Crude Oil Washing Cow

Hindustan Institute of Maritime TrainingChennai

9 CRUDE OIL W9 CRUDE OIL W9 CRUDE OIL W9 CRUDE OIL W9 CRUDE OIL WASHINGASHINGASHINGASHINGASHINGREVISED SPECIFICATIONS FOR THE DESIGN, OPERATION AND CONTROL OF CRUDE OIL

WASHING SYSTEMS

(Resolution A. 446 (XI) adopted on 15 November 1979 by the Assembly of the International MaritimeOrganisation of its eleventh session”)

THE ASSEMBLY

Recalling resolution A-297 (VIII) by which it established the Marine Environment Protection Committee andspecified the functions and responsibilities of that Committee.

Recalling also Regulation 13B (2) of Annex I of the Protocol of 1978 relating to the International Convention forthe Prevention of Pollution from Ships, 1973; concerning requirements for crude oil washing and resolution 15 of theInternational Conference on Tanker Safety and Pollution Prevention. 1978 which contains the Specification for theDesign Operation and Control of Crude Oil Washing System.

Recalling further that by the same resolution the Conference requested the Organisation to review and revise, as neces-sary, the Specifications to reflect the latest technology and practices as may be developed by the time of entry into forceof the Protocol.

Having Considered the recommendation made by the Marine Environment Protection Committee at its eleventhsession.

1. ADOPTS

(a) The revised Specifications for the Design, Operation andControl Crude Oil Washing Systems the text of which is set out inthe Annex to the present resolution to supersede the Specificationsfor the Design, Operation and Control of Crude Oil Washing Systemscontained in resolution 15 of the International Conference on TankerSafety and Pollution Prevention 1978;

(b) Agreed interpretations of certain of the provisions of therevised Specifications as shown in Appendix III of the revisedSpecifications;

2. Urges Governments of establish, in time for the entry into force of the Protocol of 1978 relating to the Interna-tional Convention for the Prevention of Pollution from Ships, 1973, requirements based on the revised Specifications ;

3. Urges Further that the requirements to be established by Administration should not impose requirements overand above those as laid down in the revised Specifications.


ANNEX

REVISED SPECIFICATIONS FOR THE DESIGN, OPERATION

AND CONTROL OF CRUDE OIL WASHING SYSTEMS

INDEX

1. Purpose 3802. Application 380

3. General provisions 3803.1 Definitions 3803.2 Initial survey 380

4. Design criteria4.1 Piping 3814.2 Tank washing machines 3824.3 Pumps 3854.4 Stripping system 3864.5 Ballast lines 387

5. Qualification of personnel 387

6. Operation6.1 Tankage to be crude oil washed 3886.2 Drainage and discharge ashore of cargo lines 3896.3 Filling of departure ballast tanks 3896.4 Crude oil washing at sea 3896.5 Discharge of oily water effluents on ballast voyage 3896.6 Use and control oil inert gas 3896.7 Precautions against electrostatic generation 3906.8 Vapour emission 390

7. Operations and Equipment Manual 390

Appendix I -List of charge when applying the Specifications to new crude oil tankersof 20,000 tons deadweight and above 393

Appendix II - Training for persons intended to assume overall charge of crude oilwashing 395

Appendix III - Agreed interpretations of certain of the provisions of the revisedSpecifications 397

1. Purpose


The purpose of these Specifications is to provide specific design criteria, operation; requirements and control andenforcement procedures for the crude oil washing of cargo tanks of crude oil carriers as specified in section 2.

2. Application

2.1 These Specifications apply to :

(a) Existing crude oil tankers of 40,000 tons deadweight and abovein accordance with Regulation 13(8) of Annex-I of MARPOL 73/78 :

(b) New crude oil tankers of 20,000 tons deadweight and above inaccordance with Regulation 13 (6) of Annex-I of MARPOL 73/78,with the changes listed in Appendix-I.

Compliance of these ships with these Specifications shall be shown on the International Oil Pollution PreventionCertificate as modified by MARPOL 73/78.

2.2 If a crude oil that is not suitable oil washing is intended to be carried as cargo in a ship that is providedwith only a crude oil washing system, then that ship must comply with segregated ballast tank requirements in accor-dance with Regulation 13 (9) of Annex-I of MARPOL 73/78.

3. GENERAL PROVISIONS

3.1 Definitions

For the purpose of these Specifications :

3.1.1. “Arrival ballast” means clean ballast as defined in Regulation 1(16) of Annex-I of MARPOL 73/78.

3.1.2. “Departure ballast” means ballast other than arrival ballast.

3.2 Initial Survey

The initial survey referred to in Regulation 4 of Annex-I of MARPOL 73/78 shall include a complete inspection ofthe crude oil washing equipment and arrangements and shall include, except for the cases specified in 4.2.11 an exami-nation of the tanks after they have been crude oil washed and the additional controls as specified in 4.2.10 to ensure thatthe washing system efficiency is in accordance with these Specifications.

4. Design Criteria

4.1 Piping

4.1.1 The crude oil washing pipes and all valves incorporates in the supply piping system shall be of steel orother equivalent material and shall be of adequate strength having regard to the pressure to which they may be subjectedand shall be properly jointed and supported.

4.1.2 The crude oil washing system shall consist of permanent pipework and shall be independent of the fire


mains and of any system other than for tank washing except than sections of the ships cargo system may be incorpo-rated in the crude oil washing system provided that they meet the requirements applicable to crude oil pipework Not-withstanding the above requirements in combination carriers the arrangement may allow.

(a) The removal of the equipment, if necessary, when carrying cargoesother than crude oil, provided that, when reinstated, the system isas originally fitted and tested for oil tightness ;

(b) The use of flexible hose pipes to connect the crude oil washingsystem to tank washing machines if it is necessary to locate thesemachines in a cargo tank hatch cover. Such flexible hose pipesmust be provided with flanged connections and be manufacturesand tested in accordance with standards acceptable to theAdministration and be consistent with the duties the hoses arerequired to perform. The length of these hoses shall be no greaterthan necessary to connect the tank washing machines to an adjacentpoint just outside the hatch coaming. These hoses shall be removedto suitably prepared and projected stowage when not in use and bepressure tested by an authority acceptable to the Administration atintervals of not more than two and a half years.

4.1.3 Provision shall be made to prevent overpressure in the tank washing supply piping. Any relief devicefitted to prevent overpressure shall discharge into the suction side of the supply pump. Alternative methods to thesatisfaction of the Administration may be accepted provided an equivalent degree of safety and environmental protectionis provided.

4.1.4. Where hydrant valves are fitted for water washing purposes on tank washing lines, all such valves shallbe of adequate strength and provision shall be made for such connections to be blanked off by blank flanges whenwashing lines may contain crude oil. Alternatively, hydrant valves shall be isolated from the crude oil washing system byspade blanks.

4.1.5 All connexions for pressure causes or other instrumentation shall be provided with isolating valvesadjacent to the lines unless the fitting is of sealed type.

4.1.6 No part of the crude oil washing system shall enter the machinery spaces. Where the tank washingsystem is fitted with a stream heater for use when water washing, the heater must be effectively isolated during crude oilwashing by double shut-off valves or by clearly identifiable blanks.

4.1.7 Where a combines crude oil-water washing supply piping is provided the piping shall be so designedthat it can be drained so far as is practicable of crude oil, before water washing is commenced, into spaces designatedin the Operations and Equipment Manual. These spaces may be the slop tank or other cargo spaces.

4.1.8. The piping system shall be of such diameter that the greatest number of tank cleaning machines required,as specified in the Operations and Equipment Manual, can be operated simultaneously at the designed pressure and


throughput. The arrangement of the piping shall be such that the required number of tank cleaning machines to eachcargo compartment, as specified in the Operation and Equipment Manual referred to in these Specifications, can beoperated simultaneously.

4.1.9 The piping system shall be tested to one and one half times the working pressure after it has beeninstalled on the ship.

4.1.10 The crude oil washing supply piping shall be anchored (firmly attached) to the ship’s structure at appro-priate locations, and means shall be provided to permit freedom of movement elsewhere to accommodate thermalexpansion and flexing of the ship. The anchoring shall be such that any hydraulic shock can be absorbed without unduemovement of the supply piping. The anchors should normally be situated at the ends furthest from the entry of the crudeoil supply to the supply piping. If tank washing machines are used to anchor the ends of branch pipes then specialarrangements are necessary to anchor these sections when the machines are removed for any reason.

4.2 Tank washing machines

4.2.1 The tank washing machines for crude oil washing shall be permanently mounted shall be of a designacceptable to the Administration.

4.2.2 The performance characteristic of a tank washing machine is governed by nozzle diameter, workingpressure and the movement pattern and timing. Each tank cleaning machines fitted shall have a characteristic such thatthe sections of the cargo tank covered by that machine will be effectively cleaned within the time specified in the Opera-tions and Equipment Manual.

4.2.3 Tank washing machines shall be mounted in each cargo and the method of support shall be to thesatisfaction of the Administration. Where the tank washing machines are positioned well below the deck level to caterfor protuberances in the tank consideration may need to be given to additional support for the machines and their supplypiping.

4.2.4 Each machine shall be capable of being isolated by means of stop valves in the supply line. If a deckmounted tank washing machine is removed for any reason, provision shall be made to blank off the oil supply line to themachine for the period the machine is removed Similarly provision shall be made to close the take opening with a plateor equivalent means.

4.2.5 Where the drive units for the tank cleaning machines are not integral with the tank cleaning machine,sufficient drive units shall be provided to ensure that no drive unit need be removed more than twice from its originalposition during cargo discharge to accomplish the washing programme as specified in the Operations and EquipmentManual.

4.2.6 The number and location of the tank washing machines shall be to the satisfaction of the Administration.

4.2.7 The location of the machines is dependent upon the characteristics detailed 4.2.2 and upon the configu-ration of the internal structure of the tank.

4.2.8. The number and location of the machines in each cargo tank shall be such that all horizontal and verticalareas are washed by direct impingement of effectively by deflection or splashing of the impinging jet. In assessing an


acceptable degree of jet deflection and splashing , particular attention shall be paid to the washing of upward facinghorizontal area and the following parameters shall be used :

(a) For horizontal areas of a tank bottom and the upper surfaces of atank’s stringers and other large primary structural members, thetotal area shielded from direct impingement by deck or bottomtransverses, main girders, stringers or similar large primarystructural members shall not exceed 10 per cent of the total horizontalarea of tank bottom, the upper surface of stringers, and other largeprimary structural members.

(b) For vertical areas of the sides of a tank, the total area of the tank’ssides shielded from direct impingement by deck or bottomtransverses, a mind girders, stringers or similar large primarystructural members shall not exceed 15 per cent of the total area ofthe tank’s sides.

(c) For existing crude oil tankers, the Administration may permit thepercentages required in (a) and (b) above to be exceeded for thankshaving complicated internal structural members, provided that thepercentages calculated over all the cargo tanks do not exceed 10per cent for horizontal areas and 15 per cent for the total areas.

In some installations it may be necessary to consider the fitting of more than one type of tank washing machine inorder to effect adequate coverage.

4.2.9. At the design stage the following minimum procedures shall be used to determine the area of the tanksurface covered by direct impingement.

(a) Using suitable structural plans, lines are set out from the tips ofeach machine to those [arts of the tank within the range of thejets.

(b) Where the configuration of the tanks is considered by theAdministrator to the complicated, a pinpoint of light simulating thetip of the tank washing machine or a scale model of the tank shallbe used.

4.2.10 (a) To confirm the cleanliness of the tank and to verify the design in respect of the member and locationof the tank washing machines, a visual inspection shall be made by entry to the tanks after a crude oil wash but prior toany water rinse which may be specified in the Operations and Equipment Manual. The bottom of the tank to be in-spected may, however, be flushed with water and stripped in order to remove any wedge of crude oil remaining on thetank bottom before gas freeing for entry. This inspection shall ensure that the tank is essentially free of oil clinged anddeposits. If the flushing procedure is adopted a similar but unflushed tanks must be used for the test specified in abelow.


(b) To verify the effectiveness of the stripping and drainage arrangement, a measurement shall be made of theamount of oil floating on top of the departure ballast. The ratio of the volume of oil on top of the total departure ballastwater to the volume of tanks that contain this water shall be carried out after crude oil washing and stripping in a tanksimilar in all relevant respects to the tank examined in accordance with (a) above, which has not been subject to waterPipes or to the interventing water flushing permissible in (a) above.

(c) To verify the design, installation and operation of the system the arrival ballast after a typical ballast voyagebefore which the arrival ballast tanks have been crude of washed and during which the tanks have been water rinsed inaccordance with the programme set out in your Operations and Equipment Manual, shall be totally discharges to theloading port harbour through an oil monitoring system approves by the Administration. The oil content of the effluent inthis test shall not exceed 15 ppm.

4.2.11 Where an Administration is satisfied that ships are similar in all relevant respects, the requirements of4.2.10 need only be applied to one such ship. Further more where a ship has a series of tanks that are similar in allrelevant respects then, for that series of tanks, the requirement of 4.2.10 (a) need only be applied to one tank of thatseries.

4.2.12 The design of the deck mounted tank washing machines shall be such that means are provided, externalto the cargo tanks, which, when crude oil washing is in progress would indicate the rotation and arc of the movement ofthe machine. Where the deck mounted machine is of the non-programmable, dual nozzle type, alternative methods tothe satisfaction of the Administration may be accepted provided an equivalent degree of verification is attained.

4.2.13 Where submerged machines are required, they should be non-programmable and in order to complywith the requirements of 4.2.8, it must be possible to verify their rotation by one of the following methods :

(a) By indicators external to the tank ;

(b) By checking the characteristic sound pattern of the machine,in which case the operation of the machine shall be verified towardsthe end of each wash cycle. Where two or more submerged machinesare installed on each machine can be verified independently of theother machines on the same supply line;

(c) By gas freeing the tank and checking the operation of themachine with water during ballast voyages. In this case the checkshall take place after a maximum of six usages of the machine butthe interval between checks shall not exceed 12 months. Eachverification shall be recorded in Supplement 2 to the Oil RecordBook.

The method of verification shall be started in the Operations and equipment Manual.

4.3 Pumps

4.3.1 The pumps supplying crude oil to the tank cleaning machines shall be either the cargo pumps or pumpsspecifically provided for the purpose.


4.3.2. The capacity of the pumps shall be sufficient to provide the necessary throughput at the required pres-sure for the maximum number of tank cleaning machines required to the operated simultaneously as specified in theOperations and Equipment Manual. In addition to the above requirement, the pumps shall, if an educator system is fittedfor tank stripping be capable of supplying of educator driving fluid

to meet the requirements of 4.4.2.

4.3.3. The capacity of the pumps shall be such that the requirements of 4.3.2. can be met with any one pumpinoperative. The pumping and piping arrangement shall be such that the crude oil washing system can be effectivelyoperated with any one pump inoperative. The pumping and piping arrangements shall be such that the crude oil washingsystem can be effectively operated with any one pump out of use.

4.3.4. The carriage of more than one grade of cargo shall prevent crude oil washing of tanks.

4.3.5 To permit crude oil washing to be effectively carried out where the back pressure presented by theshore terminal is below the pressure required for crude oil washing, provision shall be made such that an adequatepressure to the washing machines can be maintained in accordance with 4.3.2. This requirement shall be met with anyone cargo pump out of action. The minimum supply pressure requires for crude oil washing shall be specified in theOperations and Equipment Manual. Should this minimum supply pressure not be obtainable, crude oil washing opera-tions shall not be carried out.

4.4. Stripping system

4.4.1 The design of the system for stripping crude oil from the bottom of every cargo tank shall be to thesatisfaction of the Administration.

4.4.2. The design and capacity of the tank stripping system shall be such that the bottom of the tank being cleanedis kept free of accumulations of oil and sediment towards completion of the tank washing process.

4.4.3. The stripping system small be capable of removing oil at a rate 1.25 time the total throughout of all thetank cleaning machines to be operated simultaneously when washing type bottom of the cargo tanks as describer inship’s Operations and Equipment Manual.

4.4.4 Means such as level gauges, hand dipping and stripping system performance gauges as referred to in4.4.8. shall be provided at the after most portion of a cargo tank and in three other suitable locations unless otherapproved means are fitted for efficiently as ascertaining that the bottom of every cargo tank is dry. For the purpose ofthis paragraph the cargo tank bottom shall be considered dry if there is no more than a small quantity of oil near strip-ping suction with no accumulation of oil elsewhere in the tank.

4.4.5 Means shall be provided to drain all cargo pumps and lines at the completion of cargo discharge, wherenecessary, by connextion to a stripping device. The line and pump draining shall be capable of being discharged both toa cargo tank and ashore. For discharge ashore a special small diameter line shall be provided for that purpose andconnected outboard of the ships manifold valve. For new oil tankers or existing oil tankers not already fitted with such aline the cross-sectional area of this line shall not exceed 10 percent of that of a main cargo discharge line. Where such aline shall not exceed 10 percent of that of a main cargo discharge line. Where such a line if already fitted on an existingtanker a cross sectional area of not more that 25 per cent of that of a main cargo discharge line may be accepted.


4.4.6 The means for stripping oil from the cargo tanks shall be by positive displacement pump, self primingcentrifugal pump of educator or other methods to the satisfaction of the Administration. Where a stripping line is con-nected to a number of tanks, means shall be provided for isolating each tank out being stripped at that particular time.

4.4.7 The carriage of more than one grade shall not prevent crude oil washing of tanks.

4.4.8 Equipment shall have remote read-out facilities in the cargo control room or in some other safe andconvenient place easily accessible tot he officer in charge of cargo equipment shall include, as appropriate, a flowindicator, or a stroke counter or a revolution counter, and pressure gauges at the inlet and discharge connexion of thepump or equivalent. Where educators are provided, the monitoring equipment shall include pressure gauges at thedriving fluid in make and at the discharge and a pressure/vacuum gauge at the suction intake.

4.4.9 The internal structure of the tank shall be such that drainage of oil to the tank suctions of the strippingsystem is adequate to meet the requirements of 4.4.2 and 4.4.4 Care shall be taken that both longitudinal and trans-verse drainage are satisfactory and shall be verified during the inspection required by 3.2. and 4.2.10.

4.4.10 The trim conditions for crude oil washing given in the Operations and Equipment Manual shall be adheredto. In general trim by the stern is only important during that final stage of tank discharge and shall be the maximumpossible compatible with operational constraints but in no case less that recorded during the crude oil washing prior tothe inspection required by 3.2. and 4.2.10.

4.5 Ballast lines

4.5.1 Where a separate ballast water system for ballasting cargo tanks is not provided, the arrangement shallbe such that the cargo pump, manifolds and pipes used for ballasting can be safely and effectively drained of oil beforeballasting.

5. Qualification of personnel

5.1. The training requirements of ships personnel engaged in the crude oil washing of tankers shall be to thesatisfaction of the Administration.

5.2. Where a person such as the master, the chief officer or the cargo control officer assumes overall chargeof a crude oil wash he shall :

(a) Have at least one year’s experience on oil tankers where his dutieshave included the discharge of cargo and associated crude washing. Where his duties have not included crude oil washing operations,he shall have completed a training programme in crude oil washingin accordance with Appendix II tot these Specifications andsatisfactory to the Administration;

(b) Have participated at least twice in crude oil wash programmes oneof which shall be on the particular ship for which he is required to


undertake the responsibility of cargo discharge. Alternatively thislatter participation may be acceptable if undertaken on a ship thatis similar in all relevant respects ; and

(c) Be fully knowledgeable of the content of the Operations andEquipment Manual.

5.3. Where other nominated persons are intended to have particular responsibilities as defined in the Opera-tions and Equipment Manual, they shall have at least 6 months experience on oil tankers where, in the course of theirduties, they should have been involved ion the cargo discharge operation. In addition, they should have been instructedin the crude oil washing operation in the particular ship for which they are requires to undertake this responsibility and befully knowledgeable of the content of the Operations and Equipment Manual. Appendix II to these Specification shall beused as guidance in establishing the content of such instruction.

6. Operation Tankage to be crude oil washedBefore departure on a ballast voyage, after the complete discharge of cargo, sufficient tanks shall have been crude

oil washed in accordance with the procedures specified in the Operations and Equipment Manual to ensure that :(a) As a minimum, sufficient tanks have been washed to permit

compliance with the drought and trim requirements of Regulation13 (2) (a), (b) and (c) of Annex I of MARPOL 73/78 during all phasesof the ballast voyage; and

(b) Account is taken of the ship’s trading patterns and the expectedweather conditions so that additional ballast water is not put intotanks which have not been crude oil washed.

In addition to the tanks referred to in (a) above, approximately one quarter of all remaining tanks shall be crude oilwashed for cludge control on a rotational basis, but these additional tanks may include the tanks referred to in (b)above. However, for sludge control purposes, no tank need be crude oil washed more than once in every four months.Crude oil washing shall not be conducted between the final discharge and loading ports; that is to say, no crude oilwashing shall be undertaken during the ballast voyage. Ballast water shall not be put into tanks that have not been crudeoil washed. Water that is put into a tank which has been crude oil washed but not water rinsed shall be regarded as dirtyballast.

6.2 Drainage and discharge ashore of cargo lineAt the end of cargo discharge all cargo mains and stripping lines shall be drained and stripped and the drainage and

strippings discharge ashore via the special small diameter line required by 4.4.5. In addition all cargo tanks are to bestripped before the ship leaves its final port of discharge.

6.3 Filling of departure ballast tanksCare shall be taken at the completion of crude oil washing of any departure ballast tank to strip the tank as com-

pletely as possible. Where departure ballast in loaded through cargo line and pumps, these must be drained and strippedof oil using the means required by 4.4.5. before ballast is loaded.


6.4. Crude oil washing at seaAll crude oil washing must be completed before the ship leaves its final port of discharge. Where any tank is crude

oil washed while the ship is at sea between multiple discharge ports, the tank shall be left empty and available forinspection at the next discharge port before commencing the next ballast voyage. This inspection may consist of multiplesounding/dipping of the bottom of the tank when the tank is empty. Departure ballast tanks shall be ballast prior todeparture from port so that examination of the surface of the ballast water can be made. In the latter case the guidancegiven in 4.2. 10 (b) is prevalent to the inspection.

6.5 Discharge of oily water effluents on ballast voyageThe discharge of departure ballast and any other water effluent discharged during the ballast voyage shall comply

with the requirements of Regulation 9 of Annex I of MARPOL 73/78.

6.6 Use and control of inert gasOn ships to which these Specifications apply, no tank shall be crude oil washed unless the inert gas system re-

quired by Regulation 13 B (3) of Annex I of MARPOL 73/78 is in proper operation. Before each tank is crude oilwashed, the oxygen level shall be determined at a point 1 metre from the deck and at the middle region of the ullagespace and neither of these determinations shall exceed 8 per cent by volume. Where tanks have complete of partialwash bulkheads, the determinations should be taken from similar levels in each section a of the tank. The oxygen level ofthe inert gas being delivered during the washing process shall be continuously monitored. If during crude oil washing.

(a) The oxygen level of the inert gas being delivered exceeds 8 per centby volume or

(b) The pressure of the atmosphere at the tanks in no longer positive;then the washing must be stopped until satisfactory conditions arerestored.

6.7 Precautions against electrostatic generation

To avoid excessive electrostatic generation in the he washing in the washing process due to the presence ofwater in the crude oil washing fluid, the contents of any tank to the use as a source of crude oil washing fluid must forestbe discharged by a least 1 metre before being so used. Any tank used as a slop tank on the previous ballast voyageshall be completely discharged and refilled with dry crude oil if that is to be used a source of washing fluid.

6.8 Vapour emission

On ships to which these Specification apply these shall be means to avoid voyage emission during the filling ofdeparture ballast wherever local conditions require it. The method of preventing of the emission of hydrocarbon vapourinto the atmosphere shall be.

(a) By the use of permanent ballast tanks wherever these are sufficientto provide the minimum departure draught ; or

(b) By containment of vapour in empty cargo tanks by simultaneous


ballasting and cargo discharge.

Alternative methods to the satisfaction of the Administrations may be accepted provided an equivalent degree ofenvironmental protection is provided.

7. Operations and Equipment Manual

The Operations and Equipment Manual must be to the satisfaction of the Administration and shall contain thefollowing information and operational instructions :

(a) The complete text of the revised Specifications for the Design,Operation and Control of Crude Oil Washing Systems.

(b) A line drawing of the crude oil washing system showing the respectiveposition or pumps, lines and washing machines which relate to thecrude oil washing system.

(c) A description of the system and a listing of procedures for checkingthat equipment is working properly during crude oil washingoperations. This shall include a listing of the system and equipmentparameters to be monitored, such as line pressure, oxygen level,machine revolutions, duration of cycles, etc. The established valuesfor these parameter shall be included. The results of the tests carriedout in accordance with 4.2.10 and the values of all parametersmonitored during such tests shall also be included.

(d) Details of the requirements of section 6 of these Specificationstogether with advice and instructions, where appropriate, in meetingthese requirements such as :

(i) Recommended methods and programmes of crude oil washing inover to accord with all foreseeable circumstances of cargo dischargerestraints and to obtain maximum trim during the completion ofwashing and raining of each tank.

(ii) The procedure on ships to avoid vapour emission in account.

(iii) The method of draining tanks which shall include informationoptimum trim conditions as required by 4.4.10.

(iv) The method of draining cargo pumps, cargo lines, crude oilwashing lines and stripping lines, the identification of spaces intowhich they may be drained and procedures for discharge ashore ofdrainings and strippings via the small diameter discharge line oncompletion of cargo discharge.

(v) Typical washing programmes under various conditions of loadingspecifying :


(1) The tanks to be washed in accordance with 6.1 ;

(2) The method for washing each tank, that is single or multi-stage;

(3) The number of tank washing machines to be used simultaneously;

(4) The duration of the crude oil wash and water rinse where the latter is appropriate;

(5) The volume of water used for water rinse, which shall be at least equal; to thatused in the waster rinse prior to the inspections requires by 3.2. and 4.2.10 ; and

6) The preferred order which the tanks are to be washed.

(vi) The procedures for draining and stripping, where appropriate,cargo lines and pumps before being used for the loading of departureballast.

(vii) The procedure for verifying by sound patterns that bottommounted machines are operating shall be carried out towards theend of the wash cycle for each tank. When carrying out suchverification all other machines shall be shut downs if necessary.

(ix) Precise details of procedure to ensure compliance withRegulation 9 of Annex - I of MARPOL 73 / 78 in the discharge ofdeparture ballast, the water flushing of lines and the decanting ofthe slop tanks at sea.

(e) The dangers of leakage from the crude oil washing system and theprecautions necessary to prevent leakage and the action to be takenin the event of a leakage. Guidance shall be given on how the crudeoil washing system is to be operationally tested for leakage beforeeach discharge.

(f) The method of preventing the entry of oil to the engine room throughsteam heaters as required at all times to control the dual operationof discharging cargo and crude oil washing. The numbers of eachpersonnel shall include;

(i) The person meeting the requirements on 5.2 who will haveoverall control of the crude oil washing process;

(ii) Those persons meeting the requirements of 5.3 who will beexcepted to undertake the actual operation; and

(iii) At least one person on deck at all times during washing tokeep watch for leaks and malfunctioning of equipment , to test theoxygen content of tanks before washing, to check tank atmospherepressure, to sound tank bottoms if required, to lift ullage floats ifnecessary and to change drive units when this is necessary.


The duties of such persons are not necessarily mutually executive

(h) An effective means of communication between the watch keeper ondeck and the cargo control position so that in the event of a leak in,or malfunctioning of the crude oil washing system the Washing maybe stopped as soon as possible.

(i) The typical procedures for ballasting.

(j) A pre-crude oil wash operational check list for the use of the crewat each discharge which shall include the checking and calibrationof all instruments.

(k) The recommended intervals for non-inspection and maintenance ofcrude oil washing equipment in addition to statutory surveys.Reference should be made to technical manuals supplied by themanufacturers of the equipment.

(l) A list of crude oils unsuitable for the crude oil washing process andtheir origin.

Aprendix - 1

LIST OF CHANGES WHEN APPLYING THE SPECIFICATIONS TO NEWCRUDE OIL TANKERS OF 20,000 TONS DEADWEIGHT AND ABOVE

ParagraphNumber List of Change

4.2.10 Subparagraph (c) is not applicable.

6.1 Replace by the following :

6.1 Tankage to be crude oil washed

6.1.1 Before departure on a ballast voyage :

(a) Approximately one quarter of the cargo tanks shall be crudeoil washed for sludge control purposes on a rotational basis and inaccordance with the procedures specified in the Operations andEquipment Manual. However, for these purposes, no tank need tocrude oil washed more than once in every four months ; and


(b) If it is considered that additional ballast in a cargo tank ortanks may be required during the ballast voyage under theconditions and provisions specified in Regulation 13 (3) of Annex I ofMARPOL 73/78, the tank or tanks which may be used for this ballastshall be crude oil washed in accordance with the procedures specifiedin the Operation and Equipment Manual.

6.1.2 Ballast water shall not be put into cargo tanks that have not been crude oil washed. Water that is putinto a tank which has been crude oil washed but not water raised shall be regarded as dirty ballast.

6.1.3 Crude oil washing shall not be conducted between the final discharge and loading ports; that is to say,no crude oil washing shall be undertaken during the ballast voyage;

6.3 Replace by the following :6.3 Ballasting of cargo tanks

Care shall be taken at the completion of crude oil washing of any cargo tank that might contain ballast to strip thetank as completely as possible. Where this ballast is filled through cargo lines and pumps, these must be drained andstripped of oil using the means required by 4.4.5.

6.4 The last two sentences are not applicable.

6.5 Replace buy the following :

6.5. Discharge of oily water effluents on ballast voyage

The discharge of additional ballast from cargo tanks and any other water effluent discharged during the ballastvoyage shall comply with the requirements of Regulation 9 of Annex I of MARPOL 73/78.

6.8 This paragraph is not applicable.

7(d) Replace by the following :

7 (d) Details of the requirements of section 6 of these Specifications together with advice and instructions,where appropriate, in meeting these requirements such as :

(i) Recommended methods and programmes of crude oil washing in order to accord with all foreseeablecircumstances of cargo discharge restraints and to obtain maximum trim during the completion of washing and drainingof each tank.

(ii) The method of draining tanks which shall include information on optimum trim conditions as required by4.4.10.

(iii) The method of draining cargo pumps, cargo lines, crude oil washing lines and stripping lines, and spacesinto which they may be drained. Together with the final discharge ashore via the small discharge line on completion ofdischarge.

(iv) Typical washing programmes under various conditions of loading specifying :(1) The tanks to be washed in accordance with 6.1 ;


(2) The method for washing each tank, that is single- or multi-stage;

(3) The number of tank washing machines to be used simultaneously;

(4) The duration of the crude oil wash and water rinse where the latteris appropriate.

(v) The procedure for verifying by sound patterns that bottom mounted machines are operating shall becarried out towards are and of the wash cycle for each tank. When carrying out such verifications all other machinesshall be shut down if necessary.

Apprendix II

TRAINING FOR PERSONS INTENDED TO ASSUME OVERALL CHARGE OFCRUDE OIL WASHING

INTRODUCTION

Any required training shall be supervised instruction, conducted in a shore-based facility or board a suitablyequipped ship having training facilities and instructors for this purpose, dealing with the principles involved and theapplication of these principles to ship operation.

In drawing up an Administration-approves syllabus of Training, the revised Specifications for the Design, Opera-tion and Control of Crude Oil Washing Systems of tankers shall be taken into account :

(a) An introduction to the principles of crude oil washing which shall include ;_ the characteristics of crude oil as a washing fluid and its contrast

with water washing ;

_ top washing;

_ bottom washing;

_ trim requirements ;

_ methods of bleeding off from the cargo discharge ;

_ maintenance of required washing fluid pressure ;

_ washing at sea between discharge ports.

_ recirculatory washing ;

_ relative priorities and requirements for the departure ballast tanks,arrival ballast tanks and cargo only tanks.

(b) Equipment and design

(i) locations of washing machines ;(ii) washing machines deck mounted and submerged ;

_ types_ features of construction._ operating parameters.

(iii) drive units ;


(iv) washing fluid supply and distribution systems ;(v) stripping systems ;(vi) means of sounding tanks ;(vii) inert gas requirements ;

(c) Generalized crude oil washing procedures

(i) traditional pipe are ship free flow ship partial free flow ship.(ii) single multi oracle cargoes ;(iii) compazation washing procedure in order minimize extra berth time(iv) ballasting for departure with various ship and pipeline configurations(v) procedure for washing at sea between discharge ports.

(d) Associated procedure

(i) means for minimizing residues on board._ stripping of cargo tanks ;_ draining and stripping of cargo lines ;_ final discharge of cargo ashore ;

(ii) water rinsing of arrival ballast tanks ;(iii) filling and ultimate discharge of arrival ballast ;(iv) discharge of departure ballast ;(v) build-up and decanting of residues in slop tank(vi) requirement of Regulation 9 of Annex I of MARPOL 73/78.(vii) avoidance of venting in port during ballasting operations.

(e) Safety

(i) inert gas procedure ;(ii) Maintenance and monitoring of inert gas quality and pressure ;(iii) stopping of washing / discharge under abnormal inert gas conditions ;(iv) electrostatic generation and the precautions required to avoid it ;(v) pipework integrity ;(vI) avoidance of surge pressures ;(viii) spillage.

(f) Checklists

(i) before entering port ;(ii) before commencing crude oil washing ;(iii) after crude oil washing ;(iv) after sailing.

(g) Regulatory enforcement procedures

(i) Operations and Equipment Manual ;(ii) Oil Record Book ;(iii) Sounding of Tanks ;(iv) Measurement of oil on surface of departure ballast.


(h) Maintenance of plant and equipment

(i) maintenance of equipment in accordance with manufacturers instructions.(ii) additional maintenance items.

Administrations shall ensure that the training facility issues an appropriate documents to those qualified in accor-dance with this Appendix to serve as officer primarily responsible for crude oil washing.

Apprendix III

AGREED INTERPRETATIONS OF CERTAIN OF THE PROVISIONS OF THEREVISED SPECIFICATIONS

4.1.1 This paragraph requires pipes and valves to be of steel or otherequivalent material. As classification societies permit grey cast ironfor cargo piping with a maximum permissible working oil pressure of16/kg/cm2 grey cast iron may be permitted in the supply system forcrude oil washing systems when complying with nationally approvedstandards.

4.1.3. The requirements of this paragraph allow alternative arrangements.One such alternative is that where the system is served only bycentrifugal pumps so designed that the pressure derived cannot exceedthat for which the piping is designed a temperature sensing devicelocated in the pump casing is required to stop the pump in the caseof overheating.

4.1.6 On new oil tankers the steam heater referred to shall be locatedoutside the machinery spaces. However, on an existing oil tankerwith an existing steam heater located in the machinery spaces, nomore additional isolation will be required other than that whichisolates the crude oil washing system from the machinery spaces.

4.2.4. This paragraph requires each machine to be capable of being isolatedby means of stop valves in the supply line. Where more than onesubmerged machine is connected to the same supply line a singleisolating stop valve in the supply line may be acceptable provided therotation of the submerged machines can be verifies in accordancewith paragraph 4.2. 13 (a) or (c) of the revised Specifications for theDesign Operation and Control of Crude Oil Washing Systems.

4.2.8. With regard to the application of this paragraph a slop tank considered as a cargo tank.


4.2.9 Guidelines for the assessment of shadow diagrams

(a) Shadow diagrams (to be prepared in accordance in accordancewith 4.2.9) must be on drawings the scale of which must be at least;

(i) 1 : 100 for tankers of less than 100.000 tons deadweight.

(ii) 1:200 for tankers of 100.000 tons deadweight and above.

(b) The drawings must provide at least a plan view, a profileview and an end elevation for each tank, or for tanks considered tothe similar.

(c) Sufficient detailed drawings of the vessel must be provided to check that all large primary structurewhich contribute significant strength to the ship, such as web frames and girders. It is intended that smaller componentssuch as those that contribute to plate stiffening be excluded. In general the following lists, in conjunction with the diagramshowing structural components of cargo tanks, may be used to amplify this interpretation. (See diagram on page 27)

Include Disregard

(i) web frames (i) longitudinals

(ii) girders (ii) brackets

(iii) stringers (iii) stiffeners

(iv) webs (iv) ladders

(v) main bracket (v) pipe work

(vi) transverse (vi) corrugations on corrugatedbulkheads

(vii) Cross ties in transverse web (vii) face platesframes, unless itcan be verified by tank inspection the theirpresence does not effect the cleanliness of thetank. However, for the purpose of making aninitial assessment, where these are no morethan two crossties and each is less than 1/5 ofthe total depth of the tank they may be ignores.

(e) Shadows cast upon the underside of decks web frames centre and side graders can be ignored.

(f) Calculations must be provided either on the drawing or separately to show how the percentages required by4.2.8 have been arrived at. The calculations should be itemized so that it is possible to relate each item with a particularshadow area.

(g) Where a curved surface is presented to jets it is not necessary to provide exact geometric projections todetermine the resultant shadow. A reasonable estimate is acceptable.


(h) For the purpose of determining the bottom area of wing tanks, the breadth of the tank is to be taken asthe horizontal distance measures across the top of the bottom longitudinal frames to the inside of the shell plating,midway between the tank bulkhead.

(i) A swash bulkhead may be taken as a tank boundary. However inthis event the bulkhead must be assumed to have no openings in it.

4.2.10 Water rinse means the water washing process carried out in connextion with tank cleaning after crude oilwashing and is not intended to be constructed as limiting the amount of water needed in the process.

2.10 (c) (a) The “oil monitoring system” referred to in this paragraph means any approved system, includinglaboratory tests, which verifies that the oil content of the effluent does not exceed the stated level. If laboratory tests areto be conducted, standards contained in resolution A.393 (X) should be used as guidance. Oil tankers engaging in atrade where discharge of cargo takes place in one port State and cargo loading in another port State create a specialproblem with respect to verification. Two alternatives available to confirm the tanker’s capability are :

(i) The tanker could be required to conduct the entire COW operationsat the discharge port, taking inspectors to sea if necessary to observewater washing, handling of departure ballast and discharge of arrivalballast;

(ii) Co-ordination between the flag State Administrations and port Statesto obtain the required documentation.

However the test is performed, it should be decided on a case-by-case basis taking into account the service of thetanker and the availability of surveyors.

(b) The expression totally discharged to the loading port harbour” whichis used in this paragraph shall be so constructed as to mean thetotal quantity of arrival ballast except that quality which is to beretained on board as specified in section 15 of the Crude Oil washingOperations and Equipment Manual.

4.4.3. During bottom washing the stripping capacity shall;; be at least 1.25 time the total throughput of all themachines that may be simultaneously in use according to paragraph 4.4.3 This does not mean that all the machines in atank have to be operated simultaneously during bottom washing but the bottom washing may be carried out in stepsaccording to detailed procedures laid down in the Operations and Equipment Manual. The stripping capacity should beat least 1.25 times the throughput of all machines that are in operation simultaneously during any stage of the bottomwashing.

4.4.5 In crude oil tankers having individual cargo pumps in each tank, each pump having an individual pipingsystem, dispensation from the required special small diameter line may be given in cases where the combined amount ofoil left in the tank after stripping and the volume of oil in the piping system from the manifold to the tank is less than0.00085 times the volume of the cargo tank. If a deep well cargo pump system is provided with an evacuating systemfor retained oil, the above consideration should also apply.

5.2. (b) This paragraph required that officers who assume overall charge of


a crude oil washing operation must have participated in a crude oil washingoperation on the ship for which they are required to undertake theresponsibility for cargo discharge or on a similar ship. However for newships for ships changing for the first time to the carriage of crude oil forships new to a particular owner or for ships which are changing registry inwhich it may not be possible to acquire the particular experience, theAdministration may accept as an alternative ;

(i) a person such as a shore-based senior officer appointed by thecompany (additional to the ship’s complement) who is experiencedin the operations and is on board the ship :

provided that an Operations and Equipment Manual, in a language readily understood by the ship’s officers, isavailable on the ship.


II STANDARD FORMAT FOR THE CRUDE OIL WASHING OPERATIONSAND EQUIPMENT MANUAL

RECOMMENDATION ON THE STANDARD FORMAT FOR THE CRUDE OILWASHING OPERATIONS AND EQUIPMENT MANUAL

(Resolution MEPC - 3 (XII) adopted on 30 November 1979 by the(Marine Environment Protection Committee as its twelfth session)

THE MARINE ENVIRONMENT PROTECTION COMMITTEE

Noting resolution A-297 (VIII) by which the Assembly designated the Committee as the appropriate body toperform such function as are may be conferred upon the organization under international conventions for the preventionand control of pollution from ships.

NOTING FURTHER Regulation 13B of Annex I of the Protocol of 1978 relating to the international Conventionfor the Prevention of Pollution from Ships, 1973 which provides that every tanker operating with a crude oil washingsystem shall be provided with an Operations and Equipment Manual detailing the system and equipment and specifyingoperations procedures.

NOTING ALSO that the said Manual is intended not only to provide guidance to the crew of the ship for properoperation of the system, but also to provide information on the system and its operational procedures for inspectorsgoing on board for inspection in ports.

HAVING CONSIDERED proposals made by member Government for standardization of the Manual.

1. Adopts the standard format for the Crude Oil Washing operations andEquipment Manual appearing in the Annex hereto :

2. Invites Member Governments :

(a) To use the standard format for the Crude Oil Washing Operationsand Equipment Manual earn approving the Manual as called for byRegulation 13B of the Protocol of 1978 relating to the InternationalConvention for the Prevention of Pollution from Ships, 1973.

(b) To ensure that, if the language of the Manual is neither Englishnor French, the Manual shall include a translation into one of thoselanguages.

ANNEXE

STANDARD FORMAT FOR THE CRUDE OIL WASHING OPERATIONS ANDEQUIPMENT MANUAL

(The standard format consists of a standardized text of an introduction and of an index, and 17 or 18 sectionsdepending on the type of tanker)

INTRODUCTION


1. This manual is written in accordance with the requirements ofRegulation 13 B of the Protocol of 1978 relating to the InternationalConvention for the Prevention of Pollution from ships, 1973 (MARPOL73/78).

2. The purpose of the Manual is to meet the requirements for crude oilwashing in accordance with the revised Specifications for the Design,Operation and Control of Crude Oil Washing Systems (Assemblyresolution A. 446 (XI) as amended by resolution A-497 (XII). It providesstandard operational guidance In planning and performing a crude oilwashing programme and describes a safe procedures to be followed.

3. Part I of the Manual contains all the information and operationsinstructions required by the revised Specifications. Part 2 of the Manualcontains additional information and operational instructions requiredor accepted by the Administration.

4. This Manual has been approved by the Administration and no alterationor revision shall be made to any part of it without the prior approval ofthe Administration.

* If the Administration requires or accepts information and operational instructions in addition to those providedfor by the Specifications, they should be included in part 2 of the Manual. If no such additional information or operatinginstructions are required or accepted by the Administration, the Manual will consist of one part only, and paragraph 3should read. “This Manual contains all the information and operational instructions required by the revised Specifica-tions.”


Standard format for the COW Manual

INDEX OF SECTIONS

Relevantparagraph(s)

Page of the revisedSpecifications

Part I

1. Text of the revised Specifications 7 (a)

2. Drawings of the crude oil washing system 7 (b)

3. Description of the crude oil washing system and operational andequipment parameters 7 (c), 7 (d) (viii) and 7 (f)

4. Dangers of and precautions against oil leakage 7(e)

5. Use and control of inert gas 6.6

6. Precautions against electrostatic hazards 6.7

7. Personnel requirements 7 (g)

8. Methods of communication 7(h)9. List of crude oils unsuitable for crude oil washing 7 (i)10. Crude oil washing check lists 7 (j)11. Approved methods and programmes for crude oil washing 7 (d) (i)12. Typical crude oil washing programmes 7 (d) (v)13. The method of draining cargo tanks 7 (d) (iii)14. The method and procedures for draining cargo pumps

and lines 7 (d) iv and (vi)15. Typical procedures for ballasting and the methods

of preventing hydrocarbon emission 7 (d) (ii), 7 (i)16. Compliance procedures for ballasting and the

method of presenting hydrocarbon emission 7(d) (vi), (vii) and (ix)17. Inspections and maintenance of equipment 7 (k)18. Procedure for changing from crude oil trade to product trade*

Part 2(additional information and operational instructions required or accepted by the Administration, if any)

Section 18 is included in the Manual for a particular tanker only if applicable.


CONTENTS OF SECTIONS 1 to 18

SECTION 1. TEXT OF THE REVISED SPECIFICATIONS

This section contains the complete text of the revised Specifications for the Design, Operation and Control ofCrude Oil Washing Systems and the agreed interpretations of certain of the provisions of the revised Specifications(Assembly resolution A.446 (XI) as amended by resolution A.497 (XII).

SECTION 2. DRAWINGS OF THE CRUDE OIL WASHING SYSTEM

This section contains line drawings showing :(1) crude oil washing lines and valves;(2) cargo pumps, lines and valves;(3) ballast systems (where fitted);(4) stripping systems;(5) position of tank washing machines;(6) position of holes for hand dipping and tank gauges;(7) inert gas deck distribution system.

SECTION 3. DESCRIPTION OF THE CRUDE OIL WASHING SYSTEM AND OPERATIONAL ANDEQUIPMENT PARAMETERS

This section contains a description of the cargo, ballast, washing and stripping systems and in addition specifies :(1) types of tank washing machines and their standpipe length inside the tanks;(2) revolutions of the machines;(3) methods of checking the operation of tank washing machines;(4) minimum operation pressure for crude oil washing;(5) maximum permitted oxygen level in cargo tanks;(6) duration of tank washing machine cycles;(7) results of the tests performed in accordance with paragraph 4.2.10 (b) of the revised Specifications and the

method of computation;(8) method of preventing entry of oil into the engine room.

SECTION 4. DANGERS OF AND PRECAUTIONS AGAINST OIL LEAKAGEThis section contains information on the dangers of leakage from the crude oil washing system, the precautions

necessary to prevent leakage and the action to be taken into the event of leakage.

SECTION 5. USE AND CONTROL OF INERT GASThis section contains information on the inert gas requirements and the instructions to cover those periods when the

inert gas pressure is released for reasons of cargo operation. In addition it indicates the method and procedures to beused for taking samples of the tank atmosphere.

SECTION 6. PRECAUTIONS AGAINST ELECTROSTATIC HAZARDSThis section contains details of the procedures for minimizing electrostatic generation.

SECTION 7. PERSONNEL REQUIREMENTSThis section specifies the numbers of persons to be associated with the crude oil washing process and their neces-


sary qualifications. Their names and ranks may be provided on separate documents.

SECTION 8. METHODS OF COMMUNICATIONThis section gives the details of communication between the watchkeeper on deck and the cargo control position

so that, in the event of a leak or malfunctioning of the crude oil washing system, the washing may be stopped as soon aspossible.

SECTION 9. LIST OF CRUDE OIL UNSUITABLE FOR CRUDE OIL WASHINGThis section contains a list of crude oils unsuitable for crude oil washing.

In lieu of the list of crude oils unsuitable for crude oil washing to be inserted in Section 9 of the Crude Oil WashingOperations and Equipment Manual, the following standard text may be used.

(1) For a tanker not fitted with heating coils

This tanker is not fitted with heating coils in the cargo tanks andshould not carry cargoes which will require to be heated forpumpability.

(2) For a tanker fitted with heating coils

This tanker is fitted with heating coils in the cargo tanks and,subject to the limitations of the cargo heating system, can carrycargoes which require to be heated for pumpability.

Attention is drawn to the difficulties which may be encountered with certain crude oils. During the discharge of aheated cargo the crude oil washing of each tank scheduled for such operation should be carried out concurrently withthe discharging of the particular tank in order to minimize the cooling down of the tank surfaces.

As a general guidance to the suitability of an oil for crude oil washing on board this tanker the following criteriashould be used :

1. The viscosity of the oil at the discharging temperature should notexceed 600.C St;

2. The cargo should be discharged at a temperature which exceeds itspour point by at least 10.C; and

3. All necessary precautions should be taken to prevent the washing oilfrom solidifying in the COW piping system.

These criteria are for general guidance and should be used when other information is not available.

The following is an informative list of potentially difficult crude oils due to their high pour points or viscosity (the listshould not be regarded as exhaustive) :

Amna LagunillasArdjuna Lucina


Boscan MayaBu Attifel Minas (Sumatra Heavy)Cabinda Minas (Sumatra Light)Cinta SarirDuri ShengliGamba TapisJatibarang Tia Juana PesadoLabuan TilaLaguna

Note : It should be clearly understood that crude oils found to be unsuitable for crude oil washing should not becarried in this tanker.

SECTION 10. CRUDE OIL WASHING CHECKLISTSThis section contains operational checklists for the use of the crew at each discharge which shall include the

checking and calibration of all instruments.

SECTION 11. APPROVED METHODS AND PROGRAMMES FOR CRUDE OIL WASHINGThis section contains those details which form the basis of crude oil washing in the tanker and which are necessary

to formulate a washing programme which will accord with all foreseeable circumstances of cargo discharge restraints. Itincludes information on :

(1) the minimum number of tanks to be washed in accordance withparagraph 6.1 of the revised Specifications;

(2) the method of washing each tank, i.e. single or multistage;

(3) the number of tank washing machines to be used simultaneously.

(4) the crude oil washing pressure and means to maintain the requiredpressure;

(5) the duration of the crude oil wash;

(6) the preferred order in which tanks are to be washed;

(7) the minimum trim during completion of washing and draining tanks;

(8) when draining and stripping of tanks is to commence.

SECTION 12. TYPICAL CRUDE OIL WASHING PROGRAMMESThis section contains details of some typical washing programmes under various conditions of discharge such as

single or multiport discharge and single and multigrade cargoes.

SECTION 13. THE METHOD OF DRAINING CARGO TANKSThis section contains a description of the method of draining cargo tanks and should include the parameters which

indicate when the tank is dry and which will be at least all of those required by paragraph 4.4.8 of the revised Specifica-tions. The minimum trim conditions must be stated.


SECTION 14. THE METHOD AND PROCEDURES FOR DRAINING CARGO PUMPS AND LINESThis section contains a description of the method and procedures for draining cargo pumps, cargo lines, crude oil

washing lines and stripping lines and includes information on the use of the small diameter line.

SECTION 15. TYPICAL PROCEDURES FOR BALLASTING AND THE METHOD OF PREVENTINGHYDROCARBON EMISSION.

This section contains a description of typical procedures for ballasting and includes :(1) the procedure for draining and stripping before loading ballast;

(2) the procedures for preventing hydrocarbon emission into the atmosphere.

SECTION 16. COMPLIANCE PROCEDURES FOR REGULATION 9 OF ANNEX 1 OF MARPOL 73/78

This section contains information and procedures for water washing tanks and lines, discharge of departure ballastand the decanting of slops at sea to ensure compliance with Regulation 9.

SECTION 17. INSPECTIONS AND MAINTEANCE OF EQUIPMENTThis section contains information on procedures to be followed at recommended intervals for on-board inspections

and maintenance of crude oil washing equipment.

SECTION 18. PROCEDURES FOR CHANGING FROM CRUDE OIL TRADE TO PRODUCT TRADE*This section contains operational procedures for changing from crude oil trade to product trade for a tanker which

is fitted with separate independent pumping and piping arrangements for ballasting dedicated clean ballast tanks andwhich has been issued with two IOPP Certificates running concurrently with one Certificates certifying the tanker to be acrude oil tanker and the other certifying it to be a product carrier.

III. EXAMPLES OF CRUDE OIL WASHINGOPERATIONS AND EQUIPMENT MANUALS

Explanatory note

The following specimen Manuals were originally prepared by tanker owners for particular tankers which theywished to be certified as COW tankers under MARPOL 73/78. The texts of the Manuals have been reviewed in orderto ensure conformity with the standard format but editing has been kept to a minimum to show possible variations in thelanguage and in the manner of presentation of the required information.

As the flat Administration of these tankers does not require the inclusion of any information or operational instruc-tions in addition to those provided for by the revised Specifications, the specimen Manuals consist of one part only asexplained in the introduction to the standard format (see page 31 of this publication).


EXAMPLE 1

Conventional pipeline tanke

CRUDE OIL WASHING OPERATIONS AND EQUIPMENT MANUAL

Name of ship ...................................................................................................

Distinctive number or letters ................................................................................

Port of registry ................................................................................................

Deadweight tonnage ........................................................................................

INTRODUCTION

1. This Manual is written in accordance with the requirements of Regulation 13B of the Protocol of 1978 relatingto the International Convention for the Prevention of Pollution form Ships, 1973 (MARPOL 73/78).

2. The purpose of the Manual is to meet the requirements for crude oil washing in accordance with the revisedSpecifications for the Design. Operation and Control of Crude Oil Washing Systems (Assembly resolution A.446 (XI)as amended by resolutions A.497 (XII). It provides standard operational guidance in planning and performing a crudeoil washing programme and describes a safe procedure to be followed.

3. This Manual contains all the information and operational instructions required by the revised Specifications.

4. The Manual has been approved by the Administration and no alteration or revision shall be made to any partof it without the prior approval of the Administration.


INDEX OF SECTIONSRelevant

paragraph(s)Page of the revised

Specifications

1. Text of the revised Specifications 42 7 (a)

2. Drawings of the crude oil washing system 43 7 (b)

3. Description of the crude oil washing system andoperational and equipment parameters 48 7 (c), 7 (d) (viii)

and 7 (f)

4. Dangers of and precautions against oil leakage 50 7 (e)

5. Use and control of inert gas 51 6.6

6. Precautions against electrostatic hazards 51 6.7

7. Personnel requirements 51 7 (g)

8. Methods of communication 52 7 (h)

9. List of crude oils unsuitable for crude oil 52 7 (i)washing

10. Crude oil washing checklists 52 7 (j)

11. Approved methods and programmes forcrude oil washing 54 7 (d) (i)

12. Typical crude oil washing programmes 55 7 (d) (v)

13. The method of draining cargo tanks 58 7 (d) (iii)

14. The method and procedures for drainingcargo pumps and lines 59 7 (d) (iv) and (v)

15. Typical procedures for ballasting and themethod of preventing hydrocarbon emission 59 7 (d) (ii) 7 (i)

16. Compliance procedures for Regulation 9 ofAnnex I of MARPOL 73/78 60 7 (d) (vi), (vii)

and (ix)

17. Inspections and maintenance of equipment 61 7 (k)

18. Procedures for changing from crude oil trade toproduct trade* 61 —

* This Specimen Manual as originally prepared by the tanker owner for a particular tanker did not include a Section 18 as the procedures forchanging from crude oil trade to product trade were not applicable. This section has been added as an example of how the information might be presented if


required in a particular case.

SECTION 1TEXT OF THE REVISED SPECIFICATIONS

This section contains the complete text of the revised Specifications for the Design, Operation and Controlof Crude Oil Washing Systems and the agreed interpretations of certain of the provisions of the revised Specifi-cations (Assembly resolution A.446 (XI) as amended by resolution A.497 (XII).

(Text of the revised Specifications to be inserted).

SECTION 2.DRAWINGS OF THE CRUDE OIL WASHING SYSTEM

This section contains line drawings showing :

(1) crude oil washing lines and valves;

(2) cargo pumps, lines and valves;

(3) ballast systems (where fitted);

(4) stripping systems;

(5) position of tank washing machines;

(6) position of holes for hand dipping and tank gauges;

(7) inert gas deck distribution system.

(See following pages for drawings).

SECTION 3. DESCRIPTION OF THE CRUDE OIL WASHING SYSTEM AND OPERATIONAL ANDEQUIPMENT PARAMETERS

This section contains a description of the cargo, ballast, washing and stripping systems and in addition specifies :(1) types of tank washing machines and their stand pipe length inside the tanks;(2) revolutions of the machines;(3) methods of checking the operation of tank washing machines;(4) minimum operation pressure for crude oil washing;(5) maximum permitted oxygen level in cargo tanks;(6) duration of tank washing machine cycles;(7) results of the tests performed in accordance with paragraph 4.2.10 (b) of the revised Specifications and

the method of computation;(8) method of preventing entry of oil into the engine room.


Cargo system

The tank system of this vesel consists of eight centre tanks and eight pairs of wings, but with No.3 wings reservedfor permanent ballast and not connected into the cargo piping. The aftermost set of tanks, No.8 across, forms a tripleslop tank arrangement. No.8 port is the dirty slop tank with first separation across to No.8 starboard and hence asecond separation into No.8 centre. The total capacity of the three slop tanks is 20,000 m3.

Cargo is handled by four main cargo pumps each of rated capacity of 4,500 m3/hr. Each pump has a 700 mmsuction line running the fuel length upto No.1 across. No.1 and No.4 pumps are used to discharge the wing tanks andNO.2 and No.3 pumps to discharge the centre tanks. There are crossover lines between the pump suctions whichpermits a variation on the normal practice.

Stripping system

The pumps are of the VAC-STRIP type which enables them to drain tanks right out. Thus there is no stripping linebut in each tank a small stripping suction bell-mouth, separately valved, is taken off the appropriate main line. For waterwashing and occasional use during the closing stages ofcrude oil washing, two eductors are fitted, each of rated capacity900 m3/hr. which are normally powered by either No.2 or No.3 cargo pump. These eductors can be put on to any ofthe four main suction lines, and thus drain any tank. They discharge directly into the dirty slop tank, No.8 port.

One Duplex steam reciprocating pump of 350 m3/hr. is fitted for the purpose of line draining. It has suctionconnexions to the four main suction lines, the four cargo pumps, the discharge lines, the sea line and the crude oilwashing line. It can discharge to the slop tank, the oil/water separator, the main discharge lines, overboard or through aspecial 250mm line which runs along the deck and terminates outboard of the manifold gate valves. This latter 250 mmline should always be used for final line draining ashore.

Ballast system

Permanent ballast is carried in NO.3 wings and is handled by a separate pump of capacity 4,250 m3/hr. Thepump and tanks are not connected into the cargo pumps or lines and have their own separate sea suction and discharge.The permanent ballast pump also has the capacity of ballasting No.1, No.4 and No.6 centres over the top. Once thecargo is discharged from No.1, No.4 and No.6 centres, these tanks should be ballasted over the top concurrently withdischarge of cargo from other tanks. They then form the departure ballast. On the subsequent ballast passage, No.2,No.5 and No.7 centres should be washed and then used as the clean arrival ballast. Cargo tank ballast is discharged byNo.2 and No.3 cargo pumps through the pumproom high overboard discharge. Variations on the ballast arrangementare permissible to permit inspection and maintenance except that ballast should not normally be carried in wing tanks.

Washing system

The tank washing line, either crude oil or water, is fed from either No.2 or NO.3 cargo pump or alternatively theline may be fed from a cross-connexion from the midships manifold. In the latter case, any cargo pump or pumps couldfeed the washing line.

When water washing, No.2 or No.3 pump should be used drawing from the clean slop tank, No.8 centre, and thedirty washings from the tank being washed drained back with an educator which discharges into the dirty slop tank,No.8 port. One cargo pump operating on this closed cycle method is capable of driving both educators fitted andoperates ten tank washing machines while maintaining a back pressure of 10 kg/cm2. For crude oil washing, it is


preferable to feed the washing line from the manifold as long as possible as it is not then necessary to take one cargopump completely out of the discharge programme, and recirculation of “dirty” oil is avoided.

Crude oil must never be passed through the Butterworth heater which is situated in the pumproom. Apart fromfouling the heater, there is the chance of a ruptured or leaking tube allowing crude oil to pass back into the engine-roomvia the steam system. Two spare blanks are fitted, one on the inlet side and one on the outlet side of the heather andthese must always be in position when crude oil washing.

For all types of washing machines, the desired pressure on the wash line on deck is 10 kg/cm2. If the pressure onthe deck line falls below 8 kg/cm2, then crude oil washing should be stopped until such time as the pressure has beenrestored.

The complete crude oil washing system has been inspected and approved by the Administration, and no alterationsmay be made to the system or any part of the system without the approval of the Administration.

Cargo tanks were inspected after crude oil washing in accordance with the requirements of paragraph 4.2.10(a) ofthe revised Specifications and met the required standards of cleanliness, being essentially free of oil clingage and depos-its.

The surface of the departure ballast was examined in accordance with the requirements of paragraph 4.2.10 (b) ofthe revised Specifications and was found to be satisfactory.

The procedure for computing the ratio of the volume of oil on top of the total departure ballast water to the volumeof tanks that contain this water is described below :

1. Determine the thickness of the oil layer on the ballast water (tx).2. Using the tank capacity tables :1. determine the aggregate volume (100%) of all tanks that contain departure ballast (V);2. determine the volume of the ballast water and oil layer in each tank from the ullage (Ux);3. determine the volume of ballast water in each tank from the ullage plus the thickness of the oil layer (Ux + tx).3. Subtract the value obtained in 2.3 from that obtained in 2.2 for each tank and add the resultant values together

to obtain the total volume of oil (v).


4. The ratio of the volume of oil on top of the total departure ballast water to the total volume of tanks containingdeparture ballast water = v/V.

Washing Machines

This vessel is fitted with 77 deck mounted Butterworth Lavomatic machines, 13 bottom mounted Butterworth MPmachines and three fixed bottom mounted Butterworth K machines.

Deck mounted machines

Lavomatic S.A. single nozzle.

Those fitted in the centre tanks a standpipe length of 4.87 m with a natural frequency of 6.19 Hz and those fitted inthe wings have a standpipe length of 4.0 m and a natural frequency of 7.166 Hz. The propeller-induced frequency forthis vessel at full speed is 5.666 Hz.

All machines have selective arc heads which enable their angular programme to be varied as required. The timetaken to complete one full cycle is 67 minutes when operating at a pressure of 10 kg/cm2 and the output at this pressureis 140 m2/hr. The full cycle consists of an arc from Oo to 120o to Oo to -30o to 0o

The operation of these machines can be verified by observing the gearbox where both rotation and elevation aremechanically displayed.

Submerged machines, MP, single nozzle

Thirteen of these machines are fitted; one at the forward end of No.2, No.4, No.5 and No.6 and No.7 wingsand, additionally, one at the after end of No.7 wings and No.7 centre. They are positioned on the centreline of the tankon level with the third stringer down. They are piped and valved separately from the deck mounted machines. Theirprogramme is fixed and covers an arc of 240o which at an operating pressure is 100 m3/hr.

To verify the operation of these machines, all other machines in the tank and in any adjacent tank should be shutoff, and the movement of the machine identified by its sound pattner.

Submerged machines “K’ twin nozzle

One of these is fitted underneath the bottom stringer at the aft end of each of No.7 wings and one “Super K” isfitted at the bottom of the dirty slop tank No.8 port. They are valved and lined separately from any other machines.Their capacity is 30 m3/hr (60 m3/hr for the “Super K”) and the time for one full cycle is 40 minutes. A full cycleconsists of one full revolution (360o) of the machine.

It is not possible to verify their operation by sound pattern and therefore after six usage or at intervals of not morethan twelve months these machines must be sighted and seen to be working using water.

SECTION 4. DANGEROUS OF AND PRECAUTIONS AGAINST OIL LEAKAGE

This section contains information on the dangers of leakage from the crudi oil washing system, the precautionsnecessary to prevent leakage and the action to be taken in the eventof leakage.


Leakage of crude oil from the system can be a potential fire and pollution hazard. Before arrival at the dischargeport, the tank washing system should be pressure tested and examined for leaks. Any leaks found should be mademood and the resultant oil cleaned up.

During the pressure test, special attention should be given to isnpection and tightening of valve glands and offlanges and couplings on lines to prevent any leakage.

During the course of oil washing, the system must be kept under continuous observation and on completion ofwashing it must be completely drained of oil. If it is necessary for the system to be cleaned out, it should be flushedthrough with water into appropriate tanks; if the system is required to be gas-free it should be ventilated in the sameway as cargo lines.

The crude oil washing must be stopped when any sign of leakage or fault in the tank wash system is discoveredeither on deck or in the pump room.

SECTION 5. USE AND CONTROL OF INERT GAS

This section contains information on the inert gas requirements and the instructions to cover those periods when theinert gas pressure is released for reasons of cargo operation. In addition it indicates the method and procedures to beused for taking samples of the tank atmosphere.

The ship should arrive at the discharge port with all cargo tanks pressurized with good quality inert gas. Pressuremay be released for ullaging, sampling and water dips before discharge and at this stage the oxygen level in tanks shouldbe checked to ensure that it is below 8 per cent by volume. the supply of inert gas must be commenced immediatelybefore the commencement of cargo discharge to avoid a vacuum in tanks. By this means a safe condition will bemaintained throughout discharge. Apart from this intiial release of pressure the pressure in the cargo tanks shouldalways be above atmospheric pressure. Under no circumstances should air be allowed to entry any tank which is to becrude oil washed.

Before each tank is washed, the oxygen content should be checked with the portable oxygen analyser to ensurethat it does not exceed 8 per cent by volume. The sample should be taken at a point one metre below the deck and atthe middle regionl of the ullage space well clear of the inert gas inlet point. (See section 2 of this Manual for the positionof the sampling points).

The crude oil washing must be stopped if there is a failure if the inert gas plant or if the oxygen content of thedelivered inert gas exceeds 8 per cent by volume or if the pressure of the atmosphere in the cargo tanks falls belowatmospheric pressure.

SECTION 6. PRECAUTIONS AGAINST ELECTROSTATIC HAZARDS

This section contains details of the procedures for minimizing electrostatic generation.

Mixtures of oil and water can produce an electrically charged mist during tank washing. The use of dry crude istherefore important. To overcome the possibility of developing such an electrically charged mist, before crude oilwashing is commenced any tank containing crude oil which is to be used as the crude oil washing fluid is to be partially


discharged to remove any water which has settled out during the voyage. To ensure adequate safety a minimum of onemetre depth of cargo is to be discharged in this way.

For the same reason, as the slop tank will invariably contain a mixture of retained oil residues and cargo, the wholecontent of the slop tank should be discharged ashore before crude oil washing commences and then be refilled withfresh crude fromt he cargo discharge deck line, if the slop tank is to be used as a source of washing fluid. It must beremembered that this refilling will take place after the discharge of the bottom one metre depth of cargo from othertanks, referred to above, has been completed.

SECTION 7. PERSONNEL REQUIREMENTS

This section specifies the numbers of persons to be associated with the crude oil washing process and their neces-sary qualifications. Their names and rank may be provided on separate documents.

The following personnel are required to be on board to carry out the dual operation of discharging cargo andcrude oil washing :

1. The master or chief officer who will have overall responsibility for the operation. He must meet the require-ments of paragraph 5.2 of the revised Specifications. (See Section 1 of this Manual).

2. The officer who will undertake the actual operation. He must meet the requirements of paragraph 5.3 of therevised Specifications (See section 1 of the Manual).

3. A minimum of one petty officer or rating who is to be on deck at all times during washing to keep watch forleaks and malfunction of equipment, to test the oxygen content of tanks before washing, to check tank atmospherepressure, to sound tank bottoms when required and to lift ullage floats.

The duties of the persons referred to above are not necessarily mutually exclusive.

SECTION 8. METHODS OF COMMUNICATION

This section gives the details of communication between the watchkeeper on deck and the cargo control positionso that, in the event of a leak or malfunctioning of the crude oil washing system, the washing may be stopped as soon aspossible.

This ship is equipped with hand-held walkie-talkie radios which are certified intrinsically safe.

While crude oil washing is being carried out, the man patrolling the deck for the purpose of monitoring machinesand checking against any oil leakage from the system must carry one of these walkie-talkies. Additionally, in or in theimmediate vicinity of the cargo control room, there must be a second man similarly equipped with a walkie-talkie. Theprovision of two sets for crude oil washing purposes has priority over any other requirements for walkie-talkie. Novalves should be opened or closed on the crude oil washing system without the one party informing the other as to theaction he is taking.

SECTION 9. LIST OF CRUDE OILS UNSUITABLE FOR CRUDE OIL WASHING

This section contains a list of crude oils unsuitable for crude oil washing.


This vessel is not fitted with heating coils in the cargo tanks and it should not carry cargoes which will require to beheated for pumpability.

SECTION 10. CRUDE OIL WASHING CHECKLISTS

This section contains operational checklists for the use of the crew at each discharge which shall include thechecking and calibration of all instruments.

PRE-ARRIVAL CHECKS AT DISCHARGE PORT

No. ITEM

1. Has terminal been notified?

2. Is oxygen analysing equipment tested and working satisfactorily?

3. Is tank washing pipeline system isolated from water heater and engineroom?

4. Are all hydrant valves on tank washing line blanked?

5. Are all valves to fixed tank washing machines shut?

6. Have tank cleaning lines been pressurized and leakages made good?

7. Have portable drive units for fixed tank washing machines been tested?

8. Have pressure gauges on top discharge line, manifold and tank cleaningmain been checked?

9. Has the stripping system monitoring equipment been checked?

10. Has the communications system been checked and tested?

11. Has the organization plan been drawn up and posted with duties andresponsibilities defined?

12. Have the discharge / crude oil wash operation plans been drawn upand posted?

13. In case where the terminal has a standard radio checklist, has thisbeen completed and transmitted?

CHECKLIST FOR USE BEFORE, DURING AND AFTER CRUDE OIL WASH OPERATION

No. ITEM

A. Before crude oil wash operation

1. Are all pre-arrival checks and conditions in order?

2. Has discharge / crude oil wash operation been discussed with both


ship and shore staff and is agreed plan readily available for easyreference?

3. Has communication link between deck / control station and controlstation / shore been set up and is it working properly?

4. Have crude oil washa bort condition and procedures been discussedand agreed by both ship and shore staff?

5. Have fixed and portable oxygen analysers been checked and are theyworking property?

6. Is inert gas system working properly and is the oxygen content of inertgas being delivered below 5 per cent by volume?

7. Is oxygen content of tank(s) to be crude oil washed below 8 percent byvolume?

8. Have all cargo tanks positive inert gas pressure?

9. Has a responsible person been assigned to check all deck lines forleaks as soon as washing starts?

10. Are the fixed machines set for the required washing method and areportable drive units, if fitted, mounted and set?

11. Have valves and lines both in pumproom and on deck been checked?

B. During crude oil wash operation

12. Is quality of inert gas being delivered frequently checked and recorded?

13. Are all deck lines and machines being frequently checked for leaks?

14. Is crude oil washing in progress in designated cargo tanks only?

15. Is the pressure in the tank wash line as specified in this Manual?

16. Are cycle times of tank washing machines as specified in this Manual?

17. Are the washing machines in operation, together with their drive unitsif applicable, frequently checked and are they working properly?

18. Is a responsible person stationed continuously on deck?


19. Will trim be satisfactory when bottom washing is in progress as specifiedin this Manual?

20. Will recommended tank draining method be followed?

21. Have ullage gauge floats been raised and housed in tanks being crudeoil washed?

22. Is level in holding tank for tank washings frequently checked to preventany possibility of an overflow?

C. After crude oil wash operation

23. Are all valves between discharge line and tank wash line closed?

24. Has tank wash line been drained of crude oil?

25. Are all valves to washing machines closed?

26. Are cargo pumps, tanks and pipelines properly drained as specified in this Manual?

SECTION 11.APPROVED METHODS AND PROGRAMMES FOR CRUDE OIL WASHING

This section contains those details which form the basis of crude oil washing in the tanker and which are necessaryto formulate a washing programme which will accord with all foreseeable circumstances of cargo discharge restraints. Itincludes information on :

(1) the minimum number of tanks to be washed in accordance with paragraph 6.1 of the revised Specifications;(2) the method of washing each tank, ie., single or multistage;(3) the number of tank washing machines to be used simultaneously;(4) the crude oil washing pressure and means to maintain the required pressure;(5) the duration of the crude oil wash;(6) the preferred order in which tanks are to be washed;(7) the minimum trim during completion of washing and draining tanks;(8) when draining and stripping of tanks is to commence.

Before departure on a ballast voyage, both the departure and arrival ballast tanks must have been crude oilwashed. These are No.1, No.4 and No.6 centres and No.2 No.5 and No.7 centres, respectively. If for any opera-tional or maintenance reason, there is the likelihood or intention to put ballast in any other tanks during the voyage, then


these tanks must also be crude oil washed. Additionally, one quarter of the remaining tanks must be curde oil washedfor sludge control, but any exceptional ballast tanks as mentioned above may be included in the additional quarterrequired to be washed for sludge control.

In complying with the above policy and reconciling the objectives of ship safety, cargo out-turn, and minimum shipdelay, the following principles should be applied.

Discharge of wet oil

Because of the electrostatic hazards involved, oil which may contain water should not be used for crude oil wash-ing. All tanks to be discharged should therefore be debottomed by one metre before any crude oil washing is started.In particular, oil in slop tanks which have been used for load-on-top purposes must not be used. If it is required, to useslop tanks for the supply of wash oil, they should be discharged first, and then refilled with dry oil from another tank.

Sequence of tank washing

Priority should be given to crude oil washing departure ballast tanks first so that they are ready for ballasting iffreeboard problems arise and so that over the top ballasting can be concurrent with discharge, thereby avoiding theventing of tank gases to atmosphere within port areas.

Multistage washing

Each tank should be washed in two stages the side wash and the bottom wash, in order to minimize ship delay.During bottom washing the oil depth should not be allowed to increase over one metre and towards the end of thewashing, the bottom should be kept well drained to achieve the best results.

Extent of washing

In each tank being crude oil washed, all guns must be used.

The programme of the deck mounted machines shall be as follows :

Side wash : two passes, 30o-max-30o (to be started when ullage reaches approximately 23 metres).

Bottom wash : three passes, 30o-0o-30o-0o

The bottom guns in the wing tanks and NO.7 centre, are to be used in the bottom wash together with the deckmounted guns. Their cycle time is one hour and they should be started when there is a depth of one metre remaining inthe tank.

It is at this point that the draining of the tank should be considered to be started and the trim of this ship should benot less than 4 metres by the stern.

Mult-tank washing

To minimize ship delay it is desirable to crude oil wash several tanks simultaneously, provided that :

1. The maximum number of guns on any one centre tank, or pair of wing


tanks, are in use at one time;

2. Pressure on the deck wash line does not fall below 8 kg/cm2 and

3. The normal maximum number of guns that can be operated at one timeis 12 due to a maximum permissible flow rate through the line of 5.5m3/sec;

However, if more than 12 guns are required to be operatedsimultaneously, then it will be necessary to shut the block valvesituated on the wash line main amidships and feed the forward sectionof the line from the manifold bleed-off and the after section from thepumproom. In this way upto 24 guns may be operated at one time.

4. During the bottom washing the output of the guns does not exceed theavailable stripping capacity.

Supply of wash oil

The traditional method of tank washing using closed cycle recirculation via the slp tanks and eductors is not suitedto routine crude oil washing as it causes unnecessary delay. It also increases risk of passing sediment through themachines and of using oil which was lost much of its solvent effect. The wash oil therefore should be bled off from acargo pump discharge or from the manifold crossover. To retain the required pressure using the bleed-off method, itmay be necessary to reduce the number of machines being used, to ask the shore to increase back pressure, or to fullyclose one of the ship’s manifold valves. Under no circumstances should butterfly manifold valves be throttled in order tocontrol the tank wash line pressure, but it is possible to control the pressure by throttling in the discharge valve of thecargo pump used to supply the wash oil.

Alternatively, it may be necessary to dedicate one main cargo pump to supplying the wash oil and accept thereduction in the rate of discharge.

Discharge of tank washings

In order to maintain as consistent a quality in out-turn as possible, recovered residues should be co-mingled withthe main cargo discharge. During multi-stage washing of the tank sides this co-mingling occurs automatically. Duringbottom washing, it is preferable to use the self priming cargo pump to discharge the washing oil and recovered residuesdirect with the cargo. Overheating of these pumps may be avoided by draining several tanks simultaneously.

When discharge directly ashore is not possible, residues should be stripped into some convenient holding tank,taking care to avoid any over-filling before the tank is periodically discharged to shore.

Recirculation of cargo, that is dedicating the same tank both for supplying the washing oil and for receiving therecovered residues, should be avoided as long as possible. However this method does have to be used when crude oilwashing at sea between two discharge ports and on occasion towards the end of a parcel discharge when more thanone grade is being carried.


SECTION 12. TYPICAL CRUDE OIL WASHING PROGRAMMES

This section contains details of some typical washing programmes under various conditions of discharge such assingle or multiport discharge and single and multigrade cargoes.

SECTION 13. THE METHOD OF DRAINING CARGO TANKS

This section contains a description of the method of draining cargo tanks and should include the parameters whichindicate when the tank is dry and which will be at least all of those required by paragraph 4.4.8 of the revisedSpecificiations. The minimum trim conditions must be stated.

The vessel is fitted with a self priming “Vac-Strip” system where it is possible to drain tanks dry with the maincargo pumps. As a tank or tanks approach draining level the system is manually set in operation and thereafter vacuumpumps automatically draw off excess gases and the pump discharge valve closes as flow decreases.

The optimum method to use is as follows :

With a number of tanks approaching draining level ie., approximately one metre sounding, the system should be setin operation and then when the first tank reaches 1/2 metre the main sunction(s) should be shut and the process shouldbe repeated for each tank until the last tank is reached. When the level in that tank reaches 1/2 metre the pump shouldbe slowed to 800 rpm, the stripping suction(s) opened and the main suction shut slowly. The tank will then drain untilthe area around the strum is oil free. This is indicated by the following :

1. Whessoe gauge at maximum ullage (gauge should be housed whilstcrude oil washing)

2. Flow trace absolutely zero with no fluctuation.

3. Separator virtually rempty.

4. Discharge valve closed.

5. Pump nozzle steam pressure falling.

6. Vacuum on suction trace falls away.

7. Pump casing temperature rising.8. Dips showing empty.

Thereafter the process should again be repeated for each tank back along the deck.

On occasions, for example at sea between discharge ports, it may prove necessary to employ the closed cyclesystem already described in this Manual. However, where a different grade may be contained in the centre slop tank itis possible to une No.2 main cargo pump drawing from the port slop tank via No.1 bottom line across the bottompumproom crossover and thence to the tank cleaning line and eductors.

When draining tanks using eductors, a good indication that a tank is empty is when the vacuum showing on theremote eductor suction gauge in the cargo control room drops completely away. Again hand dipping must be carriedout as described when using the Vac-Strip system. Should for any reason the eductor drive pressure fall away below 6


kg/cm2 then it is imperative that the eductor suction valves should be shurt immediately to prevent the contents of theslop tank running back through the eductors to the washing tank.

When bottom crude oil washing of any tank nears completion, using either method of draining, the tank washingmachines in that tank should be shut off one at a time and when all washing is complete sufficient time should be given tocomplete the draining.

It is important that when draining tanks, also using either system, the vessel is trimmed by the stern sufficiently toenable the cargo to run aft to the tank suction. The trim should be as much as possible with due regard to berth securityand tank stresses but should not be less than 4 metres.

SECTION 14 THE METHOD AND PROCEDURES FOR DRAINING CARGO PUMPS AND LINES

This section contains a description of the method and procedures for draining cargo pumps, cargo lines, crude oilwashing lines and stripping lines and includes information on the use of the small diameter line.

On completion of discharge, all top and bottom lines should be dropped back to either wing slop tank via thedirect loading drops and bottom pumproom crossovers. The port deck line can be dropped via the port drop andNo.1 line to the port slop tank, and the star-board deck line via the starboard drop No.4 line, and to the starboard sloptank via the stripping suction. The shore staff should be asked to vent their loading arms to permit the oil to drop back.At the same time the small by pass line on each cargo pump should be opened and the stripping pump set to drain theremains of each line individually to the port slop tank.

The tank wash line should be drained by the stripping pump. If the eductor suction valves E2 and D2 are openedtogether with valves E3 and H3 then it will be possible for the stripping pump to drain the entire tank wash line to theport slop tank. A tank cleaning machine should be opened in one of the forward tanks to facilitate the line droppingback.

When all lines are drained and cargo tanks dipped manually, the stripping pump can be set to discharge the linedrainings in each wing slop tank via the direct stripping suctions discharging through the special 250 mm diameter line tothe manifold and thence to the shore.

SECTION 15. TYPICAL PROCEDURES FOR BALLASTING AND THE METHOD OF PREVENTINGHYDROCARBON EMISSION

This section contains a description of typical procedures for ballasting and includes :(1) the procedure for draining and stripping before loading ballast;(2) the procedures for preventing hydrocarbon emission into the atmosphere.

The departure ballast tanks for this vessel are No.1 centre, No.3 wings, No.4 centre, and No.6 centre tanks.No.3 wing tanks are for permanent ballast only and are supplied by a dedicated ballast pump of 4,250 m3/hr capacitywith its own pipeline. No.1 centre, No.4 centre, and No.6 centre are cargo tanks but can be supplied with ballast usingthe dedicated ballast pump via a separate discharge line over the upper deck and by direct drops to these tanks.

The typical method of ballasting No.1 centre, No.4 centre and No.6 centre is to plan the discharge so that they aredischarged as early as possible. They must be crude oil washed and good care must be taken while bottom washing,with frequent monitoring of soundings to ensure the tank bottoms are well cleared. Once the tanks are empty to the


satisfaction of the chief officer, with the main suction and stripping valve controls lashed in the closed position togetherwith all Lavomatic stop valves on those tanks checked shut then ballasting to No.1 cetnre, No.4 centre and No.6 centrecan be commenced as soon as required.

During cargo discharge there is no hydrocarbon emission to atmosphere, with the vacant cargo space beingreplaced by inert gas. Also, when ballasting No.1, No.4 and No.6 centres concurrently with the discharge of othertanks, again there should be no hydrocarbon emission as the rate of supply of inert gas is reduced automatically tomaintain the normal overpressure. However, if for any reason, cargo discharge is stopped or slowed sufficiently so thatthe deck I.G. pressure increases due to the displacement of the incoming ballast then once 1,000 mm WG is reachedfurther ballasting should be postponed until the deck pressure is reduced by the resumption of cargo discharge.

SECTION 16 COMPLIANCE PROCEDURES FOR REGULATION 9 ANNEX 1 OF MARPOL 73/78

This section contains information and procedures for water washing tanks and lines, discharge of departure ballastand the decanting of slops at sea to ensure compliance with Regulation 9.

Departure ballast is taken in No.1, No.4 and No.6 centres using the permanent ballast pump and the “over thetop” line.

On the ballast voyage, it will be necessary to wash the arrival ballast tanks, No.2, No.5 and No.7 centres, fill themwith clean ballast and then discharge No.1, No.4 and No.6 centres.

In order to wash the arrival ballast tanks, it is first necessary to charge the slop tanks with sea water. The opportu-nity should be taken at this time to give an initial wash of top and bottom lines to the dirty slop tank.

The arrival ballast tanks should be washed with cold water on the closed cycle system. Each tank must receivenot less than the following wash :

One full cycle and one hour on bottom cycle 0o to 30o. All guns must be used including the bottom mountedmachine in No.7 centre.

On completion of the tank washing the vessel is then ready to receive clean ballast. Initially the pumps and lines tobe used should be cleared to the dirty slop tank and thereafter clean ballast loaded to the required ullage in No.2, No.5and No.7 centres. Before discharging the dirty ballast it will be necessary to discharge a sufficient quantity of waterfrom the slop tanks to create sufficient ullage for the expected dirty ballast drainings. An interface of the three slop tanksshould therefore be taken to establish the limits to which discharge of slops can be taken withiout discharge of oil.

On commencement of slop tank discharge, both No.2 and No.3 main cargo pumps should be cleared, pumpingfrom No.8 centre through the eductors to the dirty slop tank, and thereafter to sea via the high overboard discharge.Pumping from No.8 centre should then the continued with the balance valves and lines open until sufficient ullage isobtained.

Once the water has been discharged from the slop tanks, the suction can be changed to No.1 centre, No.4 centreand No.6 centre, the pumps again cleared to the port slop tank via the eductor discharges and thereafter to sea via thehigh overboard discharge. Close visual attention must be paid to the overboard discharge throughout, but particularlywhen the levels in each tank approach draining level. However, when 2 1/2 metres sounding in the first tank is reached,


both main cargo pumps should be slowed to 800 rpm, and at 1 1/2 metres one cargo pump should be stopped. At onemetre sounding or at the first sight of any oil in the outgoing stream, discharge should be stopped and the system set upfor educting the remainder of the dirty ballast back to the slop tanks. On completion the lines should again be washedto the slop tanks.

Once all tank washing and the ballast operations are complete the slop tank contents can be discharged. Prefer-ably 24 hours should be given for oil / water separation; this may have to be reduced, however, on short voyages, andthen interface readings taken of each slop tank to establish the oil quantities in ech tank. The free water can then bedischarged the centre and starboard tanks to one metre from the oil layer, the port slop tank No.2 metres from the oillayer. Again, very close attention must be paid to the overboard discharge. Thereafter the quantities remaining in thecentre and starboard slop tanks should be transferred to the port slop tank using the stripping pump. Again, preferably24 hours should be allowed for separation and after an interface establishing the oil layer has been taken, the free watercan be discharged overside with the stripping pump to one metre from the oil level and thereafter to the oil/waterseparator on deck at a slow rate (maximum 100 m2/hr) until no further water can be discharged.

SECTION 17 INSPECTIONS AND MAINTENANCE OF EQUIPMENT

This section contains information on procedures to be followed at recommended intervals for on-board inspectionsand maintenance of crude oil washing equipment.

Deck mounted machines

It is not intended that these machines be removed from the tanks unless there has been an actual mechanical failure.However in the event of such a failure a lifting tripod chain block and tools are provided and must be kept in goodorder.

Normal maintenance will therefore consist of ensuring that the gearbox is topped up with lubricating oil, the filter isclear, the stop valve is tight and the machine is carrying out its programme.

During periodic dry dock, the opportunity shall be taken to confirm that the nozzles are clear. This may be doneby observing the water jet.

Bottom mounted machines

Maintenance of these machines shall consit of ensuring that the filter is clear and the stop valve is tight.

The correct operation of the machine, lube oil level and nozzle jet can be confirmed by observation whenever atank is in a gas free condition, but inspections should be made after not more than six usages or at intervals of twelvemonths, whichever is the more frequent.

SECTION 18. PROCEDURES FOR CHANGING FROM CRUDE OIL TRADE TO PRODUCT TRADE

This section contains operational procedures for changing from crude oil trade to product trade for a tanker whichis fitted with separate independent pumping and piping arrangements for ballasting dedicated clean ballast tanks andwhich has been issued with two IOPP certificates running concurrently with one certificate certifying the tanker to be acrude oil tanker and the other certifying it to be a product carrier.


Note : This section was not included in the Manual as originally prepared by the tanker owner as it was notapplicable to the particular tanker concerned. It has been added to this specimen Manual as an example of how theinformation relating to section 18 might be presented if required in a particular case.

This oil tanker is equipped with a COW system for the crude oil trade and also has a CBT system for the producttrade with separate independent pumping and piping arrangements for ballasting the dedicated clean ballast tanks; itmay therefore change from the crude oil trade to the product trade without undergoing a survey. When making thischange from the crude oil trade operating with a COW system to the product trade operating with dedicated cleanballast tanks, the following procedures shall be followed :

1. during the discharge of the crude oil cargo, the tanks that are to beused as dedicated clean ballast tanks when the vessel is in the producttrade should be crude oil washed in accordance with the approvedmethods and programmes contained in section 11 of this Manual. Thesetanks are to be crude oil washed in addition to those that are requiredto be crude oil washed by section 11;

2. to remove any oily water mixtures that might remain in the separateindependent pumping and piping arrangements, this separate systemshould be flushed by pumping sea water through the system into thetanks before water washing commences. This flushing water shouldbe discharged to the slop tank through the cargo piping connexion tothe tanks;

3. after discharging all flushing water from these tanks through teh cargopiping connexions, all valves in the cargo piping lines that are connectedto the tanks that are to be used as dedicated clean ballast tanksshould be closed and secured;

Example 1Conventional pipeline tanker

4. the tanker that are to be used as dedicated clean ballast tanks shouldbe water washed in accordance with the procedures used for preparingarrival ballast tanks contained in section 16 of this Manual prior tothe loading of the next cargo;

5. after completion of water washing of these tanks, all wash water shouldbe discharged to the slop tank;

6. at the loading port, product cargo can be loaded on the vessel, but itmay not be loaded into the tanks that are designated as dedicatedclean ballast tanks while the vessel is in the product trade;

7. the vessel should now operate as a product carrier with a CBT systemand the Dedicated Clean Ballast Tank Operation Manual should beused while the vessel is in this trade.


IV. GUIDELINES FOR IN-PORT INSPECTION OF CRUDE OIL WASHING PROCEDURES

1. INTRODUCTION

1.1 Guidelines for the in-port inspection of crude oil washing procedures as called for by resolution 7 of theInternational Conference on Tanker Safety and Pollution Prevention, 1978, are required to provide a uniform andeffective control of crude oil washing to ensure compliance of ships at all times with the provisions of the Protocol of1978 relating to the International Convention for the Prevention of Pollution from Ships, 1973 (MARPOL 73/78).

1.2 The design of the crude oil washing installation is subject to the approval of the Administration of the flagState. However, although the operational aspects of crude oil washing is also subject to the approval of the sameAdministration it might be necessary for the authority of a port State to see to it that continuing compliance with agreedprocedures and parameters is ensured.

1.3 The Operations and Equipment Manual contains all the necessary information relating to the operation ofcrude oil washing on a particular tanker. The objectives of the inspection are therefore to ensure that the provisions ofthe Manual dealing with safety procedures and with pollution prevention are being

strictly adhered to.

1.4 The method of the inspection is at the discretion of the port State and and actual inspection may cover theentire crude oil washing operation or only those parts of the operation which occur when the inspector is on board.

1.5 Inspection will be governed by Articles 5 and 6 of MARPOL 73/78.

2. Inspections

2.1 A port State should make the appropriate arrangements so as to ensure compliance with requirements gov-erning the crude oil washing of tankers. This is not, however, to be constructed as relieving terminal operators andshipowners of their obligations to ensure that the operation is undertaken in accordance with the regulations.

2.2 The inspection may cover the entire operation of crude oil washing or only certain aspects of it. It is thus in theInterest of all times so that an inspector may verify those operations undertaken prior to his inspection.

3. Ship’s Personnel

3.1 The person in charge and the other nominated persons whohave responsibilities in respect of the crude oil washing operation should be identified. They must, if required, be

able to show that their qualifications meet the requirements as appropriate of paragraphs 5.2 and 5.3 of the revisedSpecifications for the Design, Operation and Control of Crude Oil Washing Systems as adopted by IMO.

3.2. The verification may be accomplished by reference to the individual’s discharge papers, testimonials issued bythe ship’s operator or by certificates issued by a training centre approved by an Administration. The numbers of suchpersonnel should be at least as stated in the manual.


4. Documentation

4.1. The following documents will be available for inspections :

4.1.1 The International Oil Pollution Prevention Certificate, to determine;

1.1 whether the vessel is fitted with a crude oil washing system as required in regulation 13(6) or (8) of Annex I ofMARPOL 73/78; and

1.2 whether the crude oil washing system is according to and complying with the requirements of Regulation13(B) of Annex I of MARPOL 73/78.

1.3 the identification of the Operations and Equipment Manual;1.4 the validity of the Certificate;

4.1.2. the approved Operations and Equipment Manual;

4.1.3 the Oil Record Book and attached Supplement;

4.1.4 the Cargo Ship Safety Equipment Certificate to confirm that the inert gas syste conforms to Regulationscontained in Chapter II-2 of the International Convention for the Safety of Life at Sea, 1974, as modified and added toby the Protocol of 1978.

5. Inert Gas System

5.1 Regulations covering inert gas systems require that instrumentation shall be fitter for continuously indicating andpermanently recording the pressure and oxygen content of the gas in the inert gas supply main at all times when inert gasis being supplied. The permanent recorder should indicate if the system has been operating in a satisfactory mannerbefore and during the cargo discharge.

5.2 If conditions specified in the Operations and Equipment Manual are not being met the washing must bestopped until satisfactory conditions are restored.

5.3 As a further precautionary measure, the oxygen level in each tank to be washed is to be determined at thetank. The meters used should be calibrated and inspected to ensure that they are in good working order. Readingsfrom tanks already washed in port prior to inspection should be available for checking. Spot checks on readings maybe instituted.

6. ELECTROSTATIC GENERATION

6.1 It should be confirmed, either from the cargo log or by questioning the person in charge, the presence of waterin the crude oil is being minimized as required by paragraph 6.7 of the revised Specifications.

7. COMMUNICATION

7.1 It should be established that effective means of communication exist between the person in charge and theother persons concerned with the COW operation.

8. LEAKAGE ON DECK


8.1 Inspectors should ensure that the COW piping system has been operationally tested for leakage before cargodischarge and that the fact has been noted in the ship’s Oil Record Book.

9. EXCLUSION OF OIL FROM ENGINE ROOM

9.1 It should be ascertained that the method of exclusing cargo oil from the machinery space is being maintainedby inspecting the isolating arrangements of the tank washing heater (if fitted) or of any part of the tank washing systemwhich enters the machinery space.

10. SUITABILITY OF THE CRUDE OIL

10.1 The types of crude oil being carried should not be on the list provided in the Operations and EquipmentManual as being unsuitable.

11. CHECKLIST

11.1 It should be determined from the ship’s records that the checks in the pre-crude wash operational checklistwere carried out and that all instruments functioned correctly. Spot checks on certain items may be instituted.

12. WASH PROGRAMMES

12.1 Where the tanker is engaged in a multiple port discharge the Oil Record Book should indicate if tanks werecrude oil washed at previous discharge ports or at sea. It should be determined that all tanks which will be, or may be,used to contain ballast on the forthcoming voyage will be crude oil washed before the ship leaves the port. There is noobligation to wash any tank other than ballast tanks at a discharge port except that each of these other tanks must bewashed at least in accordance with paragraph 6.1 of the revised Specifications. The Oil Record Book should beinspected to check that this is being complied with.

12.2 All crude oil washing must be completed before a ship leaves its final port of discharge.

12.3 If tanks are not being washed in one of the preferred orders given in the Manual, the inspector should satisfyhimself that the reason for this and the proposed order of tank washing are acceptable.

12.4 For each tank being washed it should be ensured that the operation is in accordance with the Operations andEquipment Manual in that :

12.4.1 the operation of deck mounted machines and submerged machines is verified by reference either toindicators, or to the sound patterns of the machines, or by other approved methods;

12.4.2 the deck mounted machines, where applicable, are programmed as stated;

12.4.3 the duration of the wash is as required;

12.4.4 the number of tank washing machines being used simultaneously does not exceed that specified.

13. STRIPPING OF TANKS


13.1 The minimum trim conditions and the parameters of the stripping operations are to be as stated in the Opera-tions and Equipment Manual.

13.2 All tanks which have been crude oil washed are to be stripped. The adequacy of the stripping is to bechecked by hand dipping at least in the aftermost hand dipping location in each tank or by such other means as areprovided and described in the Manual. It should be ascertained that the adequacy of stripping has been checked or willbe checked before the ship leaves its final port of discharge.

14. BALLASTING

14.1 Tanks that were crude oil washed at sea will be recorded in the Oil Record Book. These tanks must be leftempty between discharge ports for inspection at the next discharge port. Where these tanks are the designated depar-ture ballast tanks they may be required to be ballasted at a very early stage of the discharge. This is for operationalreasons and also because they must be ballasted during cargo discharge if hydrocarbon emission is to be contained onthe ship. If these tanks are to be inspected when empty, this must be done shortly after the tanker berths. If an inspec-tor arrives after the tanks have begun accepting ballast, the sounding of the tank bottom will not be available to him.However, an examination of the surface of the ballast water is then possible. The thickness of the oil film should not begreater than that specified in paragraph 4.2.10 (b) of the revised Specifications.

14.2 The tanks that are designated ballast tanks will be listed in the Manual. It is, however, left to the discretion ofthe master or responsible officer to decide which tanks may be used for ballast on the forthcoming voyage. It should bedetermined from the Oil Record Book that all such tanks have been washed before the tanker leaves its last dischargeport. It should be noted that where a tanker back-loads a cargo of crude oil at an intermediate port into tanks desig-nated for ballast then it should not be required to wash those tanks at that particular port but at a subsequent port.

14.3 It should be determined from the Oil Record Book that additional ballast water has not been put into tankswhich had not been crude oil washed during previous voyages.

14.4 It should be seen that the departure ballast tanks are stripped as completely as possible. Where departureballast is filled through cargo lines and pumps, these must be stripped either into another cargo tank or ashore by thespecial small diameter line provided for this purpose.

14.5 The methods of avoiding vapour emission where locally required will be specified in the Manual and theymust be adhered to. The inspector should ensure that this is being complied with.

14.6 The typical procedures for ballasting listed in the Operations and Equipment Manual must be observed. Theinspector should ensure this is being complied with.

14.7 When departure ballast is to be shifted, the discharge into the sea must be in compliance with Regulation 9 ofAnnex I of MARPOL 73/78. The Oil Record Book should be inspected to ensure that the vessel is complying withthis.

Crude Oil Washing Cow

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