- 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 tougher hull surveys for certain general dry Cargo ships With requirements for overall and close- up examination and steel thickness measurements at annual, intermediate and renewal surveys along the lines applied already for bulk carriers and tankers.
Some ship types with relatively favorable 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 the ship.
The new hull survey requirements are given in the DNV Rules January 2003 and shall enter into force 1st July 2003.
The purpose of this document is to provide DNV clients and surveyors with information on 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 of 500 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 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 unitized form, fine granulated non-corrosive cargoes in bulk and containers)
-refrigerated cargo ships;
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 their associated 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 including approx 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 tween deck 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.
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 the attending 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 its intended 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 be examined, 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 in ballast tanks (including stiffening systems).
-All transverse webs with associated plating and framing in each ballast tank.
-All cargo hold hatch covers and coamings.
-All deck plating inside line of cargo hold hatch openings.
-All areas of inner bottom plating.
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 new requirements.
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
* A vailable on the Intranet under the IACS Blue Books, Recommendation No.55 or ordered from Witherby & Co. Ltd. in London -
For further information, please contact Ships in Operation, Hull depaliment MTPNO864, E-mail: (MTPNO864@.dnv.corn)
7
Enclosure A Minimum Extent of Close-Up Examination at Renewal Survey
Renewal survey No. lAge 5 / Renewal survey No.2
5<Age 10 / Renewal survey No.3
10< Age 15 / Renewal survey No.4
Age >15
Selected shell frames in one forward and one aft cargo
hold and associated tween deck spaces / Selected shell frames in all cargo holds and tween deck spaces / 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 shell frames in all cargo holds alld tween deck spaces including upper and lower end attachments and adjacent shell plating
One selected cargo hold transverse bulkhead / One transverse bulkhead in each cargo hold / All cargo hold transverse bulkheads / All cargo hold transverse bulkheads
All cargo hold hatch covers and coamings / All cargo hold hatch covers and coamings / All cargo hold hatch covers and coamings / All cargo hold hatch covers and coamings
Forward and aft transverse bulkhead in one side ballast tank, including stiffening system / All transverse bulkheads in all ballast tanks, including stiffening system / All transverse bulkheads in all ballast tanks, including stiffening system
One transverse web with associated plating and framing in two representative ballast tanks of each type (i.e. topside, hopper side, side tank of double bottom tank. Peak tanks to be included, if applicable) / All transverse webs with associated plating and framing in each ballast tank(i.e. topside, hopper side, side tank or double bottom tank. Peak tanks to be included, if applicable) / All transverse webs with associated plating and framing in each ballast tank(i.e. topside, hopper side, side tank or double bottom tank. Peak tanks to be included, if applicable)
Selected areas of deck plating inside line of hatch openings between cargo hold hatches / All deck plating inside line of hatch openings between cargo hold hatches / All deck plating inside line of hatch openings between cargo hold hatches
Selected areas of inner bottom plating / All areas of inner bottom plating / All areas of inner bottom plating
Note:
Close-up examination of cargo hold transverse bulkheads is be carried out at the following levels:
-Immediately above the inner bottom and immediately above the tween decks, as applicable.
-About mid-height of the bulkheads for holds without tween deck.
-Immediately below the main deck and immediately below the tween deck, as applicable
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. lAge 5 / Renewal survey No.2
5<Age 10 / Renewal survey No.3
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 sections within the cargo length area, where at least one section abreast of a cargo hold within 0.5L amidship. / Three transverse sections within the cargo length area, where at least two section abreast of two different cargo hold within 0.5L 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 in all cargo holds and tween deck spaces
-One transverse bulkhead in each cargo hold
-All cargo hold hatch covers and coamings
-Forward and aft transverse bulkhead in one site ballast tank, including stiffening system
-One transverse web with associated plating and framing in two representative ballast tanks of each type
-Selected areas of deck plating inside line of hatch openings between cargo hold hatches
-Selected areas of inner bottom plating / Measurement, for general assessment and recording of corrosion pattern, of those structural members subject to close-up examination, i.e.
-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 hold transverse buldheads
-All cargo hold hatch covers and coamings
-All transverse bulkheads in all ballast tanks, including stiffening system
-All transverse webs with associated plating and framing in each ballast tank
-All deck plating inside line of hatch openings between cargo hold hatches
-All areas of inner bottom plating / Measurement, for general assessment and recording of corrosion pattern, of those structural members subject to close-up examination, i.e.
-All shell frames in all cargo holds and tween deck spaces including upper and lower end attachments and adjacent shell plating
-All cargo hold transverse bulkheads
-All cargo hold hatch covers and coamings
-All transverse buldheads in all ballast tanks, including stiffening system
-All transverse webs with asscociated plating and framing in each ballast tank
-All deck plating inside line of hatch openings between 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 plates full 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.
Renewal survey No. 1
Age 5 / Renewal survey No.2
5<Age 10 / Renewal survey No.3
10< Age 15 / Renewal survey No.4
Age > 15
Each bottom plate, including lower turn of bilge, within the cargo length area.
Duct keet or pipe tunnel plating and internals within the cargo length area.
All keel plates full length Selected bottom plates in way of cofferdams, machinery space and tanks outside the cargo length area.
lnternals in forepeak tank / Internals in forepeak tank and after peak tanks.
Representative exposed superstructure deck plating (poop, bridge and forecastle)
Plating of sea chests.
Shell plating in way of overboard discharges as considered necessary by the surveyor
Air pipes and ventilators on fore deck (forward quarter length).
Air pipes to day tanks and selected air pipes and ventilators aft of forward quarter length. / Air pipes and ventilators on fore deck (forward quarter length).
Air pipes to day tanks and selected air pipes and ventilators aft of forward quarter length.
Note:
I) Thickness measurement locations should be selected to provide the best representative sampling of areas likely to be most exposed to corrosion. considering cargo and ballast history and arrangement and condition of protective coatings.
2) For ships less than 100m 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).