -Manual recording NOTE: CBT
tankers shall fit oil content meters not later than the first scheduled dry
dock after the commencement of these Regulations CONTROL UNIT -The complete
control system as required by regulation 15(3)(a) of these Regulations
COMPUTING UNIT -Computer with manual input of speed and flow rate. Automatic
input of ppm and a built-in clock. The output information is automatically
recorded CALCULATING UNIT -A calculating device capable of converting ppm,
speed and flow rate information to 1/mile
(and total quantity) available for use during the discharge operation. An
automatic recording is not required □ -Information presented on permanent
record "Oil discharge monitoring and control system"
(油類排放監察及控制系統) "Control unit" (控制部件) "Computing
unit" (運算部件) "Calculating unit" (計算部件) "Starting interlock"
(起動連鎖) "discharge valve control" (排放閥門控制器)