CRUDE
OIL
WASHING
SYSTEMS
including amendments adopted by the MEPC at its
forty-third session {28 June to 2 July 1999)
and...
First published in 1980
by the INTERNATIONAL MARITIME ORGANIZA710N
4 Albert Embankment, London SEI 7SR
Second edition 1982...
FOREWORD
This publication contains:
• Revised Specifications for the design, operation and control of crude oil washing sy...
Crude oil washing systems
CRUDE Oil WASHING OPERATIONS AND EQUIPMENT MANUAL
Every tanker which operates with crude oil was...
r
p
pil
Foreword
The Conference recognized that in order to implement effectively the requirements of regulations l3 and
1...
CONTENTS
Revised Specifications for the design, operation and control of crude oil washing systems
Resolution A.446{XI}, a...
I
REVISED SPECIFICATIONS FOR THE
DESIGN, OPERATION AND CONTROL OF
CRUDE OIL WASHING SYSTEMS .
.,
Crude oil washing systems
Index
Page
Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
d
Revised Specifications
1 Purpose
The purpose of these Specifications is to provide specific design criteria, operational...
Crude oil washing systems
(a) the removal of the equipment, if necessary, when carrying cargoes other than crude oil, pro-...
f
a
Revised Specifications
4.2.2 The performance characteristic of a tank washing machine is governed by nozzle diameter, ...
Crude oil washing systems
4.2.10 To confirm the effectiveness of the crude oil washing system and stripping system, the cr...
:l
Revised Specifications
washing survey requirements, the Administration may require an internal examination of the
tanks...
Crude oil washing systems
4.4 Stripping system
4.4.1 The design of the system for stripping crude oil from the bottom of e...
Revised Specifications
4.5 Ballast lines
Vhere a separate ballast water system for ballasting cargo tanks is not provided,...
Crude oil washing systems
6.2 Drainage and discharge ashore of cargo lines
At the end of cargo discharge all cargo mains a...
e
Revised Specifications
(a) by the use of permanent ballast tanks wherever these are sufficient to provide the minimum
de...
Crude oil washing systems
12
(5) the volume of water used for water rinse, which shall be at least equal to that used in
t...
Revised Specifications: Appendix I
Appendix I
List of changes when applying the Specifications to
new crude oil tankers of...
Crude oil washing systems
14
(i) recommended methods and programmes of crude oil washing in order to accord with
all fores...
g
e
Revised Specifications: Appendix II
Introduction
Appendix II
Training for persons intended to assume
overall charge of...
Crude oil washing systems
(iv) ballasting for departure with various ship and pipeline configurations;
(v) procedure for w...
ed in
Revised Specifications: Appendix Ill
Appendix Ill
Agreed interpretations of certain of the provisions of
the Revised...
Crude oil washing systems
Include
(vi) transverses
(vii) crossties in transverse web
frames, unless it can be ve-
rified b...
be
per-
that
etric
IS to
inal
ead
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~d in
tern,
~eed
ution
~e of
ecial
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Revised Specificat...
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Longitudinal
Longitudinal bulkhead
f=~}frfrpritf~!~_-Longttudinal
Upper deck Longitudinal
Deck girder
Stiffener
/l~~
1...
II
STANDARD FORMAT FOR
THE CRUDE OIL WASHING
OPERATIONS AND EQUIPMENT MANUAL
Standard format for the COW Manual
STANDARD FORMAT FOR THE
CRUDE OIL WASHING OPERATIONS AND EQUIPMENT MANUAL
(The standard...
Crude oil washing systems
Index of sections
Relevant
paragraph(s)
of the Revised
Page Specifications
Part 1
Text of the Re...
")
Standard format for the COW Manual
Contents of sections 1 to 18
SECTION 1: TEXT OF THE REVISED SPECIFICATIONS
This sect...
Crude oil washing systems
SECTION 6: PRECAUTIONS AGAINST ELECTROSTATIC HAZARDS
This section contains details of the proced...
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ntrol
may
g.
'ons
~Ned
for
s of
hout
e oil
~loud
phase
goes
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udge
Standard format for the COW Manua...
Crude oil washing systems
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Crude oil washing systems
SECTION 12: TYPICAL CRUDE OIL WASHING PROGRAMMES
This section contains details of some typical w...
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eters
the
lines,
line.
ure
ard
lean
one
Ill
EXAMPLES OF CRUDE OIL WASHING
OPERATIONS AND EQUIPMENT MANUALS
Explanator...
Example 1: Conventional pipeline tanker
Example 1
Conventional pipeline tanker
CRUDE OIL WASHING OPERATIONS AND EQUIPMENT ...
Crude oil washing systems
INTRODUCTION
1 This Manual is written in accordance with the requirements of regulation 13B of t...
!col of
RPOL
jth the
embly
1tional
1 to be
evised
11-de to
Example 1: Conventional pipeline tanker
Index of sections
of th...
Crude oil washing systems
SECTION 1: TEXT OF THE REVISED SPECIFICATIONS
This section contains the complete text of the Rev...
hydraulict-:1 Butterfly valve,
hydraulic &
t:+::J Gate valve, lly operated
manual, loca
[:::f<1 Gate valve, manual
b lkhea...
Example 7: Conventional pipeline tanker
Ives, ballast and stripping systems
'400
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& T
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£
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37
1g lines and valves and position of tank washing machines
No 6 PORT WING CARGO TANK n> ,..p No 4 PORT WING CARGO TANK
M/c
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Crude oil washing systems
CARGO AND
STRIPPING LINES
(PUMP ROOM)
5.2.1(2)
164
Figure 2: Crude oil washing lines and valv
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Crude oil washing systems
SECTION 3: DESCRIPTION OF THE CRUDE Oil WASHING SYSTEM
AND OPERATIONAL AND EQUIPMENT PARAMETERS
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Crude oil washing systems
1. Determine the thickness of the oil layer on the ballast water (txl·
2. Using the tank capacit...
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Example 1: Conventional pipeline tanker
possible to verify their op...
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  1. 1. CRUDE OIL WASHING SYSTEMS including amendments adopted by the MEPC at its forty-third session {28 June to 2 July 1999) and by the Assembly at its twenty-first session {15 to 26 November 1999) (Q "-".....,, ~ International Maritime Organization London, 2000
  2. 2. First published in 1980 by the INTERNATIONAL MARITIME ORGANIZA710N 4 Albert Embankment, London SEI 7SR Second edition 1982 Third edition 1983 Fourth edition 2000 Printed in the United Kingdom by Ashford Press 2 4 6 8 10 9 7 5 3 1 ISBN 92-801-5094-4 IMO PUBLICATION Sales number: IM0-61 7E Copyright © IMO 2000 All rights reserved. No part of this publication may, for sales purposes, be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, electrostatic, magnetic tape, mechanical, photocopying or othetwise, without prior permission in writing from the International Maritime Organization.
  3. 3. FOREWORD This publication contains: • Revised Specifications for the design, operation and control of crude oil washing systems (resolution A.446(XI), as amended by resolutions A.497(Xll) and A.897(21 )); • standard format for the Crude Oil Washing Operations and Equipment Manuals (resolution MEPC.3(Xll), as amended by resolution MEPC.81(43)); • examples of Crude Oil Washing Operations and Equipment Manuals; • Guidelines for in-port inspection of crude oil washing procedures. REVISED SPECIFICATIONS The International Conference on Tanker Safety and Pollution Prevention (TSPP Conference) convened by the International Maritime Organization (IMO) in February 1978 adopted, inter alia, the Protocol of 1978 relating to the International Convention for the Prevention of Pollution from Ships, 1973, which modified the 1973 Convention.* MARPOL 73/78 (regulation 13 of Annex I) requires certain ships to operate with a cargo tank cleaning system using crude oil washing. The crude oil washing installation, associated equipment and arrangements must meet the requirements established by the Administration based on the Specifications for the design, operation and control of crude oil washing systems adopted by the Conference in resolution 15 and as may be revised by the Organization (regulation 138 of Annex I of MARPOL 73/78). The Conference requested the Organization to review and revise the Specifications, as necessary, in order that the Revised Specifications would reflect the latest technology and practices which might be developed by the time of entry into force of MARPOL 73/78. The task of reviewing and revising the Specifications was carried out by the Marine Environment Protection Committee (MEPC) of the Organization at its 1Oth and 11 th sessions as a matter of urgency. In the course of its work, the MEPC found that there was a need, not only to revise certain provisions of the Specifications, but also to agree on interpretations of some of the provisions. The IMO Assembly, at its 11 th session (November 1979), received and examined the recommendations made by the MEPC on this matter and adopted, by resolution A.446(XI), the Revised Specifications for the design, operation and control of crude oil washing systems, together with agreed interpretations of certain of the provisions of the Revised Specifications. As stated in the resolution, the Revised Specifications supersede the Specifications contained in the annex to resolution 15 of the TSPP Conference. Since the 11 th session of the Assembly, the MEPC has kept the Revised Specifications under review and recommended certain amendments and additions both to the Revised Specifications and to the agreed interpretations; these were adopted by the Assembly at its 12th session (November 1981) by resolution A.497(Xll), and at its 21st session (November 1999) by resolution A.897(21). The attention of Governments is drawn to the fact that the Assembly urged them to establish, in time for the entry into force of MARPOL 73/78, requirements for crude oil washing installations and associated equipment and arrangements based on the Revised Specifications, and urged further that such requirements should not impose requirements over and above those laid down in the Revised Specifications. * The 1973 Convention, as modified by its 1978 Protocol, is referred to throughout this publication as MARPOL 73/78. iii
  4. 4. Crude oil washing systems CRUDE Oil WASHING OPERATIONS AND EQUIPMENT MANUAL Every tanker which operates with crude oil washing, in accordance with regulation 13, must be provided with an Operations and Equipment Manual approved by the Administration. The Manual must detail the system and equipment and specify operational procedures (regulation 138 of Annex I of MARPOL 73/78). As the purpose of the Operations and Equipment Manual is not only to provide guidance to the crew of the ship on the proper operation of the system but also to provide information on the system and its operational procedures for inspectors going on board for inspection in ports, the MEPC decided to develop a standard format for the Manual. This was adopted by the MEPC at its 12th session by resolution MEPC.3(Xll). The MEPC adopted revisions to the standard format at its 43rd session by resolution MEPC.81 (43). It is hoped that the standard format will help shipowners in preparing the Manuals for their ships and Administrations in approving them. The standard format contains: • standardized wording for the introduction of the Manual; • index of the Manual; • eighteen sections, detailing the information or operational instructions to be provided under each section as required by the Revised Specifications for the design, operation and control of crude oil washing systems, including the revised section 9 (resolution MEPC.81 (43)). Administrations may require information and operational instructions to be included in the Manual in addition to those specified in the standard format. Such information should be included in part 2 of the Manual. If no such information or operational instructions are required, the Manual will consist of one part only. This publication also contains two examples of the Manual, developed by tanker owners in accordance with the standard format, for two actual tankers, one of which is a cooventional pipeline tanker of about 31 5,000 . tons deadweight and the other a full free flow tanker of about 270,000 tons deadweight. As will be seen from these two exampl~s, the information and operational instructions under the corresponding sections vary considerably in their wording and presentation. It should be noted in this connection that: • what is standardized is the type of information to be included in the Manual under each section and not its presentation; • the two examples show how the Manuals may be presented. Although some sections may be generally applicable to all ships, these are merely examples and should be treated as such. The attention of Governments is drawn to the recommendation made by the MEPC, inviting them to use the standard format when approving the Manual and to ensure that, if the language of the Manual is neither English nor French, the Manual includes a translation into one of those languages. GUIDELINES FOR IN-PORT INSPECTION By resolution 7 the TSPP Conference recommended that the Organization take urgent action to develop guidelines for the performance of in-port inspections of the results of cargo tank cleaning using crude oil washing, which should be implemented by Governments as soon as they are adopted by the Organization. iv
  5. 5. r p pil Foreword The Conference recognized that in order to implement effectively the requirements of regulations l3 and 13B of Annex I of MARPOL 73/78, continuing strong emphasis should be placed on the effective operation of crude oil washing procedures, and also that uniform guidelines for the extent and particulars of in-port inspections of the results of cargo tank cleaning are a prerequisite for ensuring that crude oil tankers using crude oil washing systems comply at all times with the provisions of MARPOL 73/78. The MEPC at its 12th session adopted the Guidelines for in-port inspection of crude oil washing procedures and requested the Secretariat to circulate them to Governments. Governments were invited, by an MEPC circular, to take note of the Guidelines for implementation. v
  6. 6. CONTENTS Revised Specifications for the design, operation and control of crude oil washing systems Resolution A.446{XI}, as amended by resolutions A.497(Xll} and A.897(21) Appendix I - List of changes when applying the specifications to new crude oil tankers of 20,000 tons deadweight and above . . . . . . . . . . . . . . . 13 Appendix II - Training for persons intended to assume overall charge of crude oil washing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Appendix Ill - Agreed interpretations of certain of the provisions of the Revised Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 II Standard format for the Crude Oil Washing Operations and Equipment Manual Resolution MEPC.3(Xll) Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Index of sections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Sections 1 to 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 111 Examples of Crude Oil Washing Operations and Equipment Manuals Explanatory note . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Example 1 - Conventional pipeline tanker. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Example 2 - Full free-flow tanker. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 IV Guidelines for in-port inspection of crude oil washing procedures . . . . . . . . . . . . . . . . . 85 vii
  7. 7. I REVISED SPECIFICATIONS FOR THE DESIGN, OPERATION AND CONTROL OF CRUDE OIL WASHING SYSTEMS .
  8. 8. ., Crude oil washing systems Index Page Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 3 4 5 6 7 Application . . ....... . . .. . . . . ... . .. . .. . ... ... . . .. . .............. . . . . General provisions 3.1 Definitions ...................... . .... . ...... . . .. .... . ... ... . . . . 3.2 Initial survey ........ .. ........... . ............... . ........... . . Design criteria 4.1 Piping .. . ...... .. .................. . . . . . . . ... .. .... . .... .. ... . 4.2 Tank washing machines . .. . ... . . . .. . .... ..... . .. ...... .. ..... . ... . 4.3 Pumps .. .. . ...... . ......... . .... . . . . . ........ . ......... . ..... . 4.4 Stripping system .......... .. ......... .. .... . ... . .. . .......... . . . . 4.5 Ballast lines ...................... ... . . ... . .. .. . .. .... . .. . .... . . Qualification of personnel ................... .. . . ... . . . ....... . ..... . . . Operation 6.1 Tankage to be crude oil washed ..... . ........... . ....... . .. . ...... . 6.2 Drainage and discharge ashore of cargo lines .... .. . . . . .. . ...... .. .. . .. . 6.3 Filling of departure ballast tanks ...... . .. . .. .... . .... ..... .. . . ...... . 6.4 Crude oil washing at sea .. . ... ........ .... . ........ .. .......... . . . 6.5 Discharge of oily water effluents on ballast voyage .......... . ........... . 6.6 Use and control of inert gas . .. . ...... . ... .. .. .. ........ . ...... ... . . 6.7 Precautions against electrostatic generation ....... . ..... . . . ....... . . .. . 6.8 Vapour emission ... . ...................... . ..... . .............. . Operations and Equipment Manual ..... . .... .....·. .. . . . . ............. . . . Appendix I - List of changes when applying the Specifications to new crude oil tankers of 3 3 3 3 4 7 8 9 9 9 10 10 10 10 10 10 10 11 20,000 tons deadweight and above . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Appendix II - Training of persons intended to assume overall charge of crude oil washing. 15 Appendix Ill - Agreed interpretations of certain of the provisions of the Revised Specifications 17 Note: The Revised Specifications comprise the annex to resolution A.446(XI), as amended by resolutions A.497(Xll) and A.897(21 ). 2
  9. 9. d Revised Specifications 1 Purpose The purpose of these Specifications is to provide specific design criteria, operational requirements and control and enforcement 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 above in accordance with regulation 13{8} of Annex I of MARPOL 73/78; and (b) new crude oil tankers of 20,000 tons deadweight and above in accordance 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 Prevention Certificate as modified by MARPOL 73/78. 2.2 If a crude oil that is not suitable for crude oil washing is intended to be carried as cargo in a ship that s provided with only a crude oil washing system, then that ship must comply with segregated ballast tank requirements in accordance with regulation 13{7) or dedicated clean ballast tank requirements in accordance 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 1 The initial survey referred to in regulation 4 of Annex I of MARPOL 73/78 shall include a complete inspection of the crude oil washing equipment and arrangements and shall include, except for the cases specified in 4.2.11, an examination of the tanks after they have been crude oil washed and the additional controls as specified in 4.2.10 to ensure that the 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 incorporated in the supply piping system shall be of steel ·or other equivalent material and shall be of adequate strength having regard to the pressure to which they may be subjected, and shall be properly jointed and supported. 4.1.2 The crude oil washing system shall consist of permanent pipework al'ld shall be independent of the fire mains and of any system other than for tank washing except that sections of the ship's cargo system may be incorporated in the crude oil washing system provided that they meet the requirements applicable to crude oil pipework. Notwithstanding the above requirements, in combination carriers the arrangements may allow: 3
  10. 10. Crude oil washing systems (a) the removal of the equipment, if necessary, when carrying cargoes other than crude oil, pro- vided that, when reinstated, the system is as originally fitted and tested for oil tightness; (b) the use of flexible hosepipes to connect the crude oil washing system to tank washing machines if it is necessary to locate these machines in a cargo tank hatch cover. Such flexible hosepipes must be provided with flanged connections and be manufactured and tested in accordance with standards acceptable to the Administration and be consistent with the duties the hoses are required to perform. The length of these hoses shall be no greater than necessary to connect the tank washing machines to an adjacent point just outside the hatch coaming. These hoses shall be removed to suitably prepared and protected stowage when not in use and be pressure- tested by an authority acceptable to the Administration at intervals 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 device fitted to prevent overpressure shall discharge into the suction side of the supply pump. Alternative methods to the satisfaction of the Administration may be accepted provided an equivalent degree of safety and environmental protection is provided. 4.1.4 Where hydrant valves are fitted for water washing purposes on tank washing lines, all such valves shall be of adequate strength and provision shall be made for such connections to be blanked off by blank flanges when washing lines may contain crude oil. Alternatively, hydrant valves shall be isolated from the crude oil washing system by spade blanks. 4.1.5 All connections for pressure gauges or other instruments shall be provided with isolating valves adjacent to the lines unless the fitting is of the sealed type. 4.1.6 No part of the crude oil washing system shall enter the machinery spaces. Where the tank washing system is fitted with a steam heater for use when water washing, the heater must be effectively isolated during crude oil washing by double shut-off valves or by clearly identifiable blanks. 4.1.7 Where a combined crude oil-water washing supply piping is provided the piping shall be so designed that it can be drained so far as is practicable of crude oil, before water washing is commenced; into spaces designated in the Crude Oil Washing 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 each cargo compartment, as specified in the Operations and Equipment Manual referred to in these Specifications, can be operated simultaneously. 4.1.9 The piping system shall be tested to one and one half times the working pressure after it has been installed on the ship. 4.1.10 The crude oil washing supply shall be anchored (firmly attached) to the ship's structure at appropriate locations, and means shall be provided to permit freedom of movement elsewhere to accommodate thermal expansion and flexing of the ship. The anchoring shall be such that any hydraulic shock can be absorbed without undue movement of the supply piping. The anchors should normally be ·situated at the ends furthest from the entry of the crude oil supply piping. If tank washing machines are used to anchor the ends of branch pipes then special arrangements 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 and shall be of a design acceptable to the Administration. 4
  11. 11. f a Revised Specifications 4.2.2 The performance characteristic of a tank washing machine is governed by nozzle diameter, working pressure and the movement pattern and timing. Each tank cleaning machine fitted shall have a characteristic such that the sections of the cargo tank covered by that machine will be effectively cleaning within the time specified in the Operations and Equipment Manual. 4.2.3 Tank washing machines shall be mounted in each cargo tank and the method of support shall be to the satisfaction of the Administration. Where the tank washing machines are positioned well below the deck ,evel to cater for protuberances in the tank, consideration may need to be given to additional support for e machines and their supply piping. 4.2.4 Each machine shall be capable of being isolated by means of stop valves in the supply line. If a deck- ounted tank washing machine is removed for any reason, provision shall be made to blank off the oil supply line to the machine for the period the machine is removed. Similarly, provision shall be made to close e tank opening with a plate or equivalent means. 4.2.5 Where the drive units for the tank cleaning machines are not integral with the tank cleaning achine, sufficient drive units shall be provided to ensure that no drive unit need be moved more than ice from its original position during cargo discharge to accomplish the washing programme as specified in e Operations and Equipment Manual. 4.2.6 The number and location of the tank washing machines shall be to the satisfaction of the dministration. 4.2.7 The location of the machines is dependent upon the characteristics detailed in 4.2.2 and upon the configuration 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 'ertical areas are washed by direct impingement or effectively by deflection or splashing of the impinging ·et In assessing an acceptable degree of jet deflection and splashing, particular attention shall be paid to the washing of upward-facing horizontal areas and the following parameters shall be used: (a) For horizontal areas of a tank bottom and the upper surfaces of a tank's stringers and other large primary structural members, the total area shielded from direct impingement by deck or bottom transverses, main girders, stringers or similar large primary structural members shall not exceed 10% of the total horizontal area of tank bottom, the upper surface of stringers and other large primary structural members. (b) For vertical areas of the sides of a tank, the total area of the tank's sides shielded from direct impingement by deck or bottom transverses, main girders, stringers or similar large primary structural members shall not exceed 15% of the total area of the tank's sides. (c) For existing crude oil tankers, the Administration may permit the percentages required in (a) and (b) above to be exceed for tanks having complicated internal structural members provided that the percentages calculated over all the cargo tanks do not exceed 10% for horizontal areas and 15% for vertical areas. In some installations it may be necessary to consider the fitting of more than one type of tank washing machine in order to effect adequate coverage. 4.2.9 At the design stage the following minimum procedures shall be used to determine the area of the tank surface covered by direct impingement: (a) Using suitable structural plans, lines are set out from the tips of ~ach machine to those parts of the tank within the range of the jets. (b) Where the configuration of the tanks is considered by the Administration to be complicated, a pinpoint of light simulating the tip of the tank washing machine in a scale model of the tank shall be used. 5
  12. 12. Crude oil washing systems 4.2.10 To confirm the effectiveness of the crude oil washing system and stripping system, the crude oil washing operation should be witnessed to the satisfaction of the Administration. 6 (a) For ships that comply with regulation 13F(3), the crude oil washing operations are to be carried out using the approved crude oil washing equipment and as specified in the approved Ope- rations and Equipment Manual. For at least one tank of a group of tanks of similar configuration, the Administration should: (i) confirm the operation of the stripping system by observing the monitoring devices and monitoring the oil level (by dipping or other means) during bottom washing; (ii) monitor the proper operation of the washing machines with particular reference to supply pressure, cycle times and machine function. On completion of washing and final draining, the tanks are to be hand dipped, as close as practical to the forward end, centre and aft end in each tank and a record of these dips should be made in the Operations and Equipment Manual. An Administration may require an internal examination as described in subparagraph (b)(i) of this section, or by an alternative method acceptable to the Administration, if deemed necessary. (b) For ships other than those complying with regulation 13F(3), where fitted with cargo tanks intended to be used in certain circumstances as ballast tanks, the following requirements apply in addition to those specified in paragraph (a) of this section: (i) To ensure that the tank is essentially free of clingage and deposits, the Administration may require that the cleanliness of the tank be confirmed by a visual inspection made by entering the tanks after a crude oil washing but prior to any water rinse which may be specified in the Operations and Equipment Manual. If the tanks cannot be gas-freed for safe entry of the surveyor, an internal examination should not be conducted and the stripping test specified in paragraph 4.2.1 O{b)(ii) will be acceptable. In this case, the bottom of the tank to be inspected may be flushed with water and stripped in order to remove any wedge of liquid crude oil remaining on the tank bottom before gas-freeing for entry. If the flushing procedure is adopted, a similar but unflushed tanK must be used for the test specified in (ii) below. (ii) To verify the effectiveness of the stripping and drainage arrangements, a measurement should be made of the amount of oil floating on top of the departure ballast. The ratio of the volume of oil on top of the total departure ballast water to the volume of tanks that contain this water should not exceed 0.00085. This test should be carried out after crude oil washing and stripping in a tank similar in all relevant respects to the tank examined in accordance with (b)(i) above, which has not been subjected to a water rinse or to the intervening water flushing permissible in (b)(i) above. (iii) To verify the design, installation and operation of the system, the arrival ballast, after a typical ballast voyage before which the arrival ballast tanks have been crude oil washed and during which the tanks have been water rinsed in accordance with the programme set out in the Operations and Equipment Manual, should be totally discharged to the loading port harbour through an oil discharged monitoring and control {ODM) system approved by the Administration. The oil content of the effluent in this test should not exceed 15 ppm. Alternatively, the option of taking ballast water samples t<;> be analysed in a shore-based laboratory is also acceptable. (c) During all crude oil washing system surveys, internal visual inspections of the tanks by in- spectors should not be considered a mandatory requirement. When an Administration consi- ders that there is a possible failure of the crude oil washing system indicated by other crude oil
  13. 13. :l Revised Specifications washing survey requirements, the Administration may require an internal examination of the tanks involved. Internal examinations may be completed using alternative methods, e.g., video survey or other new technology, as accepted by the Administration. 4.2.11 Where an Administration is satisfied that ships are similar in all relevant respects, the requirements of 4.2.10 need only be applied to one such ship. Furthermore, where a ship has a series of tanks that are similar in all relevant respects then, for that series of tanks, the requirements of 4.2.1O(a) need only be applied to one tank of that series. 4.2.12 The design of the deck-mounted tank washing machines shall be such that means are provided, external to the cargo tanks, which, when crude oil washing is in progress, would indicate the rotation and arc of the movement of the machine. Where the deck-mounted machine is of the non-programmable, dual nozzle type, alternative methods to the 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 comply with 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 towards the end of each wash cycle. Where two or more submerged machines are installed on the same supply line, valves shall be provided and arranged so that operation of each machine can be verified independently of the other machines on the same supply line; (c) by gas-freeing the tank and checking the operation of the machine with water during ballast voyages. In this case the check shall take place after a maximum of six usages of the machine but the interval between checks shall not exceed 12 months. Each verification shall be recorded in Supplement 2 to the Oil Record Book. The method of verification shall be stated in the Operations al)d 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 pumps specifically provided for the purpose. 4.3.2 The capacity of the pumps shall be sufficient to provide the necessary throughput at the required pressure for the maximum number of tank cleaning machines required to be operated simultaneously as specified in the Operations and Equipment Manual. In addition to the above requirement, the pumps shall, if an eductor system is fitted for tank stripping, be capable of supplying the eductor 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 pump inoperative. The pumping and piping arrangements shall be such that the crude oil washing system can be effectively operated with any one pump out of use. 4.3.4 The carriage of more than one grade of cargo shall not 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 the shore terminal is below the pressure required for crude oil washing, provision shall be made that such an adequate pressure to the washing machines can be maintained in accordance with 4.3.2. This requirement shall be met with any one cargo pump out of action. The minimum supply pressure required for crude oil washing shall be specified in the Operations and Equipment Manual. Should this minimum supply pressure not be obtainable, crude oil washing operations shall not be carried out. 7
  14. 14. Crude oil washing systems 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 the satisfaction 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 cleaned is kept free of accumulations of oil and sediment towards completion of the tank washing process. 4.4.3 The stripping system shall be capable of removing oil at a rate of 1.25 times the total throughput of all the tank cleaning machines to be operated simultaneously when washing the bottom of the cargo tanks as described in the ship's Operations and Equipment Manual. 4.4.4 Means such as level gauges, hand dipping and stripping system performance gauges as referred to in 4.4.8 shall be provided for checking that the bottom of every cargo tank is dry after crude oil washing. Suitable arrangements for hand dipping must be provided at the aftermost portion of a cargo tank and in three other suitable locations unless other approved means are fitted for efficiently ascertaining that the bottom of every cargo tank is dry. For the purpose of this paragraph, the cargo tank bottom shall be considered "dry" if there is no more than a small quantity of oil near the stripping 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, where necessary, by connection to a stripping device. The line and pump draining shall be capable of being discharged both to a cargo tank and ashore. For discharge ashore a special small-diameter line shall be provided for that purpose and connected outboard of the ship's manifold valve. For new oil tankers or existing oil tankers not already fitted with such a line the cross-sectional area of this line shall not exceed 10% of that of a main cargo discharge line. Where such a line is already fitted on an existing tanker, a cross- sectionaf area of not more than 25% of that of a main cargo discharge line may be accepted. 4.4.6 The means of stripping oil from the cargo tanks shall be_by positive displacement pump, self-priming centrifugal pump or eductor or other methods to the satisfaction of the Administration. Where a stripping line is connected to a number of tanks, means shall be provided for isolating each tank not being stripped at that particufar time. ' 4.4.7 The carriage of more than one grade of cargo shall not prevent crude oil washing of tanks. 4.4.8 Equipment shall be provided for monitoring the efficiency of the stripping system. All such equipment shall have remote read-out facifities in the cargo control room or in some other safe and convenient place easily accessible to the officer in charge of cargo and crude oil washing operations. Where a stripping pump is provided, the monitoring equipment shall include, as appropriate, a flow indicator, or a stroke counter or a revolution counter, and pressure gauges at the inlet and discharge connections of the pump or equivalent. Where eductors are provided, the monitoring equipment shall include pressure gauges at the driving fluid intake 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 stripping system is adequate to meet the requirements of 4.4.2 and 4.4.4. Care shall be taken that both longitudinal and transverse 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 adhered to. In general, trim by the stern is only important during the final stages of tank discharge and shall be the maximum possible compatible with operational constraints but in no case fess than that recorded during the crude oil washing prior to the inspection required by 3.2 and 4.2.10. 8
  15. 15. Revised Specifications 4.5 Ballast lines Vhere a separate ballast water system for ballasting cargo tanks is not provided, the arrangement e such that the cargo pump, manifolds and pipes used for ballasting can be safely and effectively • ed of oil before ballasting. Qualification of personnel The training requirements of ships' personnel engaged in the crude oil washing of tankers shall be to a isfaction of the Administration. here a person such as the master, the chief officer or the cargo control officer assumes overall a ge of a crude oil wash he shall: (a) have at least one year's experience on oil tankers where his duties have 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 washing in accordance with appendix II to these Specifications and satisfactory to the Administration; (b) have participated at least twice in crude oil wash programmes one of which shall be on the particular ship for which he is required to undertake the responsibility of cargo discharge. Alternatively, this latter participation may be acceptable if undertaken on a ship that is similar in all relevant respects; and (c) be fully knowledgeable of the contents of the Operations and Equipment Manual. Where other nominated persons are intended to have particular responsibilities as defined in the 0:1E!rations and Equipment Manual, they shall have at least six months' experience on oil tankers where, in e course of their duties, they should have been involved in the cargo discharge operation. In addition, they uld have been instructed in the crude oil washing operation in the particular ship for which they are .u red to undertake this responsibility and be fully knowledgeable of the contents of the Operations and u pment Manual. Appendix II to these Specifications shouJd be used as guidance in establishing the co tent of such instruction. Operation 6.1 Tankage to be crude oil washed ore departure on a ballast voyage, after the complete discharge of cargo, sufficient tanks shall have been ·ude oil washed in accordance with the procedures specified in the Operations and Equipment Manual to sure that: (a) as a minimum, sufficient tanks have been washed to permit compliance with the draught and trim requirements of regulation 13(2)(a), (b) and (c) of Annex I of MARPOL 73/78 during all phases of the ballast voyage; and (b) account is taken of the ship's trading pattern and the expected weather conditions so that additional ballast water is not put into tanks 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 oil washed for sludge 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 neea 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 oil washing shall be undertaken during the ballast voyage. Ballast ater shall not be put into tanks that have not been crude oil washed. Water that is put into a tank which has been crude oil washed but not water rinsed shall be regarded as dirty ballast. 9
  16. 16. Crude oil washing systems 6.2 Drainage and discharge ashore of cargo lines At the end of cargo discharge all cargo mains and stripping lines shall be drained and stripped and the drainings and strippings discharged ashore via the special small-diameter line required by 4.4.5. In addition all cargo tanks are to be stripped before the ship leaves its final port of discharge. 6.3 Filling of departure ballast tanks Care shall be taken at the completion of crude oil washing of any departure ballast tank to strip the tank as completely as possible. Where departure ballast is loaded through cargo lines and pumps, these must be drained and stripped of oil using the means required by 4.4.5 before ballast is loaded. 6.4 Crude oil washing at sea All 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 for inspection at the next discharge port before commencing the next ballast voyage. This inspection may consist of multiple sounding/dipping of the bottom of the tank when the tank is empty. Departure ballast tanks shall be ballasted prior to departure from port so that examination of the surface of the ballast water can be made. In the latter case the guidance given in 4.2.1 O(b) is relevant to the inspection. 6.5 Discharge of oily water effluents on ballast voyage The 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 gas On ships to which these Specifications apply, no tank shall be crude oil washed unless the inert gas system required by regulation 138(3) of Annex I of MARPOL 73/78 is in proper operation. Before each tank is crude oil washed, the oxygen level shall be determined at a point 1 m from the deck and at the middle region of the ullage space and neither of these determinations shall exceed 8% by volume. Where tanks have complete or partial wash bulkheads, the determinations should be taken from similar levels in each section of the tank. The oxygen level of the 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°/o by volume; or (b) the pressure of the atmosphere at the tanks is no longer positive then the washing must be stopped until satisfactory conditions are restored. 6.7 Precautions against electrostatic generation To avoid excessive electrostatic generation in the washing process due to the presence of water in the crude oil washing fluid, the contents of any tank to be used as a source of crude oil washing fluid must first be discharged by at least 1 m before being so used. Any tank used as a slop tank on the previous ballast voyage shall be completely discharged and refilled with dry crude oil if that tank is to be used as a source of washing fluid. 6.8 Vapour emission On ships to which these Specifications apply there shall be means to avoid vapour emission during the filling of departure ballast wherever local conditions require it. The method of preventing the emission of hydrocarbon vapour into the atmosphere shall be: 10
  17. 17. e Revised Specifications (a) by the use of permanent ballast tanks wherever these are sufficient to provide the minimum departure draught; or (b) by containment of vapour in empty cargo tanks by simultaneous ballasting and cargo dis- charge. Alternative methods to the satisfaction of the Administrations may be accepted provided an equivalent degree of environmental protection is provided. 7 Operations and Equipment Manual e Operations and Equipment Manual must be to the satisfaction of the Administration and shall contain 'he following 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 respective position of pumps, lines and washing machines which relate to the crude oil washing system. (c) A description of the system and a listing of procedures for checking that equipment is working properly during crude oil washing operations. This shall include a listing of the system and equipment parameters to be monitored, such as line pressure, oxygen level, machine revolu- tions, duration of cycles, etc. The established values for these parameters shall be included. The results of the tests carried out in accordance with 4.2.10 and the values of all parameters monitored during such tests shall also be included. (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 foreseeable circumstances of cargo discharge restraints and to obtain maximum trim during the completion of washing and draining of each tank; (ii) the procedure on ships to avoid vapour emission in accordance with 6.8; (iii) the method of draining tanks which shall include information on optimum trim conditions as required by 4.4.1 O; (iv) the method of draining cargo pumps, cargo lines, crude oil washing lines and stripping lines, the identification of spaces into which they may be drained and procedures for discharge ashore of drainings and strippings via the small-diameter discharge line on completion of cargo discharge; (v) 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 latter is appropriate; 11
  18. 18. Crude oil washing systems 12 (5) the volume of water used for water rinse, which shall be at least equal to that used in the water rinse prior to the inspection required by 3.2 and 4.2.1 O; and (6) the preferred order in which the tanks are to be washed; (vi) the procedure for draining and stripping, where appropriate, cargo lines and pumps before being used for the loading of departure ballast; (vii) the procedure for water washing lines before discharge of departure ballast and the loading and final discharge of arrival ballast; (viii) the procedure for verifying by sound patterns that bottom-mounted machines are ope- rating shall be carried out towards the end of the wash cycle for each tank. When carrying out such verification all other machines shall be shut down if necessary; (ix) precise details of procedure to ensure compliance with regulation 9 of Annex I of MARPOL 73/78 in the discharge of departure ballast, the water flushing of lines and the decanting of the slop tanks at sea. (e) The dangers of leakage from the crude oil washing system and the precautions necessary to prevent leakage and the action to be taken in the event of a leakage. Guidance shall be given on how the crude oil washing system is to be operationally tested for leakage before each discharge. (f) The method of preventing the entry of oil to the engine room through steam heaters as required by 4.1.6. (g) The personnel required at all times to conduct the dual operation of discharging cargo and crude oil washing. The numbers of such personnel shall include: (i) the person meeting the requirements of 5.2 who will have overall control of the crude oil washing process; (ii) those persons meeting the requirements of 5.3 who will be expected to undertake the act'ual operation; and (iii) at least one person on deck at all times during washing to keep watch for leaks and malfunctioning of equipment, to test the oxygen content of tanks before washing, to check tank atmosphere pressure, to sound tank bottoms if required, to lift ullage floats if nec- essary and to change drive units when this is necessary; The duties of such persons are not necessarily mutually exclusive. (h) An effective means of communication between the watchkeeper on deck and the cargo control position so that in the event of a leak in, or malfunctioning of, the crude oil washing system the washing may be stopped as soon as possible. (i) The typical procedures for ballasting. (j) A pre-crude oil wash operational checklist for the use of the crew at each discharge which shall include the checking and calibration of all instruments. (k) The recommended intervals for on-board inspection and maintenance of crude oil washing equipment in addition to statutory surveys. Reference should be made to technical manuals supplied by the manufacturers of the equipment. (I) A list of crude oils unsuitable for the crude oil washing process and their origin.
  19. 19. Revised Specifications: Appendix I Appendix I List of changes when applying the Specifications to new crude oil tankers of 20,000 tons deadweight and above List of changes - .10 Subparagraph (c) is not applicable. 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 crude oil washed for sludge control purposes on a rotational basis in accordance with the procedures specified in the Operations and Equipment Manual. However, for these purposes, no tank need be crude oil washed more than once in every four months; and (b) if it is considered that additional ballast in a cargo tank or tanks may be required during the ballast voyage under the conditions and provisions specified in regulation 13(3) of Annex I of MARPOL 73/78, the tank or tanks which may be used for this ballast shall be crude oil washed in accordance with the procedures specified in the Operations and Equipment Manual. 6.1.2 Ballast water shall not be put into cargo tanks that have not been crude oil washed. Water at is put into a tank which has been crude oil washed but not water rinsed shall be regarded as d"rty ballast. .1 .3 Crude oil washing shall not be conducted between the final discharge and loading ports; that • o say, no crude oil washing shall be undertaken during the ballast voyage. I eplace 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 ai1ast to strip the tank as completely as possible. Where this ballast is filled through cargo lines and umps, these must be drained and stripped of oil using the means required by 4.4.5. e last two sentences are not applicable. eplace by the following: .5 Discharge of oil water effluents on ballast voyage e discharge of additional ballast from cargo tanks and any other water effluent discharged during "e ballast voyage shall comply with the requirements of regulation 9 of Annex I of MARPOL 73/78. s paragraph is not applicable. eplace by the following: ; d Details of the requirements of section 6 of these Specifications together with advice and instructions, where appropriate, in meeting these requirements such as: 13
  20. 20. Crude oil washing systems 14 (i) recommended methods and programmes of crude oil washing in order to accord with all foreseeable circumstances of cargo discharge restraints and to obtain maximum trim during the completion of washing and draining of each tank; (ii) the method of draining tanks which shall include information on optimum trim condi- tions as required by 4.4.1 O; (iii) the method of draining cargo pumps, cargo lines, crude oil washing lines and stripping lines, and spaces into which they may be drained, together with the final discharge ashore via the small discharge line on completion of discharge; (vi) 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 latter is appropriate; (v) The procedure for verifying by sound patterns that bottom-mounted machines are operating shall be carried out towards the end of the wash cycle for each tank. When carrying out such verification all other machines shall be shut down if necessary.
  21. 21. g e Revised Specifications: Appendix II Introduction Appendix II Training for persons intended to assume overall charge of crude oil washing .ny required training shall be supervised instruction, conducted in a shore-based facility or aboard a suitably equipped ship having training facilities and instructors for this purpose, dealing with the principles involved and the application of these principles to ship operation. I drawing up an Administration-approved syllabus of training, the Revised Specifications for the design, operation and control of crude oil washing systems of tankers shall be taken into account. eh training shall include but not necessarily be limited to: (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) location of washing machines; (ii) washing machines, deck-mounted and submerged: - types; - characteristics; - 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 pipeline ship/free-flow ship/partial free-flow ship; (ii) single-/multi-parcel cargoes; (iii) optimization of washing procedure in order to minimize extra berth time; 15
  22. 22. Crude oil washing systems (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) requirements of regulation 9 of Annex I of MARPOL 73/78; (vii) avoidance of venting in port during ballasting operation. (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; (vii) 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 document to those quaiified in accordance with this appendix to serve as officers primarily responsible for crude oil washing. 16
  23. 23. ed in Revised Specifications: Appendix Ill Appendix Ill Agreed interpretations of certain of the provisions of the Revised Specifications 4.1.l This paragraph requires pipes and valves to be of steel or other equivalent material. As classification societies permit grey cast iron for cargo piping with a maximum permissible working oil pressure of 16 kg/cm 2 , grey cast iron may be permitted in the supply system for crude oil washing systems when complying with nationally approved standards. 1 The requirements of this paragraph allow alternative arrangements. One such alternative is that where the system is served only by centrifugal pumps so designed that the pressure derived cannot exceed that for which the piping is designed, a temperature sensing device located in the pump casing is required to stop the pump in the case of overheating. •1.6 On new oil tankers the steam heater referred to shall be located outside the machinery spaces. However, on an existing oil tanker with an existing steam heater located in the machinery spaces, no more additional isolation will be required other than that which isolates the crude oil washing system from the machinery spaces. .2.4 This paragraph requires each machine to be capable of being isolated by means of stop valves in the supply line. Where more than one submerged machine is connected to the same supply line a single isolating stop valve in the supply line may be acceptable provided the rotation of the submerged machines can be verified in accordance with paragraph 4.2.13(a) or (c) of the Revised Specifications for the design, operation and control of crude oil washing systems. •2.8 With regard to the application of this paragraph a slop tank is considered as a cargo tank. •2.9 Guidelines for the assessment of shadow diagrams (a) Shadow diagrams (to be prepared in accordance with 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 profile view and an end elevation for each tank, or for tanks considered to be similar. (c) Sufficient detailed drawings of the vessel must be provided to check that all large primary structural members have been included. (d) The term large primary structural members is to be construed as those components of a tank structure which contribute significant strength to the ship, such as web frames and girders. It is intended that smaller components such as those that contribute to plate stiffening be excluded. In general the following lists, in conjunction with the diagram showing structural components of cargo tanks, may be used to amplify this interpretation. (See diagram on page 20.) 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 17
  24. 24. Crude oil washing systems Include (vi) transverses (vii) crossties in transverse web frames, unless it can be ve- rified by tank inspection that their presence does not af- fect the cleanliness of the tank. However, for the pur- pose of making an initial as- sessment, where there are no more than two crossties and each is less than 1/1 5 of the total depth of the tank they may be ignored. .Disregard (vi) corrugations on corrugated bulkheads (vii) face plates (e) Shadows cast upon the underside of decks, web frames, centre and side girders can be ignored. (f) Calculations must be provided either on the drawing or separately to show how the per- centages required by 4.2.8 have been arrived at. The calculations should be itemized so that it is possible to relate each item with a particular shadow area. (g) Where a curved surface is presented to jets it is not necessary to provide exact geometric projections to determine 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 as the horizontal distance measured across the top of the bottom longitudinal frames to the inside of the shell plating, midway between the tank bulkheads. (i) A swash bulkhead may be taken as a tank boundary. However, in this 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 connection with tank cleaning after crude oil washing and is not intended to be construed as limiting the amount of water needed in the process. 4.2.10(c) (a) The oil monitoring system referred to in this paragraph means any approved system, including laboratory tests, which verifies that the oil content of the effluent does not exceed the stated level. If laboratory tests are to be conducted, standards contained in resolution A.393(X) should be used as guidance. Oil tankers engaging in a trade where discharge of cargo takes place in one port State and cargo loading in another port State create a special problem with respect to verification. Two alternatives available to confirm the tanker's capability are: 18 (i) the tanker could be required to conduct the entire crude oil washing operations at the discharge port, taking inspectors to sea if necessary to observe water washing, handling of departure ballast and discharge of arrival ballast; (ii) co-ordination between the flag State Administration and port States to obtain the re- quired documentation. However the test is performed, it should be decided on a case-by-case basis taking into account the service of the tanker and the availability of surveyors.
  25. 25. be per- that etric IS to inal ead after ~d in tern, ~eed ution ~e of ecial er's t the ling e re- : into Revised Specifications: Appendix Ill b) The expression totally discharged to the loading port harbour which is used in this paragraph hall be so construed as to mean the total quantity of arrival ballast except that quantity hich is to be retained on board as specified in section 15 of the Operations and Equipment anual. D ng bottom washing the stripping capacity shall be at least 1.25 times the total throughput of a e machines that may be simultaneously in use according to paragraph 4.4.3. This does not ean that all machines in a tank have to be operated simultaneously during bottom washing but e bottom washing may be carried out in steps according to detailed procedures laid down in the Operations and Equipment Manual. The stripping capability should be at least 1.25 times the roughput of all machines that are in operation simultaneously during any stage of the bottom ashing. crude oil tankers having individual cargo pumps in each tank, each pump having an individual ping system, dispensation from the required special small-diameter line may be given in cases ,, here the combined amount of oil left in the tank after stripping and the volume of oil in the piping system from the manifold to the tank is less than 0.00085 times the volume of the cargo tank. If a deepwell cargo pump system is provided with an evacuating system for retained oil, the above consideration should also apply. This paragraph requires that officers who assume overall charge of a crude oil washing operation must have participated in a crude oil washing operation on the ship for which they are required to undertake the responsibility for cargo discharge, or on a similar ship. However, for new ships, for ships changing for the first time to the carriage of crude oil, for ships new to a particular owner, or for ships which are changing registry in which it may not be possible to acquire the particular experience, the Administration may accept as an alternative: (i) a person such as a shore-based senior officer appointed by the company (additional to the ship's complement) who is experienced in the operation of crude oil washing and is present to advise the ship's personnel; or (ii) a senior member of the crew such as the ma~ter, chief officer or cargo control officer who has participated in at least four crude oil washing operations and is on board the ship; provided th'at an Operations and Equipment Manual, in a language readily understood by the ship's officers, is available on the ship. 19
  26. 26. N 0 Longitudinal Longitudinal bulkhead f=~}frfrpritf~!~_-Longttudinal Upper deck Longitudinal Deck girder Stiffener /l~~ 1 1 Main bracket Main bracket . c 11 Web frame Transverse bulkhead/ Side shell Stiffener Stringer Longitudinal Crosstie Web (on bulkhead) ---H-- Main bracket Main bracket ! ~' ~ . !j ~ j "1. I I~ .,, ~ .& Bottom transverse - Bottom shell Bottom girder Keel plate Bottom girder c ~- Dl 3 "':::r 0 ~-::I OQ :!:...c ~ c iiJ 8 3 "C 0 ::I tD ::I !il" s. Q ..QQ 0 -Ill ::I ~ "' ~ ~ ~ ~ "'::r s· "'~ fii 3 "'
  27. 27. II STANDARD FORMAT FOR THE CRUDE OIL WASHING OPERATIONS AND EQUIPMENT MANUAL
  28. 28. Standard format for the COW Manual STANDARD FORMAT FOR THE CRUDE OIL WASHING OPERATIONS AND EQUIPMENT MANUAL (The standard format consists of a standardized text of an introduction and of an index, and 17 or 18 sections depending on the type of tanker) INTRODUCTION 1 This Manual is written in accordance with the requirements of regulation 138 of the Protocol of 1 8 relating to the International Convention for the Prevention of Pollution from Ships, 1973 (MARPOL 73/ 8). 2 The purpose of the Manual is to meet the requirements for crude oil washing in accordance with the 1 ed Specifications for the design, operation and control of crude oil washing systems {Assembly 'ution A.446{XI} as amended by resolutions A.497(Xll} and A.897(21 )). It provides standard operational dance in planning and performing a crude oil washing programme and describes a safe procedure to be ed. Part 1 of the Manual contains all the information and operational instructions required by the · ed Specifications. Part 2 of the Manual contains additional information and operational instructions red or accepted by the Administration.* This Manual has been approved by the Administration and no alteration or revision shall be made to part of it without the prior approval of the Administration. e standard format comprises the annex to resolution MEPC.3(Xll), as amended by resolution MEPC.81 (43). dministration requires or accepts information and operational instructions in addition to those provided for by the ~~can·ons, they should be included in part 2 of the Manual. If no such additional information or operating instructions are ed or accepted by the Administration, the Manual will consist of one part only, and paragraph 3 should read: "This a contains all the information and operational instructions required by the revised Specifications." 23
  29. 29. Crude oil washing systems Index of sections Relevant paragraph(s) of the Revised Page Specifications Part 1 Text of the Revised Specifications .................... . [25] 7(a) 2 Drawings of the crude oil washing system . . ........... . [25] 7(b) 3 Description of the crude oil washing system and operational [25] 7(c), 7(d)(viii) and equipment parameters .................. ... . .. . and 7(f} 4 Dangers of and precautions against oil leakage .. .. ..... . [25] 7(e) 5 Use and control of inert gas ............... . . ....... . [25] 6.6 6 Precautions against electrostatic hazards ..... .. .. . .... . [26] 6.7 7 Personnel requirements ..... ...... ... . . ... ..... . .. . [26] 7(g) 8 Methods of communication ................. . . ... .. . [26] 7(h) 9 Determination of the suitability of a crude oil for use in crude oil washing .... ......... .. ............. . . . [26] 7(1) 10 Crude oil washing checklists ........................ . [29] 70} 11 Approved methods and programmes for crude oil washing . [29] 7(d)(i) 12 Typical crude oil washing programmes .. .. ..... .. ..... . [30] 7(d)(v) 13 The method of draining cargo tanks . .... . ............ . [30] 7(d)(iii) 14 The method and procedures for draining cargo pumps and lines ...1 • •• • • • • • • • • ••• •••• • • ••• • • • • • • • • • • • • • [30] 7(d)(iv) and (vi) 15 Typical procedures for ballasting and the method of preventing hydrocarbon emission .. ... .. ... . ... . . . . ..... ... . . . [30] 7(d)(ii), 7(i) 16 Compliance procedures for regulation 9 of Annex I of [30] 7(d)(vi), (vii) MARPOL 73/78 .............. . ...... .. . .. . . ..... . and (ix) 17 Inspections and maintenance of equipment ......... ... . [30] 7(k) 18 Procedure for changing from crude oil trade to product trade* [30] 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. 24
  30. 30. ") Standard format for the COW Manual 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 of crude oil washing systems and the agreed interpretations of certain of the provisions of the Revised Specifications (Assembly resolution A.447(XI} as amended by resolutions A.497(Xll} and A.897(21 )). SECTION 2: DRAWINGS OF THE CRUDE OIL WASHING SYSTEM is 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 OPERATION AND EQUIPMENT PARAMETERS section contains a description of the cargo, ballast, washing and stripping systems and in addition ~teS: (1) (2) (3) (4) (5) (6) (7) (8) types of tank washing machines and their standpipe length inside the tanks; revolutions of the machines; methods of checking the operation of tank washing machines; minimum operation pressure for crude oil washing; maximum permitted oxygen level in cargo tanks; duration of tank washing machine cycles; results of the tests performed in accordance with paragraph 4.2.1 O(b) of the Revised Specifi- cations and the method of computation; method of preventing entry of oil into the engine room. 0 4: DANGERS OF AND PRECAUTIONS AGAINST OIL LEAKAGE ·on contains information on the dangers of leakage from the crude oil washing system, the preQlJtJons necessary to prevent leakage and the action to be taken in the event of leakage. SICTJO 5: USE AND CONTROL OF INERT GAS ·on contains information on the inert gas requirements and the instructions to cover those periods e inert gas pressure is released for reasons of cargo operation. In addition it indicates the method ocedures to be used for taking samples of the tank atmosphere. 25
  31. 31. Crude oil washing systems SECTION 6: PRECAUTIONS AGAINST ELECTROSTATIC HAZARDS This section contains details of the procedures for minimizing electrostatic generation. SECTION 7: PERSONNEL REQUIREMENTS This section specifies the numbers of persons to be associated with the crude oil washing process and their necessary qualifications. Their names and ranks may be provided on separate documents. SECTION 8: METHODS OF COMMUNICATION This 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 as possible. SECTION 9: DETERMINATION OF THE SUITABILITY OF A CRUDE OIL FOR USE IN CRUDE OIL WASHING This section contains guidance in determining the suitability of a crude oil for use in crude oil washing. In lieu of a list of crude oils unsuitable for carriage and crude oil washing to be inserted in the Operations and Equipment Manual the following standard text maybe used: 26 (1) For a tanker not fitted with heating coils This tanker is not fitted with heating coils in the cargo tanks and should not carry cargoes which will require to be heated either to obtain pumpability criteria or to avoid excessive sludging of both the designated clean ballast tanks and the vessel's tanks to be washed for sludge control. Notes and definitions: - Pumpability criterion is determined by the qil's kinematic viscosity at the observed temperature of the cargo prior to its discharge. In order to attain optimum efficiency for discharge this viscosity should not exceed 250 centistokes and never in excess of 600 cenfistokes. - Excessive sludging criterion is determined primarily by the crude oil's temperature throughout its transportation and storage. If the cargo's temperature is likely to drop below the crude oil cargo's cloud point temperature then s/udging of cargo tanks is to be expected. The cloud point temperature is the temperature at which the crude oil's wax and associated oil phase separates from the bulk liquid phase of the cargo. (2) For a tanker fitted with heating coils in slop tank(s) This tanker is fitted with heating coils only in her slop tank(s) and should not carry cargoes which will require to be heated for pumpability. Notes: If sludge deposition is suspected or determined in the main cargo tanks then an alternative crude oil washing programme should be utilized. Recommendations regarding this programme and procedure are to be found in section 11 of this Manual. (3) For a tanker fitted with heating coils This tanker is fitted with heating coils in all the cargo tanks and, subject to the limitations of the cargo heating system, can carry cargoes which require heating for either pumpability or sludge deposition/control.
  32. 32. their ntrol may g. 'ons ~Ned for s of hout e oil ~loud phase goes ~rude ~ and f the udge Standard format for the COW Manual General guidance Attention is drawn to the difficulties which may be encountered with certain crude oils. During the discharge of crude oils that exhibit the necessary criteria that would create either pumpability problems or sludge deposition, crude oil washing of each tank scheduled for such an operation should be carried out concurrently with the discharging of the particular tank in order to minimize the effect on the crude oil residues for cooling. Cooling will increase both the kinematic and dynamic viscosities* of the tank residues and therefore affect the efficiency of the crude oil washing programme. a general guidance to the suitability of an oil for crude oil washing on board this tanker, the following I r1teria should be used: For aromatic crude oils whose kinematic viscosity is the temperature controlling characteristic, the kinematic viscosity of the oil used for crude oil washing should not exceed 60 centistokes at the oil wash medium temperature; or For paraffinic crude oils whose pour point temperature is the controlling characteristic, the temp- erature of the cargo to be used for crude oil washing should exceed its cloud point temperature by at least 10°C if excessive sludging is present and should only be used once in a "closed cycle" washing programme. The approximate cloud point temperature of an oil may be calculated by use of the following formula where the pour point temperature (x) of the crude oil is known: Cloud point temperature (0 C) = 20.2 (10°-00708 x - o.1 7s7714 ) + 8 orked example: 0 Assume the pour point temperature is + 1°C. Then: = 20.2 x {10(0.00708 x 1} - 0.1157714) + 8 = 20.2 x (100.00708 - 0.1157714) + 8 = 20.2 x {10-0.1086914) + 8 = {20.2 x 0.7785896) +8 = 15.72 + 8 Answer: approx. cloud point= 24°C Consult the accompanying graph (fig. 1), where if the pour point is known then the cloud point can be extracted. e pour point exceeds approximately 25°C then the Bondi test procedure could be used to e ermine this temperature. Orffttiorts: nematic viscosity is the measure of resistance to flow with gravitation under its own mass force. This is normally centistokes (cSt) or mm2 /s. Dynamic viscosity is the measure of resistance to flow with an induced shear stress or a e of shear. This is determined from the equation of shear stress (in pascals (Pa)) divided by rate of shear (inverse _.rvv'K s-1 )). The unit of dynamic viscosity is either the centipose (cps) or the millipascal second (mPa·s). 27
  33. 33. Crude oil washing systems 50 45 ) v / I / / Q 40 ~ ~ .) / ,, ::::> ~Q) / / ,,) / I c. 35E .2l c"(5 c. / .,,. "O ::::> 300 C3 ./..... 1......- _v / ..,..r25 ~'-""' L,.-- 1--r' 20 ~ -20 -10 0 10 20 30 40 Pour point temperature (°C) Figure 1: Graph to determine pour point temperature Bondi test procedure (see fig. 2) This method will obtain the cloud point temperature of high pour point type crude oils. 28 I Equipment and procedure (1) Obtain a representative sample of the cargo. Do not allow the cargo sample to cool before commencing the test procedure. (2) Obtain a glass container (preferably nearly spherical) that is made of heat-temperature-resistant glass and fill the container with the sample. (3) Insert a thermometer into the centre of the sample volume and heat the sample to a temp- erature of at least 30°C above the pour point temperature of the crude oil in a hot water bath. Do not tightly stopper the container during this process. (4) Prepare an alternative bath with water whose temperature is at least 15°C below the sample's pour point temperature. Have a clock or watch available with a second hand. (5) Immerse the heated sample container into the cold bath and record at very regular intervals (at least every 30 s) the temperature of the sample. (6) Graphically plot the sample temperature against time elapsed from the start of the test. De- termine the temperatures at which there was no loss of temperature with time elapsed. The first such instance detected will be the approximate cloud point temperature and the second instance, if testing time is extended to the required period, will be the approximate pour point temperature of the crude oil.
  34. 34. ~r<"' J D fore tant mp- ath. pie's s (at De- first and oint 0 'l.... •5 ~ iE 80 ~ 75 70 65 60 55 50 45 40 0 ~ "" ""' 2 Standard format for the COW Manual ~ V'Cloud / point temperature ~~ ~ .__,,_______, Pour point ~ tempejture ' ""' ./ 3 4 5 6 7 8 9 Time (minutes) Figure 2: Example Bondi test plot SECTION 10: CRUDE OIL WASHING CHECKLISTS ection contains operational checklists for the use of the crew at each discharge which shall include the ing and calibration of all instruments. SECTION 11: APPROVED METHODS AND PROGRAMMES FOR CRUDE OIL WASHING ·~ section contains those details which form the basis of crude oil washing in the tanker and which are essary to formulate a washing programme which will accord with all foreseeable circumstances of cargo harge restraints. It includes 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, i.e., single- or multi-stage; (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. 29
  35. 35. Crude oil washing systems SECTION 12: TYPICAL CRUDE OIL WASHING PROGRAMMES This section contains details of some typical washing programmes under various conditions of discharge such as single- or multi-port discharge and single- and multi-grade 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 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 Specifications. The minimum trim conditions must be stated. 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 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 PREVENTING HYDROCARBON 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 I OF MARPOL 73/78 This section contains information and procedures for water washing tanks and lines, discharge of departure ballast and the decanting of slops at sea to ensure compliance with regulation 9. SECTION 17: INSPECTIONS AND MAINTENANCE OF EQUIPMENT This section contains information on procedures to be followed at recommended intervals for on-board inpections 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 and which has been issued with two IOPP Certificates running concurrently with one Certificate certifying the tanker to be a crude oil tanker and the other certifying it to be a product carrier. * Section 18 is included in the Manual for a particular tanker only if applicable. 30
  36. 36. ~rge eters the lines, line. ure ard lean one Ill EXAMPLES OF CRUDE OIL WASHING OPERATIONS AND EQUIPMENT MANUALS Explanatory note following specimen Manuals were originally prepared by tanker owners for particular tankers which wished to be certified as COW tankers under MARPOL 73/78. The texts of the Manuals have been ~...,..,ed in order to ensure conformity with the standard format but editing has been kept to a • um to show possible variations in the language and in the manner of presentation of the required ~-ution. flag Administration of these tankers does not require the inclusion of any information or -P'r21'1nnal instructions in addition to those provided for by the Revised Specifications, the specimen -.--.i~ consist of one part only as explained in the introduction to the standard format.* 23 o• is publication.
  37. 37. Example 1: Conventional pipeline tanker Example 1 Conventional pipeline tanker CRUDE OIL WASHING OPERATIONS AND EQUIPMENT MANUAL of ship ................................. ..... ................... .. ......... . -· e number or letters .. . .................................................. . .. . ·egistry ....... ... ... .. ............ ... ..................................... . ~-.........,..ght tonnage ......... . .................. . ... ... ....... . . .. . .. ............. . 33
  38. 38. Crude oil washing systems INTRODUCTION 1 This Manual is written in accordance with the requirements of regulation 13B of the Protocol of 1978 relating to the International Convention for the Prevention of Pollution from Ships, 1973 (MARPOL 73/78). 2 The purpose of the Manual is to meet the requirements for crude oil washing in accordance with the Revised Specifications for the design, operation and control of crude oil washing systems (Assembly resolution A.446(XI) as amended by resolutions A.497(Xll) and A.897(21 )). It provides standard operational guidance in planning and performing a crude oil 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 This Manual has been approved by the Administration and no alteration or revision shall be made to any part of it without the prior approval of the Administration. 34
  39. 39. !col of RPOL jth the embly 1tional 1 to be evised 11-de to Example 1: Conventional pipeline tanker Index of sections of the Revised Specifications .................... . D a ·ngs of the crude oil washing system .. : .. . ....... . iption of the crude oil washing system and operational equipment parameters ............. . .......... . a gers of and precautions against oil leakage . .. ...... . se and control of inert gas .. . .. . .... ... .. . .. .. .... . ecautions against electrostatic hazards . . . .... ..... .. . onnel requirements . .. . .... .... . .. . ... ........ . ods of communication ....... . .......... . ..... . o· crude oils unsuitable for crude oil washing ........ . e oil washing checklists .......... .. .... ... ..... . oed methods and programmes for crude oil washing . a crude oil washing programmes . ... .. ..... .... . . ethod of draining cargo tanks .. . ... ... ... . . . ... . ethod and procedures for draining . o pumps and lines . . ...... ...... ... . . ..... .... . procedures for ballasting and the method of preventing ocarbon emission .. ..... .. . ...... . . . ....... . . . 1ance procedures for regulation 9 of Annex I RPOL 73/78 .............................. . 11n5ipec::tJOns and maintenance of equipment ............ . Page [36] [37] [40] [43] [43] [43] [44] [44] [44] [45] [46] [48] [57] [52] [52] [53] [54] Relevant paragraph(s) of the revised Specifications 7(a) 7(b) 7(c), 7(d) (viii) and 7(f) 7(e) 6.6 6.7 7(g) 7(h) 7(1) 70) 7(d)(i) 7(d)(v) 7(d)(iii) 7(d)(iv) and (vi) 7(d)(ii), 7(i) 7(d)(vi), (vii) and (ix) 7(k) ...._,..,..,..."" 'vanual as originally prepared by the tanker owner for a particular tanker did not include a section 18 as the ,_.,cl!dlures c.hanging from crude oil trade to product trade were not applicable. This section has been added as an the information might be presented if required in a particular case. 35
  40. 40. Crude oil washing systems SECTION 1: TEXT OF THE REVISED SPECIFICATIONS This section contains the complete text of the Revised Specifications for the design, operation and control of crude oil washing systems and the agreed interpretations of certain of the provisions of the Revised Specifications (Assembly resolution A.446(XI} as amended by resolutions A.497(Xll} and A.897(21 )). (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) 36
  41. 41. hydraulict-:1 Butterfly valve, hydraulic & t:+::J Gate valve, lly operated manual, loca [:::f<1 Gate valve, manual b lkhead valve, :....L.. Butterfly u o ~hydraulic ~ Non-return valve ~Eductor s lines and valve. 1. Cargo pump 'Figure · 0 Direct loading ~ de in slop tanksII casca ' ' ' 1 Blank To vacuum tank ""''::;, ' -- -,,__ - - - - - -
  42. 42. Example 7: Conventional pipeline tanker Ives, ballast and stripping systems '400 I I I C' f .. N & T ~ £ ( 37
  43. 43. 1g lines and valves and position of tank washing machines No 6 PORT WING CARGO TANK n> ,..p No 4 PORT WING CARGO TANK M/c To,..., M/G TANK CLEANING ~~-r~--<r-.._~.__~~~,-r--+-~~~~~~~-+-~_..~~~~-1f--.1.,.-!~-.~~.._~~~~+-~~~~~~~~--f~~-'T~~-t-~uNETOFORWARD 6 6 STARBOARD WING CARGO TANK T~P No 5 STARBOARD WING CARGO TANK 179 CARGO TANK Uri l.-+-----, Tltlf1b MP CARGO TANK 1"<t. No 1 STARBOARD WING CARGO TANK 210 oCTION TO MP M/c 187 No 4 STARBOARD WING CARGO TANK KEY 1><J DIAPHRAGM VALVE l><ij HOSE VALVE t><J BUTTERFLY VALVE 0 6 1 ci~Ni~~KMACHINE 0TQ MP M/G 196 ~ SECTION
  44. 44. Crude oil washing systems CARGO AND STRIPPING LINES (PUMP ROOM) 5.2.1(2) 164 Figure 2: Crude oil washing lines and valv PORT SLOP TANK No 7 PORT WING CARGO TANK TI> MP r ~ rO OT1~i~ loTo~P 0 TO'K'TYPE MIC4mOVEA TANK BOTTOM r---- 0 No 6 PORT WING CARGO TANK STARBOARD SLOP TANK M/c No 7 STARBOARD WING ·~~, No 6 STARBOARD WING CARGO TANK ' CARGO TANK 167 172 AFT SECTION No 3 PORT WING WATER BALLAST TANK No 2 POAT WING CARGO TANK TANK CLEANING LINE FROM AFT SECTION -+---""""T-----1---""""T----+--t--'------r-·-f--'--~--t--".--t---<--J No 3 STARBOARD WING WATER BALLAST TANK No 2 STARBOARD WING CARGO TANK 196 202 210 FORWARD SECTION 38
  45. 45. ( 9 1. f>. 6 ""· 3 2.. i . :::!'!.. ()Q I c: " ..... P-"-· It) ... " .. ".. ,,, I~ .. ,,, I~ • ~I " w.. I.. ... P. ... II ~ ~ :::J ~ ' </J ~ et It) .......... • ()Q .. .. I I .. • I I • " I " " I " - I I . Ill I IJl .....Ill ~I 1~10 I~ ~ ~ l~lcl ~I I<ii ~ ffil~l lc.· :::J 7'" 9-:IJl ....... ... " y • • .. ....... ... ... 0.: ~ c5 d c:..... a· ,& d :::J .. - IJl • 5 '< • IJl ft .. If .. I • ,, P.a. .. " " w " .....II I ,. I" • • 8 It) 0 3.... ~"' " I ~ I I I I ~ Ill $l) II I :::J 3c... 1J IJl iii" + Sounding point 0- Water seal 0 ~ c: Remote-operated butterfly and l.G. supply :::J nvalve c... 0 t>I:::J ~ :::J ::i Manually operated butterfly Inert gas tank inlet ()Q <: C1lvalve "O ::i ~ ~ Purge/Sounding pipe Q. t::!". Non-return valve 0 :::J ::i ..... ~~ High-velocity PN valve IJl x Sounding point 1Jwith line valve -o· ~ High-velocity pressure- C1l fffi --.release valve, manually PV/ breaker ::i C1l operated s;;;- ::i w I~<..O
  46. 46. Crude oil washing systems SECTION 3: DESCRIPTION OF THE CRUDE Oil WASHING SYSTEM AND OPERATIONAL AND EQUIPMENT 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 4.2.1 O(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 vessel consists of eight centre tanks and eight pairs of wings, but with No. 3 wings reserved for permanent ballast and not connected into the cargo piping. The aftermost set of tanks, No. 8 across, forms a triple slop tank arrangement. No. 8 port is the dirty slop tank with first separation across to No. 8 starboard and thence a second 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 /h. Each pump has a 700 mm suction line running the full length up to No. 1 across. No. 1 and No. 4 pumps are used to discharge the wing tanks and No. 2 and No. 3 pumps to discharge the centre tanks. There are crossover lines between the pump suctions which permits 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 line but in each tank a small stripping suction bell-mouth, separately valved, is taken off the appropriate main line. For water washing and occasional use during the closing stages of crude oil washing, two eductors are fitted, each of rated capacity 900 m3 /h, which are normally powered by either No. 2 or No. 3 cargo pump. These eductors can be put on to any of the 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 /h is fitted for the purpose of line draining. It has suction connections to the four main suction lines, the four cargo pumps, the discharge lines, the sea line and the crude oil washing line. It can discharge to the slop tank, the oil/water separator, the main discharge lines, overboard or through a special 250 mm line which runs along the deck and terminates outboard of the manifold gate valves. This latter 250 mm line should always be used for final line draining ashore. Sa/last system Permanent ballast is carried in No. 3 wings and is handled by a separate pump.of capacity 4,250 m3 /h. The pump 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 capability of ballasting No. 1, No. 4 and No. 6 centres over the top. Once the cargo is discharged from No. 1, No. 4 and No. 6 centres, these tanks should be ballasted over the top concurrently with discharge 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 40
  47. 47. gs •. 8 1to hks __ a to er ing ain are p. ge ·on the es, the he on p. 6 puld the and Example 1: Conventional pipeline tanker used as the clean arrival ballast. Cargo tank ballast is discharged by No. 2 and No. 3 cargo pumps ..J h the pump-room high overboard discharge. Variations on the ballast arrangement are permissible to t inspection and maintenance except that ballast should not normally be carried in wing tanks. ~ing system .s washing line, either crude oil or water, is fed from either No. 2 or No. 3 cargo pump or at ely the line may be fed from a cross-connection from the midships manifold. In the latter case, any ump or pumps could feed the washing line. 'ater washing, No. 2 or No. 3 pump should be used drawing from the clean slop tank, No. 8 centre, dirty washings from the tank being washed drained back with an eductor which discharges into the tank, No. 8 port. One cargo pump operating in this closed cycle method is capable of driving both ~-....,.,."'- •itted and operates 10 tank washing machines while maintaining a back pressure of 10 kg/cm 2 . For • ashing, it is preferable to feed the washing line from the manifold as long as possible as it is not essary to take one cargo pump completely out of the discharge programme, and recirculation of s avoided. must never be passed through the Butterworth heater which is situated in the pump-room. Apart g the heater, there is the chance of a ruptured or leaking tube allowing crude oil to pass back into room via the steam system. Two spade blanks are fitted, one on the inlet side and one on the of the heater, and these must always be in position when crude oil washing. es of washing machines, the desired pressure on the wash line on deck is 10 kg/cm2 • If the 911!'t!So;re o the deck line falls below 8 kg/cm2 , then crude oil washing should be stopped until such time as e has been restored. e e crude oil washing system has been inspected and approved by the Administration, and no •lr3ibol't.~ ay be made to the system or any part of the system without the approval of the Administration. s were inspected after crude oil washing in accordance with the requirements of paragraph o; the Revised Specifications and met the required standards of cleanliness, being essentially free a e and deposits. of the departure ballast was examined in accordance with the requirements of paragraph he Revised Specifications and was found to be satisfactory. 1WC1Ceir1~.... ·e for computing the ratio of the volume of oil on top of the total departure ballast water to the s that contain this water is described below: Port, starboard or centre Total Tank volume (m3) v Ullage space in tank (measured to top of oil layer) (m) Oil thickness (mm) Total Volume of oil (m3) v 41
  48. 48. Crude oil washing systems 1. Determine the thickness of the oil layer on the ballast water (txl· 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 (U)x; .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.C-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 containing departure ballast water =v. Washing machines This vessel is fitted with 77 deck-mounted Butterworth Lavomatic machines, 13 bottom-mounted Butterworth MP machines and 3 fixed bottom-mounted Butterworth Kmachines. Deck-mounted machines Lavomatic S.A. single-nozzle. Those fitted in the centre tanks have a standpipe length of 4.8 m with a natural frequency of 6.19 Hz and those fitted in the wings have a standpipe length of 4.0 m and a natural frequency of 7.166 Hz. The propeller-induced frequency for this 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 time taken to complete one full cycle is 67 min when operating at a pressure of 10 kg/cm2 and the output at this pressure is 140 m3 /h. The full cycle consists of an arc from 0° to 120° to 0° to -30° to 0°. The operation of these machines can be verified by observing the gearbox where both rotation and elevation are mechanically displayed. Submerged machines, MP, single-nozzle Thirteen of these machines are fitted; one at the forward end of No. 2, No. 4, No. 5, No. 6 and No. 7 wings and, additionally, one at the after end of No. 7 wings and No. 7 centre. They are positioned on the centreline of the tank on level with the third stringer down. They are piped and valved separately from the deck-mounted machines. Their programme is fixed and covers an arc of 240° which at an operating pressure of 10 kg/cm2 takes 1 h to complete. The output at this pressure is 100 m3 /h. To verify the operation of these machines, all other machines in the tank and in any adjacent tank should be shut off, and the movement of the machine identified by its sound pattern. 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" is fitted 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 /h (60 m3 /h for the "Super K") and the time for one full cycle is 40 min. A full cycle consists of one full revolution (360°) of the machine. 42
  49. 49. Jil es ks ~d nd he he at nd 1gs he he ng be >er 1ny 40 Example 1: Conventional pipeline tanker possible to verify their operation by sound pattern and therefore after six usages or at intervals of not an 12 months these machines must be sighted and seen to be working, using water. 4: DANGERS OF AND PRECAUTIONS AGAINST OIL LEAKAGE -ection contains information on the dangers of leakage from the crude oil washing system, the ... ions necessary to prevent leakage and the action to be taken in the event of leakage. : crude oil from the system can be a potential fire and pollution hazard. Before arrival at the -~'"""'"' port, the tank washing system should be pressure-tested and examined for leaks. Any leaks found made good and the resultant oil cleaned up. pressure test, special attention should be given to inspection and tightening of valve glands and ~...,.•.., and couplings on lines to prevent any leakage. course of oil washing, the system must be kept under continuous observation and on m111C:i1et_t0r of washing it must be completely drained of oil. If it is necessary for the system to be cleaned .d be flushed through with water into appropriate tanks; if the system is required to be gas-free it entilated in the same way as cargo lines. oil washing must be stopped when any sign of leakage or fault in the tank wash system is either on deck or in the pump-room. ·on contains information on the inert gas requirements and the instructions to cover those en the inert gas pressure is released for reasons of cargo operation. In addition it indicates od and procedures to be used for taking samples of the tank atmosphere. uld arrive at the discharge port with all cargo tanks pressurized with good quality inert gas. a be released for ullaging, sampling and water dips before discharge and at this stage the in tanks shoutd be checked to ensure that it is below 8% by volume. The supply of inert gas menced immediately before the commencement of cargo discharge to avoid a vacuum in . means a safe condition will be maintained throughout discharge. Apart from this initial release he pressure in the cargo tanks should always be above atmospheric pressure. Under no •-~mces should air be allowed to enter any tank which is to be crude oil washed. ank is washed, the oxygen content should be checked with the portable oxygen analyser to does not exceed 8% by volume. The sample should be taken at a point 1 m below the deck 1ddle region of the ullage space well clear of the inert gas inlet point. (See section 2 of this ~e position of the sampling points.) o ashing must be stopped if there is a failure of the inert gas plant or if the oxygen content of nert gas exceeds 8% by volume or if the pressure of the atmosphere in the cargo tanks falls oheric pressure. ·on contains details of the procedures for minimizing electrostatic generation. / . o oil and water can produce an electrically charged mist during tank washing. The use of dry ·efore important. To overcome the possibiity of developing such an electrically charged mist, 43 -

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