Z10.4

Z10.4 Hull Surveys of Double Hull Oil Tankers(Dec.
(cont’d)2001)(Rev. 1
Oct. 2002)(Rev.2
June
2005)(Rev.3
Jan 2006)(Rev.4
June 2006)(Corr.1
Sept 2006)(Rev.5
Feb 2007)(Rev.6
Nov 2007)(Rev.7
Mar 2009)(Rev.8Feb 2010)(Rev.9Mar 2011)(Rev.10
July 2011)(Rev.11
June 2013)(Rev.12Jan 2014)(Rev.13
Feb 2015)(Rev.14
Nov 2016)(Rev.15
Jan 2018)(Rev.16
May 2019)(Rev.17
May 2022)(Rev.18
Feb 2023)

CONTENTS
1.
1.1
1.2
1.3
1.4

GeneralApplication
Definitions
Repairs
Thickness Measurements And Close-Up Surveys

2.
2.1
2.2
2.3
2.4
2.5

Special Survey
Schedule
Scope
Extent of Overall and Close-up Surveys
Extent of Thickness Measurements
Extent of Tank Testing

3.
3.1
3.2

Annual Survey
Schedule
Scope

4.
4.1
4.2

Intermediate Survey
Schedule
Scope

5.
5.1
5.2
5.3
5.4
5.5
5.6
5.7

Preparation For Survey
Survey Programme
Conditions For Survey
Access To Structures
Equipment For Survey
Rescue and emergency response equipment
Survey At Sea Or At Anchorage
Survey Planning Meeting

6.
6.1
6.2
6.3
6.4

Documentation On Board
GeneralSurvey Report FileSupporting Documents
Review Of Documentation On Board

7.
7.1
7.2
7.3
7.4

Procedures For Thickness Measurement
GeneralCertification Of Thickness Measurement Firm
Number and Locations of Measurements
Reporting

8.
8.1
8.2
8.3
8.4

Acceptance Criteria
General
Acceptance criteria for pitting corrosion of CSR ships
Acceptance criteria for edge corrosion of CSR ships
Acceptance criteria for grooving corrosion of CSR ships

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9.
9.1
9.2

Reporting and Evaluation of Survey
Evaluation of Survey Report
Reporting

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ENCLOSURES
Table I:

Minimum requirements for Close-up Surveys at Special Survey of Double Hull Oil
Tankers

Table II:

Minimum requirements for thickness measurements at Special Survey of Double
Hull Oil Tankers

Table III:

Minimum requirements for tank testing at Special Survey of Double Hull Oil
Tankers

Table IV:

Requirements for extent of thickness measurements at those areas of substantial
corrosion

Table V:

Minimum requirements for overall and close-up survey and thickness
measurements at intermediate survey of double hull oil tankers

Table VI:

Owners Inspection Report

Table VII: Procedures for Certification of Firms Engaged in Thickness Gauging of Hull
Structures
Table VIII: Survey Reporting Principles
Table IX:

Executive Hull Summary

Annex I:

Guidelines for Technical Assessment in conjunction with planning forEnhanced Surveys of Double Hull Oil Tankers Special Survey - Hull

Annex II:

Recommended Procedures for Thickness Measurements of
Double Hull Oil Tankers
IACS Recommended Procedures for Thickness Measurements of
Double Hull Oil Tankers Built Under IACS Common Structural Rules

Annex III:

Criteria for Longitudinal Strength of Hull Girder for Oil Tankers
Appendix 1: Calculation criteria of section modulus of midship sectionof hull girder
Appendix II: Diminution limit of minimum longitudinal strength of ships
in service
Appendix III: Sampling method of thickness measurements forlongitudinal strength evaluation and repair methods

Annex IVA:

Survey ProgrammeAppendix 1 List of Plans
Appendix 2 Survey Planning Questionnaire
Appendix 3 Other Documentation

Annex IVB:

Survey Planning Questionnaire

Annex IVC:

Owner’s Inspection Report

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Z10.4(cont’d)Note:
1.

Changes introduced in Rev. 2 are to be uniformly implemented from 1 July 2006. The
amendments to paragraphs 2.2.3.1 and 4.2.2.2 related to the protective coating condition
are to apply to the ballast tanks of which the coating condition will be assessed at theforthcoming Special Survey and Intermediate Survey on or after 1 July 2006.

2.

Changes introduced in Rev.3 (para. 1.4, 5.5.4, 5.5.6 and 7.1.3) are to be uniformly
applied by IACS Societies on surveys commenced on or after 1 January 2007.

3.

Changes introduced in Rev.4 are to be uniformly applied by IACS Societies on surveys
commenced on or after 1 July 2007.

4.

Changes introduced in Rev.5 are to be uniformly implemented for surveys commenced
on or after 1 January 2008, whereas statutory requirements of IMO Res. MSC 197(80)apply on 1 January 2007.

5.

Changes introduced in Rev.6 are to be uniformly applied by IACS Societies for surveys
commenced on or after the 1 January 2009.

6.

Changes introduced in Rev.7 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2010. As for the requirements regarding semi-hardcoatings, these coatings, if already applied, will not be accepted from the next special orintermediate survey commenced on or after 1 July 2010, whichever comes first, withrespect to waiving the annual internal examination of the ballast tanks.

7.

Changes introduced in Rev.9 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2012.

8.

Changes introduced in Rev.10 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2012.

9.

The changes to section 6 introduced in Rev.11 are to be uniformly applied by IACS
Societies for surveys commenced on or after 1 July 2016. The other changes introduced
in Rev.11 are to be uniformly applied by IACS Societies for surveys commenced on orafter 1 July 2014.

10. Changes introduced in Rev.12 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 January 2015.
11. Changes introduced in Rev.13 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2016.
12. Changes introduced in Rev.14 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 January 2018.
13. Changes introduced in Rev.15 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 January 2019.
14. Changes introduced in Rev.16 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2020.
15. Changes introduced in Rev.17 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 January 2023.
16. Changes introduced in Rev.18 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2024

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Z10.4(cont’d)1.

GENERAL

1.1

Application

1.1.1
The requirements apply to all self-propelled Double Hull Oil Tankers.
1.1.2
The requirements apply to surveys of hull structure and piping systems in way of cargo tanks,
pump rooms, cofferdams, pipe tunnels, void spaces within the cargo area and all ballast
tanks. The requirements are additional to the classification requirements applicable to theremainder of the ship. Refer to Z7.
1.1.3
The requirements contain the minimum extent of examination, thickness measurements andtank testing. The survey is to be extended when Substantial Corrosion and/or structuraldefects are found and include additional Close-up Survey when necessary.
1.2

Definitions

1.2.1 Double Hull Oil Tanker
A Double Hull Oil Tanker is a ship which is constructed primarily for the carriage of oil1) inbulk, has the cargo tanks forming an integral part of the ship's hull and is protected by adouble hull which extends for the entire length of the cargo area, consisting of double sides
and double bottom spaces for the carriage of water ballast or void spaces.
1.2.2 Ballast Tank
A Ballast Tank is a tank which is used primarily for the carriage of salt water ballast.
1.2.2 bis A Combined Cargo/Ballast Tank is a tank which is used for the carriage of cargo orballast water as a routine part of the vessel’s operation and will be treated as a Ballast Tank.
Cargo tanks in which water ballast might be carried only in exceptional cases per MARPOL
I/18(3) are to be treated as cargo tanks.
1.2.3 Overall Survey
An Overall Survey is a survey intended to report on the overall condition of the hull structureand determine the extent of additional Close-up Surveys.
1.2.4 Close-up Survey
A Close-up Survey is a survey where the details of structural components are within the close
visual inspection range of the surveyor, i.e. normally within reach of hand.

Note:1) MARPOL Annex I cargoes

The requirements in this UR are also applicable to existing double hull tankers not complying withMARPOL Regulation 13F, but having a U-shaped midship section.

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Z10.4

Z10.4(cont’d)1.2.5 Transverse Section
A Transverse Section includes all longitudinal members such as plating, longitudinals andgirders at the deck, sides, bottom, inner bottom and longitudinal bulkheads. For transversely
framed vessels, a transverse section includes adjacent frames and their end connections in
way of transverse sections.
1.2.6 Representative Tank
Representative Tanks are those which are expected to reflect the condition of other tanks ofsimilar type and service and with similar corrosion prevention systems. When selecting
Representative Tanks account is to be taken of the service and repair history onboard andidentifiable Critical Structural Areas and/or Suspect Areas.
1.2.7 Suspect Area
Suspect Areas are locations showing Substantial Corrosion and/or are considered by theSurveyor to be prone to rapid wastage.
1.2.8 Critical Structural Area
Critical Structural Areas are locations which have been identified from calculations to requiremonitoring or from the service history of the subject ship or from similar or sister ships (ifavailable) to be sensitive to cracking, buckling or corrosion which would impair the structural
integrity of the ship.
1.2.9 Renewal Thickness
Renewal thickness (tren) is the minimum allowable thickness, in mm, below which renewal ofstructural members is to be carried out.
1.2.10 Substantial Corrosion
Substantial Corrosion is an extent of corrosion such that assessment of corrosion patternindicates a wastage in excess of 75% of allowable margins, but within acceptable limits.
For vessels built under the IACS Common Structural Rules, substantial corrosion is an extent
of corrosion such that the assessment of the corrosion pattern indicates a measured
thickness between tren + 0.5mm and tren.
1.2.11 Corrosion Prevention System
A Corrosion Prevention System is normally considered a full hard protective coating.
Hard Protective Coating is usually to be epoxy coating or equivalent. Other coating systems,
which are neither soft nor semi-hard coatings, may be considered acceptable as alternatives
provided that they are applied and maintained in compliance with the manufacturer’s
specifications.
1.2.12 Coating Condition
Coating condition is defined as follows:
•
•

GOOD
FAIR

condition with only minor spot rusting,condition with local breakdown at edges of stiffeners and weld
connections and/or light rusting over 20% or more of areas underconsideration, but less than as defined for POOR condition,
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•

POOR

(cont’d)condition with general breakdown of coating over 20% or more,or hard scale at 10% or more, of areas under consideration.

Reference is made to IACS Recommendation No.87 “Guidelines for Coating Maintenance &Repairs for Ballast Tanks and Combined Cargo / Ballast Tanks on Oil Tankers”
1.2.13 Cargo Area
Cargo Area is that part of the ship which contains cargo tanks, slop tanks and cargo/ballast
pump-rooms, cofferdams, ballast tanks and void spaces adjacent to cargo tanks and also
deck areas throughout the entire length and breadth of the part of the ship over the above
mentioned spaces.
1.2.14 Special consideration
Special consideration or specially considered (in connection with close-up surveys andthickness measurements) means sufficient close-up inspection and thickness measurements
are to be taken to confirm the actual average condition of the structure under the coating.
1.2.15 Prompt and Thorough Repair
A Prompt and Thorough Repair is a permanent repair completed at the time of survey to thesatisfaction of the Surveyor, therein removing the need for the imposition of any associatedcondition of class.
1.2.16 Pitting Corrosion
Pitting corrosion is defined as scattered corrosion spots/areas with local material reductions
which are greater than the general corrosion in the surrounding area. Pitting intensity isdefined in Figure 1.
1.2.17 Edge Corrosion
Edge corrosion is defined as local corrosion at the free edges of plates, stiffeners, primary
support members and around openings. An example of edge corrosion is shown in Figure 2.
1.2.18 Grooving Corrosion
Grooving corrosion is typically local material loss adjacent to weld joints along abutting
stiffeners and at stiffener or plate butts or seams. An example of groove corrosion is shown in
Figure 3.

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Z10.4(cont’d)Figure 1 - Pitting intensity diagrams

Figure 2 - Edge corrosion

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Z10.4(cont’d)Figure 3 - Grooving corrosion
1.3

Repairs

1.3.1
Any damage in association with wastage over the allowable limits (including buckling,
grooving, detachment or fracture), or extensive areas of wastage over the allowable limits,which affects or, in the opinion of the Surveyor, will affect the vessel’s structural, watertight orweathertight integrity, is to be promptly and thoroughly (see 1.2.14) repaired. Areas to beconsidered include:- bottom structure and bottom plating;- side structure and side plating;- deck structure and deck plating;- watertight or oiltight bulkheads,- hatch covers or hatch coamings, where fitted (combination carriers).
For locations where adequate repair facilities are not available, consideration may be given to
allow the vessel to proceed directly to a repair facility. This may require discharging the cargo
and/or temporary repairs for the intended voyage.

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Z10.4

Z10.4(cont’d)1.3.2
Additionally, when a survey results in the identification of structural defects or corrosion,
either of which, in the opinion of the Surveyor, will impair the vessel’s fitness for continued
service, remedial measures are to be implemented before the ship continues in service.
1.3.3
Where the damage found on structure mentioned in Para. 1.3.1 is isolated and of a localised
nature which does not affect the ship's structural integrity, consideration may be given by thesurveyor to allow an appropriate temporary repair to restore watertight or weather tightintegrity and impose a condition of class in accordance with IACS PR 35, with a specific time
limit.
1.4

Thickness measurements and close-up surveys

In any kind of survey, i.e. special, intermediate, annual or other surveys having the scope ofthe foregoing ones, thickness measurements, when required by Table II, of structures inareas where close-up surveys are required shall be carried out simultaneously with close-up
surveys.

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Z10.4(cont’d)2.

SPECIAL SURVEY(2)2.1

Schedule

2.1.1
Special Surveys are to be carried out at 5 years intervals to renew the Classification
Certificate.
2.1.2
The first Special Survey is to be completed within 5 years from the date of the initialclassification survey and thereafter within 5 years from the credited date of the previous
Special Survey. However, an extension of class of 3 months maximum beyond the 5th year
can be granted in exceptional circumstances.
In this case, the next period of class will start from the expiry date of the Special Survey
before the extension was granted.
2.1.3
For surveys completed within 3 months before the expiry date of the Special Survey, the next
period of class will start from the expiry date of the Special Survey. For surveys completed
more than 3 months before the expiry date of the Special Survey, the period of class will startfrom the survey completion date.
In cases where the vessel has been laid up or has been out of service for a considerable
period because of a major repair or modification and the owner elects to only carry out theoverdue surveys, the next period of class will start from the expiry date of the special survey.
If the owner elects to carry out the next due special survey, the period of class will start fromthe survey completion date.
2.1.4
The Special Survey may be commenced at the 4th Annual Survey and be progressed with aview to completion by the 5th anniversary date. When the Special Survey is commenced prior
to the 4th Annual Survey, the entire survey is to be completed within 15 months if such work
is to be credited to the Special Survey.
2.1.5
Concurrent crediting to both Intermediate Survey (IS) and Special Survey (SS) for surveys
and thickness measurements of spaces are not acceptable.

Note:

2)

Some member Societies use the term "Special Periodical Survey" others use the term"Class Renewal Survey" instead of the term "Special Survey".

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2.2

Scope

2.2.1 General
2.2.1.1
The Special Survey is to include, in addition to the requirements of the Annual Survey,
examination, tests and checks of sufficient extent to ensure that the hull and related piping,
as required in 2.2.1.3, is in a satisfactory condition and is fit for its intended purpose for the
new period of class of 5 years to be assigned, subject to proper maintenance and operationand to periodical surveys being carried out at the due dates.
2.2.1.2
All cargo tanks, Ballast Tanks, including double bottom tanks, pump rooms, pipe tunnels,
cofferdams and void spaces bounding cargo tanks, decks and outer hull are to be examined,
and this examination is to be supplemented by thickness measurement and testing as
required in 2.4 and 2.5, to ensure that the structural integrity remains effective. The aim of theexamination is to discover Substantial Corrosion, significant deformation, fractures, damages
or other structural deterioration that may be present.
2.2.1.3
Cargo piping on deck, including Crude Oil Washing (COW) piping, Cargo and Ballast piping
within the above tanks and spaces are to be examined and operationally tested to working
pressure to attending Surveyor’s satisfaction to ensure that tightness and condition remain
satisfactory. Special attention is to be given to any ballast piping in cargo tanks and any cargopiping in ballast tanks and void spaces, and Surveyors are to be advised on all occasions
when this piping, including valves and fittings are open during repair periods and can be
examined internally.
2.2.2 Dry Dock Survey
2.2.2.1
A survey in dry dock is to be a part of the Special Survey. The overall and close-up surveys
and thickness measurements, as applicable, of the lower portions of the cargo tanks andballast tanks are to be carried out in accordance with the applicable requirements for special
surveys, if not already performed.
Note: Lower portions of the cargo and ballast tanks are considered to be the parts below lightballast water line.
2.2.3 Tank Protection
2.2.3.1
Where provided, the condition of the corrosion prevention system of cargo tanks is to be
examined.
A Ballast Tank is to be examined at subsequent annual intervals where:a.

a hard protective coating has not been applied from the time of construction, orb.

a soft or semi-hard coating has been applied, orc.

substantial corrosion is found within the tank, ord.

the hard protective coating is found to be in less than GOOD condition and the hardprotective coating is not repaired to the satisfaction of the Surveyor.
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Z10.4

Z10.4(cont’d)Thickness measurements are to be carried out as deemed necessary by the surveyor.
2.3

Extent of Overall and Close-up Surveys

2.3.1
An Overall Survey of all tanks and spaces is to be carried out at each Special Survey.
2.3.2
The minimum requirements for Close-up Surveys at Special Survey are given in Table I.
2.3.3
The Surveyor may extend the Close-up Survey as deemed necessary taking into account themaintenance of the tanks under survey, the condition of the corrosion prevention system andalso in the following cases:a) in particular, tanks having structural arrangements or details which have suffered defects insimilar tanks or on similar ships according to available information,b) In tanks which have structures approved with reduced scantlings due to an approved
corrosion control system.
2.3.4
For areas in tanks where hard protective coatings are found to be in a GOOD condition as
defined in 1.2.11, the extent of Close-up Surveys according to Table I may be speciallyconsidered.
2.4

Extent of Thickness Measurements

2.4.1
The minimum requirements for thickness measurements at Special Survey are given in Table
II.
2.4.2
Provisions for extended measurements for areas with Substantial Corrosion are given in
Table IV, and as may be additionally specified in the Survey Programme as required in 5.1.
These extended thickness measurments are to be carried out before the survey is credited ascompleted. Suspect Areas identified at previous surveys are to be examined. Areas of
substantial corrosion identified at previous surveys are to have thickness measurements
taken.
For vessels built under IACS Common Structural Rules, the identified substantial corrosion
areas are required to be examined and additional thickness measurements are to be carriedout at annual and intermediate surveys.
2.4.3
The Surveyor may further extend the thickness measurements as deemed necessary.
2.4.4
For areas in tanks where hard protective coating are found to be in a GOOD condition as
defined in 1.2.11, the extent of thickness measurements according to Table II may be
specially considered.
2.4.5
Transverse sections are to be chosen where the largest reductions are suspected to occur or
are revealed from deck plating measurements.
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2.4.6
In cases where two or three sections are to be measured, at least one is to include a Ballast
Tank within 0.5L amidships.
In case of oil tankers of 130m in length and upwards (as defined in the International
Convention on Load Lines in force) and more than 10 years of age, for the evaluation of the
ship’s longitudinal strength as required in 9.1.1.1, the sampling method of thickness
measurements is given in Annex III Appendix 3.
2.5

Extent of Tank Testing

2.5.1
The minimum requirements for ballast tank testing at Special Survey are given in 2.5.3 andTable III.
The minimum requirements for cargo tank testing at Special Survey are given in 2.5.4 andTable III.
Cargo tank testing carried out by the ship’s crew under the direction of the Master may be
accepted by the surveyor provided the following conditions are complied with:a)a tank testing procedure, specifying fill heights, tanks being filled and bulkheads being
tested, has been submitted by the owner and reviewed by the Society prior to thetesting being carried out;b)

the tank testing is carried out prior to overall survey or close-up survey;c)

the tank testing is carried out within the special survey window and not more than threemonths prior to the date on which the overall or close up survey is completed;b)d) the tank testing has been satisfactorily carried out and there is no record of leakage,
distortion or substantial corrosion that would affect the structural integrity of the tank;c)the tank testing has been satisfactorily carried out within special survey window notmore than 3 months prior to the date of the survey on which the overall or close up
survey is completed;d)e) the satisfactory results of the testing is recorded in the vessel’s logbook; ande)f)

the internal and external condition of the tanks and associated structure are foundsatisfactory by the surveyor at the time of the overall and close up survey.

2.5.2
The Surveyor may extend the tank testing as deemed necessary.
2.5.3
Boundaries of ballast tanks are to be tested with a head of liquid to the top of air pipes.
2.5.4
Boundaries of cargo tanks are to be tested to the highest point that liquid will rise underservice conditions.

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2.5.5
The testing of double bottom tanks and other spaces not designed for the carriage of liquid
may be omitted, provided a satisfactory internal examination together with an examination of
the tanktop is carried out.

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Z10.4(cont’d)3.

ANNUAL SURVEY

3.1

Schedule

3.1.1
Annual Surveys are to be held within 3 months before or after anniversary date from the dateof the initial classification survey or of the date credited for the last Special Survey.
3.2

Scope

3.2.1

General3.2.1.1
The survey is to consist of an examination for the purpose of ensuring, as far as practicable,that the hull and piping are maintained in a satisfactory condition and should take into
account the service history, condition and extent of the corrosion prevention system of ballast
tanks and areas identified in the survey report file.
3.2.2 Examination of the hull
3.2.2.1
Examination of the hull plating and its closing appliances as far as can be seen.
3.2.2.2
Examination of watertight penetrations as far as practicable.
3.2.3 Examination of the weather deck
3.2.3.1
Examination of cargo tank openings including gaskets, covers, coamings and flame screens.
3.2.3.2
Examination of cargo tanks pressure/vacuum valves and flame screens.
3.2.3.3
Examination of flame screens on vents to all bunker tanks.
3.2.3.4
Examination of cargo, crude oil washing, bunker and vent piping systems, including ventmasts and headers.
3.2.4 Examination of cargo pump rooms and pipe tunnels if fitted.
3.2.4.1
Examination of all pump room bulkheads for signs of oil leakage or fractures and, in particular,
the sealing arrangements of all penetrations of pump room bulkheads.
3.2.4.2
Examination of the condition of all piping systems.

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Z10.4

Z10.4(cont’d)3.2.5 Examination of Ballast Tanks
3.2.5.1
Examination of Ballast Tanks where required as a consequence of the results of the Special
Survey (see 2.2.3) and Intermediate Survey (see 4.2.2.1 and 4.2.2.2) is to be carried out.
When considered necessary by the Surveyor, or when extensive corrosion exists, thickness
measurements are to be carried out and if the results of these thickness measurements
indicate that Substantial Corrosion is found, the extent of thickness measurements is to be
increased in accordance with Table IV. These extended thickness measurements are to be
carried out before the survey is credited as completed. Suspect Areas identified at previous
surveys are to be examined. Areas of substantial corrosion identified at previous surveys areto have thickness measurements taken.
For vessels built under IACS Common Structural Rules, the identified substantial corrosion
areas are required to be examined and additional thickness measurements are to be carriedout.

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Z10.4(cont’d)4.

INTERMEDIATE SURVEY

4.1

Schedule

4.1.1
The Intermediate Survey is to be held at or between either the 2nd or 3rd Annual Survey.
4.1.2
Those items, which are additional to the requirements of the Annual Surveys, may besurveyed either at or between the 2nd and 3rd Annual Survey.
4.1.3
Concurrent crediting to both Intermediate Survey (IS) and Special Survey (SS) for surveys
and thickness measurements of spaces are not acceptable.
4.2

Scope

4.2.1

General4.2.1.1
The survey extent is dependent on the age of the vessel as specified in 4.2.2 to 4.2.4 andshown in Table V.
4.2.1.2
For weather decks, an examination as far as applicable of cargo, crude oil washing, bunker,
ballast, steam and vent piping systems as well as vent masts and headers is to be carried out.
If upon examination there is any doubt as to the condition of the piping, the piping may berequired to be pressure-tested, thickness measured or both.
4.2.1.3
For vessels built under IACS Common Structural Rules, the identified substantial corrosion
areas are required to be examined and additional thickness measurements are to be carriedout.
4.2.2 Double Hull Oil Tankers between 5 and 10 years of age. The following is to apply:
4.2.2.1
For tanks used for salt-water ballast, an Overall Survey of Representative Tanks selected by
the Surveyor is to be carried out.
If such inspections reveal no visible structural defects, the examination may be limited to averification that the hard protective coating remains in GOOD condition.
4.2.2.2
A Ballast Tank is to be examined at subsequent annual intervals where:a.

a hard protective coating has not been applied from the time of construction, orb.

a soft or semi-hard coating has been applied, orc.

substantial corrosion is found within the tank, ord.

the hard protective coating is found to be in less than GOOD condition and the hardprotective coating is not repaired to the satisfaction of the Surveyor.

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Z10.4(cont’d)4.2.2.3
In addition to the requirements above, suspect areas identified at previous surveys are to be
examined.
4.2.3 Double Hull Oil Tankers between 10 and 15 years of age. The following is to apply:
4.2.3.1
The requirements of the Intermediate Survey are to be to the same extent as the previous
Special Survey as required in 2 and 5.1. However, pressure testing of cargo and ballast
tanks and the requirements for longitudinal strength evaluation of Hull Girder as required in
8.1.1.1.are not required unless deemed necessary by the attending Surveyor.
4.2.3.2
In application of 4.2.3.1, the intermediate survey may be commenced at the second annual
survey and be progressed during the succeeding year with a view to completion at the third
annual survey in lieu of the application of 2.1.4.
4.2.3.3
In application of 4.2.3.1, an under water survey may be considered in lieu of the requirementsof 2.2.2.
4.2.4 Double Hull Oil Tankers over 15 years of age. The following is to apply:
4.2.4.1
The requirements of the Intermediate Survey are to be to the same extent as the previous
Special Survey as required in 2 and 5.1. However, pressure testing of cargo and ballast tanks
and the requirements for longitudinal strength evaluation of Hull Girder as required in 8.1.1.1
are not required unless deemed necessary by the attending Surveyor.
4.2.4.2
In application of 4.2.4.1, the intermediate survey may be commenced at the second annual
survey and be progressed during the succeeding year with a view to completion at the third
annual survey in lieu of the application of 2.1.4.
4.2.4.3
In application of 4.2.4.1, a survey in dry dock is to be part of the intermediate survey. The
overall and close-up surveys and thickness measurements, as applicable, of the lower
portions of the cargo tanks and water ballast tanks are to be carried out in accordance withthe applicable requirements for intermediate surveys, if not already carried out.
Note: Lower portions of the cargo and ballast tanks are considered to be the parts below lightballast water line.

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Z10.4(cont’d)5.

PREPARATION FOR SURVEY

5.1

Survey Programme

5.1.1
The Owner in co-operation with the Classification Society is to work out a specific Survey
Programme prior to the commencement of any part of:-

the Special Survey-

the Intermediate Survey for oil tanker over 10 years of age

The Survey Programme at Intermediate Survey may consist of the Survey Programme at theprevious Special Survey supplemented by the Executive Hull Summary of that Special
Survey and later relevant survey reports.
The Survey Programme is to be worked out taking into account any amendments to thesurvey requirements implemented after the last Special Survey carried out.
The Survey Programme is to be in a written format based on the information in annex IVA.
The survey is not to commence until the survey programme has been agreed.
5.1.1.1 Prior to the development of the survey programme, the survey planning questionnaire
is to be completed by the owner based on the information set out in annex IVB, andforwarded to the Classification Society.
5.1.2
In developing the survey programme, the following documentation is to be collected andconsulted with a view to selecting tanks, areas, and structural elements to be examined:.1

survey status and basic ship information;.2

documentation on board, as described in 6.2 and 6.3;

.3

main structural plans of cargo and ballast tanks (scantlings drawings),
including information regarding use of high-tensile steels (HTS);.4

Executive Hull Summary;.5

relevant previous damage and repair history;.6

relevant previous survey and inspection reports from both the recognizedorganization and the owner;.7

cargo and ballast history for the last 3 years, including carriage of cargo underheated conditions;.8

details of the inert gas plant and tank cleaning procedures;.9

information and other relevant data regarding conversion or modification of the
ship’s cargo and ballast tanks since the time of construction;

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description and history of the coating and corrosion protection system(previous class notations), if any;

.11

inspections by the Owner’s personnel during the last 3 years with reference tostructural deterioration in general, leakages in tank boundaries and piping andcondition of the coating and corrosion protection system if any. Guidance forreporting is shown in Annex IVC;

.12

information regarding the relevant maintenance level during operation
including port state control reports of inspection containing hull related
deficiencies, Safety Management System non-conformities relating to hull
maintenance, including the associated corrective action(s); and.13

any other information that will help identify suspect areas and critical structuralareas(cont’d)

5.1.3
The submitted Survey Programme is to account for and comply, as a minimum, with therequirements of Tables I, II and 2.5 for close-up survey, thickness measurement and tanktesting, respectively, and is to include relevant information including at least:.1

basic ship information and particulars;.2

main structural plans (scantling drawings), including information regarding useof high tensile steels (HTS);.3

plan of tanks;.4list of tanks with information on use, corrosion prevention and condition of
coating;.5

conditions for survey (e.g., information regarding tank cleaning, gas freeing,
ventilation, lighting, etc.);.6

provisions and methods for access to structures;.7

equipment for surveys;.8

nomination of tanks and areas for close-up survey (per 2.3);.9nominations of sections for thickness measurement (per 2.4);.10

nomination of tanks for tank testing (per 2.5);.11

identification of the thickness measurement firm;.12

damage experience related to the ship in question;.13

critical structural areas and suspect areas, where relevant.

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5.1.4
The Classification Society will advise the Owner of the maximum acceptable structural
corrosion diminution levels applicable to the vessel.
5.1.5
Use may also be made of the Guidelines for Technical Assessment in Conjunction with
Planning for Enhanced Surveys of Double Hull Oil Tankers Special Survey - Hull, containedin Annex I. These guidelines are a recommended tool which may be invoked at the discretionof the Classification Society, when considered necessary and appropriate, in conjunction withthe preparation of the required Survey Programme.
5.2

Conditions for survey

5.2.1
The Owner is to provide the necessary facilities for a safe execution of the survey.
5.2.1.1 In order to enable the attending surveyors to carry out the survey, provisions forproper and safe access are to be agreed between the owner and the Classification society
are to be in accordance with IACS PR 37.
5.2.1.2 Details of the means of access are to be provided in the survey planningquestionnaire.
5.2.1.3 In cases where the provisions of safety and required access are judged by theattending surveyors not to be adequate, the survey of the spaces involved is to not proceed.
5.2.2
Tanks and spaces are to be safe for access. Tanks and spaces are to be gas free andproperly ventilated. Prior to entering a tank, void or enclosed space, it is to be verified that theatmosphere in that space is free from hazardous gas and contains sufficient oxygen.
5.2.3
In preparation for survey and thickness measurements and to allow for a thoroughexamination, all spaces are to be cleaned including removal from surfaces of all loose
accumulated corrosion scale. Spaces are to be sufficiently clean and free from water, scale,dirt, oil residues etc. to reveal corrosion, deformation, fractures, damages, or other structural
deterioration as well as the condition of the coating. However, those areas of structure whose
renewal has already been decided by the owner need only be cleaned and descaled to theextent necessary to determine the limits of the areas to be renewed.
5.2.4
Sufficient illumination is to be provided to reveal corrosion, deformation, fractures, damages
or other structural deterioration.
5.2.5
Where Soft or Semi-hard Coatings have been applied, safe access is to be provided for thesurveyor to verify the effectiveness of the coating and to carry out an assessment of the
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conditions of internal structures which may include spot removal of the coating. When safe
access cannot be provided, the soft or semi-hard coating is to be removed.

(cont’d)
5.3

Access to structures

5.3.1
For overall survey, means are to be provided to enable the surveyor to examine the hull
structure in a safe and practical way.
5.3.2
For close-up survey, one or more of the following means for access, acceptable to theSurveyor, is to be provided:
•
•
•
•



permanent staging and passages through structures;
temporary staging and passages through structures;
hydraulic arm vehicles such as conventional cherry pickers, lifts and movable
platforms;
boats or rafts;
portable ladders;
other equivalent means.

5.4

Equipment for survey

5.4.1
Thickness measurement is normally to be carried out by means of ultrasonic test equipment.
The accuracy of the equipment is to be proven to the Surveyor as required.
5.4.2
One or more of the following fracture detection procedures may be required if deemednecessary by the Surveyor:
•
•
•

•

radiographic equipment;ultrasonic equipment;
magnetic particle equipment;
dye penetrant.

5.4.3
Explosimeter, oxygen-meter, breathing apparatus, lifelines, riding belts with rope and hook
and whistles together with instructions and guidance on their use are to be made available
during the survey. A safety check-list is to be provided.
5.4.4
Adequate and safe lighting is to be provided for the safe and efficient conduct of the survey.
5.4.5
Adequate protective clothing is to be made available and used during the survey (e.g. safety
helmet, gloves, safety shoes, etc.).

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5.5

Rescue and emergency response equipment

If breathing apparatus and/or other equipment is used as ‘Rescue and emergency response
equipment’ then it is recommended that the equipment should be suitable for theconfiguration of the space being surveyed.
5.6

Survey at sea or at anchorage

5.6.1
Survey at sea or at anchorage may be accepted provided the Surveyor is given thenecessary assistance from the personnel onboard. Necessary precautions and proceduresfor carrying out the survey are to be in accordance with 5.1, 5.2, 5.3 and 5.4.
5.6.2
A communication system is to be arranged between the survey party in the tank and the
responsible officer on deck. This system is to include the personnel in charge of ballast pumphandling if boats or rafts are used.
5.6.3
Surveys of tanks by means of boats or rafts may only be undertaken with the agreement of
the Surveyor, who is to take into account the safety arrangements provided, including
weather forecasting and ship response under foreseeable conditions and provided the
expected rise of water within the tank does not exceed 0.25m.
5.6.4
When rafts or boats are used for close-up surveys, the following conditions are to beobserved:.1

only rough duty, inflatable rafts or boats, having satisfactory residual buoyancy
and stability even if one chamber is ruptured, are to be used;.2

the boat or raft is to be tethered to the access ladder and an additional person
is to be stationed down the access ladder with a clear view of the boat or raft;.3

appropriate lifejackets are to be available for all participants;.4

the surface of water in the tank is to be calm (under all foreseeable conditions
the expected rise of water within the tank is to not exceed 0.25 m) and thewater level stationary. On no account is the level of the water to be rising while
the boat or raft is in use;.5

the tank or space must contain clean ballast water only. Even a thin sheen ofoil on the water is not acceptable;.6

at no time should the water level be allowed to be within 1 m of the deepest
under deck web face flat so that the survey team is not isolated from a direct
escape route to the tank hatch. Filling to levels above the deck transverses
should only be contemplated if a deck access manhole is fitted and open in thebay being examined, so that an escape route for the survey party is available
at all times. Other effective means of escape to the deck may be considered;.7

if the tanks (or spaces) are connected by a common venting system, or inert
gas system, the tank in which the boat or raft should be used should be
isolated to prevent a transfer of gas from other tanks (or spaces).
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Z10.4(cont’d)5.6.5
Rafts or boats alone may be allowed for inspection of the under deck areas for tanks orspaces, if the depth of the webs is 1.5 m or less.
5.6.6
If the depth of the webs is more than 1.5 m, rafts or boats alone may be allowed only:.1

when the coating of the under deck structure is in GOOD condition and there isno evidence of wastage; or.2

if a permanent means of access is provided in each bay to allow safe entry andexit. This means:i. access direct from the deck via a vertical ladder and a small platform fitted
approximately 2 m below the deck in each bay; orii. access to deck from a longitudinal permanent platform having ladders to deck ineach end of the tank. The platform shall, for the full length of the tank, bearranged in level with, or above, the maximum water level needed for rafting ofunder deck structure. For this purpose, the ullage corresponding to the
maximum water level is to be assumed not more than 3m from the deck platemeasured at the midspan of deck transverses and in the middle length of thetank (See Figure 4).

If neither of the above conditions are met, then staging or an “other equivalent means”
is to be provided for the survey of the under deck areas.

Figure 4 Maximum water level in a tank
5.6.7
The use of rafts or boats alone in paragraphs 5.6.5 and 5.6.6 does not preclude the use ofboats or rafts to move about within a tank during a survey.
Reference is made to IACS Recommendation 39 - Guidelines for the use of Boats or Rafts for
Close-up surveys.
5.7

Survey Planning Meeting

5.7.1
Proper preparation and close co-operation between the attending surveyor(s) and theowner’s representatives onboard prior to and during the survey are an essential part in the

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Z10.4(cont’d)safe and efficient conduct of the survey. During the survey on board safety meetings are to
be held regularly.
5.7.2
Prior to the commencement of any part of the Special and Intermediate Survey a survey
planning meeting is to be held between the attending Surveyor(s), the Owner’s
Representative in attendance, the TM firm representative, where involved, and the master ofthe ship or an appropriately qualified representative appointed by the master or Company forthe purpose of ascertaining that all the arrangements envisaged in the survey programme arein place, so as to ensure the safe and efficient conduct of the survey work to be carried out.
See also 7.1.2.
5.7.3
The following is an indicative list of items that are to be addressed in the meeting:.1

schedule of the vessel (i.e. the voyage, docking and undocking manoeuvres,periods alongside, cargo and ballast operations etc.);.2

provisions and arrangements for thickness measurements (i.e. access,cleaning/de-scaling, illumination, ventilation, personal safety);.3extent of the thickness measurements;.4

acceptance criteria (refer to the list of minimum thicknesses);.5

extent of close-up survey and thickness measurement considering the coating
condition and suspect areas/areas of substantial corrosion;.6

execution of thickness measurements;.7

taking representative readings in general and where uneven corrosion/pitting isfound;.8

mapping of areas of substantial corrosion; and.9communication between attending surveyor(s) the thickness measurement firm
operator(s) and owner representative(s) concerning findings.

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6.

DOCUMENTATION ON BOARD

6.1

General

6.1.1
The owner is to obtain, supply and maintain on board documentation as specified in 6.2 and
6.3, which is to be readily available for the Surveyor.
6.1.2
The documentation is to be kept on board for the lifetime of the ship.
6.1.3
For tankers and bulk carriers subject to SOLAS Chapter II-1 Part A-1 Regulation 3-10, theOwner is to arrange the updating of the Ship Construction File (SCF) throughout the ship’s
life whenever a modification of the documentation included in the SCF has taken place.
Documented procedures for updating the SCF are to be included within the Safety
Management System.
6.2

Survey report file

6.2.1
A Survey Report File is to be a part of the documentation on board consisting of:•reports of structural surveys;•

Executive Hull Summary;•thickness measurement reports.

6.2.2
The Survey Report File is to be available also in the Owner's and the Classification Society's
management offices.
6.3

Supporting documents

6.3.1
The following additional documentation is to be available onboard:•

Survey Programme as required by 5.1 until such time as the Special Survey orIntermediate Survey, as applicable, has been completed;•main structural plans of cargo and ballast tanks (for CSR ships these plans are toinclude for each structural element both the as-built and renewal thickness. Any
thickness for voluntary addition is also to be clearly indicated on the plans. The
Midship Section plan to be supplied on board the ship is to include the minimum
allowable hull girder sectional properties for the tank transverse section in all cargotanks);•

previous repair history;•

cargo and ballast history;•

extent of use of inert gas plant and tank cleaning procedures;

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inspections by ship's personnel with reference to(cont’d)structural deterioration in general;leakage in bulkheads and piping;condition of coating or corrosion prevention system, if any.
A guidance for reporting is shown in Table VI (ref: Annex IVC).

•
any other information that will help identify Critical Structural Areas and/or Suspect
Areas requiring inspection;
6.3.2
For tankers and bulk carriers subject to SOLAS Chapter II-1 Part A-1 Regulation 3-10, theShip Construction File (SCF), limited to the items to be retained on board, is to be available
on board.
6.4

Review of documentation on board

6.4.1
Prior to survey, the Surveyor is to examine the completeness of the documentation onboard,and its contents as a basis for the survey.
6.4.2
For tankers and bulk carriers subject to SOLAS Chapter II-1 Part A-1 Regulation 3-10, on
completion of the survey, the surveyor is to verify that the update of the Ship Construction
File (SCF) has been done whenever a modification of the documentation included in the SCF
has taken place.
6.4.2.1 For the SCF stored on board ship, the surveyor is to examine the information on
board ship.
In cases where any major event, including, but not limited to, substantial repair andconversion, or any modification to the ship structures, the surveyor is to also verify that the
updated information is kept on board the ship.
If the updating of the SCF onboard is not completed at the time of survey, the Surveyor
records it and requires confirmation at the next periodical survey.
6.4.2.2 For the SCF stored on shore archive, the surveyor is to examine the list of information
included on shore archive.
In cases where any major event, including, but not limited to, substantial repair andconversion, or any modification to the ship structures, the surveyor is to also verify that the
updated information is stored on shore archive by examining the list of information included
on shore archive or kept on board the ship.
In addition, the surveyor is to confirm that the service contract with of the Archive Center isvalid.
If the updating of the SCF Supplement ashore is not completed at the time of survey, theSurveyor records it and requires confirmation at the next periodical survey.
6.4.3
For tankers and bulk carriers subject to SOLAS Chapter II-1 Part A-1 Regulation 3-10, on
completion of the survey, the surveyor is to verify any addition and/or renewal of materials
used for the construction of the hull structure are documented within the Ship Construction
File inventory list.

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7.

PROCEDURES FOR THICKNESS MEASUREMENT

7.1

General

7.1.1
The required thickness measurements, if not carried out by the Society itself, are to bewitnessed by a Surveyor of the Society. The Surveyor is to be on board to the extent
necessary to control the process.
7.1.2
The thickness measurement firm is to be part of the survey planning meeting to be held prior
to commencing the survey.
7.1.3
Thickness measurements of structures in areas where close-up surveys are required shall be
carried out simultaneously with close-up surveys.
7.1.4
In all cases the extent of the thickness measurements are to be sufficient as to represent theactual average condition.
7.2

Certification of thickness measurement firm

7.2.1
The thickness measurement is to be carried out by a qualified firm certified by theClassification Society according to principles stated in Table VII.
7.3

Number and locations of measurements

7.3.1

Application

The item 7.3 only applies to vessels built under the IACS Common Structural Rules1. For
vessels not built under IACS Common Structural Rules, the requirements for number andlocations of measurements are according to the Rules of the individual Classification Society
and/or specific IACS URs depending on ship’s age and structural elements concerned.
7.3.2

Number of measurements

Considering the extent of thickness measurements according to the different structuralelements of the ship and surveys (special, intermediate and annual), the locations of thepoints to be measured are given for the most important items of the structure.
7.3.3

Locations of measurements

Table 1 provides explanations and/or interpretations for the application of those requirements
indicated in the Rules, which refer to both systematic thickness measurements related to thecalculation of global hull girder strength and specific measurements connected to close-up
surveys.
Fig 5 to Fig 8 are provided to facilitate the explanations and/or interpretations given in Table 1,
to show typical arrangements of double hull oil tankers.
1 IACS Common Structural Rules mean IACS Common Structural Rules for Double Hull Oil Tankers (IACS CSR

for Oil Tankers) or IACS Common Structural Rules for Bulk Carriers and Oil Tankers (IACS CSR BC&OT).

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Table 1: Interpretations of rule requirements for the locations and number of points tobe measured
Item
Selected plates

Deck, bottom plates andwind-and-water strakes

Transverse section

Interpretation«Selected» means at leasta single point on one outof three plates, to bechosen on representative
areas of average
corrosion.
At least two points oneach plate to be taken
either at each 1/4
extremity of plate or atrepresentative areas of
average corrosion.
Measurements to be taken
on all longitudinal
members such as plating,longitudinals and girders
at the deck, side, bottom,
longitudinal bulkheads,
inner bottom and hopper.
One point to be taken oneach plate. Both web andflange to be measured on
longitudinals, if applicable.

Figure reference

Fig 5

For tankers older than 10
years of age:Transverse rings (#) in
cargo and ballast tanks

within 0.1D (where D isthe ship’s moulded depth)of the deck and bottom ateach transverse section to
be measured, every
longitudinal and girder is
to be measured on the
web and face plate, andevery plate is to bemeasured at one point
between longitudinals.
At least two points oneach plate in a staggered
pattern and two points on
the corresponding flange
where applicable.
Minimum 4 points on thefirst plate below deck.
Additional points in way of
curved parts. At least one

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Item

(cont’d)
Transverse bulkheads incargo tanks

Interpretation
point on each of two
stiffeners between
stringers / longitudinal
girders.
At least two points oneach plate. Minimum 4
points on the first plate
below main deck.

Figure reference

Fig 7

At least one point on every
third stiffener to be taken
between each stringer.
At least two points oneach plate of stringers andgirders, and two points on
the corresponding flange.
Additional points in way of
curved part.

Transverse bulkheads inballast tanks

Two points of each
diaphragm plate of stools
if fitted.
At least 4 points on plates
between stringers /longitudinal girders, or per
plate if stringers / girders
not fitted.

Fig 8

At least two points oneach plate of stringers andgirders, and two points on
the corresponding flange.
Additional points in way of
curved part.

Adjacent structuralmembers

At least one point on two
stiffeners between eachstringer / longitudinal
girder.
On adjacent structuralmembers one point perplate and one point on
every third stiffener /longitudinal.

(#°) Transverse rings means all transverse material appearing in a cross-section of the ship's
hull, in way of a double bottom floor, vertical web and deck transverse (definition from CSR)

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Z10.4(cont’d)Figure 5 - Transverse section

Figure 6 - Transverse rings in cargo and ballast tanks
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Z10.4(cont’d)Figure 7 - Transverse bulkheads in cargo tanks

Figure 8 - Transverse bulkheads in ballast tanks

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Z10.4(cont’d)7.4

Reporting

7.4.1
A thickness measurement report is to be prepared. The report is to give the location of
measurement, the thickness measured as well as corresponding original thickness.
Furthermore, the report is to give the date when the measurement was carried out, type ofmeasuring equipment, names of personnel and their qualifications and has to be signed by
the operator.
The thickness measurement report is to follow the principles as specified in the
Recommended Procedures for Thickness Measurement of Double Hull Oil Tankers,
contained in Annex II.
7.4.2
The Surveyor is to review the final thickness measurement report and countersign the cover
page.

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8.

ACCEPTANCE CRITERIA

8.1

General8.1.1 For vessels built under IACS Common Structural Rules, the Acceptance Criteria is
according to IACS Common Structural Rules1 and as specified in 8.2, 8.3 and 8.4.
8.1.2 For vessels not built under IACS Common Structural Rules, the Acceptance Criteria
are according to the Rules of the individual Classification Society and/or specific IACS URs
depending on ship’s age and structural elements concerned.
8.2

Acceptance criteria for pitting corrosion of CSR ships

8.2.1 For plates with pitting intensity less than 20%, see Figure 1, the measured thickness,tm, of any individual measurement is to meet the lesser of the following criteria:
tm ≥ 0.7 (tas-built - tvol add) mm
tm ≥ tren - 1 mm
Where:
tas-built

as-built thickness of the member, in mm

tvol add

voluntary thickness addition; thickness, in mm, voluntarily added as the Owner’s
extra margin for corrosion wastage in addition to tC

tren

renewal criteria for general corrosion as defined in IACS Common Structural
Rules28.2.2 The average thickness across any cross section in the plating is not to be less than
the renewal criteria for general corrosion given in IACS Common Structural Rules2.
8.3

Acceptance criteria for edge corrosion of CSR ships

8.3.1 Provided that the overall corroded height of the edge corrosion of the flange, or web in
the case of flat bar stiffeners, is less than 25%, see Figure 2, of the stiffener flange breadth or
web height, as applicable, the measured thickness, tm, is to meet the lesser of the following
criteria:
tm ≥ 0.7 (tas-built - tvol add) mm
tm ≥ tren - 1 mm
Where:
tas-built

as-built thickness of the member, in mm

tvol add

voluntary thickness addition; thickness, in mm, voluntarily added as the Owner’s
extra margin for corrosion wastage in addition to tC

1 Section 12 of IACS CSR for Oil Tankers, or Ch. 13, Part 1 of IACS CSR BC&OT
2 1.4.2.1 of Section 12 of IACS CSR for Oil Tankers, or 2.1.1 of Sec. 2, Ch. 13, Part 1 of IACS CSR BC&OT

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tren

renewal criteria for general corrosion as defined in IACS Common Structural
Rules1(cont’d)8.3.2 The average measured thickness across the breadth or height of the stiffener is not tobe less than that defined in IACS CSR2.
8.3.3 Plate edges at openings for manholes, lightening holes etc. may be below theminimum thickness given in IACS CSR2 provided that:a)the maximum extent of the reduced plate thickness, below the minimum given in IACS
CSR2, from the opening edge is not more than 20% of the smallest dimension of the
opening and does not exceed 100mm.

b)rough or uneven edges may be cropped-back provided that the maximum dimensionof the opening is not increased by more than 10% and the remaining thickness of the
new edge is not less than tren - 1 mm.

8.4

Acceptance criteria for grooving corrosion of CSR ships

8.4.1 Where the groove breadth is a maximum of 15% of the web height, but not more than
30mm, see Figure 3, the measured thickness, tm, in the grooved area is to meet the lesser ofthe following criteria:
tm ≥ 0.75 (tas-built - tvol add) mm
tm ≥ tren - 0.5 mm
but is not to be less thantm = 6 mm
Where:
tas-built

as-built thickness of the member, in mm

tvol add

voluntary thickness addition; thickness, in mm, voluntarily added as the Owner’s
extra margin for corrosion wastage in addition to tC

tren

renewal criteria for general corrosion as defined in IACS CSR1

8.4.2 Structural members with areas of grooving greater than those in 8.4.1 are to beassessed based on the criteria for general corrosion as defined in IACS CSR2 using the
average measured thickness across the plating/stiffener.

1 1.4.2.1 of Section 12 of IACS CSR for Oil Tankers, or 2.1.1 of Sec. 2, Ch. 13, Part 1 of IACS CSR BC&OT

2

1.4.2 of Section 12 of IACS CSR for Oil Tankers, or 2.1 of Sec. 2, Ch. 13, Part 1 of IACS CSR BC&OT

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REPORTING AND EVALUATION OF SURVEY

9.1

Evaluation of survey report

9.1.1
The data and information on the structural condition of the vessel collected during the survey
is to be evaluated for acceptability and continued structural integrity of the vessel.
9.1.1.1 In case of oil tankers of 130 m in length and upwards (as defined in the International
Convention on Load Lines in force), the ship’s longitudinal strength is to be evaluated byusing the thickness of structural members measured, renewed and reinforced, as appropriate,
during the special survey carried out after the ship reached 10 years of age in accordancewith the criteria for longitudinal strength of the ship’s hull girder for oil tankers specified in
Annex III.
9.1.1.2 The final result of evaluation of the ship’s longitudinal strength required in 9.1.1.1,
after renewal or reinforcement work of structural members, if carried out as a result of initial
evaluation, is to be reported as a part of the Executive Hull Summary.
9.2

Reporting

9.2.1
Principles for survey reporting are shown in Table VIII.
9.2.2
When a survey is split between different survey stations, a report is to be made for eachportion of the survey. A list of items examined and / or tested (pressure testing, thickness
measurements etc.) and an indication of whether the item has been credited, are to be madeavailable to the next attending Surveyor(s), prior to continuing or completing the survey.
9.2.3
An Executive Hull Summary of the survey and results is to be issued to the Owner as shownin Table IX and placed on board the vessel for reference at future surveys. The Executive
Hull Summary is to be endorsed by the Classification Society's head office or regional
managerial office.

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TABLE I

Z10.4

Minimum Requirements for Close-Up Survey
at Special Survey of Double Hull Oil Tankers(cont’d)Special Survey No.1
age ≤ 5Special Survey No.2
5 < age ≤ 10

Special Survey No.3
10 < age ≤ 15

One web frame (1), in a ballast tank(see Note 1)

All web frames (1), in a ballast tank(see Note 1)
The knuckle area and the upper part
(5 metres approximately) of one web
frame in each remaining ballast tank(6)

All web frames (1), in all ballasttanks

One deck transverse, in two cargo
oil tanks (2)All web frames (7), including
deck transverse and cross ties, if
fitted, in a cargo oil tank

One deck transverse, in a cargo oiltank (2)One transverse bulkhead (4), in aballast tank (see Note 1)
One transverse bulkhead (5), in acargo oil centre tank

One transverse bulkhead (4), ineach ballast tank (see Note 1)
One transverse bulkhead (5), in two
cargo oil centre tanks

Special Survey No.4
and Subsequent
age > 15
As for Special Survey forage from 10 to 15 years
Additional transverse
areas as deemednecessary by theSociety

One web frame (7), including
deck transverse and cross ties, if
fitted, in each remaining cargo
oil tank
All transverse bulkheads, in all
cargo oil (3) and ballast (4)tanks

One transverse bulkhead (5), in a
One transverse bulkhead (5), in acargo oil wing tank (see Note 2)
cargo oil wing tank (see Note 2)(1), (2), (3), (4), (5), (6) and (7) are areas to be subjected to close-up surveys and thickness measurements (see Figure 9 and Figure 10)(1):
Web frame in a ballast tank means vertical web in side tank, hopper web in hooper tank, floor in double bottom tank and decktransverse in double deck tank (where fitted), including adjacent structural members. In fore and aft peak tanks web frame means acomplete transverse web frame ring including adjacent structural members(2):

Deck transverse, including adjacent deck structural members (or external structure on deck in way of the tank, where applicable)(3):

Transverse bulkhead complete in cargo tanks, including girder system, adjacent structural members (such as longitudinal bulkheads)
and internal structure of lower and upper stools, where fitted(4):Transverse bulkhead complete in ballast tanks, including girder system and adjacent structural members, such as longitudinalbulkheads, girders in double bottom tanks, inner bottom plating, hopper side, connecting brackets(5):Transverse bulkhead lower part in cargo tank, including girder system, adjacent structural members (such as longitudinal bulkheads)
and internal structure of lower stool, where fitted(6):

The knuckle area and the upper part (5 metres approximately), including adjacent structural members. Knuckle area is the area of
the web frame around the connections of the slope hopper plating to the inner hull bulkhead and the inner bottom plating, up to 2
metres from the corners both on the bulkhead and the double bottom(7):

Web frame in a cargo oil tank means deck transverse, longitudinal bulkhead structural elements and cross ties, where fitted,
including adjacent structural members

Note 1:

Note 2:

Ballast tank: Apart from the fore and aft peak tanks, the term "ballast tank" has the following meaning:.1

all ballast compartments (hopper tank, side tank and double-deck tank, if separate from double-bottomtank) located on one side, i.e. portside or starboard side, and additionally double-bottom tank on portsideplus starboard side, when the longitudinal central girder is not watertight and, therefore, the doublebottom tank is a unique compartment from portside to starboard side; or.2

all ballast compartments (double-bottom tank, hopper tank, side tank and double-deck tank) located on
one side, i.e. portside or starboard side, when the longitudinal central girder is watertight and, therefore,
the portside double-bottom tank separate from the starboard-side double-bottom tank."

Where no centre cargo tanks are fitted (as in case of centre longitudinal bulkhead), transverse bulkheads in wing tanks are to be
surveyed

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Z10.4(cont’d)

TABLE II
Minimum Requirements for Thickness Measurements
at Special Survey of Double Hull Oil Tankers

Special Survey No.1
age ≤ 5
1.

Suspect areas

Special Survey No.2
5 < age ≤ 10

Special Survey No.3
10 < age ≤ 15

Special Survey No.4
and Subsequent
age > 15

1.

Suspect areas

1.

Suspect areas

1.

Suspect areas

2.

Within the cargo area:

2.

Within the cargo area:

2.

Within the cargo area:.1

Each deck plate.1

Each deck plate.1

Each deck plate.2

One transverse
section.2

Two transverse
sections (1).2Three transverse
sections (1).3All wind and water
strakes.3

Each bottom
plate

3.

Selected wind andwater strakes outside
the cargo area

3.

Selected wind andwater strakes outside
the cargo area3.

All wind and water
strakes, full length4.

Measurements, forgeneral assessment
and recording of
corrosion pattern, of
those structuralmembers subject toclose-up survey
according to Table I.

4.

Measurements, forgeneral assessment
and recording of
corrosion pattern, of
those structuralmembers subject toclose-up survey
according to Table I.

4.

Measurements, forgeneral assessment
and recording of
corrosion pattern, of
those structuralmembers subject toclose-up survey
according to Table I.

(1): at least one section is to include a ballast tank within 0.5L amidships.

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Z10.4(cont’d)

TABLE III
Minimum Requirements for Tank Testing at Special Surveyof Double Hull Oil Tankers
Age of ship (in years at time of special survey due date)Special Survey No.1
age ≤ 5Special Survey No.2 and Subsequent
age > 5All ballast tank boundaries

All ballast tank boundaries

Cargo tank boundaries facing ballast tanks,
void spaces, pipe tunnels, pump rooms or
cofferdams

All cargo tank bulkheads

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Z10.4(cont’d)

TABLE IV / Sheet 1
Requirements for extent of Thickness Measurements at those
substantial corrosion - Special Survey of Double Hull Oil
Tankers within the Cargo Area Length

areas of

BOTTOM, INNER BOTTOM AND HOPPER STRUCTURE
Structural member

Extent of measurement

Pattern of measurement

Bottom, inner bottom andhopper structure plating

Minimum of three bays
across double bottom tank,including aft bay

5-point pattern for each panel
between longitudinals andfloorsBottom, inner bottom andhopper structure longitudinals
Bottom girders, including thewatertight ones

Bottom floors, including thewatertight ones

Hopper structure web framering
Hopper structure transverse
watertight bulkhead or swash
bulkhead

Measurements around andunder all suction bell mouths
Minimum of threelongitudinals in each bay
where bottom plating
measured
At fore and aft watertightfloors and in centre of tanks

Three floors in the bays
where bottom plating
measured, withmeasurements at both ends
and middle
Three floors in bays where
bottom plating measured- lower 1/3 of bulkhead- upper 2/3 of bulkhead- stiffeners(minimum of three)

Panel stiffening

Where applicable

Page 41 of 133

Three meaurements in line
across the flange and threemeasurements on vertical
web
Vertical line of single
measurements on girder
plating with one
measurement between eachpanel stiffener, or a minimumof three measurements
5-point pattern over twosquare metre area

5-point pattern over one
square metre of plating.
Single measurements onflange- 5-point pattern over
one square metre ofplating- 5-point pattern overtwo square metre ofplating- For web, 5-point
pattern over span (twomeasurements across
web at each end
and one at centre ofspan). For flange, single
measurements at eachend and centre of spanSingle measurements

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Z10.4

Z10.4(cont’d)

TABLE IV / Sheet 2
Requirements for extent of Thickness Measurements at those
substantial corrosion - Special Survey of Double Hull Oil
Tankers within the Cargo Area Length

areas of

DECK STRUCTURE
Structural member

Extent of measurement

Pattern of measurement

Deck plating

Two transverse bands acrosstank

Minimum of threemeasurements per plate perband

Deck longitudinals

Every third longitudinal ineach of two bands with aminimum of one longitudinal

Three measurements in line
vertically on webs and two
measurements on flange (iffitted)Deck girders and brackets(usually in cargo tanks only)

At fore and aft transverse
bulkhead, bracket toes and incentre of tanks

Vertical line of single
measurements on web platingwith one measurement
between each panel stiffener,
or a minimum of threemeasurements.
Two measurements acrossflange. 5-point pattern on
girder/bulkhead brackets

Deck transverse webs

Minimum of two webs, withmeasurements at both ends
and middle of span

5-point pattern over one
square metre area.
Single measurements onflangeVertical web and transverse Minimum of two webs, andbulkhead in wing ballast
both transverse bulkheads
tank (two metres from deck)
Panel stiffening
Where applicable

5-point pattern over one
square metre area

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Single measurements

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Z10.4
TABLE IV / Sheet 3

Z10.4

Requirements for extent of Thickness Measurements at those areas of
substantial corrosion - Special Survey of Double Hull Oil
Tankers within the Cargo Area Length(cont’d)

STRUCTURE IN WING BALLAST TANKS
Structural member
Side shell and longitudinalbulkhead plating:

Extent of measurement

Pattern of measurement-

Upper strake and strakes
in way of horizontal
girders- Plating between each pairof longitidinals in aminimum of three bays
(along the tank)- Single measurement-

All other strakes- Plating between every
third pair of longitudinals
in same three bays

- Single measurement

Side shell and longitudinalbulkhead longitudinals on:-

Upper strake- Each longitudinal in same
three bays

- 3 measurements across
web and 1 measurement
on flange-

All other strakes- Every third longitudinal insame three bays

Longitudinals - brackets

Minimum of three at top,
middle and bottom of tank insame three bays

- 3 measurements across
web and 1 measurement
on flange
5-point pattern over area ofbracket

Vertical web and transverse
bulkheads (excluding
deckhead area):-

Strakes in way ofhorizontal girders- Minimum of two webs andboth transverse bulkheads- 5-point pattern overapprox. two square metre
area-

Other strakes- Minimum of two webs andboth transverse bulkheads- Two measurements
between each pair ofvertical stiffeners
Two measurements between
each pair of longitudinal
girder stiffeners
Single measurements

Horizontal girders

Plating on each girder in aminimum of three bays

Panel stiffening

Where applicable

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Z10.4(cont’d)

TABLE IV / Sheet 4
Requirements for extent of Thickness Measurements at those areas of
substantial corrosion - Special Survey of Double Hull Oil
Tankers within the Cargo Area Length
LONGITUDINAL BULKHEADS IN CARGO TANKS
Structural Member
Deckhead and bottom
strakes, and strakes in wayof the horizontal stringers oftransverse bulkheads
All other strakes
Longitudinals on deckhead
and bottom strakes

Extent of Measurement
Plating between each pair of
longitudinals in a minimum of
three bays

Pattern of Measurement
Single measurement

Plating between every thirdpair of longitudinals in same
three bays
Each longitudinal in same
three bays

Single measurement

All other longitudinals

Every third longitudinal insame three bays

Longitudinals - brackets

Minimum of three at top,
middle and bottom of tank insame three bays
Three webs with minimum of
three locations on each web,including in way of cross tie
connections

Web frames and cross ties

Lower end brackets(opposite side of web frame)

Minimum of three brackets

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Three measurements across
web and one measurement
on flange
Three measurements across
web and one measurement
on flange
5-point pattern over area ofbracket5-point pattern overapproximately two square
metre area of webs, plus
single measurements onflanges of web frame andcross ties
5-point pattern overapproximately two square
metre area of brackets, plus
single measurements onbracket flanges

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Z10.4(cont’d)

TABLE IV / Sheet 5
Requirements for extent of Thickness Measurements at those areas of
substantial corrosion - Special Survey of Double Hull Oil
Tankers within the Cargo Area Length
TRANSVERSE WATERTIGHT AND SWASH BULKHEADS IN CARGO TANKS
Stuctural member
Upper and lower stool, where
fittedDeckhead and bottom
strakes, and strakes in wayof horizontal stringers
All other strakes
Strakes in corrugatedbulkheads
Stiffeners

Brackets
Horizontal stringers

Extent of measurement- Transverse band within
25mm of welded
connection to inner
bottom/deck plating

Pattern of measurement
5-point pattern between
stiffeners over one metre
length- Transverse band within
25mm of welded
connection to shelf plate
Plating between pair ofstiffeners at three locations:approximately 1/4, 1/2 and3/4 width of tank
Plating between pair ofstiffeners at middle location
Plating of each change ofscantling at centre of panel
and at flange of fabricatedconnection
Minimum of three typicalstiffeners

5-point pattern between
stiffeners over one metre
lengthSingle measurement
5-point pattern over about
one square metre of plating

Minimum of three at top,
middle and bottom of tank
All stringers withmeasurements at both ends
and middle

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For web, 5-point pattern overspan between bracket
connections (twomeasurements across web at
each bracket connection and
one at centre of span).
For flange, single
measurements at eachbracket toe and at centre ofspan
5-point pattern over area ofbracket5-point pattern over one
square metre area, plus
single measurements nearbracket toes and on flanges

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Z10.4(cont’d)

TABLE V
Minimum Requirements for Overall and Close-Up Survey and Thickness
Measurements at Intermediate Survey of Double Hull Oil Tankers
Age of ship at time of intermediate survey due date
5 < age ≤ 10
Overall survey ofRepresentative ballast tanks
selected by the attending
surveyor(see 4.2.2)
Suspect areas identified at
previous surveys are to be
examined

10 < age ≤ 15

age > 15

The requirements of theprevious Special Survey

The requirements of theprevious Special Survey(see 4.2.3)(see 4.2.4)(see 4.2.2)

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Z10.4

Z10.4(cont’d)Figure 9 - Close-up Survey Requirements for Double Hull Oil Tankers Areas (1) to (5)Page 47 of 133

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Z10.4

Z10.4(cont’d)Figure 10 - Close-up Survey Requirements for Double Hull Oil Tankers Areas(6) and (7)Page 48 of 133

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Z10.4

Z10.4(cont’d)

TABLE VI
Note: Table VI is retitled Annex IVC.

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Z10.4
TABLE VII

Z10.4

PROCEDURES FOR CERTIFICATION OF FIRMS ENGAGED IN
THICKNESS MEASUREMENT OF HULL STRUCTURES(cont’d)1.

Application
This guidance applies for certification of the firms which intend to engage in the
thickness measurement of hull structures of the vessels.

2.

Procedures for Certification(1)

Submission of Documents:
Following documents are to be submitted to the society for approval;
a)
b)
c)
d)
e)
f)
g)

Outline of firms, e.g. organization and management structure.
Experience of the firms on thickness measurement inter alia of hull structuresof the vessels.
Technicians’ careers, i.e. experience of technicians as thickness measurement
operators, technical knowledge of hull structure etc. Operators, are to bequalified according to a recognized industrial NDT Standard.
Equipment used for thickness measurement such as ultra-sonic testingmachines and its maintenance/calibration procedures.
A guide for thickness measurement operators.
Training programmes of technicians for thickness measurement.
Measurement record format in accordance with the Recommended
Procedures for Thickness Measurements of Double Hull Oil Tankers containedin Annex II.

(2)

Auditing of the firms:
Upon reviewing the documents submitted with satisfactory results, the firm is audited
in order to ascertain that the firm is duly organized and managed in accordance withthe documents submitted, and eventually is capable of conducting thickness
measurement of the hull construction of the ships.

(3)

Certification is conditional on an onboard demonstration at thickness measurements
as well as satisfactory reporting.

3.

Certification(1)

Upon satisfactory results of both the audit of the firm in 2(2) and the demonstration
tests in 2(3) above, the Society will issue a Certificate of Approval as well as a noticeto the effect that the thickness measurement operation system of the firm has beencertified by the Society.

(2)

Renewal/endorsement of the Certificate is to be made at intervals not exceeding 3
years by verification that original conditions are maintained.

4.

Information of any alteration to the Certified Thickness Measurement Operation
SystemIn case where any alteration to the certified thickness measurement operation systemof the firm is made, such an alteration is to be immediately informed to the Society.
Re-audit is made where deemed necessary by the Society.

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5.

Cancellation of Approval
Approval may be cancelled in the following cases:(cont’d)(1)

Where the measurements were improperly carried out or the results were improperly
reported.

(2)

Where the Society's surveyor found any deficiencies in the approved thickness
measurement operation systems of the firm.

(3)

Where the firm failed to inform of any alteration in 4 above to the Society.

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Z10.4
TABLE VIII

Z10.4

SURVEY REPORTING PRINCIPLES(cont’d)

As a principle, for oil tankers subject to ESP, the surveyor is to include the following content
in his report for survey of hull structure and piping systems, as relevant for the survey.
The structure of the reporting content may be different, depending on the report system forthe respective Societies.
1. General
1.1 A survey report is to be generated in the following cases:-

In connection with commencement, continuation and / or completion of periodical hullsurveys, i.e. annual, intermediate and special surveys, as relevant
When structural damages / defects have been found
When repairs, renewals or modifications have been carried out
When condition of class has been imposed or deleted

1.2 The purpose of reporting is to provide:-

Evidence that prescribed surveys have been carried out in accordance with applicableclassification rules
Documentation of surveys carried out with findings, repairs carried out and conditionof class imposed or deleted
Survey records, including actions taken, which shall form an auditable documentary
trail. Survey reports are to be kept in the survey report file required to be on board
Information for planning of future surveys
Information which may be used as input for maintenance of classification rules andinstructions

1.3 When a survey is split between different survey stations, a report is to be made for eachportion of the survey. A list of items surveyed, relevant findings and an indication of whether
the item has been credited, is to be made available to the next attending surveyor, prior tocontinuing or completing the survey. Thickness measurement and tank testing carried out isalso to be listed for the next surveyor.
2. Extent of the survey
2.1 Identification of compartments where an overall survey has been carried out.
2.2 Identification of locations, in each tank, where a close-up survey has been carried out,
together with information of the means of access used.
2.3 Identification of locations, in each tank, where thickness measurement has been carriedout.
Note: As a minimum, the identification of location of close-up survey and thickness
measurement is to include a confirmation with description of individual structural members
corresponding to the extent of requirements stipulated in Z10.4 based on type of periodical
survey and the ship's age.
Where only partial survey is required, i.e. one web frame ring / one deck transverse, theidentification is to include location within each tank by reference to frame numbers.

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Z10.4(cont’d)

2.4 For areas in tanks where protective coating is found to be in GOOD condition and theextent of close-up survey and / or thickness measurement has been specially considered,structures subject to special consideration are to be identified.
2.5 Identification of tanks subject to tank testing.
2.6 Identification of cargo piping on deck, including crude oil washing (COW) piping, andcargo and ballast piping within cargo and ballast tanks, pump rooms, pipe tunnels and void
spaces, where:-

Examination including internal examination of piping with valves and fittings andthickness measurement, as relevant, has been carried out
Operational test to working pressure has been carried out

3. Result of the survey
3.1 Type, extent and condition of protective coating in each tank, as relevant (rated GOOD,
FAIR or POOR).
3.2 Structural condition of each compartment with information on the following, as relevant:--Identification of findings, such as:•
Corrosion with description of location, type and extent•
Areas with substantial corrosion•
Cracks / fractures with description of location and extent•
Buckling with description of location and extent•
Indents with description of location and extent
Identification of compartments where no structural damages / defects are foundThe report may be supplemented by sketches / photos.
3.3 Thickness measurement report is to be verified and signed by the surveyor controllingthe measurements on board.
3.4 Evaluation result of longitudinal strength of the hull girder of oil tankers of 130 m in lengthand upwards and over 10 years of age. The following data is to be included, as relevant:-Measured and as-built transverse sectional areas of deck and bottom flanges
Diminution of transverse sectional areas of deck and bottom flanges
Details of renewals or reinforcements carried out, as relevant (as per 4.2)

4. Actions taken with respect to findings
4.1 Whenever the attending surveyor is of the opinion that repairs are required, each item tobe repaired is to be identified in the survey report. Whenever repairs are carried out, details of
the repairs effected are to be reported by making specific reference to relevant items in thesurvey report.

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Z10.4

Z10.4(cont’d)4.2 Repairs carried out are to be reported with identification of:-Compartment
Structural member
Repair method (i.e. renewal or modification) including:•
Steel grades and scantlings (if different from the original)•
Sketches/photos, as appropriate
Repair extent
NDT / Tests

4.3 For repairs not completed at the time of survey, condition of class is to be imposed with a
specific time limit for the repairs. In order to provide correct and proper information to thesurveyor attending for survey of the repairs, condition of class is to be sufficiently detailed
with identification of each item to be repaired. For identification of extensive repairs, reference
may be given to the survey report.

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Z10.4
TABLE IX (i)Z10.4

IACS UNIFIED REQUIREMENTS FOR ENHANCED SURVEYSEXECUTIVE HULL SUMMARY(cont’d)Issued upon Completion of Special Survey
GENERAL PARTICULARSSHIP’S NAME:

CLASS IDENTIFY NUMBER:
IMO IDENTIFY NUMBER:

PORT OF REGISTRY:NATIONAL FLAG:

DEADWEIGHT (M. TONNES):GROSS TONNAGE:
NATIONAL:
ITC (69):

DATE OF BUILD:

CLASSIFICATION NOTATION:DATE OF MAJOR CONVERSION:
TYPE OF CONVERSION:a)

The survey reports and documents listed below have been reviewed by theundersigned and found to be satisfactoryb)

A summary of the survey is attached herewith on sheet 2c)

The hull special survey has been completed in accordance with the Regulations on[date]

Executive Summary
Report completed by:
OFFICE
Executive Summary
Report verified by:
OFFICE

Name

Title

Signature
DATE
Name

Title

Signature
DATE

Attached reports and documents:
1)
2)
3)
4)
5)
6)

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Z10.4
TABLE IX (ii)

Z10.4

EXECUTIVE HULL SUMMARY(cont’d)A)

General Particulars: -Ref. Table IX (i)B)

Report Review:-

Where and how survey was done

C)

Close-up Survey:-

Extent (Which tanks)

D)

Cargo & Ballast
Piping System:-

Examined-

Operationally tested-

Reference to Thickness Measurement report-

Summary of where measured-

Separate form indicating the tanks/areas with
Substantial Corrosion, and correspondingE)

F)

Thicknessmeasurements:

Tank Protection:

G)

Repairs:

H)

Conditions of Class:

I)

Memoranda:*

Thickness diminution*

Corrosion pattern

Separate form indicating:-Location of coating-

Condition of coating (if applicable)-

Identification of tanks/areas-

Acceptable defects-

Any points of attention for future surveys, e.g. forSuspect Areas.

-

Examination of ballast tanks at annual surveys Extended
Annual/Intermediate survey due to coating breakdown

J)

Evaluation results of the ship’s longitudinal strength (for oil tankers of 130 m in lengthand upwards and of over 10 years of age)

K)

Conclusion:-

Statement on evaluation/verification of survey report

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Z10.4
TABLE IX (iii) A – non CSR vessels

Z10.4

EXTRACT OF THICKNESS MEASUREMENT(cont’d)Reference is made to the thickness measurements report:
1)

2)

Position ofsubstantiallycorroded
Tanks/Areas or
Areas with deep
pitting

Thicknessdiminution[%]Corrosion pattern

Remarks:e.g. Ref. attachedsketches

Remarks
1)

Substantial corrosion, i.e. 75 – 100% of acceptable margins wasted.

2)

P = Pitting
C = Corrosion in General
Any bottom plating with a pitting intensity of 20% or more, with wastage in thesubstantial corrosion range or having an average depth of pitting of 1/3 or more ofactual plate thickness is to be noted.

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Z10.4
TABLE IX (iii) B – CSR vessels

Z10.4

EXTRACT OF THICKNESS MEASUREMENTS(cont’d)Reference is made to the thickness measurements report:
1)

2)

Position ofsubstantiallycorroded
Tanks/Areas or
Areas with deep
pittingtm – tren (mm)Corrosion pattern

Remarks: e.g. Ref.
Attached sketches

Remarks
1)

Substantial corrosion, an extent of corrosion such that the assessment of the corrosion
pattern indicates a measured thickness between tren + 0.5mm and tren.

2)

P = Pitting
C = Corrosion in General
Areas with deep pitting assessed according to 8.2 are to be recorded in this column.

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Z10.4
TABLE IX (iv)

Z10.4

TANK PROTECTION(cont’d)

1)

2)

3)

Tank Nos.

Tank protection

Coating condition

Remarks

Remarks:
1)

All segregated ballast tanks and combined cargo/ballast tanks to be listed.
2)

C = Coating

NP = No Protection

3)

Coating condition according to the following standard
GOOD

condition with only minor spot rusting.

FAIR

condition with local breakdown at edges of stiffeners and weld
connections and/or light rusting over 20% or more of areas underconsideration, but less than as defined for POOR condition.

POOR

condition with general breakdown of coating over 20% or more of areasor hard scale at 10% or more of areas under consideration.

For ballast tanks, if coating condition less than "GOOD" is given, extended annual surveys
are to be introduced tanks are to be examined at annual surveys. This is to be noted in part I)of the Executive Hull Summary.

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Z10.4

Z10.4(cont’d)

TABLE IX (v)Evaluation result of longitudinal strength of the hull girder ofoil tankers of 130 m in length and upwards and of over 10 years of age(Of sections 1, 2 and 3 below, only one applicable section is to be completed)
1
This section applies to ships regardless of the date of construction: Transverse
sectional areas of deck flange (deck plating and deck longitudinals) and bottom flange(bottom shell plating and bottom longitudinals) of the ship’s hull girder have been calculated
by using the thickness measured, renewed or reinforced, as appropriate, during the special
survey most recently conducted after the ship reached 10 years of age, and found that thediminution of the transverse sectional area does not exceed 10% of the as-built area, as
shown in the following table:
Table 1

Transverse
Section 1
Transverse
Section 2
Transverse
Section 3

Transverse sectional area of hull girder flange

Deck flange
Bottom flange
Deck flange
Bottom flange
Deck flange
Bottom flange

Measured
cm2
cm2
cm2
cm2
cm2
cm2

As-built
cm2
cm2
cm2
cm2
cm2
cm2

Diminution
cm2 (%)
cm2 (%)
cm2 (%)
cm2 (%)
cm2 (%)
cm2 (%)

2This section applies to ships constructed on or after 1 July 2002: Section moduli oftransverse section of the ship’s hull girder have been calculated by using the thickness ofstructural members measured, renewed or reinforced, as appropriate, during the special
survey most recently conducted after the ship reached 10 years of age in accordance with theprovisions of paragraph 2.2.1.1 of Annex III, and are found to be within their diminution limits
determined by the Classification Society*, as shown in the following table:
Table 2

Transverse section modulus of hull girder
Zact (cm3) *1

Transverse
Section 1
Transverse
Section 2
Transverse
Section 3

Zreq (cm3) *2

Remarks

Upper deck
BottomUpper deck
BottomUpper deck
Bottom*The actual transverse section modulus of the hull girder of oil tankers calculated underparagraph 2.2.1.1 of Annex III to UR Z10.4 is not to be less than 90% of the required section
modulus for new buildings specified in IACS Unified Requirements S7* or S11, whichever isthe greater.
* C = 1.0 cn is to be used for the purpose of this calculation.

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Z10.4

Z10.4

Notes

(cont’d)*1

Zact means the actual section moduli of the transverse section of the ship's hull
girder calculated by using the thickness of structural members measured,
renewed or reinforced, as appropriate, during the special survey, in
accordance with the provisions of paragraph 2.2.1.1 of Annex III.

*2

Zreq means diminution limit of the longitudinal bending strength of ships, ascalculated in accordance with the provisions of paragraph 2.2.1.1 of Annex III.

The calculation sheets for Zact are to be attached to this report.
3This section applies to ships constructed before 1 July 2002: Section moduli oftransverse section of the ship’s hull girder have been calculated by using the thickness ofstructural members measured, renewed or reinforced, as appropriate, during the special
survey most recently conducted after the ship reached 10 years of age in accordance with theprovisions of paragraph 2.2.1.2 of Annex III, and found to meet the criteria required by theClassification Society and that Zact is not less than Zmc (defined in *2 below) as specified inappendix 2 to Annex III, as shown in the following table:
Describe the criteria for acceptance of the minimum section moduli of the ship's hull
girder for ships in service required by the Classification Society.
Table 3

Transverse section modulus of hull girder
Zact (cm3) *1

Transverse
Section 1
Transverse
Section 2
Transverse
Section 3

Zreq (cm3) *2

Remarks

Upper deck
BottomUpper deck
BottomUpper deck
BottomNotes:*1

As defined in note *1 of Table 2.

*2

Zmc means the diminution limit of minimum section modulus calculated in accordancewith provisions of paragraph 2.2.1.2 of Annex III.

End ofMain Section
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Z10.4 Annex I

ANNEX I

Z10.4
(cont’d)

GUIDELINES FOR TECHNICAL ASSESSMENT IN CONJUNCTION WITH
PLANNING FOR ENHANCED SURVEYS OF DOUBLE HULL OIL TANKERS
SPECIAL SURVEY - HULL
Contents:
1.

INTRODUCTION

2.

PURPOSE AND PRINCIPLES
2.1
Purpose
2.2
Minimum Requirements
2.3
Timing2.4
Aspects to be Considered

3.

TECHNICAL ASSESSMENT
3.1
General
3.2
Methods
3.2.1 Design Details
3.2.2 Corrosion
3.2.3 Locations for Close-up Survey and Thickness Measurement

REFERENCES
1. IACS Unified Requirement Z10.4, "Hull Surveys of Double Hull Oil Tankers."
Recommendation 96: Double Hull Oil Tankers – Guidelines for Surveys, Assessment andRepair of Hull Structures, 2019
2.TSCF, "Guidelines for the Inspection and Maintenance of Double Hull Tanker Structures,
1995."
3.TSCF, "Guidance Manual for Tanker Structures, 1997."
1.

INTRODUCTION

These guidelines contain information and suggestions concerning technical assessments
which may be of use in conjunction with the planning of enhanced special surveys of double
hull oil tankers. As indicated in 5.1.5 of IACS Unified Requirement Z10.4, "Hull Surveys of
Double Hull Oil Tankers," (Ref. 1), the guidelines are a recommended tool which may be
invoked at the discretion of an IACS Member Society, when considered necessary andappropriate, in conjunction with the preparation of the required Survey Programme.
2.

PURPOSE AND PRINCIPLES

2.1
PurposeThe purpose of the technical assessments described in these guidelines is to assist in
identifying critical structural areas, nominating suspect areas and in focusing attention on
structural elements or areas of structural elements which may be particularly susceptible to,or evidence a history of, wastage or damage. This information may be useful in nominating
locations, areas and tanks for thickness measurement, close-up survey and tank testing.
Critical Structural Areas are locations which have been identified from calculations to requiremonitoring or from the service history of the subject ship or from similar or sister ships (ifavailable) to be sensitive to cracking, buckling or corrosion which would impair the structural
integrity of the ship.

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Z10.4 Annex I

Z10.4(cont’d)2.2
Minimum Requirements
However, these guidelines may not be used to reduce the requirements pertaining tothickness measurement, close-up survey and tank testing contained in Tables I, II and III,
respectively, of Z10.4; which are, in all cases, to be complied with as a minimum.
2.3
TimingAs with other aspects of survey planning, the technical assessments described in theseguidelines are to be worked out by the Owner or operator in cooperation with theClassification Society well in advance of the commencement of the Special Survey, i.e., prior
to commencing the survey and normally at least 12 to 15 months before the survey's
completion due date.
2.4
Aspects to be ConsideredTechnical assessments, which may include quantitative or qualitative evaluation of relative
risks of possible deterioration, of the following aspects of a particular ship may be used as abasis for the nomination of tanks and areas for survey:***

Design features such as stress levels on various structural elements, design
details and extent of use of high tensile steel.
Former history with respect to corrosion, cracking, buckling, indents andrepairs for the particular ship as well as similar vessels, where available.
Information with respect to types of cargo carried, use of different tanks forcargo/ballast, protection of tanks and condition of coating, if any.

Technical assessments of the relative risks of susceptibility to damage or deterioration ofvarious structural elements and areas are to be judged and decided on the basis ofrecognised principles and practices, such as may be found in publications of the Tanker
Structure Cooperative Forum (TSCF), (Refs. 2 and 3).
3.

TECHNICAL ASSESSMENT

3.1
GeneralThere are three basic types of possible failure which may be the subject of technicalassessment in connection with planning of surveys; corrosion, cracks and buckling. Contact
damages are not normally covered by the survey plan since indents are usually noted inmemoranda and assumed to be dealt with as a normal routine by Surveyors.
Technical assessments performed in conjunction with the survey planning process are, in
principle to be as shown schematically in Figure 1, which depicts how technical assessments
can be carried out in conjunction with the survey planning process. The approach is basicallyan evaluation of the risk based on the knowledge and experience related to design andcorrosion.
The design is to be considered with respect to structural details which may be susceptible tobuckling or cracking as a result of vibration, high stress levels or fatigue.
Corrosion is related to the ageing process, and is closely connected with the quality ofcorrosion protection at newbuilding, and subsequent maintenance during the service life.
Corrosion may also lead to cracking and/or buckling.
3.2

Methods

3.2.1 Design Details
Damage experience related to the ship in question and similar ships, where available, is themain source of information to be used in the process of planning. In addition, a selection of
structural details from the design drawings is to be included.

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Z10.4 Annex I

Z10.4(cont’d)Typical damage experience to be considered will consist of:
Number, extent, location and frequency of cracks.
Location of buckles.
This information may be found in the survey reports and/or the Owner's files, including theresults of the Owner's own inspections. The defects should be analyzed, noted and marked
on sketches.
In addition, general experience is to be utilized. For example, reference is to be be made to
the two TSCF’s publications mentioned in Ref.2 and Ref.3, which contain a catalogue oftypical damages and proposed repair methods for various tanker structural details.
Such figures are to be used together with a review of the main drawings, in order to comparewith the actual structure and search for similar details which may be susceptible to damage.
An example is shown in Figure 2. In particular, Chapter 3 of Ref.2 deals with various aspects
specific to double hull tankers, such as stress concentration locations, misalignment during
construction, corrosion trends, fatigue considerations and areas requiring special attention,
which are to be considered in working out the survey planning.
The review of the main structural drawings, in addition to using the above mentioned figures,
should include checking for typical design details where cracking has been experienced. The
factors contributing to damage are to be carefully considered.
The use of high tensile steel (HTS) is an important factor. Details showing good service
experience where ordinary, mild steel has been used may be more susceptible to damage
when HTS, and its higher associated stresses, are utilized. There is extensive and, in general,
good experience, with the use of HTS for longitudinal material in deck and bottom structures.
Experience in other locations, where the dynamic stresses may be higher, is less favourable,
e.g. side structures.
In this respect, stress calculations of typical and important components and details, inaccordance with the latest Rules or other relevant methods, may prove useful and are to beconsidered.
The selected areas of the structure identified during this process are to be recorded andmarked on the structural drawings to be included in the Survey Programme.
3.2.2 Corrosion
In order to evaluate relative corrosion risks, the following information is generally to beconsidered:-

Usage of Tanks and Spaces
Condition of Coatings
Cleaning Procedures
Previous Corrosion Damage
Ballast use and time for Cargo Tanks
Corrosion Risk Scheme (See Ref. 3, Table 2.1)
Location of Heated Tanks

Ref. 3 gives definitive examples which can be used for judging and describing coating
condition, using typical pictures of conditions.
The evaluation of corrosion risks is to be based on information in Ref. 3, together with
relevant information on the anticipated condition of the ship as derived from the informationcollected in order to prepare the Survey Programme and the age of the ship.
The various tanks and spaces are to be listed with the corrosion risks nominated accordingly.
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Z10.4 Annex I

Z10.4(cont’d)Special attention is to be given to the areas where the double hull tanker is particularly
exposed to corrosion. To do this end, the specific aspects addressing corrosion in double hulltankers indicated in 3.4 (Corrosion trends) of Ref.2 are to be taken into account.
3.2.3

Locations for Close-up Survey and Thickness Measurement

On the basis of the table of corrosion risks and the evaluation of design experience, thelocations for initial close-up survey and thickness measurement (areas and sections) may be
nominated.
The sections subject to thickness measurement are to normally be nominated in tanks andspaces where corrosion risk is judged to be the highest.
The nomination of tanks and spaces for close-up survey should, initially, be based on highest
corrosion risk, and should always include ballast tanks. The principle for the selection is to bethat the extent is increased by age or where information is insufficient or unreliable.

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Z10.4 Annex I

Z10.4(cont’d)Input:
Drawings, Reports,
Acceptable Corrosion
Allowance

Collection of Information

Coating Condition
Usage of Tanks
Corrosion Risk

Design Related Risk
Analyse:Hull Damage
This Ship

Coating condition
Usage of Tanks

Corrosion
Damage This
Ship

Analyse:Hull Damage
for Similar Ships
Where Available

Corrosion
Damage Similar
Ship where
Available

Hull Damage:
General Experience

Present Areas
where Damage has
been found andRisks consideredhigh. Mark Sketches
or Drawings

Location for Thickness Measurement and Close-Up Survey

SurveyProgramme

Acceptance byClass & Owner

SurveyFigure 1:

Technical Assessment and the Survey Planning Process
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Z10.4 Annex I

Z10.4(cont’d)Figure 2:

Typical Damage and Repair Example (Reproduced from Ref. 2) End of
Annex I
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Z10.4 Annex II

ANNEX II

Z10.4
(cont’d)

RECOMMENDED PROCEDURES FOR THICKNESS MEASUREMENTS
OF DOUBLE HULL OIL TANKERS**
Note: Annex II is recommendatory.

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Z10.4 Annex II

Z10.4(cont’d)

CONTENTS

Sheet 1

Sheet 1-

Contents

Sheet 2-

Instructions

Sheet 3-General Particulars

Sheet 4-

Report TM1-DHT for recording the thickness measurements of all deck
plating, all bottom shell plating and side shell plating

Sheet 5-

Report TM2-DHT (i) for recording the thickness measurement of shelland deck plating at transverse sections - strength deck andsheerstrake plating

Sheet 6-

Report TM2-DHT (ii) for recording the thickness measurement of shelland deck plating at transverse sections - shell plating

Sheet 7-

Report TM3-DHT for recording the thickness measurement of
longitudinal members at transverse sections (including double hull
plating)

Sheet 8-

Report TM4-DHT for recording the thickness measurement oftransverse structural members

Sheet 9-

Report TM5-DHT for recording the thickness measurement of
W.T./O.T. transverse bulkheads

Sheet 10-

Report TM6-DHT for recording the thickness measurement of
miscellaneous structural members

Sheet 11-

Typical transverse section of a double hull oil tanker (up to 150,000dwt). The diagram includes details of the items to be measured and thereport forms to be used.

Sheet 12-

Typical transverse section of a double hull oil tanker (above 150,000dwt). The diagram included details of the items to be measured and thereport forms to be used.

Sheet 13-

Transverse section outline. The diagram may be used for those ships
where the diagrams on sheet 11 and sheet 12 are not suitable

Sheet 14-

Transverse section and transverse bulkheads of a double hull
oil tanker showing typical areas for thickness measurement inassociation with close-up survey requirements, areas (1) to (5) as
defined in Table I of the UR Z10.4.

Sheet 15-

Transverse section of a double hull oil tanker showing typicalareas for thickness measurement in association with close-up survey
requirements, areas (6) to (7) as defined in Table I of the UR Z10.4.

REPORTSGUIDANCE

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Z10.4 Annex II
Sheet 2

INSTRUCTIONS

Z10.4

Recommended Procedures for Thickness Measurements of
Double Hull Oil Tankers(cont’d)1.

This document is to be used for recording thickness measurements as required by
IACS Unified Requirement Z10.4.

2.

Reporting forms TM1-DHT, TM2-DHT, TM3-DHT, TM4-DHT, TM5-DHT and TM6-DHT(sheets 4-10) are to be used for recording thickness measurements and the maximum
allowable diminution is to be stated.
The maximum allowable diminution could be stated in an attached document.

3.

The remaining sheets 11-15 are guidance diagrams and notes relating to the reporting
forms and the procedure for the thickness measurements.

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Z10.4 Annex II

Z10.4(cont’d)

Sheet 3

GENERAL PARTICULARS
Ship’s name:IMO Number:Class Identification number:Port of registry:Gross tons:Deadweight:Date of build:Classification society:-

Name of Company performing the thickness measurement:Thickness measurement company certified by:Certificate No.:Certificate valid from..................to................
Place of measurement:First date of measurement:Last date of measurement:Special survey/intermediate survey due:-*
Details of measurement equipment:Qualification of operator:Report Number:-Consisting of......Sheets

Name of operator:-........................

Name of surveyor:-........................

Signature of operator:-.

.......................

Signature of surveyor:-........................

Firm official stamp:-........................

Classification Society
Official Stamp:-........................

* Delete as appropriate

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Z10.4 Annex II

Z10.4 TM1-DHT

Report on THICKNESS MEASUREMENT of ALL DECK PLATING, ALL BOTTOM SHELL PLATING
or SIDE SHELL PLATING*(* - delete as appropriate)(cont’d)Ship’s name.........................

Class Identity No. .........................

Sheet 4

Report No. .........................

STRAKEPOSITIONPLATE
POSITION

No.
or
Letter

Org.
Thk.
mm

GaugedForward Reading
Diminution P
Diminution S

GaugedAft Reading
Diminution P

Diminution S

P

mm

P

mm

mm

S

%

mm

%

S

%

%

Mean Diminution%
P

S

Maximum
Allowable
Diminution
mm

12th forward
11th
10th
9th
8th
7th
6th
5th
4th
3rd
2nd
1st
Amidships
1st aft
2nd
3rd
4th
5th
6th
7th
8th
9th
10th
11th
12th

Operators Signature.............................................

NOTES – See Reverse

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Z10.4 Annex II

Z10.4(cont’d)NOTES TO THE REPORT TM1-DHT
1.

2.

This report is to be used for recording the thickness measurement of:1.1

All strength deck plating within the cargo area.

1.2

All keel, bottom shell plating and bilge plating within the cargo area.

1.3

Side shell plating including selected wind and water strakes outside cargo area.

1.4

All wind and water strakes within cargo area.

The strake position is to be clearly indicated as follows:2.1

For strength deck indicate the number of the strake of plating inboard from thestringer plate.

2.2

For bottom plating indicate the number of the strake of plating outboard fromthe keel plate.

2.3

For side shell plating give number of the strake of plating below sheerstrake
and letter as shown on shell expansion.

3.

Measurements are to be taken at the forward and aft areas of all and where plates
cross ballast/cargo tank boundaries separate measurements for the area of plating in
way of each type of tank are to be recorded.

4.

The single measurements recorded are to represent the average of multiple
measurements.

5.

The maximum allowable diminution could be stated in an attached document.

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Z10.4 Annex II

Z10.4 TM2-DHT (i)Sheet 5

Report on THICKNESS MEASUREMENT OF SHELL AND DECK PLATING(one, two or three transverse sections)(cont’d)Ship’s name.........................

Class Identity No. .........................

Report No. .........................

STRENGTH DECK AND SHEERSTRAKE PLATINGFIRST TRANSVERSE SECTION AT FRAME NUMBER

STRAKEPOSITION

No.
or
LetterSECOND TRANSVERSE SECTION AT FRAME NUMBER

Org.
Thk.

Max.
Alwb.
Dim.

GaugedDiminution
P

Diminution
S

mm

mm

P

mm

mm

S

%

%

No.
or
Letter

Org.
Thk.

Max.
Alwb.
Dim.

GaugedDiminution
P

Diminution
S

mm

mm

P

mm

mm

S

%

%

THIRD TRANSVERSE SECTION AT FRAME NUMBER
No.
or
Letter

Org.
Thk.

Max.
Alwb.
Dim.

GaugedDiminution
P

Diminution
S

mm

mm

P

mm

mm

S

%

StringerPlate
1st strake
inboard
2nd
3rd
4th
5th
6th
7th
8th
9th
10th
11th
12th
13th
14th
centrestrakesheerstrakeTOPSIDETOTAL

Operators Signature.............................................

NOTES – See Reverse

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Z10.4 Annex II

Z10.4

NOTES TO THE REPORT TM2-DHT (i)(cont’d)1.

This report form is to be used for recording the thickness measurements of:Strength deck plating and sheerstrake plating transverse sections:
One, two or three sections within the cargo area comprising of the structural items (0), (1)and (2) as shown on the diagrams of typical transverse sections illustrated on sheets 11
and 12 of this document.

2.

The topside area comprises deck plating, stringer plate and sheerstrake (including rounded
gunwales).

3.

The exact frame station of measurement is to be stated.

4.

The single measurements recorded are to represent the average of multiple measurements.

5.

The maximum allowable diminution could be stated in an attached document.

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Z10.4 Annex II

Z10.4 TM2-DHT (ii)

Report on THICKNESS MEASUREMENT OF SHELL AND DECK PLATING(one, two or three transverse sections)(cont’d)Ship’s name.........................

Sheet 6Class Identity No. .........................

Report No. .........................

SHELL PLATINGFIRST TRANSVERSE SECTION AT FRAME NUMBER

STRAKEPOSITION

No.
or
LetterSECOND TRANSVERSE SECTION AT FRAME NUMBER

Org.
Thk.

Max.
Alwb.
Dim.

GaugedDiminution
P

Diminution
S

mm

mm

P

mm

mm

S

%

%

No.
or
Letter

Org.
Thk.

Max.
Alwb.
Dim.

GaugedDiminution
P

Diminution
S

mm

mm

P

mm

mm

S

%

%

THIRD TRANSVERSE SECTION AT FRAME NUMBER
No.
or
Letter

Org.
Thk.

Max.
Alwb.
Dim.

GaugedDiminution
P

Diminution
S

mm

mm

P

mm

mm

S

%

1st below
sheer
strake
2nd
3rd
4th
5th
6th
7th
8th
9th
10th
11th
12th
13th
14th
15th
16th
17th
18th
19th
20th
keel strake
BOTTOM
TOTAL

Operators Signature.............................................

NOTES – See Reverse

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Z10.4 Annex II

Z10.4

NOTES TO THE REPORT TM2-DHT (ii)(cont’d)1.

This report form is to be used for recording the thickness measurements of:
Shell plating transverse sections:
One, two or three sections within the cargo area comprising of the structural items(3), (4) and (5) and (6) as shown on the diagrams of typical transverse sections
illustrated on sheets 11 and 12 of this document.

2.

The bottom area comprises keel, bottom and bilge plating.

3.

The exact frame station of measurement is to be stated.

4.

The single measurements recorded are to represent the average of multiple
measurements.

5.

The maximum allowable diminution could be stated in an attached document.

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Z10.4 Annex II

Z10.4 TM3-DHT

Report on THICKNESS MEASUREMENT OF LONGITUDINAL MEMBERS(one, two or three transverse sections)(cont’d)Ship’s name.........................

Class Identity No. .........................

FIRST TRANSVERSE SECTION AT FRAME NUMBER

STRUCTURAL
MEMBER

Item
No.

Sheet 7

SECOND TRANSVERSE SECTION AT FRAME NUMBER

Org.
Thk.

Max.
Alwb.
Dim.

GaugedDiminution
P

Diminution
S

mm

mm

P

mm

mm

S

%

Report No. ........................

%

Item
No.

Org.
Thk.

Max.
Alwb.
Dim.

GaugedDiminution
P

Diminution
S

mm

mm

P

mm

mm

Operators Signature.............................................

S

%

%

THIRD TRANSVERSE SECTION AT FRAME NUMBER
Item
No.

Org.
Thk.

Max.
Alwb.
Dim.

GaugedDiminution
P

Diminution
S

mm

mm

P

mm

mm

S

%

NOTES – See Reverse

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Z10.4 Annex II

Z10.4

NOTES TO THE REPORT TM3-DHT(cont’d)1.

This report is to be used for recording the thickness measurements of:Longitudinal Members at transverse sections:
One, two or three sections within the cargo area comprising of the appropriate
structural items (10) to (29) as shown on the diagrams of typical transverse
sections illustrated on sheets 11 and 12 of this document.

2.

The exact frame station of measurement is to be stated.

3.

The single measurements recorded are to represent the average of multiple
measurements.

4.

The maximum allowable diminution could be stated in an attached document.

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Z10.4 Annex II

Z10.4 TM4-DHT(cont’d)

Sheet 8

Report on THICKNESS MEASUREMENT OF TRANSVERSE STRUCTURAL MEMBERS
In the cargo oil and water ballast tanks within the cargo tank length

Ship’s name.........................

Class Identity No. .........................

Report No. ........................

TANK DESCRIPTION:
LOCATION OF STRUCTURE:
STRUCTURAL MEMBER

ITEM

Original
Thickness
mm

Max.
Alwb.
Dim.
mm

GaugedP

Operators Signature.............................................

Diminution
P
S

mm

Diminution
S
%

mm

%

NOTES – See Reverse

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Z10.4 Annex II

Z10.4

NOTES TO THE REPORT TM4-DHT(cont’d)1.

This report is to be used for recording the thickness measurements of:Transverse structural members, comprising of the appropriate structural items(30) to (36) as shown on diagrams of typical transverse sections illustrated on
sheets 11 and 12 of this document.

2.

Guidance for areas of measurement is indicated on sheet 14 and 15 of this document.
The single measurements recorded are to represent the average of multiple
measurements.

3.

The maximum allowable diminution could be stated in an attached document.

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Z10.4 Annex II

Z10.4 TM5-DHT(cont’d)

Sheet 9

Report on THICKNESS OF W.T./O.T. TRANSVERSE BULKHEADS
within the cargo tank or cargo hold spaces

Ship’s name.........................

Class Identity No. .........................

Report No. ........................

TANK/HOLD DESCRIPTION:
LOCATION OF STRUCTURE:
STRUCTURAL COMPONENT(PLATING/STIFFENER)

FRAME NO.:

Original
Thickness
mm

Max.
Alwb.
Dim.
mm

GaugedPort

Operators Signature.............................................

Starboard

Diminution
P
mm

Diminution
S
%

mm

%

NOTES – See Reverse

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Z10.4 Annex II

Z10.4

NOTES TO THE REPORT TM5-DHT(cont’d)1.

This report is to be used for recording the thickness measurement of:
W.T./O.T. transverse bulkheads.

2.

Guidance for areas of measurement is indicated on sheet 14 of this document.

3.

The single measurements recorded are to represent the average of multiple
measurements.

4.

The maximum allowable diminution could be stated in an attached document.

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Z10.4 Annex II

Z10.4 TM6-DHT(cont’d)Report on THICKNESS MEASUREMENT OF MISCELLANEOUS STRUCTURAL MEMBERS

Ship’s name.........................

Class Identity No. .........................

Sheet 10

Report No. ........................

STRUCTURAL MEMBER:

SKETCHLOCATION OF STRUCTURE:
Description

Org.
Thk.
mm

Max.
Alwb.
Dim.
mm

GaugedDiminution
P

Diminution
S

P

mm

mm

S

%

Operators Signature.............................................

%NOTES – See Reverse

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Z10.4 Annex II

Z10.4

NOTES TO THE REPORT TM6-DHT(cont’d)1.

This report is to be used for recording the thickness measurement of:Miscellaneous structural members.

2.

The single measurements recorded are to represent the average of multiple
measurements.

3.

The maximum allowable diminution could be stated in an attached document.

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Z10.4 Annex II

Z10.4

Thickness Measurement - Double Hull Oil Tankers(cont’d)

Sheet 11

Typical transverse section of a double hull oil tanker up to 150,000 dwt with indication of
longitudinal and transverse members

0.
1.
2.
3.
4.
5.
6.

Report on TM2-DHT(i) & (ii)Strength deck plating
Stringer plate
Sheerstrake
Side shell plating
Bilge plating
Bottom shell plating
Keel plate

Report on TM3-DHT
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.

Deck longitudinals
Sheerstrake longitudinals
Side shell longitudinals
Bilge longitudinals
Bottom longitudinals
Deck girders
Horizontal girders in wing ballast tanks
Bottom girders
Longitudinal bulkhead top strake
Longitudinal bulkhead bottom strake

20.
21.
22.
23.
24.
25.
26.
27.
28.
29.

Longitudinal bulkhead plating (remainder)
Longitudinal bulkhead longitudinals
Inner side plating
Inner side longitudinals
Hopper plating
Hopper longitudinals
Inner bottom plating
Inner bottom longitudinals
Topside tank plating
Topside tank longitudinals

Report on TM4-DHT
30.
31.
32.
33.
34.
35.
36.

Deck transverse - centre tank
Deck transverse - wing tank
Vertical web in wing ballast tank
Double bottom floor - wing tank
Double bottom floor - centre tankLongitudinal bulkhead vertical web
Cross ties

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Z10.4 Annex II

Z10.4(cont’d)

Sheet 12
Thickness Measurement - Double Hull Oil Tankers
Typical transverse section of a double hull oil tanker above 150,000 dwt with indication of
longitudinal and transverse members

0.
1.
2.
3.
4.
5.
6.

Report on TM2-DHT(i) & (ii)Strength deck plating
Stringer plate
Sheerstrake
Side shell plating
Bilge plating
Bottom shell plating
Keel plate

Report on TM3-DHT
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.

Deck longitudinals
Sheerstrake longitudinals
Side shell longitudinals
Bilge longitudinals
Bottom longitudinals
Deck girders
Horizontal girders in wing ballast tanks
Bottom girders
Longitudinal bulkhead top strake
Longitudinal bulkhead bottom strake

20.
21.
22.
23.
24.
25.
26.
27.
28.
29.

Longitudinal bulkhead plating (remainder)
Longitudinal bulkhead longitudinals
Inner side plating
Inner side longitudinals
Hopper plating
Hopper longitudinals
Inner bottom plating
Inner bottom longitudinals
Topside tank plating
Topside tank longitudinals

Report on TM4-DHT
30.
31.
32.
33.
34.
35.
36.

Deck transverse - centre tank
Deck transverse - wing tank
Vertical web in wing ballast tank
Double bottom floor - wing tank
Double bottom floor - centre tankLongitudinal bulkhead vertical web
Cross ties

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Z10.4 Annex II

Z10.4(cont’d)Thickness Measurement - Double Hull Oil Tankers

Sheet 13

Transverse section outline
The diagram may be used for those ships where the diagrams on sheet 11 and 12 are notsuitable

0.
1.
2.
3.
4.
5.
6.

Report on TM2-DHT(i) & (ii)Strength deck plating
Stringer plate
Sheerstrake
Side shell plating
Bilge plating
Bottom shell plating
Keel plate

Report on TM3-DHT
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.

Deck longitudinals
Sheerstrake longitudinals
Side shell longitudinals
Bilge longitudinals
Bottom longitudinals
Deck girders
Horizontal girders in wing ballast tanks
Bottom girders
Longitudinal bulkhead top strake
Longitudinal bulkhead bottom strake

20.
21.
22.
23.
24.
25.
26.
27.
28.
29.

Longitudinal bulkhead plating (remainder)
Longitudinal bulkhead longitudinals
Inner side plating
Inner side longitudinals
Hopper plating
Hopper longitudinals
Inner bottom plating
Inner bottom longitudinals
Topside tank plating
Topside tank longitudinals

Report on TM4-DHT
30.
31.
32.
33.
34.
35.
36.

Deck transverse - centre tank
Deck transverse - wing tank
Vertical web in wing ballast tank
Double bottom floor - wing tank
Double bottom floor - centre tankLongitudinal bulkhead vertical web
Cross ties

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Z10.4 Annex II

Z10.4(cont’d)Close-up Survey and Thickness Measurement Areas

Sheet 14

Areas subject to close-up survey and thickness measurements - areas (1) to (5) as defined inTable I of UR Z10.4 - Thickness to be reported on TM3-DHT(CSR), TM4-DHT(CSR) andTM5-DHT(CSR) as appropriate.

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Z10.4 Annex II

Z10.4(cont’d)Close-up Survey and Thickness Measurement Areas

Sheet 15

Areas subject to close-up survey and thickness measurements - areas (6) to (7) as defined inTable I of UR Z10.4 - Thickness to be reported on TM3-DHT(CSR), TM4-DHT(CSR) as
appropriate.

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Z10.4 Annex II (CSR)

Z10.4

ANNEX II (CSR)(cont’d)

IACS RECOMMENDED PROCEDURES FOR THICKNESS MEASUREMENTS
OF DOUBLE HULL OIL TANKERS BUILT UNDER
IACS COMMON STRUCTURAL RULES**
Note: Annex II (CSR) is recommendatory.

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Z10.4 Annex II (CSR)

Z10.4

CONTENTS(cont’d)

Sheet 1

Sheet 1-

Contents

Sheet 2-

Instructions

Sheet 3-General particulars

Sheet 4-

Report TM1-DHT(CSR) for recording the thickness measurement of
all deck plating, all bottom plating and side shell plating

Sheet 5-

Report TM2-DHT(CSR) (i) for recording the thickness measurement ofshell and deck plating at transverse sections - strength deck andsheerstrake plating

Sheet 6-

Report TM2-DHT(CSR) (ii) for recording the thickness measurement ofshell plating at transverse sections

Sheet 7-

Report TM3-DHT(CSR) for recording the thickness measurement of
longitudinal members at transverse sections (including double hull
plating)

Sheet 8-

Report TM4-DHT(CSR) for recording the thickness measurement oftransverse structural members

Sheet 9-

Report TM5-DHT(CSR) for recording the thickness measurement of
W.T./O.T. transverse bulkheads

Sheet 10-

Report TM6-DHT(CSR) for recording the thickness measurement of
miscellaneous structural members

Sheet 11-

Typical transverse section of a double hull oil tanker (up to 150,000dwt). The diagram includes details of the items to be measured and thereport forms to be used.

Sheet 12-

Typical transverse section of a double hull oil tanker (above 150,000dwt). The diagram includes details of the items to be measured and thereport forms to be used.

Sheet 13-

Transverse section outline. This diagram may be used for those ships
where the diagram on sheet 11 and sheet 12 is not suitable.

Sheet 14-

Transverse section and transverse bulkheads of a double hull
oil tanker showing typical areas for thickness measurement inassociation with close-up survey requirements, areas (1) to (5) as
defined in Table I of the UR Z10.4.

Sheet 15-

Transverse section of a double hull oil tanker showing typicalareas for thickness measurement in association with close-up survey
requirements, areas (6) to (7) as defined in Table I of the UR Z10.4.

REPORTSGUIDANCE

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Z10.4 Annex II (CSR)

Z10.4

INSTRUCTIONS(cont’d)

Sheet 2

IACS Recommended Procedures for Thickness Measurements of
Double Hull Oil Tankers Built under IACS Common Structural Rules
1.

This document is to be used for recording thickness measurements of double hull oiltankers built under IACS Common Structural Rules as required by the IACS Unified
Requirement Z10.4.

2.

Reporting forms TM1-DHT(CSR), TM2-DHT(CSR) (i) and (ii), TM3-DHT(CSR), TM4DHT(CSR), TM5-DHT(CSR) and TM6-DHT(CSR) (sheets 4-10) are to be used forrecording thickness measurements. The as-built thickness and the voluntary thickness
addition and renewal thickness (minimum allowable thickness) are to be stated in thesaid forms.

3.

The remaining sheets 11-15 are guidance diagrams and notes relating to the reporting
forms and the procedure for the thickness measurement.

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Z10.4 Annex II (CSR)

Z10.4

Sheet 3

GENERAL PARTICULARS(cont’d)Ships name:IMO number:Class identity number:Port of registry:Gross tons:Deadweight:Date of build:Classification Society:-

Name of Firm performing thickness measurement:Thickness measurement firm certified by:Certificate No:Certificate valid from..................to................
Place of measurement:First date of measurement:Last date of measurement:Special survey/intermediate survey due:-*
Details of measurement equipment:Qualification of operators:Report Number:-consisting of......Sheets

Name of operator:-........................

Name of surveyor:-........................

Signature of operator:-.......................

Signature of surveyor:-........................

Firm
Official Stamp:-

Classification Society
Official Stamp:-* Delete as appropriate

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Z10.4 Annex II (CSR)

Z10.4 TM1-DHT(CSR)(cont’d)Report on THICKNESS MEASUREMENT of ALL DECK PLATING, ALL BOTTOM PLATING
or SIDE SHELL PLATING*(* - delete as appropriate)

Ship’s name.........................

Class Identity No.........................

Sheet 4

Report No.........................

STRAKEPOSITIONPLATE
POSITION

No.
or
LetterAs Built
Thk.
mm

Voluntary
Thickness
Additionmm

RenewalThicknessmm(a)Forward Reading
Gauged Thk.
Remaining Corr.
mm
Addition, mm(b1)(c1)=(b1)-(a)P
S
PS

Gauged Thk.
mm
(b2)
P
S

Aft Reading
Remaining Corr.
Addition, mm(c2)=(b2)-(a)P
S

Mean Remaining Corr.
Addition, mm[(c1)+(c2)]/2
PS

12th forward
11th
10th
9th
8th
7th
6th
5th
4th
3rd
2nd
1st
Amidships
1st aft
2nd
3rd
4th
5th
6th
7th
8th
9th
10th
11th
12th

Operators Signature.............................................

NOTES – See Reverse

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Z10.4 Annex II (CSR)

Z10.4(cont’d)NOTES TO REPORT TM1-DHT(CSR)
1.

2.

This report is to be used for recording the thickness measurement of:1.1

All strength deck plating within the cargo length area.

1.2

All keel, bottom shell plating and bilge plating within the cargo length area.

1.3

Side shell plating including selected wind and water strakes outside the cargo
length area.

1.4

All wind and water strakes within the cargo length area.

The strake position is to be clearly indicated as follows:2.1

For strength deck indicate the number of the strake of plating inboard from thestringer plate.

2.2

For bottom plating indicate the number of the strake of plating outboard fromthe keel plate.

2.3

For side shell plating give number of the strake of plating sheerstrake andletter as shown on shell expansion.

3.

Measurements are to be taken at the forward and aft areas of all plates crossballast/cargo tank boundaries separate measurements for the area of plating in way ofeach type of tank are to be recorded.

4.

The single measurements recorded are to represent the average of multiple
measurements.

5.

The remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall berenewed, and the mark “R” is to be indicated in the right-hand column. If the result is
between 0 and 0.5 mm (0 included), the structure in way shall be additional gauged,
and the mark “S” is to be indicated in the right-hand column.

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Z10.4 Annex II (CSR)

Z10.4 TM2-DHT(CSR) (i)(cont’d)Report on THICKNESS MEASUREMENT OF SHELL AND DECK PLATING(one, two or three transverse sections)

Ship’s name.........................

Sheet 5Class Identity No.........................

Report No.........................

STRENGTH DECK AND SHEERSTRAKE PLATINGFIRST TRANSVERSE SECTION AT FRAME NUMBER

STRAKEPOSITION

No.
or
Letter

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm

Gauged
Thk.
mm
(b)

(a)

P

S

Remaining Corr.
Addition, mm(b)-(a)P

S

SECOND TRANSVERSE SECTION AT FRAME NUMBER
No.
or
Letter

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm

Gauged
Thk.
mm
(b)

(a)

P

S

Remaining Corr.
Addition, mm(b)-(a)P

S

THIRD TRANSVERSE SECTION AT FRAME NUMBER
No.
or
Letter

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm

Gauged
Thk.
mm
(b)

(a)

P

S

Remaining Corr.
Addition, mm(b)-(a)P

StringerPlate
1st strake
inboard
2nd
3rd
4th
5th
6th
7th
8th
9th
10th
11th
12th
13th
14th
centrestrakesheerstrakeTOPSIDETOTAL

Operators Signature.............................................

NOTES – See Reverse

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S

Z10.4 Annex II (CSR)

Z10.4(cont’d)NOTES TO REPORT TM2-DHT(CSR) (i)1.

This report is to be used for recording the thickness measurement of:Strength deck plating and sheerstrake plating transverse sections:One, two or three sections within the cargo length area, comprising of thestructural items (0), (1) and (2) as shown on the diagram of typical transverse
sections illustrated on sheets 11 and 12 of this document.

2.

The topside area comprises deck plating, stringer plate and sheerstrake (including
rounded gunwales).

3.

The exact frame station of measurement is to be stated.

4.

The single measurements recorded are to represent the average of multiple
measurements.

5.

The remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall be renewed,
and the mark “R” is to be indicated in the right-hand column. If the result is between 0
and 0.5 mm (0 included), the structure in way shall be additional gauged, and the mark“S” is to be indicated in the right-hand column.

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Z10.4 Annex II (CSR)

Z10.4 TM2-DHT(CSR) (ii)(cont’d)Report on THICKNESS MEASUREMENT OF SHELL PLATING(one, two or three transverse sections)

Ship’s name.........................

Sheet 6Class Identity No.........................

Report No.........................

SHELL PLATINGFIRST TRANSVERSE SECTION AT FRAME NUMBER

STRAKEPOSITION

No.
or
Letter

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm

Gauged
Thk.
mm
(b)

(a)

P

S

Remaining Corr.
Addition, mm(b)-(a)P

S

SECOND TRANSVERSE SECTION AT FRAME NUMBER
No.
or
Letter

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm

Gauged
Thk.
mm
(b)

(a)

P

S

Remaining Corr.
Addition, mm(b)-(a)P

S

THIRD TRANSVERSE SECTION AT FRAME NUMBER
No.
or
Letter

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm

Gauged
Thk.
mm
(b)

(a)

P

S

Remaining Corr.
Addition, mm(b)-(a)P

1st below
sheer
strake
2nd
3rd
4th
5th
6th
7th
8th
9th
10th
11th
12th
13th
14th
15th
16th
17th
18th
19th
20th
Keel strake
BOTTOM
TOTAL

Operators Signature.............................................

NOTES – See Reverse

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Z10.4 Annex II (CSR)

Z10.4(cont’d)NOTES TO REPORT TM2-DHT(CSR) (ii)1.

This report is to be used for recording the thickness measurement of:Shell plating transverse sections:One, two or three sections within the cargo length area comprising of thestructural items (3), (4) and (5) and (6) as shown on the diagram of typicaltransverse sections illustrated on sheets 11 and 12 of this document.

2.

The bottom area comprises keel, bottom and bilge plating.

3.

The exact frame station of measurement is to be stated.

4.

The single measurements recorded are to represent the average of multiple
measurements.

5.

The remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall berenewed, and the mark “R” is to be indicated in the right-hand column. If the result is
between 0 and 0.5 mm (0 included), the structure in way shall be additional gauged,
and the mark “S” is to be indicated in the right-hand column.

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Z10.4 Annex II (CSR)

Z10.4 TM3-DHT(CSR)

Report on THICKNESS MEASUREMENT OF LONGITUDINAL MEMBERS(one, two or three transverse sections)(cont’d)Ship’s name.........................

Class Identity No.........................

FIRST TRANSVERSE SECTION AT FRAME NUMBER
STRUCTURAL
MEMBER

Item
No.

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm

Gauged
Thk.
mm
(b)

(a)

P

S

Remaining Corr.
Addition, mm(b)-(a)P

S

Report No........................

SECOND TRANSVERSE SECTION AT FRAME NUMBER
Item
No.

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Sheet 7

Ren.
Thk.
mm

Gauged
Thk.
mm
(b)

(a)

P

Operators Signature.............................................

S

Remaining Corr.
Addition, mm(b)-(a)P

S

THIRD TRANSVERSE SECTION AT FRAME NUMBER
Item
No.

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm

Gauged
Thk.
mm
(b)

(a)

P

S

Remaining Corr.
Addition, mm(b)-(a)P

NOTES – See Reverse

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S

Z10.4 Annex II (CSR)

Z10.4(cont’d)NOTES TO REPORT TM3-DHT(CSR)
1.

This report is to be used for recording the thickness measurement of:Longitudinal Members at transverse sections:One, two or three sections within the cargo length area, comprising of theappropriate structural items (10) to (29) as shown on the diagram of typicaltransverse sections illustrated on sheets 11 and 12 of this document.

2.

The exact frame station of measurement is to be stated.

3.

The single measurements recorded are to represent the average of multiple
measurements.

4.

The remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall berenewed, and the mark “R” is to be indicated in the right-hand column. If the result is
between 0 and 0.5 mm (0 included), the structure in way shall be additional gauged,
and the mark “S” is to be indicated in the right-hand column.

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Z10.4 Annex II (CSR)

Z10.4 TM4-DHT(CSR)(cont’d)Report on THICKNESS MEASUREMENT OF TRANSVERSE STRUCTURAL MEMBERS
In the cargo oil and water ballast tanks within the cargo tank length

Ship’s name.........................

Class Identity No.........................

Sheet 8

Report No........................

TANK DESCRIPTION:
LOCATION OF STRUCTURE
STRUCTURAL MEMBERITEM

As Built
Thicknessmm

Voluntary
Thickness
Additionmm

RenewalThicknessmm(a)Operators Signature.............................................

Gauged Thickness
mm
(b)

P

S

Remaining Corr. Additionmm(b)-(a)PS

NOTES – See Reverse

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Z10.4 Annex II (CSR)

Z10.4(cont’d)NOTES TO REPORT TM4-DHT(CSR)
1.

This report is to be used for recording the thickness measurement of:Transverse structural members, comprising of the appropriate structural items(30) to (36) as shown on diagram of typical transverse section, illustrated on
sheets 11 and 12 of this document.

2.

Guidance for areas if measurement is indicated on the diagrams shown on sheet 14
and 15 of this document.

3.

The single measurements recorded are to represent the average of multiple
measurements.

4.

The remaining corrosion addition is to be recorded with result of gauged
thickness minus renewal thickness. If the result is negative, the structure in way
shall be renewed, and the mark “R” is to be indicated in the right-hand column. If
the result is between 0 and 0.5 mm (0 included), the structure in way shall be
additional gauged, and the mark “S” is to be indicated in the right-hand column.

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Z10.4 Annex II (CSR)

Z10.4 TM5-DHT(CSR)(cont’d)Report on THICKNESS OF W.T./O.T. TRANSVERSE BULKHEADS
Within the cargo and ballast tanks

Ship’s name.........................

Sheet 9Class Identity No.........................

Report No........................

TANK DESCRIPTION:
LOCATION OF STRUCTURE:
STRUCTURAL COMPONENT(PLATING/STIFFENER)

FRAME NO.:As Built
Thicknessmm

Voluntary
Thickness
Additionmm

RenewalThicknessmm(a)Operators Signature.............................................

Gauged Thickness
mm
(b)

P

S

Remaining Corr. Additionmm(b)-(a)PS

NOTES – See Reverse

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Z10.4 Annex II (CSR)

Z10.4(cont’d)NOTES TO REPORT TM5-DHT(CSR)
1.

This report is to be used for recording the thickness measurement of:W.T./O.T. transverse bulkheads.

2.

Guidance for areas of measurement is indicated on the diagrams shown on sheet 14of this document.

3.

The single measurements recorded are to represent the average of multiple
measurements.

4.

The remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall berenewed, and the mark “R” is to be indicated in the right-hand column. If the result is
between 0 and 0.5 mm (0 included), the structure in way shall be additional gauged,
and the mark “S” is to be indicated in the right-hand column.

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Z10.4 Annex II (CSR)

Z10.4 TM6-DHT(CSR)

Report on THICKNESS MEASUREMENT OF MISCELLANEOUS STRUCTURAL MEMBERS

Sheet 10(cont’d)Ship’s name.........................

Class Identity No.........................

Report No........................

STRUCTURAL MEMBER:

SKETCHLOCATION OF STRUCTURE:
Description

As
Built
Thk.
mm

Voluntary
Thickness
Additionmm

Renewal Gauged Thickness
Thickness
mm
mm
(b)
(a)

P

S

Operators Signature.............................................

Remaining Corr. Additionmm(b)-(a)PS

NOTES – See Reverse

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Z10.4 Annex II (CSR)

Z10.4(cont’d)NOTES TO REPORT TM6-DHT(CSR)
1.

This report is to be used for recording the thickness measurement of:Miscellaneous structural members.

2.

The single measurements recorded are to represent the average of multiple
measurements.

3.

The remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall berenewed, and the mark “R” is to be indicated in the right-hand column. If the result is
between 0 and 0.5 mm (0 included), the structure in way shall be additional gauged,
and the mark “S” is to be indicated in the right-hand column.

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Z10.4 Annex II (CSR)

Z10.4

Sheet 11
Thickness Measurement - Double Hull Oil Tankers(cont’d)Typical transverse section of a double hull oil tanker up to 150,000 dwt with indication of
longitudinal and transverse members

0.
1.
2.
3.
4.
5.
6.

Report on TM2-DHT(CSR)(i) & (ii)Strength deck plating
Stringer plate
Sheerstrake
Side shell plating
Bilge plating
Bottom shell plating
Keel plate

Report on TM3-DHT(CSR)
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.

Deck longitudinals
Sheerstrake longitudinals
Side shell longitudinals
Bilge longitudinals
Bottom longitudinals
Deck girders
Horizontal girders in wing ballast tanks
Bottom girders
Longitudinal bulkhead top strake
Longitudinal bulkhead bottom strake

20.
21.
22.
23.
24.
25.
26.
27.
28.
29.

Longitudinal bulkhead plating (remainder)
Longitudinal bulkhead longitudinals
Inner side plating
Inner side longitudinal
Hopper plating
Hopper longitudinal
Inner bottom plating
Inner bottom longitudinals
Topside tank plating
Topside tank longitudinals

Report on TM4-DHT(CSR)

30.
31.
32.
33.
34.
35.
36.

Deck transverse - centre tank
Deck transverse - wing tank
Vertical web in wing ballast tank
Double bottom floor - wing tank
Double bottom floor - centre tankLongitudinal bulkhead vertical web
Cross ties

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Z10.4 Annex II (CSR)
Sheet 12

Z10.4

Thickness Measurement - Double Hull Oil Tankers(cont’d)Typical transverse section of a double hull oil tanker above 150,000 dwt with indication of
longitudinal and transverse members

0.
1.
2.
3.
4.
5.
6.

Report on TM2-DHT(CSR)(i) & (ii)Strength deck plating
Stringer plate
Sheerstrake
Side shell plating
Bilge plating
Bottom shell plating
Keel plate

Report on TM3-DHT(CSR)
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.

Deck longitudinals
Sheerstrake longitudinals
Side shell longitudinals
Bilge longitudinals
Bottom longitudinals
Deck girders
Horizontal girders in wing ballast tanks
Bottom girders
Longitudinal bulkhead top strake
Longitudinal bulkhead bottom strake

20.
21.
22.
23.
24.
25.
26.
27.
28.
29.

Longitudinal bulkhead plating (remainder)
Longitudinal bulkhead longitudinals
Inner side plating
Inner side longitudinal
Hopper plating
Hopper longitudinal
Inner bottom plating
Inner bottom longitudinals
Topside tank plating
Topside tank longitudinals

Report on TM4-DHT(CSR)
30.
31.
32.
33.
34.
35.
36.

Deck transverse - centre tank
Deck transverse - wing tank
Vertical web in wing ballast tank
Double bottom floor - wing tank
Double bottom floor - centre tankLongitudinal bulkhead vertical web
Cross ties

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Z10.4 Annex II (CSR)

Z10.4

Thickness Measurement - Double Hull Oil Tankers(cont’d)

Transverse section outline

Sheet 13The diagram may be used for those ships where the diagrams on sheet 11 and 12 are notsuitable

0.
1.
2.
3.
4.
5.
6.

Report on TM2-DHT(CSR)(i) & (ii)Strength deck plating
Stringer plate
Sheerstrake
Side shell plating
Bilge plating
Bottom shell plating
Keel plate

Report on TM3-DHT(CSR)
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.

Deck longitudinals
Sheerstrake longitudinals
Side shell longitudinals
Bilge longitudinals
Bottom longitudinals
Deck girders
Horizontal girders in wing ballast tanks
Bottom girders
Longitudinal bulkhead top strake
Longitudinal bulkhead bottom strake

20.
21.
22.
23.
24.
25.
26.
27.
28.
29.

Longitudinal bulkhead plating (remainder)
Longitudinal bulkhead longitudinals
Inner side plating
Inner side longitudinal
Hopper plating
Hopper longitudinal
Inner bottom plating
Inner bottom longitudinals
Topside tank plating
Topside tank longitudinals

Report on TM4-DHT(CSR)
30.
31.
32.
33.
34.
35.
36.

Deck transverse - centre tank
Deck transverse - wing tank
Vertical web in wing ballast tank
Double bottom floor - wing tank
Double bottom floor - centre tankLongitudinal bulkhead vertical web
Cross ties

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Z10.4 Annex II (CSR)

Z10.4(cont’d)Close-up Survey and Thickness Measurement Areas

Sheet 14

Areas subject to close-up survey and thickness measurements - areas (1) to (5) as defined inTable I of UR Z10.4 - Thickness to be reported on TM3-DHT(CSR), TM4-DHT(CSR) andTM5-DHT(CSR) as appropriate.

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Z10.4 Annex II (CSR)

Z10.4(cont’d)Close-up Survey and Thickness Measurement Areas

Sheet 15

Areas subject to close-up survey and thickness measurements - areas (6) to (7) as defined inTable I of UR Z10.4 - Thickness to be reported on TM3-DHT(CSR), TM4-DHT(CSR) as
appropriate.

End ofAnnex II

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Z10.4 Annex III

Z10.4(cont’d)

ANNEX III
CRITERIA FOR LONGITUDINAL STRENGTH OF HULL GIRDER FOR OIL TANKERS

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Z10.4 Annex III

Z10.4

ANNEX III(cont’d)

CRITERIA FOR LONGITUDINAL STRENGTH OF HULL
GIRDER FOR OIL TANKERS
1

General1.1
These criteria is to be used for the evaluation of longitudinal strength of the ship's hull
girder as required by section 8.1.1.1.
1.2
In order that ship’s longitudinal strength to be evaluated can be recognized as valid,fillet welding between longitudinal internal members and hull envelopes is to be in soundcondition so as to keep integrity of longitudinal internal members with hull envelopes.
2

Evaluation of longitudinal strength

On oil tankers of 130 m in length and upwards and of over 10 years of age, the longitudinalstrength of the ship's hull girder is to be evaluated in compliance with the requirements of thisannex on the basis of the thickness measured, renewed or reinforced, as appropriate, during
the special survey.
The condition of the hull girder for longitudinal strength evaluation should be determined inaccordance with the methods specified in appendix 3.
2.1

Calculation of transverse sectional areas of deck and bottom flanges of hull
girder

2.1.1 The transverse sectional areas of deck flange (deck plating and deck longitudinals)
and bottom flange (bottom shell plating and bottom longitudinals) of the ship’s hull girder is tobe calculated by using the thickness measured, renewed or reinforced, as appropriate, during
the special survey.
2.1.2 If the diminution of sectional areas of either deck or bottom flange exceeds 10% of
their respective as-built area (i.e. original sectional area when the ship was built), either oneof the following measures is to be taken:

2.2

.1

to renew or reinforce the deck or bottom flanges so that the actual sectional
area is not less than 90% of the as-built area; or.2

to calculate the actual section moduli (Zact) of transverse section of the ship’s
hull girder by applying the calculation method specified in appendix 1, by using
the thickness measured, renewed or reinforced, as appropriate, during thespecial survey.

Requirements for transverse section modulus of hull girder

2.2.1 The actual section moduli of transverse section of the ship’s hull girder calculated inaccordance with the foregoing paragraph 2.1.2.2 is to satisfy either of the following provisions,as applicable:.1

for ships constructed on or after 1 July 2002, the actual section moduli (Zact) of
the transverse section of the ship's hull girder calculated in accordance withthe requirements of the foregoing paragraph 2.1.2.2 should is not to be lessthan the diminution limits determined by the Classification Society*; orPage 115 of 133

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Z10.4 Annex III

Z10.4

.2

(cont’d)*for ships constructed before 1 July 2002, the actual section moduli (Zact) of thetransverse section of the ship's hull girder calculated in accordance with therequirements of the foregoing paragraph 2.1.2.2 is to meet the criteria forminimum section modulus for ships in service required by the Classification
Society, provided that in no case Zact is to be less than the diminution limit of
the minimum section modulus (Zmc) as specified in appendix 2.

The actual transverse section modulus of the hull girder of oil tankers calculated underparagraph 2.2.1.1 of Annex III to UR Z10.4 is not to be less than 90% of the required
section modulus for new buildings specified in IACS Unified Requirements S7* or S11,
whichever is the greater.
* C = 1.0 cn is to be used for the purpose of this calculation.

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Z10.4 Annex III

Z10.4

APPENDIX 1(cont’d)

CALCULATION CRITERIA OF SECTION MODULI OF MIDSHIPSECTION OF HULL GIRDER
1When calculating the transverse section modulus of the ship's hull girder, the sectional
area of all continuous longitudinal strength members is to be taken into account.
2
Large openings, i.e. openings exceeding 2.5m in length or 1.2m in breadth andscallops, where scallop welding is applied, are always to be deducted from the sectional
areas used in the section modulus calculation.
3
Smaller openings (manholes, lightening holes, single scallops in way of seams, etc.)
need not be deducted provided that the sum of their breadths or shadow area breadths in one
transverse section does not reduce the section modulus at deck or bottom by more than 3%
and provided that the height of lightening holes, draining holes and single scallops inlongitudinals or longitudinal girders does not exceed 25% of the web depth, for scallops
maximum 75mm.
4
A deduction-free sum of smaller opening breadths in one transverse section in thebottom or deck area of 0.06(B - ∑b) (where B = breadth of ship, ∑b = total breadth of large
openings) may be considered equivalent to the above reduction in sectional modulus.
5
The shadow area will be obtained by drawing two tangent lines with an opening angleof 30˚.
6

The deck modulus is related to the moulded deck line at side.

7

The bottom modulus is related to the base line.

8
Continuous trunks and longitudinal hatch coamings are to be included in thelongitudinal sectional area provided they are effectively supported by longitudinal bulkheads
or deep girders. The deck modulus is then to be calculated by dividing the moment of inertia
by the following distance, provided this is greater than the distance to the deck line at side:xy t  y  0.9  0.2 Bwhere:
y=distance from neutral axis to top of continuous strength member,x=
distance from top of continuous strength member to centreline of the ship.
x and y to be measured to the point giving the largest value of yt.
9Longitudinal girders between multi-hatchways will be considered by special
calculations.

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Z10.4 Annex III

Z10.4

APPENDIX 2(cont’d)

DIMINUTION LIMIT OF MINIMUM LONGITUDINAL STRENGTH
OF SHIPS IN SERVICE
1
The diminution limit of the minimum section modulus (Zmc) of oil tankers in service isgiven by the following formula:Zmc = cL2B (Cb + 0.7)k (cm3)
where
L

=

Length of ships. L is the distance, in metres, on the summer loadwaterline from the fore side of stem to the after side of the rudder post,or the centre of the rudder stock if there is no rudder post. L is not to beless than 96%, and need not be greater than 97%, of the extreme
length on the summer load waterline. In ships with unusual stern andbow arrangement the length L may be specially considered.

B=

Greatest moulded breadth in metres.

Cb=

Moulded block coefficient at draught d corresponding to summer loadwaterline, based on L and B. Cb is not to be taken less than 0.60.

moulded displaceme nt (m3 ) at draught d
Cb 
LBd
c

=

0.9 cn1.5

 300  L 
cn  10.75   100 for 130 m ≤ L ≤ 300 m

cn  10.75

for 300 m < L < 350 m
1.5 L  350 
cn  10.75   150 k=for 350 m ≤ L ≤ 500 m

material factor, e.g.
k = 1.0 for mild steel with yield stress of 235N/mm2 and over;k = 0.78 for high tensile steel with yield stress of 315N/mm2 and over;k = 0.72 for high tensile steel with yield stress of 355N/mm2 and over.

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Z10.4 Annex III

Z10.4(cont’d)2
Scantlings of all continuous longitudinal members of the ship's hull girder based on
the section modulus requirement in 1 are to be maintained within 0.4L amidships. However,in special cases, based on consideration of type of ship, hull form and loading conditions, thescantlings may be gradually reduced towards the end of 0.4L part, bearing in mind the desire
not to inhibit the ship’s loading flexibility.
3
However, the above standard may not be applicable to ships of unusual type ordesign, e.g. for ships of unusual main proportions and/or weight distributions.

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Z10.4 Annex III

Z10.4

APPENDIX 3(cont’d)

SAMPLING METHOD OF THICKNESS MEASUREMENTS
FOR LONGITUDINAL STRENGTH EVALUATION
AND REPAIR METHODS
1Extent of longitudinal strength evaluation

Longitudinal strength should be evaluated within 0.4L amidships for the extent of the hull
girder length that contains tanks therein and within 0.5L amidships for adjacent tanks which
may extend beyond 0.4L amidships, where tanks means ballast tanks and cargo tanks.
2

Sampling method of thickness measurement

2.1
Pursuant to the requirements of section 2.4 of Z10.4, transverse sections should bechosen such that thickness measurements can be taken for as many different tanks incorrosive environments as possible, e.g. ballast tanks sharing a common plane boundary withcargo tanks fitted with heating coils, other ballast tanks, cargo tanks permitted to be filled withsea water and other cargo tanks. Ballast tanks sharing a common plane boundary with cargotanks fitted with heating coils and cargo tanks permitted to be filled with sea water should beselected where present.
2.2
The minimum number of transverse sections to be sampled should be in accordancewith Table II of Z10.4. The transverse sections should be located where the largest thickness
reductions are suspected to occur or are revealed from deck and bottom plating
measurements prescribed in 2.3 and should be clear of areas which have been locallyrenewed or reinforced.
2.3
At least two points should be measured on each deck plate and/or bottom shell plate
required to be measured within the cargo area in accordance with the requirements of Table
II of Z10.4.
2.4
Within 0.1D (where D is the ship’s moulded depth) of the deck and bottom at eachtransverse section to be measured in accordance with the requirements of Table II of Z10.4,
every longitudinal and girder should be measured on the web and face plate, and every plateshould be measured at one point between longitudinals.
2.5
For longitudinal members other than those specified in 2.4 to be measured at eachtransverse section in accordance with the requirements of Table II of Z10.4, every
longitudinal and girder should be measured on the web and face plate, and every plateshould be measured at least in one point per strake.
2.6
The thickness of each component should be determined by averaging all of themeasurements taken in way of the transverse section on each component.
3

Additional measurements where the longitudinal strength is deficient

3.1
Where one or more of the transverse sections are found to be deficient in respect of
the longitudinal strength requirements given in this annex, the number of transverse sections
for thickness measurement should be increased such that each tank within the 0.5L
amidships region has been sampled. Tank spaces that are partially within, but extend beyond,the 0.5L region, should be sampled.

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Z10.4 Annex III

Z10.4(cont’d)3.2
Additional thickness measurements should also be performed on one transverse
section forward and one aft of each repaired area to the extent necessary to ensure that theareas bordering the repaired section also comply with the requirements of Z10.4.
4Effective repair methods

4.1
The extent of renewal or reinforcement carried out to comply with this annex should
be in accordance with 4.2.
4.2
The minimum continuous length of a renewed or reinforced structural member should
be not less than twice the spacing of the primary members in way. In addition, the thickness
diminution in way of the butt joint of each joining member forward and aft of the replaced
member (plates, stiffeners, girder webs and flanges, etc.) should not be within the substantial
corrosion range (75% of the allowable diminution associated with each particular member).
Where differences in thickness at the butt joint exceed 15% of the lower thickness, atransition taper should be provided.
4.3
Alternative repair methods involving the fitting of straps or structural member
modification should be subject to special consideration. In considering the fitting of straps, it
should be limited to the following conditions:.1

to restore and/or increase longitudinal strength;.2

the thickness diminution of the deck or bottom plating to be reinforced
should not be within the substantial corrosion range (75% of the allowablediminution associated with the deck plating);.3

the alignment and arrangement, including the termination of the straps, isin accordance with a standard recognized by the Classification Society;.4

the straps are continuous over the entire 0.5L amidships length; and.5continuous fillet welding and full penetration welds are used at butt
welding and, depending on the width of the strap, slot welds. The welding
procedures applied should be acceptable to the Classification Society.

4.4
The existing structure adjacent to replacement areas and in conjunction with the fitted
straps, etc. should be capable of withstanding the applied loads, taking into account thebuckling resistance and the condition of welds between the longitudinal members and hullenvelope plating.

End ofAnnex III

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Z10.4 Annex IV

Z10.4(cont’d)

ANNEX IV

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Z10.4 Annex IVA

Z10.4

ANNEX IVA

(cont’d)SURVEY PROGRAMME
Basic information and particulars

Name of ship:
IMO number:
Flag State:
Port of registry:
Gross tonnage:
Deadweight (metric tonnes):
Length between perpendiculars (m):Shipbuilder:
Hull number:Classification Society:
Class ID:
Date of build of the ship:
Owner:
Thickness measurement firm:

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Z10.4 Annex IVA

Z10.4(cont’d)Preamble
1.1

Scope

1.1.1 The present survey programme covers the minimum extent of overall surveys, close-up
surveys, thickness measurements and pressure testing within the cargo area, cargo tanks,
ballast tanks, including fore and aft peak tanks, required by UR Z10.4.
1.1.2 The arrangements and safety aspects of the survey are to be acceptable to theattending surveyor(s).
1.2Documentation

All documents used in the development of the survey programme are to be available onboard
during the survey as required by section 6.
2

Arrangement of tanks and spaces

This section of the survey programme is to provide information (either in the form of plans ortext) on the arrangement of tanks and spaces that fall within the scope of the survey.
3

List of tanks and spaces with information on their use, extent of coatings andcorrosion protection system

This section of the survey programme is to indicate any changes relating to (and is to update)the information on the use of the tanks of the ship, the extent of coatings and the corrosion
protective system provided in the Survey Planning Questionnaire.
4

Conditions for survey

This section of the survey programme is to provide information on the conditions for survey,
e.g. information regarding cargo hold and tank cleaning, gas freeing, ventilation, lighting, etc.
5

Provisions and method of access to structures

This section of the survey programme is to indicate any changes relating to (and is to update)the information on the provisions and methods of access to structures provided in the Survey
Planning Questionnaire.
6

List of equipment for survey

This section of the survey programme is to identify and list the equipment that will be madeavailable for carrying out the survey and the required thickness measurements.
7

Survey requirements

7.1

Overall survey

This section of the survey programme is to identify and list the spaces that are to undergo an
overall survey for the ship in accordance with 2.3.1.

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Z10.4 Annex IVA

Z10.4(cont’d)

7.2

Close-up survey

This section of the survey programme is to identify and list the hull structures that are toundergo a close-up survey for the ship in accordance with 2.3.2.
8Identification of tanks for tank testingThis section of the survey programme is to identify and list the tanks that are to undergo tanktesting for the ship in accordance with 2.5.
9Identification of areas and sections for thickness measurements

This section of the survey programme is to identify and list the areas and sections where
thickness measurements are to be taken in accordance with 2.4.1.
10

Minimum thickness of hull structures

This section of the survey programme is to specify the minimum thickness for hull structuresof this ship that are subject to UR Z10.4 (indicate either (a) or preferably (b), if suchinformation is available):(a)

Determined from the attached wastage allowance table and the original thickness tothe hull structure plans of the ship;(b)

Given in the following table(s):Area or location

Original asbuilt thickness(mm)

Minimum
thickness(mm)

Substantial
corrosion
thickness
(mm)

Deck
Plating
Longitudinals
Longitudinal girders
BottomPlating
Longitudinals
Longitudinal girders
Ship side
Plating
Longitudinals
Longitudinal girders
Longitudinal bulkhead
Plating
Longitudinals
Longitudinal girders
Inner bottom
Plating
Longitudinals
Longitudinal girders
Transverse bulkheads
Plating
Stiffeners

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Z10.4 Annex IVA

Z10.4(cont’d)

Transverse web frames, floors
and stringers
Plating
Flanges
Stiffeners
Cross ties
Flanges
Webs
Note: The wastage allowance tables are to be attached to the survey programme.
For vessels built under IACS Common Structural Rules, the renewal thickness of the hull
structure elements is indicated in the appropriate drawings.
11

Thickness measurement firmThis section of the survey programme is to identify changes, if any, relating to theinformation on the thickness measurement firm provided in the Survey Planning
Questionnaire.
12

Damage experience related to the ship

This section of the survey programme is to, using the tables provided below, provide detailsof the hull damages for at least the last three years in way of the cargo and ballast tanks andvoid spaces within the cargo area. These damages are subject to survey.
Hull damages sorted by location for the ship
Tank or
space
number or
area

Possiblecause, if
known

Descriptionof thedamages

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Location

RepairDate ofrepair

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Z10.4 Annex IVA

Z10.4

Hull damages for sister or similar ships (if available) in the case ofdesign related damage(cont’d)Tank or
space
number or
area

13

Possiblecause, if
known

Descriptionof thedamages

Location

RepairDate ofrepairAreas identified with substantial corrosion from previous surveys

This section of the survey programme is to identify and list the areas of substantial corrosion
from previous surveys.
14

Critical structural areas and suspect areas

This section of the survey programme is to identify and list the critical structural areas and thesuspect areas, if such information is available.
15

Other relevant comments and information

This section of the survey programme is to provide any other comments and information
relevant to the survey.

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Z10.4 Annex IVA

Z10.4(cont’d)Appendices
Appendix 1 - List of plans
Paragraph 5.1.3.2 requires that main structural plans of cargo and ballast tanks (scantling
drawings), including information regarding use of high tensile steel (HTS), to be available.
This appendix of the survey programme is to identify and list the main structural plans which
form part of the survey programme.
Appendix 2 - Survey Planning Questionnaire
The Survey Planning Questionnaire (annex IVB), which has been submitted by the owner, is
to be appended to the survey programme.
Appendix 3 - Other documentation
This part of the survey programme is to identify and list any other documentation that forms
part of the Plan.
Prepared by the owner in co-operation with the Classification Society for compliance with
5.1.3.

Date:…………………………………. (name and signature of authorized owner’s
representative)
Date:…………………………………. (name and signature of authorized representative of theClassification Society)

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Z10.4 Annex IVB

Z10.4

ANNEX IVB

(cont’d)SURVEY PLANNING QUESTIONNAIRE
The following information will enable the owner in co-operation with the Classification Society
to develop a survey programme complying with the requirements of UR Z10.4. It is essentialthat the owner provides, when completing the present questionnaire, up-to-date information.
The present questionnaire, when completed, is to provide all information and material
required by UR Z10.4.
Particulars
Ship's name:
IMO number:
Flag State:
Port of registry:
Owner:Classification Society:
Class ID:
Gross tonnage:
Deadweight (metric tonnes):
Date of build:
Information on access provision for close-up surveys and thickness measurement:
The owner is to indicate, in the table below, the means of access to the structures subject toclose-up survey and thickness measurement. A close-up survey is an examination where thedetails of structural components are within the close visual inspection range of the attending
surveyor, i.e. normally within reach of hand.

Tank
No.

Structure

F.P.
A.P.

Fore Peak
Aft Peak
Under deck
Side shell
Bottomtransverse
Longitudinal
Transverse
Underdeck
Bottomtransverse
Transverse

Wing
Tanks

CentreTanks

C(Cargo)/B(Ballast)

Permanent
Means ofAccessTemporarystaging

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Rafts

Ladders

DirectaccessOther
means(pleasespecify)

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Z10.4 Annex IVB

Z10.4(cont’d)History of cargo with H2S content or heated cargo for the last 3 years together withindication as to whether cargo was heated and, where available, Marine Safety Data
Sheets (MSDS)** Refer to resolution MSC. 150(77) on Recommendation for material safety data sheets for
MARPOL Annex I cargoes and marine fuel oils.
Owner’s inspections
Using a format similar to that of the table below (which is given as an example), the owner isto provide details of the results of their inspections for the last 3 years on all cargo and ballast
tanks and void spaces within the cargo area, including peak tanks.
Tank No.

Corrosion
protection(1)

Coating
extent(2)

Coating
condition(3)

Structural
deterioration
(4)

Tank
damagehistory(5)

Cargocentre tanks

Cargo wing
tanks

Slop

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Z10.4 Annex IVB

Z10.4

Tank No.

(cont’d)Corrosion
protection(1)

Coating
extent(2)

Coating
condition(3)

Structural
deterioration
(4)

Tank
damagehistory(5)

Ballast tanks
Aft peakFore peak
Miscellaneous
spaces

Note:

Indicate tanks which are used for oil/ballast.

1)

HC=hard coating; SC=soft coating;SH=semi-hard coating; NP=no protection

2)

U=upper part; M=middle part;
L=lower part; C=complete

3)

G=good; F=fair; P=poor;
RC=recoated (during the last 3 years)

4)

N=no findings recorded; Y=findings recorded,
description of findings is to be attached to the questionnaire

5)DR=damage & repair; L=leakages;
CV=conversion(description is to be attached to this questionnaire)

Name of owner’s representative:
Signature:
Date:

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Z10.4 Annex IVB

Z10.4(cont’d)Reports of Port State Control inspections
List the reports of Port State Control inspections containing hull structural related
deficiencies and relevant information on rectification of the deficiencies:

Safety Management System

List non-conformities related to hull maintenance, including the associated corrective
actions:

Name and address of the approved thickness measurement firm:

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Z10.4 Annex IVC

Z10.4

ANNEX IVC

(cont’d)OWNER’S INSPECTION REPORT
Structural condition
Ship’s name:For tank No:
Grade of steel:

Elementsdeck:bottom:CracksBucklesside:
longitudinal bulkhead:
Corrosion

Coating
condition

Pitting

Modification/
repairOther

Deck
BottomSide
Longitudinalbulkhead
Transverse
bulkhead
Repairs carried out due to:Thickness measurements carried out(dates):Results in general:
Overdue surveys:
Outstanding conditions of class:Comments:

Date of inspection:
Inspected by:
Signature:

Annex IV end
Document end

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