dnv-gdc information paper

8/16/2019 DNV-GDC Information Paper

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Information Paper

New Hull Survey Requirements for

General Dry Cargo Ships

By

Det Norske Veritas

April 2003


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1. Introduction

A major initiative to reduce general cargo ships casualties has been taken by the

International Association of Classification Societies (IACS).

In June 2002 IACS’ Council adopted new unified requirements which introduce tougherhull surveys for certain general dry cargo ships with requirements for overall and close-

up examination and steel thickness measurements at annual, intermediate and renewalsurveys along the lines applied already for bulk carriers and tankers.

Some ship types with relatively favourable casualty records are, however, excluded.

The requirements apply to surveys of hull structures and piping systems in way of cargo

holds, cofferdams, pipe tunnels and void spaces within the cargo area and all ballast tanks

and are additional to the classification requirements applicable to the remainder of theship.

The new hull survey requirements are given in the DNV Rules January 2003 and shallenter into force 1

st July 2003.

The purpose of this document is to provide DNV clients and surveyors with informationon application, scope and implementation of the new hull survey requirements.

2. Application

The requirements apply after construction to all self-propelled general dry cargo ships of500 GT and above carrying solid cargoes (tonnage measured in accordance with

International Convention on Tonnage Measurements of Ships, 1969).

Typical configurations for general dry cargo ships are illustrated in Fig. 1 to 4.

The following ship types are exempted from the new hull survey requirements:

- dedicated container carriers;

- ro-ro cargo ships

- pure car carriers- dedicated forestry product carriers

(a fully open hatch vessel with box-shaped cargo holds, double plane transverse bulkheads, pontoon type weather deck hatch covers and designed primarily for the carriage of pulp, paper

products (newsprint, linerboard etc.), general forestry products, other cargoes in unitised form, fine granulated non-corrosive cargoes in bulk and containers)

- refrigerated cargo ships;

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Fig.1 General view of a typical General Dry Cargo Ship

Fig.2 Cargo Hold Structural Configurations of typical General Dry Cargo Ships

Single deck ship

Tween deck ship

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Fig.3 Typical Transverse Section in way of Cargo Hold (without tween deck)

Fig.4 Typical Transverse Section in way of Cargo Hold (with one tween deck)

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3. Scope

The new requirements define minimum extent of overall and close-up examination, i.e.

‘within reach of hand’, applicable for cargo holds and ballast tanks, and more extensive

requirements for steel thickness measurements.

3.1 Annual Survey

The survey is to consist of an examination for the purpose of ensuring, as far as

practicable, that the hull including hatch covers and coamings are maintained in a

satisfactory condition. Examination of watertight penetrations shall be carried out as far

as practicable.

For examination of cargo holds, the following minimum requirements apply;

For Cargo Ships 10-15 Years of age:

-

Overall examination of one forward and one after cargo hold and theirassociated tween deck spaces.

For Cargo Ships over 15 years of age: - Overall examination of all cargo holds and tween deck spaces.

- Close-up examination of sufficient extent, minimum 25% of frames, to

establish the condition of the lower region of the shell frames includingapprox. lower one third length of side frame at side shell and side frame

end attachment and the adjacent shell plating in a forward lower cargo

hold and one other selected lower cargo hold.Where this level of survey reveals the need for remedial measures, the

survey is to be extended to include a Close-up examination of all of the shell frames and adjacent shell plating of those cargo holds and

associated tween deck spaces (as applicable) as well as a Close-up

examination of sufficient extent of all remaining cargo holds and tweendeck spaces (as applicable).

- All piping and penetrations in cargo holds, including overboard piping,

are to be examined.

3.2 Intermediate Survey:

For examination of cargo holds, the following minimum requirements apply;

For Cargo Ships 5 - 10 Years of age: - An Overall Survey of one forward and one after cargo hold and their

associated tween deck spaces.

For Cargo Ships 10-15 Years of age: - An Overall Survey of all cargo holds and tween deck spaces.


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For Cargo Ships over 15 years of age: - The requirements of the intermediate survey shall be substantially to the

same extent as for the previous renewal survey

- (note: in lieu of dry-docking as required for the renewal survey, an in-water survey may

be considered as equivalent, tank testing is not required unless deemed necessary by theattending surveyor).

3.3 Renewal Survey

The survey is to include examination, tests and checks of sufficient extent to ensure that

the hull and related piping are in a satisfactory condition and that the ship is fit for itsintended purpose, subject to proper maintenance and operation and to periodical surveys

being carried out when due.

All cargo holds, salt water ballast tanks, including double bottom tanks, pipe tunnels,

cofferdams and void spaces bounding cargo holds, decks and outer hull are to beexamined, and this examination is to be supplemented by thickness measurement and

testing as deemed necessary, to ensure that the structural integrity remains effective.

All piping systems within the above spaces are to be examined and tested under working

conditions to ensure that the condition remains satisfactory.

A survey of the ship in dry-dock is to be a part of the renewal survey.

The close-up examination requirements are introduced at the 1st renewal survey (age 5),

becoming more extensive with age such that at the 3rd

renewal survey (age 15) they take

in;

- All shell frames in the forward lower cargo hold and 25% of the shell

frames in each of the remaining cargo holds and tween deck spaces,including upper and lower end attachments and adjacent shell plating.

- All cargo hold transverse bulkheads and all transverse bulkheads inballast tanks (including stiffening systems).

- All transverse webs with associated plating and framing in each ballasttank.

- All cargo hold hatch covers and coamings.

- All deck plating inside line of cargo hold hatch openings.

- All areas of inner bottom plating.


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At the 4th

renewal survey, this is further increased to include all shell frames in all cargo

holds and tween decks.

Structural members subject to close-up examination shall be thickness measured for

general assessment and recording of corrosion pattern.

4. Implementation

4.1 Schedule

The new requirements are applicable at annual, intermediate or renewal surveys

commenced on or after 1st July 2003.

4.2 Procedure

A Memo to Owner (MO) will be issued for the ship stating applicability of the newrequirements.

5. References

5.1 DNV Rules for Classification of Ships, January 2003 (Part 7 Chapter 2)

5.2 IACS Recommendation No.55* - GENERAL CARGO SHIPS

Guidelines for Surveys, Assessment and Repair of Hull Structure

*Available on the Intranet under the IACS Blue Books, Recommendation No.55 or

ordered from Witherby & Co. Ltd. in London - www.witherbys.com

For further information, please contact Ships in Operation, Hull department MTPNO864, E-mail:

([email protected])

http://www.witherbys.com/http://www.witherbys.com/


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Enclosure B Minimum Extent of Thickness Measurements at Renewal Survey

(text in bold indicates the additional requirements for general dry cargo ships)

Renewal survey No. 1

Age ≤ 5


5 < Age ≤ 10


10 < Age ≤ 15

Renewal survey No.4

Age > 15

Suspect areas Suspect areas Suspect areas Suspect areas

One transverse section of deck plating abreast of a cargo hold

within 0.5L amidship.

Two transverse sectionswithin the cargo length area,

where at least one sectionabreast of a cargo hold within0.5 L amidship.

Three transverse sectionswithin the cargo length area,

where at least two sectionsabreast of two different cargoholds within 0.5 L amidship,as applicable.

Measurement, for general

assessment and recording of

corrosion pattern, of those

structural members subject

to close-up examination, i.e.

-

Selected shell frames inall cargo holds and

tween deck spaces

- One transverse bulkheadin each cargo hold

- All cargo hold hatchcovers and coamings

- Forward and afttransverse bulkhead in

one side ballast tank,

including stiffening

system

- One transverse web with

associated plating and

framing in two

representative ballasttanks of each type

- Selected areas of deck plating inside line of

hatch openings between

cargo hold hatches

- Selected areas of innerbottom plating






-

All shell frames in the forward lower cargo

hold and 25% of shell

frames in each of the

remaining cargo holds

and tween deck spaces

including upper and

lower end attachments

and adjacent shell

plating

- All cargo holdtransverse bulkheads

- All cargo hold hatch

covers and coamings

- All transverse bulkheads

in all ballast tanks,including stiffening

system

- All transverse webs withassociated plating and

framing in each ballast

tank

- All deck plating insideline of hatch openings

between cargo hold

hatches

- All areas of inner bottom plating






-

All shell frames in allcargo holds and tween

deck spaces including

upper and lower end

attachments and

adjacent shell plating

- All cargo hold transversebulkheads

- All cargo hold hatch

covers and coamings

- All transverse bulkheadsin all ballast tanks,

including stiffening

system

- All transverse webs with

associated plating and framing in each ballast

tank

- All deck plating insideline of hatch openingsbetween cargo hold

hatches

- All areas of inner bottom plating

Each deck plate outside line

of cargo hatch openings

within the cargo area.

All exposed main deck platesfull length.

All wind and water strakes

within the cargo length area.

Selected wind and water

strakes outside the cargo

length area.

All wind and water strakes

full length of ship.


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Age ≤ 5


5 < Age ≤ 10


10 < Age ≤ 15

Renewal survey No.4 Age > 15

Each bottom plate, including

lower turn of bilge, within

the cargo length area.

Duct keel or pipe tunnelplating and internals within

the cargo length area.

All keel plates full lengthSelected bottom plates in way

of cofferdams, machineryspace and tanks outside thecargo length area.

Internals in forepeak tank. Internals in forepeak tank and

after peak tanks.

Representative exposedsuperstructure deck plating

(poop, bridge and forecastle).

Plating of sea chests.

Shell plating in way of

overboard discharges asconsidered necessary by thesurveyor.

Air pipes and ventilators onfore deck (forward quarter

length).

Air pipes to day tanks andselected air pipes and

ventilators aft of forwardquarter length.

Air pipes and ventilators onfore deck (forward quarter

length).

Air pipes to day tanks andselected air pipes and

ventilators aft of forwardquarter length.

Notes:

1) Thickness measurement locations should be selected to provide the best representative sampling of areas likely to be mostexposed to corrosion, considering cargo and ballast history and arrangement and condition of protective coatings.

2) For ships less than 100 m in length, the number of transverse section required at renewal survey no. 3 may be reduced to one

(1), and the number of transverse sections at subsequent renewal surveys may be reduced to two (2).

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