Onderwerp: Bezoek-historie

ItoRO no. 28 - Automatic air pipe closing devices in the damage stability calculation
Geldigheid:18-10-2022 t/m Versie:vergelijk Status: Geldig vandaag

Dit onderwerp bevat de volgende rubrieken.

1 Introduction

This Instruction to Recognised Organisations no. 28 (hereafter: Instruction) provides further guidance to 'The guidelines for Automatic air pipe closing devices Preventing progressive down Flooding (APF) as circulated under circular letter 3573' (hereafter: the guidelines), which is included in GISIS under reference XQ 5521. All ships shall comply with these guidelines, unless all air pipe closing devices fitted on that ship are considered as weathertight opening in the damage stability calculations.

This instruction aims at a uniform application of the guidelines to cargo ships:

  1. for which the damage stability calculation shall be calculated in accordance with the SOLAS probabilistic damage stability calculations, as referred to in SOLAS Chapter II-1, part B;

  2. on which automatic air pipe closing devices preventing progressive down flooding (APFs), which have been tested and certified in accordance with Annex A to the guidelines, are or will be installed and maintained in accordance with Annex B to the guidelines; and

  3. for which the APFs are subsequently not required to be considered a down flooding point in the ship's probabilistic damage stability calculation.

For the Netherlands' national legislation, the guidelines are considered as an Equivalent Arrangement which may be accepted by the Head of the Netherlands Shipping Inspectorate based on article 47 of the Ships Decree 2004.

National type approval certificates for APFs compliant with the guidelines are issued by the NSI under article 34 of the Regulation Safety Seagoing Vessels.

For every item, a reference is made to the relevant article of the guidelines.

Note that this alternative methodology was accepted under regulation II-1/4.2 of the 1974 SOLAS Convention, which is renumbered to regulation II-1/4.3 as per January 1st, 2020.

The NSI has issued a type approval certificate for several APFs, which have been successfully tested in accordance with Circular Letter No. 3573 and have been found compliant. The list of type approved APFs can be found here.

2 Guidance for type approval of APFs

a) Accreditation of test laboratories (Annex A, article 2)

Accreditation of test laboratories should be in accordance with ISO/IEC 17025. See also: Testlaboratoria - Raad voor Accreditatie. When a test laboratory has no accreditation for the intended tests, as referred to in article 5 and 6 of Annex A, the RO shall verify that testing equipment, testing procedures, qualifications of personnel and other related items are of an equivalent standard to standard ISO/IEC 17025, to ensure that the results of the test are valid and do reflect the actual situation.

Recognition based on class rules or (inter)national standards can be accepted. The RO shall confirm in the test report to the NSI that the test is performed at an accredited test location or a test location acceptable to the RO and that the test procedure and test results are in accordance with the prescribed requirements.

b) Testing of series of APFs (Annex A, article 3.3)

When the RO is convinced that the performance of a series is such that testing of each size and/or model is not necessary, a well-founded proposal for a test of one or more representative APFs may be presented to the NSI. The NSI will decide on a case-by-case basis whether testing of all sizes / models is necessary or not. Testing of several APFs in one test run (parallel testing) is acceptable as long as the performance of the APFs do not influence the performance of the other APF in the same test run.

c) APFs fitted with appendages (Annex A, article 3.5)

Only when it is has been determined, in consultation with the manufacturer, that an appendage will never have any influence on the test results, the RO may allow a single test of the APF with or without the appendage. In that case, a single type approval certificate will be issued with a notice that the device may be fitted with a particular appendage (Annex A, article 7.3).

d) Communication about type test results (Annex A, article 3.6)

After completion of all prescribed tests and checks, the RO shall provide the following information in writing to the NSI:

  • A confirmation that the test laboratory is accredited or grounds on which the alternative quality system is accepted (A-2).

  • A confirmation that the device complies with the required maintenance free period (A-4.2) and how long the device is guaranteed to be maintenance free by the manufacturer. This may be fulfilled by a manufacturer's statement.

  • A confirmation that the APF is of a fool proof design (A-4.3).

  • A confirmation that the APF is suitable for use in the intended environment (A-4.4).

  • A confirmation that all non-metallic parts are constructed of suitable materials (A-4.5).

  • A confirmation that the design of the APF allows the required checks of the APF without removal of parts (A-4.6).

  • A confirmation that the device is permanently marked with the year of production and product name and/or type number (A-4.7).

  • A confirmation that the test of A-5.1 has been performed successfully.

  • The results of the tests specified in A-5.2 and A-5.3.

  • A confirmation that the results of the tests specified in A-5.2 and A-5.3 comply with the criteria as set out in A-6.

e) Maintenance free period (Annex A, article 4.2).

The RO may, during the type approval process, communicate any possible doubts or questions regarding the maintenance free period of the APF to the manufacturer. The manufacturer shall answer any questions and dispel any doubts of the RO. In case the manufacturer does not submit a maintenance/operation manual which:

  1. specifies the maintenance free period of the APF; and

  2. associates manufacturer's recommendations for maintenance of the APF, if any,

the RO shall:

  1. advise the NSI not to issue a type approval certificate; and

  2. advise the manufacturer not to start with the endurance test and submersion tests, as referred to in A-5.2.

f) Fool proof design (Annex A, article 4.3)

An APF with one or more design features, as listed in the following non-exhaustive list of examples, shall not be considered to be of a fool proof design:

  • Visors which can be mounted upside down;

  • Threaded holes for bolts through the housing, allowing free entrance of water when a bolt is missing;

  • Loose (not fixated) plastic rings for galvanic separation of parts;

  • Screw down devices that prevent the ball to move freely when partly closed;

  • Appendage that render the device inoperable when mounted incorrectly.

g) Test pressure (Annex A, article 5.2)

The two different pressures shall be measured from the lowest point from which water may enter the APF in case the closing mechanism would fail. For the upright measurements, as referred to in A-5.3, the lowest point will in general be the upper edge of the seal of the APF. For the inclined measurements, as referred to in A-5.3, the lowest point is in general the lowest point where water may flow over the seal of the APF.

h) Type approval certificate (Annex A, article 7.1)

In case a type of APF has been in production prior to the date of testing of that APF type in accordance with the guidelines, the NSI may accept the installation of such APF of that type on a ship prior to testing of that type of APF. In that case, the NSI consider to include a note, including conditions if any, on the type certificate of that type of APF stating the acceptance of APFs of that type which have been manufactured before the date of testing of that APF type, for installation on board of a ship. This may facilitate that APFs already fitted on board of ships before the date of testing may be accepted under the type approval. However, this procedure may only be considered in case:

  1. the manufacturer of the APF declares that the APFs produced before type testing are identical to the tested APF;

  2. when it is beyond doubt that:

    1. APFs produced before the date of testing are identical to the tested APFs; and

    2. all requirements referred to in Annex A are met; and

  3. measures on board shall be applied according annex B of the guidelines.

A Cargo Ship Safety Construction Certificate shall not be issued to a ship equipped with such an APF before the type approval certificate has been issued.

i) Withdrawal of type approval certificate (Annex A, article 7.6)

In case the NSI has reason to believe that an APF does not meet the standards required by the guidelines (i.e. based on information received from an RO that an annual survey, as referred to in B-3.1, indicates a significant need of replacement during annual inspections), the NSI will thoroughly investigate the performance of that APF type. In case the investigation reveals that the APF type does not comply with the guidelines, the NSI will withdraw the type approval certificate of that APF type, and inform all authorized ROs and ship owners accordingly.

APFs of that type which have already been installed on the ship do not need to be replaced until:

  1. the APF needs to be replaced or repaired due to malfunctioning;

  2. the end of the maintenance free period; or

  3. the first renewal survey of the ship's Safety Construction Certificate after withdrawal of the type certificate.

In this case specific additional measures could be required by the manufacturer or NSI guaranteeing the correct functioning of the APFs that may remain on board under the conditions specified.

Note: An APF which has been installed on board the ship and requires replacement or repair after any damage as a result of an accident, is not to be considered as 'not maintenance free' and does not need to be reported as such to the NSI.

j) Form to be used (Annex B, article 3.4)

In case non-compliant APFs are detected during surveys as stipulated in Annex B, article 3.4, the NSI shall be notified by the RO, using the standard reporting form ('Non-compliance reporting form'), as attached to this Instruction.

3 Guidance for implementation on board of ships

a) Type of ship (regulation 2.1 of the 'Application')

APFs are only accepted as means to prevent down flooding on cargo ships for which a SOLAS probabilistic damage stability calculation is required. Ships built and certified according instruments referred to in SOLAS regulation II-1/4, such as special purpose ships, oil tankers, gas tankers and chemical tankers, shall not use the principles outlined in the guidelines.

b) Use of APFs to comply with SOLAS Chapter II-1 part B-1 requirements (regulation 2.2 of the 'Application')

The use of APFs is limited to SOLAS regulation II-1/6 – II-1/7-3. For general cargo ships for which the probabilistic damage stability calculation is made according to SOLAS Chapter II-1, part B-1, openings fitted with APFs may be considered to prevent progressive flooding through an opening (i.e. air pipe). However, for such an opening the 'factor si' is not required to be taken as zero, as referred to in SOLAS-regulation II-1/7-2. When no damage stability calculation need to be made, or where another standard is used as accepted in SOLAS regulation II-1/ (up to December 31st, 2019: SOLAS regulation II-1/4.1), compliance with SOLAS part B-1 shall be established without the use of APFs.

c) Relation between APFs and other openings in the damage stability calculation (regulation 2.3 of the 'Application')

In general, by using APFs, the draught of a ship may increase compared to ships not fitted with APFs. As a result, other openings such as doors and hatches may become immersed sooner after damage of the ship. Moreover, as air pipes are generally fitted on the freeboard deck next to hatchway coamings, the air pipes are the first openings to become submerged. When submersion of air pipes does not result in progressive flooding through that opening, due to APF being fitted, the immersion of other openings may be a limiting factor for the damage stability calculation. Therefore special attention during approval of the damage stability calculation for these other openings is necessary.

d) Maximum allowable submersion of APF (regulation 2.4 of the 'Application')

The APF is tested for a maximum pressure of 100 kPa (correlating to an immersion of 10 metres). For a normal ship's configuration, a damage scenario with such an immersion still contributing to the attained subdivision index A, as referred to in SOLAS regulation II-1/7, is considered exceptional. However, for extreme long or otherwise unconventional shaped ships, a larger immersion in a damage scenario contributing to the attained subdivision index A may occur. In those cases the RO shall require evidence that the immersion of the air pipe heads of intact spaces does not exceed 10 metres in those damage cases that contribute to the attained subdivision index A.

e) Novel design, special design and strength of structures. (regulation 2.5 of the 'Application')

In case any doubts arises about the application of the APF principle on ships of unusual or novel design and/or ships with special features, where the safe, uninterrupted and proper working of APFs may be doubtful, the NSI shall be contacted by the RO for guidance.

f) APF on openings of non-accessible voids (regulation 3.2 and 3.3 of the 'Definitions')

Following the definition of 'automatic closing device' and of 'APF', the use of APF is limited to de-aeration openings of tanks and normally not-accessible voids (e.g. cofferdams and pipe ducts).

g) APF on openings other than air pipes (regulation 3.3 of the 'Definitions')

On existing ships (ships for which the first CSSC was issued before June 1st, 2016), the principle of APF may be applied on ventilation openings of stores, CO2 rooms and comparable spaces. Application of APF compliance with the guidelines may in these cases be accepted by the RO and the NSI shall be informed in writing about such applications. In case required by SOLAS, a separate fire damper shall be fitted on the de-aeration opening. For a new ship, application of APFs on ventilation openings (on ventilation openings of stores, CO2 rooms and comparable spaces) is not allowed.

h) Notification on ships certificate and documentation (regulation 4 'Documentation and Certificates')

The openings of a ship:

  • on which APFs are fitted; and

  • for which these APFs in the context of the probabilistic calculation of the damage stability of the ship are not considered to prevent progressive flooding through these openings,

shall be clearly identified in the damage stability booklet.

The following reference to Circular Letter No. 3573 containing the Netherlands' Equivalent Arrangement (XQ 5521) shall be made on the ship's Cargo Ship Safety Certificate or Cargo Ship Safety Construction Certificate: 'Automatic air pipe closing devices preventing progressive flooding fitted as per IMO Circular Letter No. 3573.'

i) Notification on damage control plan for existing ships (Annex B, article 1.2)

On existing ships where the damage control plan does not yet contain a reference to separate air pipes, a reference as stipulated in Annex B, article 1.2 in the damage control booklet may be accepted in lieu of a reference in the damage control plan.

j) Spare parts (Annex B, article 2.3)

The ship owner shall ensure that sufficient spare parts are carried on board. In this respect, the following is considered sufficient:

  • For each type and size of APF fitted on board at least one spare floatation device and one seal, if these can be replaced by the crew;

  • If the manufacturer of the APF specifies a detailed replacement set, one of such a set for each size and type of APF is considered sufficient; or

  • If the producer does not allow replacement of parts by the crew, no spare parts need to be carried, but a complete reserve APF shall be available for each size and type of APF installed on the ship.

k) Notification of defects during inspection to NSI (Annex B, article 3.4)

In case the RO or ship owner finds any APF not fit for service, the NSI shall be notified by the RO and/or the shipowner, using the standard reporting form ('Non-compliance reporting form'), as attached to this Instruction.


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