Z10.1

Z10.1
Z10.1 Hull Surveys of Oil Tankers(1992)(cont’d)(Rev.1
1994)(Rev. 2
1994)
(Rev. 3
1995)
(Rev. 4
1996)
Rev 5
1997)
(Rev. 6
July 1999)(Rev.6.1
Dec. 1999)(Rev.7
Sept.2000)(Rev.8
Nov. 2000)(Rev.8.1
June 2001)(Rev.9Mar. 2002)(Rev.10
Oct.2002)(Rev.11
August 2003)(Rev.12June 2005)(Rev.13Jan. 2006)(Corr.1
Sept 2006)(Rev.14
Feb 2007)(Rev.15
Nov 2007)(Rev.16
Mar 2009)(Rev.17
Feb 2010)(Rev.18
Mar 2011)(Rev.19
July 2011)(Rev.20
May 2013)(Rev.21
Jan 2014)(Rev.22
Feb 2015)(Rev.23
Jan 2018)(Rev.24
May 2019)(Rev.25
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
2.2.1
2.2.2
2.2.3
2.3
2.4
2.5

Special Survey
Schedule
Scope
GeneralDry Dock Survey
Tank Protection
Extent of Overall and Close-up Survey
Extent of Thickness Measurement
Extent of Tank Testing

3.
3.1
3.2
3.2.1
3.2.2
3.2.3
3.2.4
3.2.5

Annual Survey
Schedule
Scope
GeneralExamination of the Hull
Examination of Weather decks
Examination of Cargo pump rooms
Examination of Ballast Tanks

4.
4.1
4.2
4.2.1
4.2.2
4.2.3
4.2.4

Intermediate Survey
Schedule
Scope
GeneralOil Tankers 5 - 10 years of Age
Oil Tankers 10 - 15 years of Age
Oil Tankers Exceeding 15 years of Age

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

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Z10.1(cont’d)

7.
7.1
7.2
7.3

Procedures for Thickness Measurements
GeneralCertification of Thickness Measurement Firm
Reporting

8.
8.1
8.2

Reporting and Evaluation of Survey
Evaluation of Survey Report
Reporting

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Z10.1(cont’d)

ENCLOSURES
Table I:

Minimum requirements to Close-up Surveys at Special Survey of Oil Tankers,
Ore/Oil Ships and etc.

Table II:

Minimum requirements to thickness measurements at Special Survey of Oil
Tankers, Ore/Oil Ships and etc.

Table III:

Minimum requirements to tank testing at Special Survey of Oil Tankers, Ore/Oil
Ships etc.

Table IV:

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

Table V:

Owners Inspection Report

Table VI:

Superseded by Annex 1

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 Oil Tankers Special Survey - Hull

Annex II:

Recommended Procedures for Thickness Measurements of Oil Tankers
Ore/Oil Ships and etc.

Annex III:

Criteria for Longitudinal Strength of Hull Girder for Oil Tankers
Appendix 1: Calculation criteria of section modulus of midship section of hull
girderAppendix II: Diminution limit of minimum longitudinal strength of ships inservice
Appendix III: Sampling method of thickness measurements for longitudinalstrength 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

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Z10.1

Z10.1(cont’d)Notes:
1.

Revision 4, 1996 of Unified Requirements Z10.1 have been approved by Council for
uniform application from 1 January 1997.

2.

Changes introduced in Rev.6 to UR Z10.1 are to be applied by all Member Societies
and Associates from 1 September 1999.

3.

Changes introduced in Rev.6.1 to UR Z10.1, i.e. 2.2.1.3 are to be applied by all
Member Societies and Associates from 1 July 2000.

4.

Changes introduced in Rev.7 to UR Z10.1 are to be applied by all Member Societies
and Associates from 1 July 2001.

5.

Changes introduced in Rev.8 and Rev.8.1 to UR Z10.1 are to be applied by all
Member Societies and Associates from 1 July 2001.

6.

Changes introduced in Rev.9 to UR Z10.1, which come from Res MSC.105(73) andMSC.108(73), i.e. 4.2.4.3(dry-dock in intermediate survey for ships over 15 years),8(evaluation of longitudinal strength), Table VIII, Table IX(ii), Table (IX(v) and Annex
III, are to be applied by all Member Societies and Associates from 1 July 2002.
Changes introduced in Rev.9 to UR Z10.1, other than the above, are to be
implemented by all Member Societies and Associates within one year of the adoption
by Council.

7.

Changes introduced in Rev.12 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 beassessed at the forthcoming Special Survey and Intermediate Survey onor after 1 July 2006.

8.

Changes introduced in Rev.13 (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.

9.

Changes introduced in Rev.14 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.

10.

Changes introduced in Rev.15 are to be uniformly applied by IACS Societies forsurveys commenced on or after the 1 January 2009.

11.

Changes introduced in Rev.16 are to be uniformly applied by IACS Societies forsurveys commenced on or after 1 July 2010.
As for the requirements regarding semi-hard coatings, these coatings, if alreadyapplied, will not be accepted from the next special or intermediate survey commenced
on or after 1 July 2010, whichever comes first, with respect to waiving the annualinternal examination of the ballast tanks.

12.

Changes introduced in Rev.18 are to be uniformly applied by IACS Societies forsurveys commenced on or after 1 July 2012.

13.

Changes introduced in Rev.19 are to be uniformly applied by IACS Societies forsurveys commenced on or after 1 July 2012.
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Z10.1(cont’d)

14.

Changes introduced in Rev.20 are to be uniformly applied by IACS Societies forsurveys commenced on or after 1 July 2014.

15.

Changes introduced in Rev.21 are to be uniformly applied by IACS Societies forsurveys commenced on or after 1 January 2015.

16.

Changes introduced in Rev.22 are to be uniformly applied by IACS Societies forsurveys commenced on or after 1 July 2016.

17.

Changes introduced in Rev.23 are to be uniformly applied by IACS Societies forsurveys commenced on or after 1 January 2019.

18.

Changes introduced in Rev.24 are to be uniformly applied by IACS Societies forsurveys commenced on or after 1 July 2020.

19.

Changes introduced in Rev.25 are to be uniformly applied by IACS Societies forsurveys commenced on or after 1 July 2024.

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Z10.1

Z10.1(cont’d)1.

GENERAL

1.1

Application

1.1.1 The requirements apply to all self-propelled Oil Tankers other than Double Hull Oil
Tankers, as defined in 1.1.1 of UR Z 10.4.
1.1.2 The requirements apply to surveys of hull structure and piping systems in way ofcargo tanks, pump rooms, cofferdams, pipe tunnels, void spaces within the cargo area andall ballast tanks. The requirements are additional to the classification requirements applicableto the remainder of the ship. Refer to Z7.
1.1.3 The requirements contain the minimum extent of examination, thickness
measurements and tank testing. The survey is to be extended when Substantial Corrosion
and/or structural defects are found and include additional Close-up Survey when necessary.
1.2

Definitions

1.2.1 Oil Tanker: An Oil Tanker is a ship which is constructed primarily to carry oil in bulk in
cargo tanks forming an integral part of the ship's hull, and includinges ship types such as
combination carriers (Ore/Oil ships etc.) but excluding ships carrying oil in independent tanks
not part of the ship's hull such as asphalt carriers.
1.2.2 Ballast Tank: A Ballast Tank is a tank which is used solely primarily for the carriageof salt water ballast.
1.2.2 bis A Combined Cargo/Ballast Tank is a tank which is used for the carriage of cargoor ballast 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 structure and 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 structuralcomponents are within the close visual inspection range of the surveyor, i.e. normally withinreach of hand.
1.2.5 Transverse Section: A Transverse Section includes all longitudinal members such as
plating, longitudinals and girders at the deck, side, bottom, inner bottom and longitudinalbulkheads. 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 of similar type and service and with similar corrosion prevention
systems. When selecting Representative Tanks account is to be taken of the service andrepair history onboard and identifiable Critical Structural Areas and/or Suspect Areas.
1.2.7 Suspect Area: Suspect Areas are locations showing Substantial Corrosion and/or are
considered by the Surveyor to be prone to rapid wastage.
1.2.8 Critical Structural Area: Critical Structural Areas are locations which have been
identified from calculations to require monitoring or from the service history of the subject ship
or from similar or sister ships (if available) to be sensitive to cracking, buckling or corrosion
which would impair the structural integrity of the ship.
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Z10.1(cont’d)1.2.9 Substantial Corrosion: Substantial Corrosion is an extent of corrosion such thatassessment of corrosion pattern indicate a wastage in excess of 75% of allowable margins,
but within acceptable limits.
1.2.10 Corrosion Prevention System: A Corrosion Prevention System is normallyconsidered 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.
1.2.11 Coating Condition: Coating condition is defined as follows:
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,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”.
1.2.12 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 cargotanks and also deck areas throughout the entire length and breadth of the part of the shipover the above mentioned spaces.
1.2.13 Special consideration: Special consideration or specially considered (in connection
with close-up surveys and thickness measurements) means sufficient close-up inspection
and thickness measurements are to be taken to confirm the actual average condition of thestructure under the coating.
1.2.14 Prompt and Thorough Repair: A Prompt and Thorough Repair is a permanent repair
completed at the time of survey to the satisfaction of the Surveyor, therein removing the needfor the imposition of any associated condition of class.
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).
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Z10.1(cont’d)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.
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 the surveyor to allow an appropriate temporary repair to restore watertight orweather tight integrity 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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Z10.1

Z10.1(cont’d)2.

SPECIAL SURVEY1

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 startfrom 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 ofclass will start from 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 modificationand the owner elects to only carry out the overdue surveys, the next period of class will startfrom 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 from the survey completion date.
2.1.4 The Special Survey may be commenced at the 4th Annual Survey and be progressedwith a view to completion by the 5th anniversary date. When the Special Survey iscommenced 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.
2.2

Scope

2.2.1

General2.2.1.1 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, pumprooms, pipetunnels, 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 andtesting required in 2.4 and 2.5, to ensure that the structural integrity remains effective. The
aim of the examination is to discover Substantial Corrosion, significant deformation, fractures,
damages or other structural deterioration, that may be present.

_______________________

1 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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Z10.1(cont’d)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 toworking 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 andcargo piping 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 andcan 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
and ballast 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
light ballast 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.

Thickness measurements are to be carried out as deemed necessary by the surveyor.
2.3

Extent of Overall and Close-up Survey

2.3.1

An Overall Survey of all tanks and spaces is to be carried out at each Special Survey.

2.3.2
I.

The minimum requirements for Close-up Surveys at Special Survey are given in Table

2.3.3 The Surveyor may extend the Close-up Survey as deemed necessary taking into
account the maintenance of the tanks under survey, the condition of the corrosion prevention
system and also in the following cases:a)

In particular, tanks having structural arrangements or details which have suffereddefects in similar 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.

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Z10.1

Z10.1(cont’d)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
specially considered.
2.4

Extent of Thickness Measurement

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 by 5.1.
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 are to have thickness measurements
taken.
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 tooccur or are revealed from deck plating measurements.
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 8.1.1.1, 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
and Table 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 vessel’s ship’s crew under the direction of the Mastermay 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 3months 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;
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Z10.1(cont’d)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;de)the satisfactory results of the testing is recorded in the vessel’s logbook; andef)

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
under service conditions.

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Z10.1

Z10.1(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 fromthe date of 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 aspracticable, 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 ofballast 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 weather decks

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
vent masts and headers.
3.2.4

Examination of Cargo pump rooms and pipe tunnels if fitted.

3.2.4.1 Examination of all pumproom bulkheads for signs of oil leakage or fractures and, inparticular, the sealing arrangements of all penetrations of pumproom bulkheads.
3.2.4.2 Examination of the condition of all piping systems.
3.2.5

Examination of Ballast Tanks

3.2.5.1 Examination of Ballast Tanks where required as a consequence of the results of theSpecial Survey (see 2.2.3) and Intermediate Survey (see 4.2.2.1 and 4.2.2.2) is to be carriedout. 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 are to have thickness measurements taken.

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Z10.1

Z10.1(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.
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 be required to be pressure tested, thickness measured or both.
4.2.2

Oil Tankers 5 – 10 Years of Age, the following is to apply:

4.2.2.1 All Ballast Tanks are to be examined. When considered necessary by the surveyor,
thickness measurement and testing are to be carried out to ensure that the structural integrity
remains effective.
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.

4.2.2.3 In addition to the requirements above, suspect areas identified at previous surveys
are to be examined.
4.2.3

Oil Tankers 10 - 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 theprevious Special Survey as required in 2 and 5.1. However, pressure testing of cargo andballast 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 thethird annual survey in lieu of the application of 2.1.4.

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Z10.1(cont’d)4.2.3.3 In application of 4.2.3.1, an under water survey may be considered in lieu of therequirements of 2.2.2.
4.2.4

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 theprevious Special Survey as required in 2 and 5.1. However, pressure testing of cargo andballast 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 thethird 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 performed.
Note: Lower portions of the cargo and ballast tanks are considered to be the parts below
light ballast water line.

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Z10.1(cont’d)5.

PREPARATIONS FOR SURVEY

5.1

Survey Programme

5.1.1 The Owner in co-operation with the Classification Society is to work out a specificSurvey 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 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. The Survey
Programme at Intermediate Survey may consist of the Survey Programme at the previous
Special Survey supplemented by the Executive Hull Summary of that Special Survey andlater relevant survey reports.
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.
The Survey Programme is to be worked out taking into account any amendments to thesurvey requirements implemented after the last Special Survey carried out.
5.1.2 In developing the survey programme, the following documentation is to be collected
and consulted 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;.10

description and history of the coating and corrosion protection system(including 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 Table V;.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); andPage 16 of 92

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Z10.1(cont’d)any other information that will help identify suspect areas and critical structuralareas

5.1.3 The submitted survey programme is to account for and comply, as a minimum, with therequirements of Tables I, II and III 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 of cargo and ballast tanks (scantling drawings), including
information regarding use of high tensile steels (HTS);.3

arrangement of tanks;.4list of tanks with information on their use, extent of coatings and corrosion
protection systems;.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

identification of tanks and areas for close-up survey (see 2.3);.9identification of areas and sections for thickness measurement (see 2.4);.10identification of tanks for tank testing (see 2.5);.11

identification of the thickness measurement firm;.12

damage experience related to the ship in question; and.13

critical structural areas and suspect areas, where relevant.

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 Oil Tankers Special Survey - Hull, contained in Annex
I. These guidelines are a recommended tool which may be invoked at the discretion of theClassification Society, when considered necessary and appropriate, in conjunction with the
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
and 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.

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Z10.1(cont’d)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 not to 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 the surveyor to verify the effectiveness of the coating and to carry out an assessment of
the conditions of internal structures which may include spot removal of the coating. Whensafe access cannot be provided, the soft or semi-hard coating is to be removed.
5.3

Access to Structures

5.3.1 For overall survey, means are to be provided to enable the surveyor to examine thehull 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:

5.4-

permanent staging and passages through structures-

temporary staging and passages through structures-

hydraulic arm vehicles such as conventional cherry pickers, lifts andmovable platforms-

boats or rafts-

portable ladders-

other equivalent means

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

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Z10.1(cont’d)-ultrasonic equipment-

magnetic particle equipment-

dye penetrant.

5.4.3 Explosimeter, oxygen-meter, breathing apparatus, lifelines, riding belts with rope andhook and whistles together with instructions and guidance on their use are to be madeavailable 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 thesurvey.
5.4.5 Adequate protective clothing is to be made available and used (e.g. safety helmet,
gloves, safety shoes, etc) during the survey.
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 andthe responsible officer on deck. This system is also to include the personnel in charge ofBallast pump handling if boats or rafts are used.
5.6.3 Surveys of tanks by means of boats or rafts may only be undertaken with theagreement 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 will be used for close-up survey 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;

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Z10.1.6

at no time is the water level to 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 isonly to be contemplated if a deck access manhole is fitted and open in the bay
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 is to be used is to be isolated toprevent a transfer of gas from other tanks (or spaces).

(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, be arrangedin level with, or above, the maximum water level needed for rafting of under deck
structure. For this purpose, the ullage corresponding to the maximum water level isto be assumed not more than 3m from the deck plate measured at the midspan ofdeck transverses and in the middle length of the tank (See Figure 1).
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 1 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 theuse of boats 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.
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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 thesafe and efficient conduct of the survey. During the survey on board safety meetings are to
be held regularly.
5.7.2 Prior to commencement of any part of the renewal and intermediate survey, a survey
planning meeting is to be held between the attending surveyor(s), the owner’s representativein attendance, the thickness measurement firm operator (as applicable) and the master of theship or an appropriately qualified representative appointed by the master or Company for the
purpose to ascertain that all the arrangements envisaged in the survey programme are inplace, 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;.8.9

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

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Z10.1(cont’d)

6.

DOCUMENTATION ON BOARD

6.1

General6.1.1 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 life time of the ship.

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 or Intermediate Survey, as applicable, has been completed.

–

Main structural plans of cargo and ballast tanks–

Previous repair history–

Cargo and ballast history–

Extent of use of inert gas plant and tank cleaning procedures–

Inspections by ship's personnel with reference to
•
•
•
•

–
6.4

structural deterioration in generalleakages in bulkheads and piping
condition of corrosion prevention system, if any
A guidance for reporting is shown in Table V.

Any other information that will help identify Critical Structural Areas and/or
Suspect Areas requiring inspection.

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.

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7.

PROCEDURES FOR THICKNESS MEASUREMENTS

7.1

General7.1.1 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 beheld 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 is to be sufficient as torepresent the actual average condition.
7.2

Certification of Thickness Measurement Firm

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

Reporting

7.3.1 A thickness measurement report is to be prepared. The report is to give the location of
measurements, the thickness measured as well as corresponding original thickness.
Furthermore, the report is to give the date when the measurements were carried out, type ofmeasurement equipment, names of personnel and their qualifications and has to be signedby the operator. The thickness measurement report is to follow the principles as specified in
the Recommended Procedures for Thickness Measurements for Oil Tankers, Ore/Oil Ships
and etc., contained in Annex II.
7.3.2 The Surveyor is to review the final thickness measurement report and countersign the
cover page.

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8.

REPORTING AND EVALUATION OF SURVEY

8.1

Evaluation of Survey Report

8.1.1 The data and information on the structural condition of the vessel collected during thesurvey is to be evaluated for acceptability and continued structural integrity of the vessel.
8.1.1.1 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.
8.1.1.2 The final result of evaluation of the ship’s longitudinal strength required in 8.1.1.1,
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.
8.2

Reporting

8.2.1

Principles for survey reporting are shown in Table VIII.

8.2.2 When a survey is split between different survey stations, a report is to be made foreach portion 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 made available to the next attending Surveyor(s), prior to continuing or completing thesurvey.
8.2.3 An Executive Hull Summary of the survey and results is to be issued to the Owner asshown in 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 orregional managerial office.

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TABLE I
Table of Minimum Requirements to Close-up Surveys
at Special Survey of Oil Tankers, Ore/Oil Ships and etc.

Special Survey No.1
age ≤ 5Special Survey No.2
5 < age ≤ 10

Special Survey No.3
10 < age ≤ 15

Special Survey No.4 andSubsequent
age > 15A)

ONE WEB FRAME
RING in a ballast wing tank, ifany, or a cargo wingtank used primarily forwater ballast

A)

ALL WEB FRAMERINGS in a ballast wing tank, ifany, or a cargo wingtank, used primarily forwater ballast

A)

ALL WEB FRAMERINGS in all ballast tanks

As special survey No.3

B)

ONE DECKTRANSVERSE in a cargo oil tankB)

ONE DECKTRANSVERSE in each of the remaining
ballast tanks, if any

A)

ALL WEB FRAMERINGS in a cargo wing tank

Additional transverses
included as deemednecessary by theClassification Society

D)

ONE TRANVERSE
BULKHEAD in a ballast tankB)

ONE DECKTRANSVERSE in a cargo wing tankA)

A minimum of 30% of
all web frame rings ineach remaining cargo
wing tank (see Note 1)

D)

ONE TRANSVERSE
BULKHEAD in a cargo oil wing tankB)

ONE DECKTRANSVERSE in two cargo centre
tanks

C)

ALL TRANSVERSE
BULKHEADS in all cargo and ballast
tanks

D)

ONE TRANSVERSE
BULKHEAD in a cargo oil centre
tank

C)

BOTH TRANSVERSE
BULKHEADS in a wing ballast tank, ifany, or a cargo wingtank used primarily forwater ballast

E)

A minimum of 30% ofdeck and bottom
transverses including
adjacent structuralmembers in each cargo
centre tankD)

ONE TRANSVERSE
BULKHEAD in each remaining
ballast tankF)

As considerednecessary by thesurveyor

D)

ONE TRANSVERSE
BULKHEAD in a cargo oil wing tankD)

ONE TRANSVERSE
BULKHEAD in two cargo centre
tanks

A)
B)
C)
D)
E)
F)

Complete transverse web frame ring including adjacent structural members
Deck transverse including adjacent deck structural members
Transverse bulkhead complete – including girder system and adjacent structural members
Transverse bulkhead lower part – including girder system and adjacent structural members
Deck and bottom transverse including adjacent structural members
Additional complete transverse web frame ring
See sketches in Sheet 15.
Note 1: The 30% is to be rounded up to the next whole integer.

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TABLE II
Minimum Requirements to Thickness Measurements at Special Surveyof Oil Tankers, Ore/Oil Ships and etc.

Special Survey No.1
age ≤ 5Special 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

1.

Suspect areas

2.

One section of deck
plating for the full
beam of the ship
within the cargo area
(in way of a ballast
tank, if any, or acargo tank usedprimarily for waterballast)2.

Within the cargo area:

2.

Within the cargo area:

2.

Within the cargo area:

4.

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

.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 plate3.

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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TABLE III
Minimum Requirements to Tank Testing at Special Surveyof Oil Tankers, Ore/Oil Ships and etc.
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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TABLE IV / Sheet 1
Requirements for extent of thickness measurement at those areasof substantial corrosion.
Special Survey of Oil Tankers, Ore/Oil Ships and etc.
within the cargo tank length.
BOTTOM STRUCTURE
STRUCTURAL MEMBER

EXTENT OF
MEASUREMENT
Minimum of 3 bays acrosstank aft bay
Measurements around andunder all bell mouths

PATTERN OFMEASUREMENT
5 point pattern for each panel
between longitudinals andwebs

2. Bottom Longitudinals

Minimum of 3 longitudinals ineach bay where bottom
plating measured

3 measurements in line
across flange and 3
measurements on verticallyweb

3. Bottom girders andbrackets

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

Vertical line of single
measurements on web
plating with one
measurement between eachpanel stiffener, or a minimumof three measurements.
Two measurements acrossface flat. 5 point pattern on
girder/bhd brackets.

4. Bottom transverse webs

3 webs in bays where bottom
plating measured, withmeasurements at both ends
and middle

5 point pattern over 2 square
metre area. Single
measurements on face flat.

5. Panel stiffening

Where provided

Single measurements

1. Bottom plating

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TABLE IV / Sheet 2
Requirements for extent of thickness measurement at those areasof substantial corrosion.
Special Survey of Oil Tankers, Ore/Oil Ships and etc.
within the cargo tank length.
DECK STRUCTURE
STRUCTURAL MEMBER

EXTENT OF
MEASUREMENT
Two bands across tank

PATTERN OFMEASUREMENT
Minimum of threemeasurements per plate perband

2. Deck Longitudinals

Minimum of 3 longitudinals ineach of two bays

3 measurements in line
vertically on webs, and 2
measurements on flange (iffitted)3. Deck girders andbrackets

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

Vertical line of single
measurements on web
plating with one
measurement between eachpanel stiffener, or a minimumof three measurements. Twomeasurements across faceflat. 5 point pattern on
girder/bhd brackets.

4. Deck transverse webs

Minimum of two webs withmeasurements at middle andboth ends of span

5 point pattern over about 2
square metre areas. Single
measurements on face flat.

5. Panel stiffening

Where provided

Single measurements

1. Deck plating

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TABLE IV / Sheet 3
Requirements for extent of thickness measurement at those areasof substantial corrosion.
Special Survey of Oil Tankers, Ore/Oil Ships etc.
within the cargo tank length.
SIDE SHELL AND LONGITUDINAL BULKHEADSSTRUCTURAL MEMBER

EXTENT OF
MEASUREMENT
Plating between each pair of
longitudinals in a minimum of
3 baysPATTERN OFMEASUREMENT
Single measurement

2. All other strakes

Plating between every 3rdpair of longitudinals in same 3
bays

Single measurement

3. Longitudinals- deckhead and bottom
strakes

Each longitudinal in same 3bays

3 measurements across web
and 1 measurement on flange

4. Longitudinals- all others

Every third longitudinal insame 3 bays

3 measurements across web
and 1 measurement on flange

5. Longitudinals- bracket

Minimum of three at top,
middle and bottom of tank insame 3 bays

5 point pattern over area ofbracket6. Web frames and crossties

3 webs with minimum of threelocations on each web,including in way of cross tie
connections

5 point pattern over about 2
square metre area, plus single
measurements on web frameand cross tie face flats

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1. Deckhead and bottom
strakes, and strakes in
way of stringer
platforms

Z10.1TABLE IV / Sheet 4

Z10.1

Requirements for extent of thickness measurement at those areasof substantial corrosion.
Special Survey of Oil Tankers, Ore/Oil Ships and etc.
within the cargo tank length.

(cont’d)

TRANSVERSE BULKHEADS AND SWASH BULKHEADSSTRUCTURAL MEMBER

EXTENT OF
MEASUREMENT
1. Deckhead and bottom Plating between pair ofstrakes, and strakes in stiffeners at three locations way of stringer
approx. 1/4, 1/2 and 3/4 width
platformsof tank

PATTERN OFMEASUREMENT
5 points pattern between
stiffeners over 1 metre length

2. All other strakes

Plating between pair ofstiffeners at middle location

Single measurement

3. Strakes in corrugatedbulkheads

Plating for each change ofscantling at centre of panel
and at flange or fabricatedconnection

5 point pattern over about 1
square metre of plating

4. Stiffeners

Minimum of three typicalstiffeners

For web, 5 point pattern overspan between bracket
connections (2 measurements
across web at each bracket
connection, and one at centreof span). For flange, single
measurements at each bracket
toe and at centre of span

5. Brackets

Minimum of three at top,
middle and bottom of tank

5 point pattern over areas ofbracket6. Deep webs andgirders

Measurements at toe ofbracket and at centre of span

For web, 5 point pattern overabout 1 square metre. 3
measurements across faceflat.

7. Stringer platforms

All stringers withmeasurements at both ends
and middle

5 point pattern over 1 square
metre of area plus single
measurements near bracket
toes and on face flats

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TABLE V
Ship Name: ................................
OWNERS INSPECTION REPORT - Structural Condition
For Tank No: .......................
Grade of Steel:

Deck
Bottom: .................
: .................

Elements
Other

BucklesCorrosion

CracksSide
Long. Bhd
Coating
cond.

Pitting: .................
: .................
Mod.
/Rep.

Deck:

Bottom:

Side:

Long.
Bulkheads:
Transv.
Bulkheads:
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:

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TABLE VI
Note: Table VI is superseded by Annex I: Guidelines for Technical Assessment in conjunction
with planning for Enhanced Surveys of Oil Tankers Special Survey - Hull.

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Z10.1TABLE VII

Z10.1

PROCEDURES FOR THE CERTIFICATION OF FIRMS ENGAGED IN THICKNESSMEASUREMENT OF HULL STRUCTURE(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 structures ofthe vessels.
Technicians’ careers, i.e. experience of technicians as thickness measurement
operators, technical knowledge of hull structure etc. Operators, are to be qualified
according to a recognized industrial NDT Standard.
Equipment used for thickness measurement such as ultra-sonic testing machines
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 Oil Tankers, Ore/Oil Ships and etc., contained in
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 organised 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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Z10.1

Z10.1

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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Z10.1TABLE VIII

Z10.1

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 Z10.1 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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Z10.1

Z10.1(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 controlling themeasurements 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.
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
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Z10.1

Z10.1(cont’d)-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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Z10.1TABLE IX (i)Z10.1

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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Z10.1TABLE IX (ii)

Z10.1

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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Z10.1TABLE IX (iii)

Z10.1

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

2)

Positions of
substantially corroded
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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Z10.1TABLE IX (iv)

Z10.1

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

3)

Coating condition according to the following standard

NP = No Protection

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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Z10.1TABLE IX (v)Z10.1

Evaluation result of longitudinal strength of the hull girder of oil 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)(cont’d)1This 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 withthe provisions 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 1
Transverse
Section 2
Transverse
Section 3*

Transverse section modulus of hull girder

Upper deck
BottomUpper deck
BottomUpper deck
BottomZact (cm3) *1

Zreq (cm3) *2

Remarks

The actual transverse section modulus of the hull girder of oil tankers calculated underparagraph 2.2.1.1 of Annex III to UR Z10.1 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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Z10.1

Z10.1

Notes
*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 accordancewith the provisions of paragraph 2.2.1.1 of Annex III.

(cont’d)*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 withthe provisions 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 forships in service required by the Classification Society.
Table 3
Transverse
Section 1
Transverse
Section 2
Transverse
Section 3

Transverse section modulus of hull girder

Upper deck
BottomUpper deck
BottomUpper deck
BottomZact (cm3) *1

Zmc (cm3) *2

Remarks

Notes:*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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Z10.1 Annex I

ANNEX I

Z10.1
(cont’d)

GUIDELINES FOR TECHNICAL ASSESSMENT IN CONJUNCTION WITH
PLANNING FOR ENHANCED SURVEYS OF 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 Z10.1, "Hull Surveys of Oil Tankers."
21.TSCF, "Guidance Manual for the Inspection and Condition Assessment of Tanker
Structures, 1986."
32.TSCF, "Condition Evaluation and Maintenance of Tanker Structures, 1992."
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 oiltankers. As indicated in section 5.1.5 of IACS Unified Requirement Z10.1, "Hull Surveys of Oil
Tankers," (Ref. 1), the guidelines are a recommended tool which may be invoked at thediscretion of an IACS Member Society, when considered necessary and appropriate, 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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Z10.1 Annex I

Z10.1(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 Z10.1; 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 andextent of use of high tensile steel.
Former history with respect to corrosion, cracking, buckling, indents and repairs for theparticular ship as well as similar vessels, where available.
Information with respect to types of cargo carried, use of different tanks for cargo/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. 21 and 32).
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 depicts, schematically, how technicalassessments can be carried out in conjunction with the survey planning process.
The approach is basically an evaluation of the risk based on the knowledge and experience
related to design and corrosion.
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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Z10.1 Annex I

Z10.1(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 should be made to
TSCF's "Guidance Manual for the Inspection and Condition Assessment of Tanker
Structures," (Ref. 21), which contains a catalogue of typical 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.
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. 32, Table 3.1)
Location of Heated Tanks

Ref. 32 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. 32, 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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Z10.1 Annex I

Z10.1(cont’d)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 (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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Z10.1 Annex I

Z10.1(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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Z10.1 Annex I

Z10.1(cont’d)Figure 2:

Typical Damage and Repair Example (Reproduced from Ref. 21)

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Z10.1 Annex II

ANNEX II

Z10.1
(cont’d)

Recommended Procedures for Thickness Measurements of
Oil Tankers, Ore/Oil Ships and etc.**
Note: Annex II is recommendatory.

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Z10.1 Annex II

Z10.1(cont’d)

CONTENTS

Sheet 1

Sheet 1-

Contents

Sheet 2-

Instructions

Sheet 3-General Particulars

Sheet 4-

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

Sheet 5-

Report TM2-T (i) for recording the thickness measurement of shell anddeck plating at transverse sections - strength deck and sheerstrake
plating

Sheet 6-

Report TM2-T (ii) for recording the thickness measurement of shell anddeck plating at transverse sections - shell plating

Sheet 7-

Report TM3-T for recording the thickness measurement of longitudinal
members at transverse sections

Sheet 8-

Report TM4-T recording the thickness measurement of transverse
structural members

Sheet 9-

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

Sheet 10-

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

Sheet 11-

Oil tanker typical transverse sections. The diagram includes details of
the items to be measured and the report forms to be used.

Sheet 12-

Ore/Oil ship typical transverse section. The diagram includes details of
the items to be measured and the report 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-

Oil tank and Ore/Oil Ship, diagrams showing the typical longitudinal
members in a transverse section

Sheet 15-

Transverse sections of oil tankers and ore/oil ships showing typicalareas for thickness measurement in association with close-up survey
requirements

REPORTSGUIDANCE

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Z10.1 Annex II
INSTRUCTIONS

Z10.1

Sheet 2

Recommended Procedures for Thickness Measurements of
Oil Tankers, Ore/Oil Ships, etc.

(cont’d)1.

This document is to be used for recording thickness measurements as required by
IACS Unified Requirement Z10.1.

2.

Reporting forms TM1-T, TM2-T, TM3-T, TM4-T, TM5-T and TM6-T(sheets 4-10) are to be used for recording thickness measurements andthe 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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Z10.1 Annex II
Sheet 3

Z10.1
(cont’d)

GENERAL PARTICULARS
Ship’s name:IMO Number:Class Identification 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 operator:Report Number:-consisting of.....Sheets

Names 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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Z10.1 Annex II

Z10.1(cont’d)

TM1-T

Report on THICKNESS MEASUREMENT of ALL DECK PLATING, ALL BOTTOM SHELL PLATING
or SIDE SHELL PLATING*(* - delete as appropriate)

Ship’s name.........................
STRAKEPOSITIONPLATE
POSITION
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

No.
or
Letter

Org.
Thk.
mm

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

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

GaugedForward Reading
Diminution P
Diminution S

GaugedAft Reading
Diminution P

Diminution S

P

mm

P

mm

mm

S

%

mm

%

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

Sheet 4S%%

Mean Diminution%
P

S

Maximum
Allowable
Diminutionmm

NOTES – See Reverse

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Z10.1 Annex II

Z10.1(cont’d)

NOTES
1.

2.

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

- All strength deck plating within the cargo area.

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

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

D- 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 from thekeel plate.

2.3

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

3.

For oil tankers all deck plating strakes are to be recorded, for ore/oil ships only the deck
plating strakes outside line of openings are to be recorded.

4.

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.

5.

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

6.

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

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Z10.1 Annex II

Z10.1(cont’d)TM2-T (i)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
StringerPlate
1st strake
inboard
2nd
3rd
4th
5th
6th
7th
8th
9th
10th
11th
12th
13th
14th
centrestrakesheerstrakeTOPSIDE
TOTAL

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

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

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

%

NOTES – See Reverse

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Z10.1 Annex II

Z10.1

NOTES

(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(1), (2) and (3) as shown on the diagrams of typical transverse sections.

2.

For oil tankers all deck plating strakes are to be recorded and for ore/oil ships only thedeck plating strakes outside the line of openings are to be recorded.

3.

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

4.

The exact frame station of measurement is to be stated.

5.

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

6.

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

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Z10.1 Annex II

Z10.1 TM2-T (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
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

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

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

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

%

NOTES – See Reverse

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Z10.1 Annex II

Z10.1(cont’d)NOTES
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 (4), (5)and (6) and (7) as shown on the diagrams of typical transverse sections.

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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Z10.1 Annex II

Z10.1(cont’d)TM3-T

Report on THICKNESS MEASUREMENT OF LONGITUDINAL MEMBERS(one, two or three transverse sections)

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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Z10.1 Annex II

Z10.1(cont’d)NOTES
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 (8) to (20) as shown on the diagrams of typical transverse sections.

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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Z10.1 Annex II

Z10.1(cont’d)TM4-T

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 MEMBER

ITEM

Original
Thickness
mm

Max.
Alwb.
Dim.
mm

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

GaugedP

Diminution
P
S

mm

Diminution
S
%

mm

%

NOTES – See Reverse

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Z10.1 Annex II

Z10.1(cont’d)NOTES
1.

This report is to be used for recording the thickness measurements of transverse structuralmembers, comprising of the appropriate structural items (25) to (33) as shown on diagrams oftypical transverse section.

2.

Guidance for areas of measurement is indicated on sheet 15 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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Z10.1 Annex II

Z10.1 TM5-T(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

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

GaugedPort

Starboard

Diminution
P
mm

Diminution
S
%

mm

%

NOTES – See Reverse

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Z10.1 Annex II

Z10.1(cont’d)NOTES
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 15 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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Z10.1 Annex II
TM6-T

Report on THICKNESS MEASUREMENT OF MISCELLANEOUS STRUCTURAL MEMBERS

Z10.1 Ship’s name.........................

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

(cont’d)

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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Z10.1 Annex II

Z10.1(cont’d)NOTES
1.

This report is to be used for recording the thickness measurement of miscellaneous
structural members including the structural items (36), (37) and (38).

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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Z10.1 Annex II
Sheet 11

Z10.1
(cont’d)

1.
2.
3.
4.
5.
6.
7.

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

8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.

Report on TM3-T
Deck longitudinals
Deck girders
Sheerstrake longitudinals
Longitudinal bulkhead top strake
Bottom longitudinals
Bottom girders
Bilge longitudinals
Longitudinal bulkhead lower strake
Side shell longitudinals
Longitudinal bulkhead plating (remainder)
Longitudinal bulkhead longitudinals
Inner bottom plating
Inner bottom longitudinals

25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.

36.
37.
38.
39.
40.

Page 69 of 92

Report on TM4-T
Deck transverse centre tank
Bottom transverse centre tank
Deck transverse wing tank
Side shell vertical web
Longitudinal bulkhead vertical web
Bottom transverse wing tank
StrutsTransverse web face plate
D.B. Floors

Report on TM6-T
Hatch coamings
Deck plating between hatches
Hatch covers

IACS Req. 1992/Rev.25 2023

Z10.1 Annex II
Sheet 12

Z10.1
(cont’d)

1.
2.
3.
4.
5.
6.
7.

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

8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.

Report on TM3-T
Deck longitudinals
Deck girders
Sheerstrake longitudinals
Longitudinal bulkhead top strake
Bottom longitudinals
Bottom girders
Bilge longitudinals
Longitudinal bulkhead lower strake
Side shell longitudinals
Longitudinal bulkhead plating (remainder)
Longitudinal bulkhead longitudinals
Inner bottom plating
Inner bottom longitudinals

25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.

36.
37.
38.
39.
40.

Page 70 of 92

Report on TM4-T
Deck transverse centre tank
Bottom transverse centre tank
Deck transverse wing tank
Side shell vertical web
Longitudinal bulkhead vertical web
Bottom transverse wing tank
StrutsTransverse web face plate
D.B. Floors

Report on TM6-T
Hatch coamings
Deck plating between hatches
Hatch covers

IACS Req. 1992/Rev.25 2023

Z10.1 Annex II

Z10.1

Sheet 13(cont’d)

1.
2.
3.
4.
5.
6.
7.

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

8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.

Report on TM3-T
Deck longitudinals
Deck girders
Sheerstrake longitudinals
Longitudinal bulkhead top strake
Bottom longitudinals
Bottom girders
Bilge longitudinals
Longitudinal bulkhead lower strake
Side shell longitudinals
Longitudinal bulkhead plating (remainder)
Longitudinal bulkhead longitudinals
Inner bottom plating
Inner bottom longitudinals

25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.

36.
37.
38.
39.
40.

Page 71 of 92

Report on TM4-T
Deck transverse centre tank
Bottom transverse centre tank
Deck transverse wing tank
Side shell vertical web
Longitudinal bulkhead vertical web
Bottom transverse wing tank
StrutsTransverse web face plate
D.B. Floors

Report on TM6-T
Hatch coamings
Deck plating between hatches
Hatch covers

IACS Req. 1992/Rev.25 2023

Z10.1 Annex II
Sheet 14

Z10.1
(cont’d)Page 72 of 92

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Z10.1 Annex II
Sheet 15

Z10.1
(cont’d)

End ofAnnex II
Page 73 of 92

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Z10.1 Annex III

Z10.1(cont’d)

ANNEX III
Criteria for Longitudinal Strength of Hull Girder for Oil Tankers

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Z10.1 Annex III

Z10.1

Annex III(cont’d)Criteria for Longitudinal Strength of Hull Girder for Oil Tankers
1General1.1
These criteria are 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 are 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 is to 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 are
to be 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 is not to be less than thediminution limits determined by the Classification Society*; orPage 75 of 92

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Z10.1 Annex III

Z10.1(cont’d).2

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 Z10.1 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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Z10.1 Annex III

Z10.1

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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Z10.1 Annex III

Z10.1

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.

Cb =cmoulded displaceme nt (m3 ) at draught d
L×B×d=

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.

2
Scantlings of all continuous longitudinal members of the ship's hull girder based on
the section modulus requirement in 1 above are to be maintained within 0.4L amidships.
However, in special cases, based on consideration of type of ship, hull form and loading
conditions, the scantlings 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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Z10.1 Annex III

Z10.1

APPENDIX 3(cont’d)Sampling method of thickness measurements for longitudinal strength
evaluation and repair methods
1

Extent 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 Z10.1, 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 Z10.1. 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 Z10.1.
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 Z10.1,
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 Z10.1, 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.
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 Z10.1.
Page 79 of 92

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Z10.1 Annex III

Z10.1 4
(cont’d)Effective 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 appliedshould 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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Z10.1 Annex IV

Z10.1(cont’d)

ANNEX IV

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Z10.1 Annex IVA

Z10.1

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:
1

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 Z10.1.
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.

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Z10.1

3

(cont’d)

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.
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.

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Z10.1(cont’d)

10

Minimum thickness of hull structures

This section of the survey programme is to specify the minimum thickness for hull structuresof the ship that are subject to UR Z10.1 (indicate either (a) or preferably (b), if suchinformation is available):(a)

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

Given in the following table(s):Original asbuilt thickness(mm)Area or location
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
Transverse web frames, floors
and stringers
Plating
Flanges
Stiffeners
Cross ties
Flanges
Webs

Minimum
thickness(mm)

Substantial
corrosion
thickness(mm)

Note: The wastage allowance tables are to be attached to the survey programme.

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Z10.1 Annex IVA

Z10.1(cont’d)11

Thickness measurement firmThis section of the survey programme is to identify changes, if any, relating to the informationon 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

Location

RepairDate ofrepairHull damages for sister or similar ships (if available) in the case ofdesign related damage
Tank or
space
number or
area

Possiblecause, if
known

Descriptionof thedamages

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Location

RepairDate ofrepair

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Z10.1 Annex IVA

Z10.1(cont’d)13

Areas 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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Z10.1(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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Z10.1 Annex IVB

Z10.1

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 Z10.1. 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 Z10.1.
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
Under deck
Bottomtransverse
Transverse

Wing
Tanks

CentreTanks

C(Cargo)/B(Ballast)

Temporarystaging

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Rafts

Ladders

DirectaccessOther
means(pleasespecify)

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Z10.1 Annex IVB

Z10.1(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.

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Z10.1 Annex IVB

Z10.1(cont’d)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)

Cargo centre
tanks

Coating
condition(3)

Structural
deterioration
(4)

Tank
damagehistory(5)

Cargo wing
tanks

Slop

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Z10.1 Annex IVB

Z10.1

Tank No.

(cont’d)Corrosion
protection(1)

Coating
extent(2)

Coating
condition(3)

Structural
deterioration(4)

Ballast tanks

Tankdamagehistory(5)

Aft peakFore peak
Miscellaneous
spacesNote: 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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Z10.1 Annex IVB

Z10.1(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:

Annex IV end
Document end

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