semi submersible cargo ships

Semi Submersible Cargo Ships

May 2016

Rule Note NR 628 DT R00 E

Marine & Offshore Division 92571 Neuilly sur Seine Cedex – France

Tel: + 33 (0)1 55 24 70 00 – Fax: + 33 (0)1 55 24 70 25 Website: http://www.veristar.com

Email: [email protected] 2016 Bureau Veritas - All rights reserved

ARTICLE 1

1.1. - BUREAU VERITAS is a Society the purpose of whose Marine & Offshore Division (the "Society") isthe classification (" Classification ") of any ship or vessel or offshore unit or structure of any type or part ofit or system therein collectively hereinafter referred to as a "Unit" whether linked to shore, river bed or seabed or not, whether operated or located at sea or in inland waters or partly on land, including submarines,hovercrafts, drilling rigs, offshore installations of any type and of any purpose, their related and ancillaryequipment, subsea or not, such as well head and pipelines, mooring legs and mooring points or otherwiseas decided by the Society.The Society:

• "prepares and publishes Rules for classification, Guidance Notes and other documents (" Rules ");

• "issues Certificates, Attestations and Reports following its interventions (" Certificates ");• "publishes Registers.

1.2. - The Society also participates in the application of National and International Regulations or Stand-ards, in particular by delegation from different Governments. Those activities are hereafter collectively re-ferred to as " Certification ".1.3. - The Society can also provide services related to Classification and Certification such as ship andcompany safety management certification; ship and port security certification, training activities; all activi-ties and duties incidental thereto such as documentation on any supporting means, software, instrumen-tation, measurements, tests and trials on board.

1.4. - The interventions mentioned in 1.1., 1.2. and 1.3. are referred to as " Services ". The party and/or itsrepresentative requesting the services is hereinafter referred to as the " Client ". The Services are pre-pared and carried out on the assumption that the Clients are aware of the International Maritimeand/or Offshore Industry (the "Industry") practices.

1.5. - The Society is neither and may not be considered as an Underwriter, Broker in ship's sale or char-tering, Expert in Unit's valuation, Consulting Engineer, Controller, Naval Architect, Manufacturer, Ship-builder, Repair yard, Charterer or Shipowner who are not relieved of any of their expressed or impliedobligations by the interventions of the Society.ARTICLE 2

2.1. - Classification is the appraisement given by the Society for its Client, at a certain date, following sur-veys by its Surveyors along the lines specified in Articles 3 and 4 hereafter on the level of compliance ofa Unit to its Rules or part of them. This appraisement is represented by a class entered on the Certificatesand periodically transcribed in the Society's Register.

2.2. - Certification is carried out by the Society along the same lines as set out in Articles 3 and 4 hereafterand with reference to the applicable National and International Regulations or Standards.

2.3. - It is incumbent upon the Client to maintain the condition of the Unit after surveys, to presentthe Unit for surveys and to inform the Society without delay of circumstances which may affect thegiven appraisement or cause to modify its scope.2.4. - The Client is to give to the Society all access and information necessary for the safe and efficientperformance of the requested Services. The Client is the sole responsible for the conditions of presenta-tion of the Unit for tests, trials and surveys and the conditions under which tests and trials are carried out.

ARTICLE 33.1. - The Rules, procedures and instructions of the Society take into account at the date of theirpreparation the state of currently available and proven technical knowledge of the Industry. Theyare a collection of minimum requirements but not a standard or a code of construction neither aguide for maintenance, a safety handbook or a guide of professional practices, all of which areassumed to be known in detail and carefully followed at all times by the Client.Committees consisting of personalities from the Industry contribute to the development of those docu-ments.3.2. - The Society only is qualified to apply its Rules and to interpret them. Any reference to themhas no effect unless it involves the Society's intervention.3.3. - The Services of the Society are carried out by professional Surveyors according to the applicableRules and to the Code of Ethics of the Society. Surveyors have authority to decide locally on matters re-lated to classification and certification of the Units, unless the Rules provide otherwise.

3.4. - The operations of the Society in providing its Services are exclusively conducted by way of ran-dom inspections and do not in any circumstances involve monitoring or exhaustive verification.

ARTICLE 44.1. - The Society, acting by reference to its Rules:

• "reviews the construction arrangements of the Units as shown on the documents presented by the Cli-ent;

• "conducts surveys at the place of their construction;

• "classes Units and enters their class in its Register;• "surveys periodically the Units in service to note that the requirements for the maintenance of class are

met. The Client is to inform the Society without delay of circumstances which may cause the date or theextent of the surveys to be changed.ARTICLE 5

5.1. - The Society acts as a provider of services. This cannot be construed as an obligation bearingon the Society to obtain a result or as a warranty.

5.2. - The certificates issued by the Society pursuant to 5.1. here above are a statement on the levelof compliance of the Unit to its Rules or to the documents of reference for the Services provided for.

In particular, the Society does not engage in any work relating to the design, building, productionor repair checks, neither in the operation of the Units or in their trade, neither in any advisory serv-ices, and cannot be held liable on those accounts. Its certificates cannot be construed as an im-plied or express warranty of safety, fitness for the purpose, seaworthiness of the Unit or of its valuefor sale, insurance or chartering.

5.3. - The Society does not declare the acceptance or commissioning of a Unit, nor of its construc-tion in conformity with its design, that being the exclusive responsibility of its owner or builder.

5.4. - The Services of the Society cannot create any obligation bearing on the Society or constitute anywarranty of proper operation, beyond any representation set forth in the Rules, of any Unit, equipment ormachinery, computer software of any sort or other comparable concepts that has been subject to any sur-vey by the Society.

ARTICLE 6

6.1. - The Society accepts no responsibility for the use of information related to its Services which was notprovided for the purpose by the Society or with its assistance.

6.2. - If the Services of the Society or their omission cause to the Client a damage which is provedto be the direct and reasonably foreseeable consequence of an error or omission of the Society,its liability towards the Client is limited to ten times the amount of fee paid for the Service havingcaused the damage, provided however that this limit shall be subject to a minimum of eight thou-sand (8,000) Euro, and to a maximum which is the greater of eight hundred thousand (800,000)Euro and one and a half times the above mentioned fee. These limits apply regardless of fault in-cluding breach of contract, breach of warranty, tort, strict liability, breach of statute, etc.The Society bears no liability for indirect or consequential loss whether arising naturally or not asa consequence of the Services or their omission such as loss of revenue, loss of profit, loss of pro-duction, loss relative to other contracts and indemnities for termination of other agreements.

6.3. - All claims are to be presented to the Society in writing within three months of the date when the Serv-ices were supplied or (if later) the date when the events which are relied on of were first known to the Client,and any claim which is not so presented shall be deemed waived and absolutely barred. Time is to be in-terrupted thereafter with the same periodicity. ARTICLE 7

7.1. - Requests for Services are to be in writing.

7.2. - Either the Client or the Society can terminate as of right the requested Services after givingthe other party thirty days' written notice, for convenience, and without prejudice to the provisionsin Article 8 hereunder.

7.3. - The class granted to the concerned Units and the previously issued certificates remain valid until thedate of effect of the notice issued according to 7.2. here above subject to compliance with 2.3. here aboveand Article 8 hereunder.7.4. - The contract for classification and/or certification of a Unit cannot be transferred neither assigned.

ARTICLE 8

8.1. - The Services of the Society, whether completed or not, involve, for the part carried out, the paymentof fee upon receipt of the invoice and the reimbursement of the expenses incurred.

8.2. - Overdue amounts are increased as of right by interest in accordance with the applicable leg-islation.

8.3. - The class of a Unit may be suspended in the event of non-payment of fee after a first unfruitfulnotification to pay.

ARTICLE 9

9.1. - The documents and data provided to or prepared by the Society for its Services, and the informationavailable to the Society, are treated as confidential. However:

• "Clients have access to the data they have provided to the Society and, during the period of classifica-tion of the Unit for them, to the classification file consisting of survey reports and certificates which have been prepared at any time by the Society for the classification of the Unit ;

• "copy of the documents made available for the classification of the Unit and of available survey reports can be handed over to another Classification Society, where appropriate, in case of the Unit's transfer of class;

• "the data relative to the evolution of the Register, to the class suspension and to the survey status of the Units, as well as general technical information related to hull and equipment damages, may be passed on to IACS (International Association of Classification Societies) according to the association working rules;

• "the certificates, documents and information relative to the Units classed with the Society may be reviewed during certificating bodies audits and are disclosed upon order of the concerned governmen-tal or inter-governmental authorities or of a Court having jurisdiction.

The documents and data are subject to a file management plan.

ARTICLE 10

10.1. - Any delay or shortcoming in the performance of its Services by the Society arising from an eventnot reasonably foreseeable by or beyond the control of the Society shall be deemed not to be a breach ofcontract.

ARTICLE 11

11.1. - In case of diverging opinions during surveys between the Client and the Society's surveyor, the So-ciety may designate another of its surveyors at the request of the Client.

11.2. - Disagreements of a technical nature between the Client and the Society can be submitted by theSociety to the advice of its Marine Advisory Committee.

ARTICLE 1212.1. - Disputes over the Services carried out by delegation of Governments are assessed within theframework of the applicable agreements with the States, international Conventions and national rules.12.2. - Disputes arising out of the payment of the Society's invoices by the Client are submitted to the Courtof Nanterre, France, or to another Court as deemed fit by the Society.12.3. - Other disputes over the present General Conditions or over the Services of the Society areexclusively submitted to arbitration, by three arbitrators, in London according to the ArbitrationAct 1996 or any statutory modification or re-enactment thereof. The contract between the Societyand the Client shall be governed by English law.

ARTICLE 13

13.1. - These General Conditions constitute the sole contractual obligations binding together theSociety and the Client, to the exclusion of all other representation, statements, terms, conditionswhether express or implied. They may be varied in writing by mutual agreement. They are not var-ied by any purchase order or other document of the Client serving similar purpose.13.2. - The invalidity of one or more stipulations of the present General Conditions does not affect the va-lidity of the remaining provisions. 13.3. - The definitions herein take precedence over any definitions serving the same purpose which mayappear in other documents issued by the Society.

BV Mod. Ad. ME 545 L - 7 January 2013

MARINE & OFFSHORE DIVISIONGENERAL CONDITIONS

RULE NOTE NR 628

NR 628Semi Submersible Cargo Ships

SECTION 1 GENERAL

SECTION 2 GENERAL ARRANGEMENT

SECTION 3 STABILITY, SUBDIVISION AND LOAD LINE

SECTION 4 HULL STRUCTURE

SECTION 5 MACHINERY AND SYSTEMS

SECTION 6 ELECTRICAL INSTALLATIONS AND CONTROLS

SECTION 7 SAFETY FEATURES

SECTION 8 INSPECTION AND TESTING

May 2016

Section 1 General1 General 5

1.1 Application1.2 Scope1.3 Classification notations1.4 Applicable rules

2 References and definitions 6

2.1 Referenced documents2.2 Definitions

3 Documents to be submitted 7

3.1 General3.2 Submersion operating manual

Section 2 General Arrangement1 General 8

1.1 Draft marks

2 Ballast system 8

2.1 General2.2 Central ballast control station

Section 3 Stability, Subdivision and Load Line1 General 9

1.1 Loading instrument1.2 Stability verification in temporary submerged conditions1.3 Submersion procedure

2 Loading conditions 9

2.1 Transit conditions2.2 Temporary submerged conditions

3 Intact stability in transit conditions 9

3.1 General3.2 Buoyancy of the cargo

4 Damage stability in transit conditions 10

4.1 General4.2 Buoyancy of the cargo4.3 Type B freeboard4.4 Type B-60 and B-100 freeboard

5 Intact stability in temporary submerged conditions 11

5.1 Criteria

6 Damage stability in temporary submerged conditions 11

6.1 General6.2 Extent of damage6.3 Compartment permeability6.4 Damage criteria6.5 Intermediate stage of flooding

2 Bureau Veritas May 2016

7 Load line 12

7.1 General7.2 International Load Line Certificate7.3 Reserve buoyancy7.4 Watertight openings7.5 Openings

Section 4 Hull Structure

1 Materials and welding 13

1.1 General1.2 Welding and weld connections

2 Net scantling approach 13

2.1 Principle2.2 Corrosion additions2.3 Corrosion protection

3 Loading conditions 13

3.1 General3.2 Loading manual3.3 Loading conditions and load cases during temporary submerged conditions

4 Design loads 13

4.1 Vertical wave bending moments4.2 Horizontal wave bending moments4.3 Vertical wave shear forces4.4 Still water and inertial pressures

5 Hull girder strength 14

5.1 General

6 Hull scantlings 14

6.1 General6.2 Structural models

7 Connection of the buoyancy casings 14

7.1 General7.2 Design loads7.3 Strength criteria

8 Fatigue strength assessment 15

8.1 General8.2 Structural details8.3 Spectral fatigue analysis8.4 Deterministic fatigue analysis

Section 5 Machinery and Systems

1 General 16

1.1 Sea pressure

May 2016 Bureau Veritas 3

2 Ballast system 16

2.1 FMEA2.2 Failure modes2.3 Definitions2.4 Safety principles2.5 Air pipes2.6 Overflow tanks2.7 Valves and actuators2.8 Pressurized ballast tanks2.9 Control and monitoring

3 Scuppers and sanitary discharges 17

3.1 Arrangement of scuppers and sanitary discharges

Section 6 Electrical Installations and Controls

1 Emergency source of power 18

1.1 Essential service

2 Controls 18

2.1 Draft mark automatic gauges2.2 Ballast tanks gauging system2.3 Ballast valves monitoring2.4 Communication means

Section 7 Safety Features

1 Fire safety 19

1.1 General1.2 Fire hydrants

2 Means of escape 19

2.1 Transit conditions2.2 Temporary submerged conditions

3 Life-saving appliances 19

3.1 Temporary submerged conditions

Section 8 Inspection and Testing

1 General 20

1.1 Application1.2 In-service survey

2 Commissioning 20

2.1 At quay2.2 Sea trials


NR 628, Sec 1

SECTION 1 GENERAL

1 General

1.1 Application

1.1.1 This Rule Note provides the requirements for the clas-sification of cargo ships intended to perform loading andunloading operations of a floating cargo by submersion ofthe freeboard deck.

Note 1: This type of ships is also known as semi-submersible heavylift transport vessel.

1.1.2 This Rule Note does not cover the floating docks.

1.2 Scope

1.2.1 General

This Rule Note addresses the requirements specific to thetype of ships defined in [1.1.1], i.e.:

• load line and stability criteria for transit and temporarysubmerged conditions

• ballast system and auxiliary equipment

• structural assessment of the hull in the temporary sub-merged conditions

• electrical installations

• safety features

• sea trials.

1.2.2 Submerged conditions

a) Stability:

The stability verification required in this Rule Note islimited to the assumptions made on some typical float-ing cargoes as mentioned in the stability booklet.

As a rule, the stability and buoyancy are to be checkedbefore any submersion operation with the actualdescription of the floating cargo, as specified in Sec 3.

b) Bottom contact:

For units requiring sea bottom contact when submerg-ing, the soil is to be surveyed to obtain information onthe character of the soil and to localize obstacles possi-bly present.

c) Environmental conditions:

Limitations on the environmental conditions (waves,wind and current) to carry out the submersion proce-dure in a safe and controllable manner, taking intoaccount the actual behaviour of the ship and the float-ing cargo, are under the responsibility of the operator ofthe ship.

1.3 Classification notations

1.3.1 Service notation and additional service feature

Ships complying with the requirements of this Rule Noteare eligible for the assignment of the service notation semi-submersible cargo ship.

The service notation semi-submersible cargo ship is to becompleted by the additional service feature heavycargo

[AREA1, X1 kN/m2 - AREA2, X2 kN/m2 - …].

This additional service feature is granted when the deckareas are designed to support heavy cargoes in accordancewith the characteristics given between square brackets. Thevalues Xi indicate the maximum allowable local pressureson the various zones AREAi where the cargo is intended tobe stowed.

1.3.2 Additional class notations

One of the additional class notations LI-HG-S2 or LI-HG-S3is to be assigned when the service notation semi-submersi-ble cargo ship is granted. These notations involve that theloading instrument performing intact stability, damage sta-bility and hull girder calculations is reviewed by the Soci-ety.

Note 1: When the loading instrument allows the definition of abuoyant cargo and/or damage cases, the approval is to be speciallyconsidered.

The following additional class notations are also of particu-lar interest for semi-submersible cargo ships:

• MON-HULL

Equipment continuously monitoring ship's dynamicloads through measurements of motions in waves andstresses/deformations in the hull structure. This notationmay be assigned to the ship for monitoring the accelera-tions under the scope of classification.

• STAR-MACH SIS

Planned Maintenance Survey System (PMS) for machin-ery reviewed by the Society. This notation may beassigned to the ship for having the scope of in-servicesurveys of the ballast systems based on a risk assess-ment.

Note 2: The different additional class notations which may beassigned to a ship are listed in NR467, Pt A, Ch 1, Sec 2.


NR 628, Sec 1

Table 1 : Applicable requirements

1.4 Applicable rules

1.4.1 The applicable requirements for the classification andsurveys of ships having the service notation semi-submersi-ble cargo ship are summarized in Tab 1.

2 References and definitions

2.1 Referenced documents

2.1.1 Bureau Veritas Rules, Rule Notes and Guidance Notes

• NR216 Rules on Materials and Welding for the Classifi-cation of Marine Units.

• NR467 Rules for the Classification of Steel Ships.• NR566 Hull Arrangement, Stability and Systems for

Ships less than 500 GT.• NR600 Hull Structure and Arrangement for the Classifi-

cation of Cargo Ships less than 65 m and Non CargoShips less than 90 m.

• NI539 Spectral Fatigue Analysis Methodology for Shipsand Offshore Units

When reference is made to these documents, the latest ver-sion of these documents is applicable.

2.1.2 International Maritime Organisation (IMO)SOLAS means the Convention for the Safety Of Life At Sea,as amended.

ICLL means the International Convention on Load Lines1966, as amended.

2.1.3 International Association of Classification Societies (IACS)

IACS UI LL means the Unified Interpretation on Load Lines,as amended.

2.2 Definitions

2.2.1 Transit conditionTransit condition means all ship movements from one geo-graphical location to another.

2.2.2 Temporary submerged conditionTemporary submerged condition means any situation wherea floating cargo is loaded (or unloaded) onto the semi-sub-merged cargo ship which has its cargo deck under the seasurface.

2.2.3 Maximum submerged draftThe maximum submerged draft is the distance, in m, mea-sured vertically on the midship transverse section, from themoulded base line to the uppermost considered waterlinein temporary submerged condition (no trim).

2.2.4 Fore and aft endsThe fore and aft ends are as defined in NR467, Pt B, Ch 1,Sec 2.

2.2.5 Maximum submerged draft at fore end (FE)The maximum submerged draft FE is the distance, in m, mea-sured vertically at the fore end, from the moulded base line tothe uppermost considered waterline in temporary submergedconditions, taking into account the maximum trim of the ship.

Item Cargo ships equal to or greater than 500 GT Cargo ships less than 500 GT

Ship arrangement

L ≥ 65 m• NR467, Part B• Sec 2

• NR566• Sec 2

L < 65 m• NR600• Sec 2

• NR566• Sec 2

Structural assessment

L ≥ 65 m• NR467, Part B• Sec 4

• NR467, Part B• Sec 4

L < 65 m• NR600• Sec 4

• NR600• Sec 4

Stability• NR467, Part B• Sec 3

• NR566• Sec 3

Machinery and systems• NR467, Part C• Sec 5

• NR566• Sec 5

Electrical installations and automation• NR467, Part C• Sec 6

• NR566• Sec 6

Fire protection, detection and extinction• NR467, Part C• Sec 7

• NR566• Sec 7

Materials and welding NR216

Classification and survey NR467, Part A and Sec 8

Note 1:L : Rule length, in m, as defined in NR467, Pt B, Ch 1, Sec 2.


NR 628, Sec 1

2.2.6 Maximum submerged draft at aft end (AE)The maximum submerged draft AE is the distance, in m, mea-sured vertically at the aft end, from the moulded base line tothe uppermost considered waterline in temporary submergedconditions, taking into account the maximum trim of the ship.

2.2.7 Cargo deckThe cargo deck is the deck on which the floating cargo isbeing transported. It is generally equivalent to the freeboarddeck as defined in the ICLL 66.

2.2.8 Central ballast control stationThe central ballast control station is a control station fromwhich the submersion operations are performed.

3 Documents to be submitted

3.1 General

3.1.1 The documents listed in Tab 2 are to be submitted, asa minimum, in addition to documents listed in the applica-ble Rules defined in [1.4].

Relevant additional drawings and calculation notes may berequested by the Society in complement to the hereaftermentioned documents.

3.2 Submersion operating manual

3.2.1 A submersion operating manual including the follow-ing is to be submitted:

• stability assessment method

• procedure for ballast operations including the fillingsequence and the designation of the pumps and tanksused simultaneously

• definition of the ballast capacity with respect to associatedtype of operation (float-on/float-off or load-on/load-off) andfor the different failure modes defined in Sec 5, [2.2]

• commissioning procedure

• contingency plan

Table 2 : Document to be submitted

No. Documents to be submitted I/A (1)

1.1 General arrangement showing the maximum submerged draft I

1.2 Submersion operating manual I

Stability

2.1 Trim and stability booklet A

2.2 Loading instrument certification booklet A

2.3 Loading instrument operating procedure when cargo is considered buoyant (see Sec 3) I

2.4 Justification of the reserve buoyancy I

Structure

3.1 Justification of the hull girder loads in limited environmental conditions, when relevant I

3.2 Description of the connection of the buoyancy casings on deck A

Machinery and systems

4.1 Description of the ballast system (single line diagram, specifications, failure modes etc.) A

4.2 Owner performance request of the ballast system, if any, for each failure mode I

4.3 Ballast system FMEA I

4.4 Planned Maintenance System of the ballast system I

4.5 Overflow tank drainage capacity calculations I

4.6 Arrangement for hydraulic and pneumatic controlled valves A

Electrical installations

5.1 Description of electrical arrangement principles, failure scenarios, redundancy principles, emergency arrangement, etc.

A

5.2 Power supply and control system diagrams of the ballast system A

5.3 Description of the draft gauging system I

5.4 Description of the ballast tanks gauging system I

Safety features

6.1 Drawing showing the means of escape A

6.2 Description of the means of fire-fighting for the open deck A

6.3 Description of the arrangements for life-saving appliances I

(1) To be submitted: A = for approval ; I = for information.


NR 628, Sec 2


SECTION 2 GENERAL ARRANGEMENT

1 General

1.1 Draft marks

1.1.1 Accurate draft marks are to be positioned on the hulland casings in order to remain visible in temporary sub-merged conditions and with the maximum trim.

The draft marks and gauges are to be positioned sufficientlyat the ends of the ship in order that the trim can be readaccurately.

As a rule, the draft scales are to extend above the maximumsubmerged draft with a height equal to 1,0 m or (0,75L/100),whichever is the greater, where:

L : Rule length, in m, as defined in NR467, Pt B, Ch1, Sec 2.

Draft marks above the summer load line should be highlyvisible with indicating figures 0,5 m in height, 0,5 m apart.

1.1.2 The maximum submerged draft is to be clearly indi-cated with a mark near each draft scale.

1.1.3 Automatic draft gauges and alarms are to be providedas defined in Sec 6.

2 Ballast system

2.1 General

2.1.1 Requirements for the ballast system are given in Sec 5.

2.1.2 Special arrangement to reduce the air entrapped inthe ballast tanks are to be considered.

2.2 Central ballast control station

2.2.1 A central ballast control station is to be provided.

2.2.2 The central ballast control station is to be locatedabove the maximum submerged draft and in a space notwithin the assumed extent of damage referred to in Sec 3,[6].

2.2.3 The central ballast control station is to contain allmeans necessary to conduct the submersion operation asdefined in Sec 5.

NR 628, Sec 3

SECTION 3 STABILITY, SUBDIVISION AND LOAD LINE

1 General

1.1 Loading instrument

1.1.1 A loading instrument is to be provided on-board andaccessible from the central ballast control station.

1.1.2 Ballast gauging systemIt is recommended that the loading instrument be con-nected to the ballast tank monitoring system so as to checkthe stability using the actual filling level values.

1.1.3 Transit conditionsThe loading instrument is to comply with the requirementsof NR467, Pt B, Ch 10, Sec 2, as relevant, in addition tothose of the present Section.

When the cargo may be considered buoyant, the provisionsof [1.1.4] are to be complied with.

1.1.4 Buoyant cargoWhen the cargo may be considered buoyant, the proceduredescribing the input of the new set of data into the loadinginstrument is to be submitted.

The procedure should include the definition of the newbuoyant volume and of the new damage cases under theprovisions of [4.2].

1.1.5 Temporary submerged conditionsThe loading instrument should be able to perform simula-tions of the ballast loading sequence and to check the sta-bility criteria for the intermediate conditions duringsubmersion operation.

The loading instrument is to be able to perform stability ver-ification up to the maximum submerged draft and the maxi-mum trim.

1.2 Stability verification in temporary submerged conditions

1.2.1 In addition to the typical loading conditions assumedfor the temporary submerged condition in the trim and sta-bility booklet defined in [2.2], specific stability calculationsare to be performed before any submersion operation.

A description of the method used for the assessment of sta-bility in the temporary submerged conditions is to be sub-mitted to the Society.

1.3 Submersion procedure

1.3.1 A detailed procedure of the ballasting operation dur-ing submersion operation is to be submitted to the Societyfor the typical loading conditions assumed in the trim andstability booklet.

The procedure should include the sequence of ballast tankfilling and stability verification for several intermediatestages.

2 Loading conditions

2.1 Transit conditions

2.1.1 The trim and stability booklet is to include the load-ing conditions specified in NR467, Part B, for the transitconditions.

Loading conditions with typical cargoes are to be submit-ted, including the full draft condition.

The windage area of the deck cargo is to be considered.

Buoyancy of the deck cargo may be considered subject tothe provisions detailed in Articles [3] and [4].


2.2.1 The trim and stability booklet is to include the follow-ing temporary submerged conditions:

• no cargo on deck

• typical loading conditions including buoyant cargo(es)on deck.

The loading conditions are to include initial transit draft andmaximum submerged draft with several intermediate stages.

Several trim values are to be considered, including maxi-mum trim.

The free surface effect resulting from partial filling of theballast tanks is to be considered.

The buoyant volume of the cargo is to be included in thehydrostatic calculations.Note 1: The stability in temporary submerged conditions is to bechecked before any loading or unloading operation.

3 Intact stability in transit conditions

3.1 General

3.1.1 The intact stability in transit condition is to complywith the requirements of NR467, Part B, Chapter 3.

3.2 Buoyancy of the cargo

3.2.1 Buoyancy of the cargo may be considered in the sta-bility calculations, on case-by-case basis.Note 1: Special agreement from the Administration should begranted.

The buoyancy and the watertight integrity of the cargo is tobe documented.


NR 628, Sec 3

3.2.2 For any loading condition involving the buoyancy ofthe deck cargo, stability calculations with the buoyancydata are to be performed prior to the operation.

3.2.3 Lift-off of buoyant cargo

When the cargo is considered buoyant, assessment of thelift-off of the cargo at heel is to be submitted.

The cargo should not lift-off at an angle of heel less than20°.

Note 1: Lift-off occurs when the cargo is partially floating, i.e. thetilting moment due to hydrostatic pressure on the cargo is higherthan the moment due to gravity.

4 Damage stability in transit conditions

4.1 General

4.1.1 The damage stability in transit condition is to complywith the requirements defined in [4.3] or [4.4], dependingon the intended freeboard and the cargo buoyancy.

4.2 Buoyancy of the cargo

4.2.1 Buoyancy of the cargo may be considered in the sta-bility calculations on case-by-case basis.

Note 1: Special agreement from the Administration should begranted.

The buoyancy and the watertight integrity of the cargo is tobe documented.

4.2.2 For any loading condition involving the buoyancy ofthe deck cargo, stability calculations with the buoyancydata are to be performed prior to the operation.

4.3 Type B freeboard

4.3.1 For type B freeboard, IMO SOLAS Chapter II-1 is tobe complied with.Note 1: When the criteria on the maximum allowable vertical cen-tre of gravity (KG) are not met, compliance with ICLL Reg. 27 maybe considered as an alternative subject to acceptance by the Soci-ety. Special agreement from the Administration should also begranted.

Note 2: For voyage with a buoyant cargo, the stability verificationsare to be directly performed and are to comply with ICLL Reg. 27.

4.4 Type B-60 and B-100 freeboard

4.4.1 For reduced freeboard type B-60 and B-100, ICLLRegulation 27 and IACS UI LL65 are to be complied with.Note 1: For voyage with a buoyant cargo, the stability verificationsmay be directly performed and to comply with ICLL Reg. 27.

4.4.2 Extent of damageUnits with a type B-60 freeboard are to comply with therequirements of ICLL for one compartment damaged.

Units with a type B-100 freeboard are to comply with therequirements of ICLL for two compartments damaged.

4.4.3 Extent of damage with protruding cargoWhen the cargo is considered buoyant and is protrudingfrom the side shell of the ship, the transversal penetrationmay include the cargo overhang as shown in Fig 1.

In that case, the cargo is considered part of the hull provid-ing the vertical distance between the cargo and the sealevel is small, typically less than 4,5 m, and the cargo struc-ture is considered strong enough.

The transverse extent of damage is to be in accordance withICLL, measured inboard from the side of the ship or fromthe side of the cargo, on a line perpendicular to the ship'scentreline, whichever is the farthest.Note 1: In specific cases, the definition of the extent of damagemay need to be supported by a collision analysis in order to assessthe effective protection of the hull provided by the cargo.

Figure 1 : Extent of damage with protruding buoyant cargo

CL

TOP VIEWColumn stabilisedunit (cargo)

Semi-submersiblecargo ship

Extent of damage including buoyant cargo


NR 628, Sec 3

5 Intact stability in temporary submerged conditions

5.1 Criteria

5.1.1 The intact stability in temporary submerged condi-tions is to be checked with the following criteria:

a) The metacentric height GM is to be not less than 0,30 m

b) The range of stability is to be positive over a range of atleast 15°

c) Within the range of GZ curve of 15°, the GZ lever maxi-mum is to be not less than 0,10 m

d) The maximum GZ value shall not occur at an angle ofheel less than 10°

e) In equilibrium condition, the distance between thewaterline and any weathertight opening through whichprogressive flooding can occur is to be at least 1,0 m or,with a heel angle of 5°, the weathertight opening is tobe above the waterline, whichever is the greatest (seeFig 2).

Figure 2 : Zone of weathertight integrity

6 Damage stability in temporary submerged conditions

6.1 General

6.1.1 Damage stability during temporary submerged condi-tions as a result of a collision with the cargo or flooding dueto a failure of the water ballast system is to be considered.

6.2 Extent of damage

6.2.1 Horizontal penetration

A one-compartment extent of damage is to be assumed onvertical surface adjacent to the exposed deck with:

• longitudinal/ transversal extent of 5,00 m

Note 1: One-compartment extent with a damage length of 5 mimply that a watertight bulkhead may be considered to remainintact provided that the distance with adjacent bulkheadsexceeds 5m.

• penetration of 0,76 m

• vertical extent 3,0 m occurring at any level between theexposed deck and 5 m above the maximum submergeddraft.

This includes all sides of casings, superstructure bulkheadsand hull surface adjacent to the exposed deck within a dis-tance of 2,5 m measured from the superstructure bulkhead.

6.2.2 Vertical penetration

A one-compartment extent of damage is to be assumed onthe exposed deck with:

• longitudinal extent of 5,00 m

• transversal extent of 5,00 m

• vertical penetration of 0,76 m.

Note 1: One-compartment extent with a damage length of 5 mimply that a watertight bulkhead may be considered to remainintact provided that the distance with adjacent bulkheads exceeds5 m.

6.3 Compartment permeability

6.3.1 The permeability of damaged compartments (voidsand water ballast) is to be taken as 0,95. The permeability ofmachinery spaces is to be taken as 0,85.

6.4 Damage criteria

6.4.1 The following damage stability criteria are to be com-plied with:

a) The final waterline after flooding is to be below anynon-watertight opening through which progressiveflooding may take place

b) The equilibrium angle is not to exceed 15° of heel

c) The righting lever curve is to have a positive range of atleast 7° beyond the equilibrium angle

d) The maximum righting lever is to be at least 0,05 mwithin the range of positive stability.

6.5 Intermediate stage of flooding

6.5.1 Damage stability at intermediate stages of flooding isto be verified.

A1,0 mB 5°

Maximum submergeddraft

Full draftin transit

A : 1.0m - Zone of weathertightness

B : 5 degrees - Zone of weathertightness

CL


NR 628, Sec 3

7 Load line

7.1 General

7.1.1 This Article provides requirements to be consideredin addition to the relevant provisions of the ICLL.

7.2 International Load Line Certificate

7.2.1 An international load line certificate is to be issued inaccordance with the ICLL for the transit conditions.For the temporary submerged conditions, an exemption cer-tificate under the provisions of the ICLL Article 6 should begranted.Note 1: Special agreement from the Administration should begranted.

7.3 Reserve buoyancy

7.3.1 CriteriaThe reserve buoyancy at maximum submerged draft is to beassessed.

The reserve buoyancy volume, i.e. the volume with weath-ertight integrity above the maximum submerged waterline,is to be at least 1,5% higher than the submerged volume.

The reserve buoyancy ratios of the fore end and aft endstructures considered separately are to be at least 4,5%higher than the submerged volume.

7.3.2 AlternativeAs an alternative to the reserve buoyancy criteria, the ship isto provide sufficient buoyancy and stability at the maximumsubmerged draft in order to withstand the accidental flood-

ing of any watertight compartment wholly or partiallybelow the waterline in submerged conditions, which is aballast pump room or a room containing ballast system pip-ing, in compliance with the following criteria:

a) the angle of inclination after flooding should not begreater than 25°

b) any opening below the final waterline should be madewatertight

c) a range of positive stability should be provided, beyondthe calculated angle of inclination in these conditions,of at least 7°

7.4 Watertight openings

7.4.1 Openings which could be submerged during tempo-rary submerged conditions are to be closed with two effec-tive watertight means to maintain the watertight integrity ifone means fails.

The fitting of a second door or hatch of equivalent strengthand watertightness is an acceptable arrangement.

A leakage detection device shall be provided in the com-partment between the two doors. Drainage of this compart-ment to the bilges, controlled by a readily accessible screw-down valve, is to be arranged. The outer door is to openoutwards.

7.5 Openings

7.5.1 Openings which are to remain open during the tem-porary submerged conditions, such as the engine room airintakes, are to be provided with remote controlled quick-closing appliances.


NR 628, Sec 4

SECTION 4 HULL STRUCTURE

Symbols

TS : Maximum submerged draft, in m, defined inSec 1, [2.2]

nS : Navigation coefficient in temporary submergedconditions defined in Tab 1

L, B, CB : As defined in NR467, Pt B, Ch 1.

1 Materials and welding

1.1 General

1.1.1 Structural elements are to comply with the require-ments relating to materials for construction given in NR467,Pt B, Ch 4, Sec 1 or NR600, as applicable.

1.2 Welding and weld connections

1.2.1 The requirements stipulated in NR467, Pt B, Ch 11,Sec 1 or NR600, as applicable, are to be applied.

2 Net scantling approach

2.1 Principle

2.1.1 For ships greater than or equal to 65m in length andexcept when otherwise specified, the scantlings obtained byapplying the criteria specified in this Rule Note and in theapplicable requirements of the NR467, Pt B, Ch 4, Sec 2 arenet scantlings.

2.2 Corrosion additions

2.2.1 The corrosion additions as defined in NR467, Pt B,Ch 4, Sec 2 are to be applied.

2.3 Corrosion protection

2.3.1 The requirements of NR467, Part B, Chapter 10 are tobe fulfilled.

3 Loading conditions

3.1 General

3.1.1 Design loads are to be determined for the variousload cases in the following two situations:

• navigation situation, as defined in NR467, Part B, Ch 5,Sec 1 or NR600, as applicable

• temporary submerged conditions.

3.2 Loading manual

3.2.1 A loading manual is to be submitted for approval.

As a minimum, the loading manual is to comply with therelevant requirements of NR467, Pt B, Ch 10, Sec 2, [2] andPt B, Ch 10, Sec 2, [3].

3.3 Loading conditions and load cases dur-ing temporary submerged conditions

3.3.1 As a minimum, the loading conditions during tempo-rary submerged conditions defined in Tab 1 are to be con-sidered.

Note 1: As an alternative to the rule-based formulae, a directhydrodynamic analysis may be performed in order to obtain thedesign wave loads.

Table 1 : Load cases and coefficients nS during tem-porary submerged conditions

4 Design loads

4.1 Vertical wave bending moments

4.1.1 In addition to the vertical wave bending momentsMWV, H and MWV, S in navigation situation defined in NR467,Pt B, Ch 5, Sec 2, or NR600, as applicable, the verticalwave bending moments during temporary submerged con-ditions at any hull transverse section are to be obtained, inkN⋅m, from the following formulae:

• in hogging conditions:

MWV, H, D = 190 FM nS C L2 B CB 10−3

• in sagging conditions:

MWV, S, D = − 110 FM nS C L2 B (CB + 0,7) 10−3

where:

FM : Distribution factor defined in NR467, Pt B, Ch5, Sec 2

C : Wave parameter defined in NR467, Pt B, Ch 5,Sec 2.

Loading condition

Description Draught nS

1 Temporary submerged conditions in sheltered area

TS 0,33

2 Temporary submerged conditions in harbour

TS 0,20


NR 628, Sec 4

4.2 Horizontal wave bending moments

4.2.1 In addition to the horizontal wave bending momentMWH in navigation situation defined in NR467, Pt B, Ch 5,Sec 2, or NR600, as applicable, the horizontal wave bend-ing moment during temporary submerged conditions at anyhull transverse section is to be obtained, in kN⋅m, from thefollowing formula:

MWH, D = 0,42 FM nS H L2 TS CB

where:FM : Distribution factor defined in NR467, Pt B, Ch

5, Sec 2H : Wave parameter defined in NR467, Pt B, Ch 5,

Sec 2.

4.3 Vertical wave shear forces

4.3.1 In addition to the vertical wave shear force QW innavigation situation defined in NR467, Pt B, Ch 5, Sec 2, orNR600, as applicable, the vertical wave shear force duringtemporary submerged conditions at any hull transverse sec-tion is to be obtained, in kN, from the following formula:

QW, D = 30 FQ nS C L B (CB + 0,7) 10−2

where:FQ : Distribution factor defined in NR467, Pt B, Ch

5, Sec 2C : Wave parameter defined in NR467, Pt B, Ch 5,

Sec 2.

4.4 Still water and inertial pressures

4.4.1 Upper deckThe still water and inertial pressures transmitted to the struc-ture of the upper deck intended to carry loads are to beobtained, in kN/m2, as specified in NR467, Pt B, Ch 5, Sec6.

4.4.2 External boundariesThe still water pressure at any point of the hull is to be thesea pressure at the maximum submerged draft.

For temporarily submerged conditions, the dynamic part ofthe sea pressure may be reduced by nS.

4.4.3 Watertight boundariesThe still water pressure pSF , in kN/m2, and the inertial pres-sure pWF , in kN/m2, to be considered as acting on structuralelements located below the deepest equilibrium waterlineincluding doors, hatches and penetrations but excludingside shell structural elements, which constitute boundariesbetween two compartments not intended to carry liquidsshall be based on the deepest equilibrium waterline in dam-aged transit or damaged temporary submerged conditions.

4.4.4 Internal pressureIn order to limit the pressure head in the tanks, the cargoship may be fitted with an overflow system.

When overflow tanks complying with the relevant provi-sions of Sec 5 are installed, the pressure head may be takenat the top of the overflow tank instead of the top of the airpipe.

5 Hull girder strength

5.1 General

5.1.1 Hull girder strength is to meet the applicable require-ments of NR467, Part B, Chapter 6, or NR600, as applica-ble, regarding for the two following situations:

• navigation situation

• temporary submerged conditions, considering the hullgirder loads defined in Article [4]

Note 1: Due to the low depth of the hull girder, special attention isto be paid to the requirement regarding the moment of inertia givenin NR467, Pt B, Ch 6, Sec 2, [4.4], or NR600 as applicable. Thisrequirement is to be satisfied over a minimum length of 0,40 L inthe midship area.

6 Hull scantlings

6.1 General

6.1.1 Hull scantlings are to be in accordance with theapplicable requirements of NR467, Part B, Chapter 7, orNR600, as applicable, for the two following situations:

• navigation situation

• temporary submerged conditions, considering the hullgirder loads defined in Article [4].

Where intermediate situations are considered more severedue to specific loading conditions of the cargo ship, thescantlings are to be determined according to the mostsevere situation.

6.2 Structural models

6.2.1 For cargo ships of more than 170 m in length, a finiteelement analysis is to be performed.

7 Connection of the buoyancy casings

7.1 General

7.1.1 The scantlings of the structures in way of the connec-tion between the hull structure and the buoyancy casingsare to be obtained through direct calculations.

7.2 Design loads

7.2.1 Still water loads

Still water pressures are to be calculated as defined inNR467, Pt B, Ch 5, Sec 5, or NR600, as applicable, takinginto account the maximum draught at the location of thebuoyancy casing.

7.2.2 Wave loads

Wave pressures acting on the buoyancy casings are to becalculated as defined in NR467, Pt B, Ch 5, Sec 5 (loadcases a and b), or NR600, as applicable.


NR 628, Sec 4

The reference value of the ship relative motion h1, asdefined in NR467, Pt B, Ch 5, Sec 4, or NR600, as applica-ble, is to be calculated taking into account the navigationcoefficient nS given in Tab 1 for temporary submerged situa-tion.Note 1: As an alternative to the rule-based formulae, a directhydrodynamic analysis may be performed in order to obtain thedesign wave loads.

7.2.3 Internal pressuresInternal pressures of ballast tanks in the buoyancy casingsare to be calculated based on the requirements of NR467,Pt B, Ch 5, Sec 6 or NR600, as applicable.

7.3 Strength criteria

7.3.1 The local stresses in the elements of the buoyancycasings and in connections with the hull structure are to sat-isfy the following conditions:

where:

Ry : Minimum yield strength, in N/mm2, of the mate-rial, to be taken equal to 235/k N/mm2, unlessotherwise specified

k : Material factor defined in NR467, Pt B, Ch 4,Sec 1 or NR600, as applicable

γm , γr : Partial safety factors covering uncertaintiesregarding, respectively:

• material: γm = 1,02

• resistance: γr = 1,30.

8 Fatigue strength assessment

8.1 General

8.1.1 Fatigue assessment is to be carried out on ships equalto or greater than 170 m in length.

It may also be required on ships less than 170 m in length, ifdeemed necessary by the Society.

8.1.2 The fatigue life and sea conditions of the ship are tobe specified by the Owner, and to be indicated on the mid-ship section drawing.

8.1.3 Fatigue calculations are to be provided to the Societyfor review.

8.2 Structural details

8.2.1 The structural details to be checked are to be selectedfrom those defined in NR467, Pt B, Ch 11, App 2, as rele-vant.

8.3 Spectral fatigue analysis

8.3.1 For ships intended to be granted the additional classnotation Spectral Fatigue, a spectral fatigue analysis is to beperformed according to NI539.

Otherwise, a deterministic fatigue calculation is to be car-ried out according to [8.4].

8.4 Deterministic fatigue analysis

8.4.1 Deterministic fatigue calculations are to be carriedout based on the methodology given in NR467, Part B,Chapter 7.

σ Ry

γmγr

---------≤

τ 0 5Ry

γmγr

---------,≤


NR 628, Sec 5

SECTION 5 MACHINERY AND SYSTEMS

1 General

1.1 Sea pressure

1.1.1 Any equipment on the hull and submitted to the seapressure is to withstand the pressure due to the maximumsubmerged draft.

2 Ballast system

2.1 FMEA

2.1.1 A Failure Modes and Effects Analysis is to be per-formed regarding the ballast system, including its controland monitoring systems.

2.1.2 The FMEA is to address the ballast functions with ref-erence to the different modes of operation defined in [2.2],and regarding float-on / float-off or load-on / load-off opera-tions.

2.1.3 The FMEA method described in NR467, Pt E, Ch 2,App 1, may be used as a guidance.

2.2 Failure modes

2.2.1 Principle

The ballast system is to be designed in order to meet thesafety principles defined in [2.4] in the following failuremodes:

• Normal conditions, refer to [2.3.1]

• Degraded conditions, refer to [2.3.2]

• Emergency conditions, refer to [2.3.3].

2.3 Definitions

2.3.1 Normal ballast functions

The normal ballast functions means the design ballastcapacity, control and monitoring functions allowing to per-form ballasting and de-ballasting procedure of the semi-submersible cargo ship in the intended manner regardingfloat-on / float-off or load-on / load-off operations.

2.3.2 Degraded ballast functions

The degraded ballast functions means the ballast capacity,control and monitoring functions which remain available incase of a single failure on any active component of the bal-last system, as defined in [2.3.4].

The degraded ballast functions are to be defined by theOwner and addressed in the FMEA.

2.3.3 Emergency ballast functionsThe emergency ballast functions means the ballast capacity,control and monitoring functions available in case of mainsource of electrical power failure.

The emergency ballast functions are to be defined by theOwner and addressed in the FMEA.

2.3.4 Active component of the ballast systemAn active component of the ballast system means any com-ponent of the ballast system which is not a pipe, an electri-cal cable, a manually controlled valve or a tank.

Active components include the machinery items (pumps,remote controlled valves, filters, etc.) and the control sys-tem items (gauges, sensors, switchboards).

2.4 Safety principles

2.4.1 Degraded conditionsAny single failure on an active component in the ballast sys-tem is not to lead to a situation where the degraded ballastfunctions are not met or to unintended flooding.

Note 1: Duplicate of components of the ballast control system maybe required.

2.4.2 Emergency conditionsFailure of the main source of electrical power is not to leadto a situation where the emergency ballast functions are notmet or to unintended flooding.

2.5 Air pipes

2.5.1 GeneralEffective means to reduce the air entrapped in the ballasttanks while filling up are to be provided, such as:

• sufficient air holes in tank internal structures, and

• air pipe connected to the highest point during the bal-last operations.

Note 1: If the venting system requires operational restrictions (i.e.no trim by the bow when submersing), this should be specificallynoted in the submersion operating manual.

2.5.2 ValvesInstallation of valves on ballast tank air pipes may beaccepted, subject to the following conditions:

• the lay-out of the air pipe system and of the control andsupply systems is to be of fail-safe design. In this design,both the risk of flooding and pressurisation are to betaken into account

• an interlock system is provided between filling tanklines and air vent valves.


NR 628, Sec 5

2.6 Overflow tanks

2.6.1 General

When overflow tanks are fitted to reduce tank pressures incase of overfilling, means are to be provided to drain theoverflow tank with sufficient capacity to allow uninter-rupted ballasting in normal conditions.

2.6.2 Design pressure and alarms

The design head of pressure considered for the ballast tanksstructural assessment may be taken as the overflow tank toplevel, instead of the top of the air pipe, providing that thefollowing alarms are fitted:

• High level alarm or overflow alarm

• High-High level alarm at max 98% level with shut-down of ballast pumps.

2.6.3 Overflow tank capacity

The overflow tanks are to have a capacity Voverflow, in m3,not less than:

Where:

Tfilling : Filling time, in minute, to be taken the lesser of:

• 10 min, or

• time matching the design ballast philosophy,or

• when alarms in compliance with [2.6.2] andan automatic draining system are provided,the greatest of:

- the time elapsed before the drain systemis switched on, and

- 3 min.

Qnormal : Ballast rate in normal conditions, in m3/hr

Qdraintotal : Total drain pump rate, in m3/hr

Qdrainpump: Rate of the largest drain pump, in m3/hr.

Note 1: The rate of the largest pump is considered in order tocope with the single failure of a drain pump.

2.7 Valves and actuators

2.7.1 Every ballast tank is to be provided with remote iso-lating valves for filling and/or emptying purposes.

The valves are to be able to be operated from the centralballast control station.

An emergency system is to be provided to operate theremote ballast valves.

The isolating ballast tank valves should be closed in case ofloss of power.

The flow may be controlled by isolating valve when thisvalve is designed to reduce the wear associated with sealingsurface contact and to maintain the sealing integrity. Othermeans may be provided to ensure tightness of the valve.

The arrangement for hydraulic and pneumatic controlledvalves is to be submitted to the Society.

A speed control system is to be installed for remote valvesin order to adjust the operating time. The operating time isto be long enough to avoid any water hammering in thevalve and pipe, whist being in accordance with the manu-facturer's recommendation.

The valves and actuators are to be certified as sea sidevalves.

2.8 Pressurized ballast tanks

2.8.1 Compressed air systems used to fill or empty the bal-last tanks are to be specially considered.

Adequate means to control and to mitigate the risks of over-pressure are to be provided.

A description of the air pressure system is to be submitted.

2.9 Control and monitoring

2.9.1 Central ballast control station

The central ballast control station defined in Sec 2, [2.2] isto include the following:

• a ballast pump control system

• a ballast pump status-indicating system

• a ballast valves control system

• a ballast valves position-indicating system

• a ballast tank level indicating and monitoring system asdefined in Sec 6

• a ballast valve status monitoring system as defined inSec 6

• a draught indicating system, indicating the draught ateach draft scale of the unit or at presentative positions asrequired by the Society

• a power availability indicating system (main and emer-gency)

• a ballast system hydraulic / pneumatic pressure-indicat-ing system

• a permanently installed means of communication, inde-pendent of the unit's main source of electrical power,between the control station and those spaces containingthe ballast pumps and valves or their manual controls,or other spaces that may contain equipment necessaryfor the operation of the ballast system.

3 Scuppers and sanitary discharges

3.1 Arrangement of scuppers and sanitary discharges

3.1.1 The requirements for scuppers and sanitary dis-charges are to be in compliance with NR467, Pt C, Ch 1,Sec 10, or NR566, as applicable, and where the maximumsubmerged waterline is to be taken as the summer water-line.

VoverflowTfilling

60------------- Qnormal Qdraintotal– Qdrainpump+( )×=


NR 628, Sec 6


SECTION 6 ELECTRICAL INSTALLATIONS AND CONTROLS

1 Emergency source of power

1.1 Essential service

1.1.1 In addition to the requirements of NR467 or NR566,as applicable, the emergency source of power is to be ableto supply the emergency ballast functions defined in Sec 5,[2.3.3].

2 Controls

2.1 Draft mark automatic gauges

2.1.1 An automatic draft gauging system is to be fitted andthe information is to be displayed on the central ballast con-trol station.

In case of submersion to the maximum draft, an automaticvisible and audible alarm is to be provided in the centralballast control station.

Note 1: The alarm should be triggered when the mean sea level ishigher than the maximum submerged draft.

2.2 Ballast tanks gauging system

2.2.1 The ballast tanks are to be provided with effectivemeans of measuring the filling level. The variations of waterballast level are to be able to be directly observed.

2.2.2 An automatic gauging system is to be provided withthe information accessible from the central ballast controlstation.

2.2.3 The ballast tank filling level is to be continuouslymonitored during ballasting operations and compared withthe provisional values.

2.3 Ballast valves monitoring

2.3.1 The open/close status of valves is to be continuouslymonitored.

2.4 Communication means

2.4.1 The communication system should be arranged fordirect 2-way communication between the central ballastcontrol station and:• the bridge or command centre of the ship• the dynamic positioning control stand, when relevant.

NR 628, Sec 7


SECTION 7 SAFETY FEATURES

1 Fire safety

1.1 General

1.1.1 The cargo deck is to be protected by a fire-fightingsystem readily accessible in case of fire during a transit andin accordance with NR467 or NR566, as applicable.

1.2 Fire hydrants

1.2.1 Fire hydrant located forward and aft of the cargo deckon both sides and with sufficient hose length to reach all thecargo deck area may be considered acceptable as an alter-native to SOLAS requirements.Note 1: For SOLAS ships, special agreement from the Administra-tion is to be granted for alternative arrangement to SOLAS require-ments on the fire-fighting systems.

2 Means of escape

2.1 Transit conditions

2.1.1 Means of safe transfer between aft and fore parts ofthe ship are to be provided and to be practical in transitconditions.


2.2.1 Internal spaces of buoyancy towers are normallyunmanned during temporary submerged conditions.

3 Life-saving appliances


3.1.1 If buoyancy casings are manned during temporarysubmerged conditions, they should be provided with life-saving appliances suitable for the intended number of per-sons present on the casing in case of ship abandonment.

NR 628, Sec 8


SECTION 8 INSPECTION AND TESTING

1 General

1.1 Application

1.1.1 The present Section provides requirements for inspec-tion and testing specific to the submersion function of theship.

The submersion testing is to be conducted according to thesubmersion procedure submitted to the Society by the Inter-ested Party.

The Society is to be duly informed of the time and place ofthe commissioning tests of the ballasting equipment and ofthe submersion trials.

Any additional testing not mentioned in the present Sectionmay be required, to the satisfaction of the attending Sur-veyor.

1.2 In-service survey

1.2.1 The scope of in-service surveys for the maintenanceof classification is described in NR467, Part A.

2 Commissioning

2.1 At quay

2.1.1 Before putting the equipment into service, the inspec-tion and testing should include, as a minimum, the:

a) verification of the presence on board of the submersionprocedure as defined in Sec 1

b) examination of the connection of the buoyancy casingswith the hull

c) functional testing of the ballasting system including itscontrol and monitoring system for the different modes ofoperation defined in Sec 5, [2.2]

d) functional testing of the interface between the ballastsystem and the loading instrument

e) examination of ballast tank gauging system.

2.2 Sea trials

2.2.1 Submersion trials are to be performed under survey ofthe Society.