Z7

Z7
Z7(1990)(cont’d)(Rev.1

1990)(Rev.2
1992)(Rev.3
1994)(Rev.4
1996)(Rev.5
July 1998)(Rev.6
April 1999)(Rev.7
Nov 2000)(Rev.8Mar 2002)(Rev.9Oct 2002)(Rev.10Apr 2004)(Rev.11
June 2005)(Rev.12Jan 2006)(Rev.13
Aug 2006)(Rev.14
Oct 2006)(Rev.15
Nov 2007)(Rev.16
Mar 2009)(Rev.17
May 2010)(Rev.18
Jan 2011)(Rev.19
July 2011)(Rev.20
May 2013)(Rev.21
Jan 2014)(Rev.22
Feb 2015)(Rev.23
July 2015)(Rev.24
Feb 2016)(Rev.25
June 2016)(Rev.26
Jan 2018)(Rev.27
Oct 2018)(Rev.28
May 2019)(Corr.1
Dec 2020)(Rev.29
May 2022)(Corr.1
May 2024)

Hull Classification Surveys
CONTENTS
1 General
1.1 Application
1.2 Definitions
1.3 Repairs
1.4 Thickness measurements and close-up surveys
1.5 Thickness measurements Acceptance Criteria
1.6 Remote Inspection Techniques (RIT)
2 Special Survey
2.1 Schedule
2.2 Scope
3 Annual Survey
3.1 Schedule
3.2 Scope
4 Intermediate Survey
4.1 Schedule
4.2 Scope
5 Preparation for survey
5.1 Conditions for Survey
5.2 Access to Structures
5.3 Equipment for Survey
5.4 Survey at sea or at anchorage

TABLE 1MINIMUM REQUIREMENTS FOR THICKNESS MEASUREMENTS AT SPECIAL SURVEYSTABLE 2GUIDANCE FOR ADDITIONAL THICKNESS MEASUREMENTS IN WAY OF
SUBSTANTIAL CORROSIONTABLE 3MINIMUM REQUIREMENTS FOR INTERNAL EXAMINATION AT HULL SPECIAL
SURVEYS OF FUEL OIL, LUBE OIL AND FRESHWATER TANKSTABLE 4SURVEY REQUIREMENTS FOR AUTOMATIC AIR PIPE HEADS AT SPECIAL SURVEY
ANNEX IIACS RECOMMENDED PROCEDURES FOR THICKNESS MEASUREMENTS OF SHIPS
ANNEX II (Net Scantling Design)
IACS RECOMMENDED PROCEDURES FOR THICKNESS MEASUREMENTS OF SHIPSBUILT ACCORDING TO THE NET SCANTLING APPROACH

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(cont’d)Note:
1.

Changes introduced in Rev.7 are to be applied by all Members and Associates from 1
July 2001.

2.

Rev.10 deletes para. 5.4.5 and is effective from the date of adoption by Council (21 Apr
2004).

3.

Change introduced in Rev.11 are to be uniformly implemented from 1 July 2006.

4.

Changes introduced in Rev. 12 are to be uniformly applied by IACS Societies on surveys
commenced on or after 1 January 2007.

5.

Changes introduced in Rev. 13 (paragraph 1.1.5) are to be uniformly applied by IACS
Societies at special and annual surveys, as applicable, carried out after the ship has
been made compliant with the requirements of SOLAS II-1/23-3 and II-1/25, andcommenced on or after 1 July 2007 (see UR Z7.1 Rev. 4).

6.

Changes introduced in Rev. 14 are to be uniformly applied by IACS Societies on surveys
commenced on or after 1 Jan 2008.

7.

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

8.

Changes introduced in Rev.16 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2010.
As for the requirements regarding semi-hard coatings, these coatings, if already applied,
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 annual internal
examination of the ballast tanks.

9.

Changes introduced in Rev.17 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2011.

10. Changes introduced in Rev.18 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 January 2012.
11. Changes introduced in Rev.19 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2012.
12. Changes introduced in Rev.20 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2014.
13. Changes introduced in Rev.21 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 January 2015.
14. Changes introduced in Rev.22 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2016.
15. Changes introduced in Rev.23 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2016.

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(cont’d)

16. Changes introduced in Rev.24 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2017.
17. Changes introduced in Rev.25 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2017.
18. Changes introduced in Rev.26 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 January 2019.
19. Changes introduced in Rev.27 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 January 2020.
20. Changes introduced in Rev.28 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2020.
21. Changes introduced in Rev.29 are to be uniformly applied by IACS Societies for surveys
commenced on or after 1 July 2023.

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(cont’d)1.

General1.1

Application

1.1.1 These requirements apply to all self-propelled vessels.
1.1.2 For additional items, refer to Z1.
1.1.3 For additional requirements for hull structure, piping systems and ballast tanks
applicable to tankers, bulk carriers, chemical tankers, double hulled tankers, double side skinbulk carriers, general dry cargo ships and liquefied gas carriers, refer to Z10.1, Z10.2, Z10.3,
Z10.4, Z10.5, Z7.1 and Z7.2 respectively.
1.1.4 For additional requirements applicable to cargo installations on ships carrying liquefied
gases in bulk, refer to Z16.
1.1.5 For additional requirements applicable to water level detectors fitted on single holdcargo ships, refer to UR Z7.1.
1.1.6 Special consideration may be given in application of relevant sections of this Unified
Requirement to commercial vessels owned or chartered by Governments, which are utilized
in support of military operations or service.
1.2

Definitions

1.2.1 Ballast Tank
A Ballast Tank is a tank that is being used primarily for salt water ballast.
1.2.2 Spaces
Spaces are separate compartments including holds and tanks.
1.2.3 Close-Up Survey
A Close-Up Survey is a survey where the details of structural components are within theclose visual inspection range of the surveyor i.e. normally within reach of hand.
1.2.4 Transverse Section
A Transverse Section includes all longitudinal members such as plating, longitudinals andgirders at the deck, sides, bottom, inner bottom, and longitudinal bulkhead. For transversely
framed vessels, a transverse section includes adjacent frames and their end connections in
way of transverse sections.
1.2.5 Representative Space
Representative Spaces are those which are expected to reflect the conditions of other spacesof similar type and service and with similar corrosion prevention systems. When selecting
representative spaces, account is to be taken of the service and repair history on board andidentifiable Critical Structural Areas and/or Suspect Areas.
1.2.6 Critical Structural Area
Critical Structural Areas are locations which have been identified from calculations to requiremonitoring or from the service history of the subject ship or from similar ships or sister ships,
if applicable, to be sensitive to cracking, buckling or corrosion which would impair the
structural integrity of the ship.

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(cont’d)1.2.7 Suspect Area
Suspect Areas are locations showing Substantial Corrosion and/or are considered by theSurveyor to be prone to rapid wastage.
1.2.8 Substantial Corrosion
Substantial Corrosion is an extent of corrosion such that assessment of corrosion patternindicates a wastage in excess of 75% of allowable margins, but within acceptable limits.
1.2.9 Corrosion Prevention System
A Corrosion Prevention System is normally considered a full hard protective coating.
Hard Protective Coating is usually to be epoxy coating or equivalent. Other coating systems,
which are neither soft nor semi-hard coatings, may be considered acceptable as alternatives
provided that they are applied and maintained in compliance with the manufacturer’s
specifications.
1.2.10 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
under consideration, but less than as defined for POOR
condition

POOR

condition with general breakdown of coating over 20% or moreof areas or hard scale at 10% or more of areas underconsideration

1.2.11 Prompt and Thorough Repair
A Prompt and Thorough Repair is a permanent repair completed at the time of survey to thesatisfaction of the Surveyor, therein removing the need for the imposition of any associatedcondition of classification.
1.2.12 Special consideration
Special consideration or specially considered (in connection with close-up surveys andthickness measurements) means sufficient close-up inspection and thickness measurements
are to be taken to confirm the actual average condition of the structure under the coating.
1.2.13 Air pipe head
Air pipe heads installed on the exposed decks are those extending above the freeboard deckor superstructure decks.
1.2.14 Cargo Length Area
Cargo Length Area is that part of the ship which contains all cargo holds and adjacent areas
including fuel tanks, cofferdams, ballast tanks and void spaces.
1.2.15 Remote Inspection Techniques(RIT)
Remote Inspection Technique is a means of survey that enables examination of any part ofthe structure without the need for direct physical access of the surveyor(refer to Rec.42).

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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 1.2.11) repaired. Areas to beconsidered include:-side shell frames, their end attachments and adjacent shell plating;deck structure and deck plating;bottom structure and bottom plating;watertight or oiltight bulkheads;
hatch covers and hatch coamings;
items in 3.2.3.5, 3.2.3.6 and 3.2.3.8.

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

1.4.1 In any kind of survey, i.e. special, intermediate, annual or other surveys having thescope of the foregoing ones, thickness measurements of structures in areas where close-up
surveys are required, shall be carried out simultaneously with close-up surveys.
1.4.2 Consideration may be given by the attending Surveyor to allow use of Remote
Inspection Techniques (RIT) as an alternative to close-up survey. Surveys conducted using a
RIT are to be completed to the satisfaction of the attending Surveyor. When RIT is used for aclose-up survey, temporary means of access for the corresponding thickness measurements
is to be provided unless such RIT is also able to carry out the required thickness
measurements.
1.4.3 For structure built with a material other than steel, alternative thickness measurement
requirements may be developed and applied as deemed necessary by the Society.
1.5

Thickness measurements Acceptance Criteria

The acceptance criteria for thickness measurements are according to the Rules of theindividual Classification Society and/or specific IACS URs depending on ship’s age andstructural elements concerned, e.g UR S181 for corrugated transverse bulkhead, UR S213 or
UR S21A2 for all cargo hatch covers and coamings on exposed decks.

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(cont’d)__________________
1 UR S18 Revision 7 or subsequent revisions or corrigenda as applicable.
2 UR S21A applies for ships contracted for construction on or after 1 July 2012, Rev.1 of UR S21 A applies forships contracted for construction on or after 1 July 2016. UR S21A was withdrawn from 1 July 2024 and replacedby UR S21 Rev.6.
3 UR S21 Revision 6 applies for ships contracted for construction on or after 1 July 2024.

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(cont’d)

1.6

Remote Inspection Techniques (RIT)

1.6.1 The RIT is to provide the information normally obtained from a close-up survey. RIT
surveys are to be carried out in accordance with the requirements given here-in and therequirements of IACS Recommendation 42 ‘Guidelines for Use of Remote Inspection
Techniques for surveys’. These considerations are to be included in the proposals for use of
a RIT which are to be submitted in advance of the survey so that satisfactory arrangements
can be agreed with the Classification Society.
1.6.2 The equipment and procedure for observing and reporting the survey using a RIT are
to be discussed and agreed with the parties involved prior to the RIT survey, and suitable
time is to be allowed to set-up, calibrate and test all equipment beforehand.
1.6.3 When using a RIT as an alternative to close-up survey, if not carried out by theSociety itself, it is to be conducted by a firm approved as a service supplier according to UR
Z17 and is to be witnessed by an attending surveyor of the Society.
1.6.4 The structure to be examined using a RIT is to be sufficiently clean to permit
meaningful examination. Visibility is to be sufficient to allow for a meaningful examination.
The Classification Society is to be satisfied with the methods of orientation on the structure.
1.6.5 The Surveyor is to be satisfied with the method of data presentation including pictorial
representation, and a good two-way communication between the Surveyor and RIT operator
is to be provided.
1.6.6 If the RIT reveals damage or deterioration that requires attention, the Surveyor may
require traditional survey to be undertaken without the use of a RIT.
2.

Special Survey

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 5 years from the credited date of the previous Special
Survey. However, an extension of class of 3 months maximum beyond the 5th year can be
granted in exceptional circumstances.
In this case, the next period of class will start from the expiry date of the Special Survey
before the extension was granted.
2.1.3 For surveys completed within 3 months before the expiry date of the Special Survey,
the next period of class will start from the expiry date of the Special Survey. For surveys
completed more than 3 months before the expiry date of the Special Survey, the period 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 is
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(cont’d)commenced prior to the 4th Annual Survey, the entire survey is to be completed within 15
months if such work is to be credited to the Special Survey.
2.1.5 A survey planning meeting is to be held prior to the commencement of the survey.
2.1.6 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 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, equipment andrelated piping, as required in 2.2.12, are in satisfactory condition and fit for the intended
purpose for the new period of class of five years to be assigned, subject to proper
maintenance and operation and the periodical surveys being carried out at the due dates.
2.2.2 The examinations of the hull are to be supplemented by testing and thickness
measurements as required in 2.2.9 and 2.2.11, 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.
2.2.3 The Special Survey is to include examination of underwater parts per Z3.
2.2.4 The anchors and chain cables are to be ranged, examined and the requiredcomplement and condition verified. The chain locker, holdfasts, hawse pipes and chain
stoppers are to be examined and pumping arrangements of the chain locker tested. At
Special Survey No. 2 and subsequent Special Surveys, chain cables are to gauged andrenewed in cases where their mean diameter is worn below the limits allowed by the Society.
2.2.5 All spaces including holds and their ‘tween decks where fitted; double bottom, deep,ballast, peak and cargo tanks; pumprooms, pipe tunnels, duct keels, machinery spaces, dry
spaces, cofferdams and voids are to be internally examined including the plating and framing,bilges and drain wells, sounding, venting, pumping and drainage arrangements. Internal
examination of fuel oil, lube oil and fresh water tanks is to be carried out in accordance with
Table 3. At special survey No.3 and subsequent special surveys, structural downflooding
ducts and structural ventilation ducts are to be internally examined.
2.2.6 Engine room structure is to be examined. Particular attention is to be given to tank
tops, shell plating in way of tank tops, brackets connecting side shell frames and tank tops,and engine room bulkheads in way of tank top and bilge wells. Particular attention is to begiven to the sea suctions, sea water cooling pipes and overboard discharge valves and theirconnections to the shell plating. Where wastage is evident or suspect, thickness
measurements are to be carried out, and renewals or repairs made when wastage exceeds
allowable limits.
2.2.7 Where provided, the condition of corrosion prevention system of ballast tanks is to be
examined. For ballast tanks, excluding double bottom tanks, where a hard protective coating
is found in POOR condition and it is not renewed, where soft or semi-hard coating has been
applied, or where a hard protective coating was not applied from time of construction, thetanks in question are to be examined at annual intervals. Thickness measurements are to be
carried out as deemed necessary by the surveyor.
2.2.8 When such breakdown of hard protective coating is found in double bottom ballast
tanks and it is not renewed, where a soft or semi-hard coating has been applied, or where ahard protective coating was not applied from the time of construction, the tanks in question
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(cont’d)may be examined at annual intervals. When considered necessary by the surveyor, or where
extensive corrosion exists, thickness measurements are to be carried out.
2.2.9 Boundaries of double-bottom, deep, ballast, peak, and other tanks, including holds
adapted for the carriage of salt water ballast, are to be tested with a head of liquid to the topof air pipes or to near the top of hatches for ballast/cargo holds. Boundaries of fuel oil, lube oiland fresh water tanks are to be tested with a head of liquid to the highest point that liquid willrise under service conditions. Tank testing of fuel oil, lube oil and fresh water tanks may be
specially considered based on a satisfactory external examination of the tank boundaries,
and a confirmation from the Master stating that the pressure testing has been carried out
according to the requirements with satisfactory results. The Surveyor may extend the testing
as deemed necessary.
2.2.10 Hatch Covers and Coamings
The hatch covers and coamings are to be surveyed as follows:
2.2.10.1 A thorough inspection of the items listed in 3.2.3, including close-up survey of hatch
cover plating and hatch coaming plating, is to be carried out. Subject to cargo hold hatch
covers of approved design which structurally have no access to the internals, close-up survey
shall be done of accessible parts of hatch covers structures.
2.2.10.2 Checking of the satisfactory operation of all mechanically operated hatch covers is to
be made, including:- stowage and securing in open condition;- proper fit and efficiency of sealing in closed conditions;- operational testing of hydraulic and power components, wires, chains and link drives.
2.2.10.3 Checking the effectiveness of sealing arrangements of all hatch covers by hosetesting or equivalent is to be carried out.
2.2.11 Thickness measurements are to be carried out in accordance with Table 1. The
Surveyor may extend the thickness measurements as deemed necessary. When thickness
measurements indicate substantial corrosion, the extent of thickness measurements is to be
increased to determine areas of substantial corrosion. Table 2 may be used as guidance forthese additional thickness measurements. These extended thickness measurements are to
be carried out before the survey is credited as completed.
2.2.12 All bilge and ballast piping systems are to be examined and operationally tested toworking pressure to attending Surveyor’s satisfaction to ensure that tightness and condition
remain satisfactory.
2.2.13 For all ships except for passenger ships, automatic air pipe heads are to be completely
examined (both externally and internally) as indicated in Table 4.
For designs where the inner parts cannot be properly inspected from outside, this is toinclude removal of the head from the air pipe. Particular attention is to be paid to the conditionof the zinc coating in heads constructed from galvanised steel.

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(cont’d)3.

Annual Surveys

3.1

Schedule

Annual Surveys are to be held within 3 months before or after each anniversary date of thedate of the initial classification survey or the completion of the last Special Survey.
3.2

Scope

3.2.1 The survey is to consist of an examination for the purpose of ensuring, as far aspracticable, that the hull, hatch covers, hatch coamings, closing appliances, equipment andrelated piping are maintained in a satisfactory condition.
3.2.2 For additional items refer to Z1.
3.2.3 Examination of weather decks, ship side plating above water line, hatch covers andcoamings.
3.2.3.1 Confirmation is to be obtained that no unapproved changes have been made to thehatch covers, hatch coamings and their securing and sealing devices since the last survey.
3.2.3.2 Where mechanically operated steel covers are fitted, checking the satisfactory
conditions, as applicable, of:-hatch covers;
tightness devices of longitudinal, transverse and intermediate cross junctions(gaskets, gasket lips, compression bars, drainage channels);clamping devices, retaining bars, cleating;chain or rope pulleys;
guides;guide rails and track wheels;
stoppers, etc.;
wires, chains, gypsies, tensioning devices;
hydraulic system essential to closing and securing;safety locks and retaining devices.

Where portable covers, wooden or steel pontoons are fitted, checking the satisfactory
condition where applicable, of:-wooden covers and portable beams, carriers or sockets for the portable beam, andtheir securing devices;
steel pontoons,tarpaulins;
cleats, battens and wedges;
hatch securing bars and their securing devices;loading pads/bars and the side plate edge;
guide plates and chocks;
compression bars, drainage channels and drain pipes (if any).

3.2.3.3 Checking the satisfactory condition of hatch coaming plating and their stiffeners,
where applicable.
3.2.3.4 Random checking of the satisfactory operation of mechanically operated hatch covers
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(cont’d)-stowage and securing in open condition;
proper fit and efficiency of sealing in closed condition;
operational testing of hydraulic and power components, wires, chains, and link drives.

3.2.3.5 Examination of the weld connection between air pipes and deck plating.
3.2.3.6 External examination of all air pipe heads installed on the exposed decks.
3.2.3.7 Examination of flame screens on vents to all bunker tanks.
3.2.3.8 Examination of ventilators, including closing devices, if any.
3.2.4 Suspect Areas
Suspect Areas identified at previous surveys are to be examined. Thickness measurements
are to be taken of the areas of substantial corrosion and the extent of thickness
measurements is to be increased to determine areas of substantial corrosion. Table 2 may be
used as guidance for these additional thickness measurements. These extended thickness
measurements are to be carried out before the annual survey is credited as completed.
Note: these requirements are not applicable to cargo tanks of oil tankers, chemical tankers
and double hull oil tankers, surveyed in accordance with URs Z10.1, Z10.3 and Z10.4.
3.2.5 Examination of Ballast Tanks
3.2.5.1 Examination of ballast tanks when required as a consequence of the results of theSpecial Survey and Intermediate Survey is to be carried out. When considered necessary by
the surveyor, or where extensive corrosion exists, thickness measurement is to be carriedout. If the results of these thickness measurements indicate that Substantial Corrosion isfound, then the extent of thickness measurements is to be increased to determine areas of
substantial corrosion. Table 2 may be used as guidance for these additional measurements.
These extended thickness measurements are to be carried out before the annual survey iscredited as completed.

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(cont’d)4.

Intermediate Survey

4.1

Schedule

4.1.1 The Intermediate Survey is to be carried out either at or between the second and third
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 A survey planning meeting is to be held prior to the commencement of the survey.
4.1.4 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 The scope of the second or third Annual Survey is to be extended to include thefollowing:
4.2.1.1 For ships between 5 and 10 years of age, a general, internal examination ofrepresentative ballast tanks is to be carried out. If there is no hard protective coating, soft orsemi-hard coating, or POOR coating condition, the examination is to be extended to otherballast tanks of the same type.
4.2.1.2 For ships over 10 years of age, a general, internal examination of all ballast tanks is tobe carried out.
4.2.2 If such examinations reveal no visible structural defects, the examination may be limited
to a verification that the corrosion prevention system remains effective.
4.2.3 For ballast tanks, excluding double bottom ballast tanks, if there is no hard protective
coating, soft or semi-hard coating, or POOR coating condition and it is not renewed, the tanks
in question are to be internally examined at annual intervals.
4.2.4 When such conditions are found in double bottom ballast tanks, the tanks in question
may be internally examined at annual intervals.
4.2.5 In the case of dry cargo ships over 15 years old, other than bulk carriers subject toZ10.2 or Z10.5 or general dry cargo ships subject to Z7.1, an internal examination of selectedcargo holds is to be carried out.
4.2.6 In the case of ships over 10 years of age, other than ships engaged in the carriage ofdry cargoes only or ships subject to Z10.1, Z10.3, Z10.4 or Z7.2, an internal examination of
selected cargo spaces is to be carried out.

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(cont’d)5.

Preparations for Survey

5.1

Conditions for survey

5.1.1 The Owner is to provide the necessary facilities for a safe execution of the survey.
5.1.2 Tanks and spaces are to be safe for access, i.e. gas freed, ventilated and illuminated.
5.1.3 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. However, those areas of structure whose renewal has already been decided by
the Owner need only be cleaned and descaled to the extent necessary to determine the limitsof the areas to be renewed.
5.1.4 Sufficient illumination is to be provided to reveal corrosion, deformation, fractures,
damages or other structural deterioration.
5.1.5 Where soft or semi-hard coatings have been applied, safe access is to be provided forthe surveyor to verify the effectiveness of the coating and to carry out an assessment of theconditions of internal structures which may include spot removal of the coating. When safe
access cannot be provided, the soft or semi-hard coating is to be removed.
5.1.6 Casings, ceilings or linings, and loose insulation, where fitted, are to be removed, as
required by the Surveyor, for examination of plating and framing. Compositions on plating are
to be examined and sounded, but need not be disturbed if found adhering satisfactorily to theplating.
5.1.7 In refrigerated cargo spaces the condition of the coating behind the insulation is to be
examined at representative locations. The examination may be limited to verification that theprotective coating remains effective and that there are no visible structural defects. Where
POOR coating condition is found, the examination is to be extended as deemed necessary by
the Surveyor. The condition of the coating is to be reported. If indents, scratches, etc., aredetected during surveys of shell plating from the outside, insulations in way are to be
removed as required by the Surveyor, for further examination of the plating and adjacentframes.
5.2

Access to structures

5.2.1 For survey, means are to be provided to enable the surveyor to examine the hull
structure in a safe and practical way.
5.2.2 For survey in cargo holds and ballast tanks, one or more of the following means foraccess, acceptable to the Surveyor, is to be provided:
•
•
•
•
•

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

Page 14 of 52

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Z7

Z7

(cont’d)5.2.3 For Surveys conducted by use of a remote inspection technique, one or more of thefollowing means for access, acceptable to the Surveyor, is to be provided:
•
•
•
•
5.3

Unmanned robot arm
Remotely Operated Vehicles (ROV)
Unmanned Aerial Vehicles / Drones
Other means acceptable to the Classification Society.
Equipment for survey

5.3.1 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.
Thickness measurements are to be carried out by a firm approved by the society inaccordance with UR Z17, except that in respect of measurements of non-ESP ships less than
500 gross tonnage and all fishing vessels, the firm need not be so approved.
5.3.2 One or more of the following fracture detection procedures may be required if deemednecessary by the Surveyor:
•
•
•
•
5.4

radiographic equipment;ultrasonic equipment;
magnetic particle equipment;
dye penetrant.
Survey at sea or at anchorage

5.4.1 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 and 5.3.
5.4.2 A communication system is to be arranged between the survey party in the tank orspace and the responsible officer on deck. This system must also include the personnel incharge of ballast pump handling if boats or rafts are used.
5.4.3 When boats or rafts are used, appropriate life jackets are to be available for allparticipants. Boats or rafts are to have satisfactory residual buoyancy and stability even if one
chamber is ruptured. A safety checklist is to be provided.
5.4.4 Surveys of tanks by means of boats or rafts may only be undertaken at the sole
discretion of the Surveyor, who is to take into account the safety arrangements provided,
including weather forecasting and ship response in reasonable sea conditions.
See footnote **Reference is made to IACS Recommendation 39 - Guidelines for use of Boats or Rafts for
Close-up surveys.
Page 15 of 52

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Z7

Z7

(cont’d)

TABLE 1MINIMUM REQUIREMENTS FOR THICKNESS MEASUREMENTS AT
SPECIAL SURVEY
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
15 < Age

1) Suspect areas
throughout thevessel.

1) Suspect areas
throughout thevessel.
2) One transverse
section of deck
plating within theamidships 0.5L (inway of a cargospace, if applicable)

1) Suspect areas
throughout thevessel.
2) Two transverse
sections within theamidships 0.5L (inway of two cargospaces, if applicable)

1) Suspect areas
throughout thevessel.
2) A minimum of
three transverse
sections within theamidships 0.5L. (inway of cargo spaces,
if applicable)
3) All cargo holdhatch covers andcoamings (plating
and stiffeners).
4) Internals in
forepeak andafterpeak ballast
tanks.
5) All exposed main
deck plating fulllength.
6) Representative
exposedsuperstructure deck
plating((poop, bridge,
and forecastle deck).
7) Lowest strake andstrakes in way of‘tween decks of alltransverse bulkheads
in cargo spaces
together withinternals in way.
8) All wind – andwater strakes, port
and starboard, fulllength.
9) All keel plates fulllength. Also,
additional bottom
plates in way ofcofferdams,
machinery space,and aft end of tanks.

Page 16 of 523) All cargo holdhatch covers andcoamings (plating
and stiffeners).
4) Internals in
forepeak andafterpeak ballast
tanks.

IACS Req. 1990/Rev.29 Corr.1 2024

Z710) Plating ofseachests. Shellplating in way ofoverboard discharges
as considerednecessary by theattending surveyor

Z7(cont’d)Notes:For thickness measurements reporting, the forms included in Annex I or Annex II may be
used, as appropriate. The annexed forms are a recommendation and are not a mandatory
requirement under this UR Z7.
1. Thickness measurement locations are to be selected to provide the best representative
sampling of areas likely to be most exposed to corrosion, considering cargo and ballast
history and arrangement and condition of protective coatings.
2. Thickness measurements of internals may be specially considered by the Surveyor if thehard protective coating is in GOOD condition.
3. For ships less than 100 meters in length, the number of transverse sections required atSpecial Survey No. 3 may be reduced to one (1), and the number of transverse sections
required at Subsequent Special Surveys may be reduced to two (2).
4. For ships more than 100 meters in length, at Special Survey No. 3, thickness
measurements of exposed deck plating within amidship 0.5 L may be required.
5. Subject to cargo hold hatch covers of approved design which structurally have no accessto the internals, thickness measurement shall be done of accessible parts of hatch covers
structures.

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Z7

Z7

(cont’d)

TABLE 2GUIDANCE FOR ADDITIONAL THICKNESS MEASUREMENTS IN
WAY OF SUBSTANTIAL CORROSIONSTRUCTURAL MEMBER

EXTENT OF
MEASUREMENTPATTERN OFMEASUREMENT

Plating

Suspect area and adjacentplates.

5 point pattern over 1 square
meter.

Stiffeners

Suspect area.

3 measurements each in line
across web and flange.

Page 18 of 52

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Z7

Z7

(cont’d)

TABLE 3MINIMUM REQUIREMENTS FOR INTERNAL EXAMINATION AT HULL
SPECIAL SURVEYS OF FUEL OIL, LUBE OIL AND FRESH WATER
TANKS
Tank

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

-Engine Room

None

None

One

One

-Cargo Length
Area

None

One

Two

Half, minimum 2-If no tanks in
Cargo LengthArea, additional
fuel tank(s)outside ofEngine Room (iffitted)

None

One

One

Two

Lube Oil

None

None

None

One

Fresh Water

None

One

All

All

Fuel Oil
Bunkertanks

Notes
1) These requirements apply to tanks of integral (structural) type.
2) If a selection of tanks is accepted to be examined, then different tanks are to be examinedat each special survey, on a rotational basis.
3) Peak tanks (all uses) are subject to internal examination at each special survey.
4) At special surveys no 3 and subsequent surveys, one deep tank for fuel oil in the cargo
length area is to be included, if fitted.

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Z7

Z7

(cont’d)

TABLE 4SURVEY REQUIREMENTS FOR AUTOMATIC PIPE HEADS AT
SPECIAL SURVEYS
Special Survey no.1
Age ≤ 5--Special Survey no.2
5 < age ≤ 10

Two air pipe heads,
one port and one
starboard, located on
the exposed decks inthe forward 0.25 L,
preferably air pipes
serving ballast tanks.

-

All air pipe heads
located on the
exposed decks in theforward 0.25L.

-

At least 20% of air
pipe heads on the
exposd decks serving
spaces aft of 0.25 L,
preferably air pipes
serving ballast tanks

Two air pipe heads,
one port and one
starboard, on
exposed decks,
serving spaced aft of
0.25 L, preferably air
pipes serving ballast
tanks.
(1) (2)(1) (2)

Special Survey No.3 andsubsequent
Age > 10- All air pipe heads
located on the
exposed decks(3)(1) The selection of air pipe heads to be examined is left to the attending Surveyor.
(2) According to the results of this examination, the Surveyor may require the examination ofother heads located on the exposed decks.
(3) Exemption may be considered for air pipe heads where there is substantial evidence of
replacement after the last special survey.

Page 20 of 52

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Z7 Annex I

Z7

ANNEX I*

(cont’d)

Sheet 1

IACS RECOMMENDED PROCEDURES FOR THICKNESS MEASUREMENTS
OF SHIPS**Note: Annex I is recommendatory.

Page 21 of 52

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Z7 Annex I

Z7(cont’d)1.

This document may be used for recording thickness measurements as required by the
IACS Unified Requirement Z7.

2.

Reporting forms TM1-G, TM2-G (i) and (ii), TM3-G, TM4-G, TM5-G (sheets 4-9) may be
used for recording thickness measurements and the maximum allowable diminution is
to be stated.
The maximum allowable diminution could be stated in an attached document.

Page 22 of 52

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Z7 Annex I

Z7(cont’d)

CONTENTS
Sheet 1

- Front cover

Sheet 2

- Contents

Sheet 3- General particulars

Sheet 2REPORTS
Sheet 4

- Report TM1-G for recording the thickness measurement of all deck plating, allbottom shell plating and side shell plating.

Sheet 5

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

Sheet 6

- Report TM2-G (ii) for recording the thickness measurement of shell and deck
plating at transverse sections - shell plating.

Sheet 7

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

Sheet 8- Report TM4-G for recording the thickness measurement of transverse
bulkheads.

Sheet 9- Report TM5-G for recording the thickness measurement of miscellaneous
structural members.

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Z7 Annex I

Z7(cont’d)

GENERAL PARTICULARS

Sheet 3Ship’s name:IMO number:Class identity number:Port of registry:Gross tons:Deadweight:Date of build:Classification Society:-

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

SheetsNames of operator:-........................

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

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

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

Company official stamp:-

Classification Society
Official Stamp:-* Delete as appropriate

Page 24 of 52

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Z7 Annex I

Z7(cont’d)

TM1-G

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

Page 25 of 52

Sheet 4S%%

Mean Diminution%
P

S

Maximum
Allowable
Diminutionmm

NOTES – See Reverse

IACS Req. 1990/Rev.29 Corr.1 2024

Z7 Annex I

Z7(cont’d)NOTES TO REPORT TM1-G
1.

This report may be used for recording the thickness measurement of:A - All strength deck plating within cargo length area.
B - Keel, bottom shell plating and bilge plating within the cargo length area.
C - Side shell plating that is all wind and water strakes within the cargo length area.
D - Side shell plating that is selected wind and water strakes outside the cargo length
area.

2.

The strake position is to be cleared indicates 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 sheerstrake and letteras shown on shell expansion.

3.

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 plates and the single
measurements recorded are to represent the average of multiple measurements.

5.

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

Page 26 of 52

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Z7 Annex I

Z7

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

Ship’s name.........................

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

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

STRENGTH DECK AND SHEERSTRAKE PLATINGFIRST TRANSVERSE SECTION AT FRAME NUMBER
STRAKEPOSITION
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.............................................

Page 27 of 52

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

IACS Req. 1990/Rev.29 Corr.1 2024%

Z7 Annex I

Z7(cont’d)NOTES TO REPORT TM2-G (i)1.

This report may be used for recording the thickness measurement of:Strength deck plating and sheerstrake plating transverse sections:Two or three section within the cargo length area, comprising of the structural
items.

2.

Only the deck 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.

Page 28 of 52

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Z7 Annex I

Z7

TM2-G (ii)(cont’d)Report on THICKNESS MEASUREMENT OF SHELL AND DECK PLATING(one, two or three transverse sections)

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

Page 29 of 52

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

IACS Req. 1990/Rev.29 Corr.1 2024%

Z7 Annex I

Z7(cont’d)NOTES TO REPORT TM2-G (ii)1.

This report may be used for recording the thickness measurement of:Shell plating transverse sections:Two or three sections within the cargo length area, comprising of the structural
items.

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.

Page 30 of 52

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Z7 Annex I

Z7(cont’d)TM3-G

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

Page 31 of 52

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

IACS Req. 1990/Rev.29 Corr.1 2024%

Z7 Annex I

Z7(cont’d)NOTES TO REPORT TM3-G
1.

This report may be used for recording the thickness measurement of:Longitudinal Members at transverse sections:Two, or three sections within the cargo length area, comprising of the appropriate
structural items.

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.

Page 32 of 52

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Z7 Annex I

Z7(cont’d)TM4-G

Report on THICKNESS OF TRANSVERSE BULKHEADS

Ship’s name.........................

Sheet 8Class Identity No. .........................

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

LOCATION OF STRUCTURE:

FRAME NO.:STRUCTURAL COMPONENT (PLATING/STIFFENER)
Original
Thickness
mm

Max.
Alwb.
Dim.
mm

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

Page 33 of 52

GaugedPort

Starboard

Diminution
P
mm

Diminution
S
%

mm

%

NOTES – See Reverse

IACS Req. 1990/Rev.29 Corr.1 2024

Z7 Annex I

Z7(cont’d)NOTES TO REPORT TM4-G
1.

This report form may be used for recording the thickness measurement of cargo holdtransverse bulkheads.

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.

Page 34 of 52

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Z7 Annex I

Z7(cont’d)TM5-G

Report on THICKNESS MEASUREMENT OF MISCELLANEOUS STRUCTURAL MEMBERS

Ship’s name.........................

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

Sheet 9

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

Page 35 of 52%%

NOTES – See Reverse

IACS Req. 1990/Rev.29 Corr.1 2024

Z7 Annex I

Z7(cont’d)NOTES TO REPORT TM5-G
1.

This report may be used for recording the thickness measurement of miscellaneous
structural members.

2.

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

3.

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

Page 36 of 52

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Z7 Annex II (NSD)

Z7(cont’d)

ANNEX II (Net Scantling Design)*

Sheet 1

IACS RECOMMENDED PROCEDURES FOR THICKNESS MEASUREMENTS
OF SHIPS BUILT ACCORDING TO THE NET SCANTLING APPROACH**Note: Annex II (NSD) is recommendatory.

Page 37 of 52

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Z7 Annex II (NSD)Z71.

This document may be used for recording thickness measurements of ships built
according to the net scantling approach as required by the IACS Unified Requirement
Z7.

2.

Reporting forms TM1-G(NSD), TM2-G(NSD) (i) and (ii), TM3-G(NSD), TM4-G(NSD),
TM5-G(NSD) (sheets 4-9) may be used for recording thickness measurements. The asbuilt thickness and the voluntary thickness addition and renewal thickness (minimum
allowable thickness) are to be stated in the said forms.

(cont’d)Page 38 of 52

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Z7 Annex II (NSD)

Z7(cont’d)

CONTENTS
Sheet 1

- Front cover

Sheet 2

- Contents

Sheet 3- General particulars

Sheet 2REPORTS
Sheet 4

- Report TM1-G(NSD) for recording the thickness measurement of all deck
plating, all bottom plating and side shell plating.

Sheet 5

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

Sheet 6

- Report TM2-G(NSD) (ii) for recording the thickness measurement of shell
plating at transverse sections.

Sheet 7

- Report TM3-G(NSD) for recording the thickness measurement of longitudinal
members at transverse sections.

Sheet 8- Report TM4-G(NSD) for recording the thickness measurement of transverse
bulkheads.

Sheet 9- Report TM5-G(NSD) for recording the thickness measurement of
miscellaneous structural members.

Page 39 of 52

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Z7 Annex II (NSD)

Z7(cont’d)

GENERAL PARTICULARS

Sheet 3

Ships name:IMO number:Class identity number:Port of registry:Gross tons:Deadweight:Date of build:Classification Society:-

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

SheetsNames of operator:-........................

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

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

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

Company official stamp:-

Classification Society
Official Stamp:-* Delete as appropriate

Page 40 of 52

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Z7 Annex II (NSD)

Z7(cont’d)

TM1-G(NSD)

Report on THICKNESS MEASUREMENT of ALL DECK PLATING, ALL BOTTOM 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
LetterAs Built
Thk.
mm

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

Voluntary
Thickness
Additionmm

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

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

Page 41 of 52

Sheet 4

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

Gauged Thk.
mm
(b2)
P
S

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

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

NOTES – See Reverse

IACS Req. 1990/Rev.29 Corr.1 2024

Z7 Annex II (NSD)

Z7(cont’d)NOTES TO REPORT TM1-G(NSD)
1.

This report may be used for recording the thickness measurement of:A - All strength deck plating within cargo length area.
B - Keel, bottom shell plating and bilge plating within the cargo length area.
C - Side shell plating that is all wind and water strakes within the cargo length area.
D - Side shell plating that is selected wind and water strakes outside the cargo length
area.

2.

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 sheerstrake and letteras shown on shell expansion.

3.

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 plates and the single
measurements recorded are to represent the average of multiple measurements.

5.

The remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall be renewed,
and the mark “R” is to be indicated in the right-hand column. If the result is between 0
and substantial corrosion allowable limits (according to the individual classification
Society’s Rules) the structure in way shall be additional gauged, and the mark “S” is to
be indicated in the right-hand column.

Page 42 of 52

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Z7 Annex II (NSD)Z7

TM2-G(NSD) (i) Report on THICKNESS MEASUREMENT OF SHELL AND DECK PLATING(one, two or three transverse sections)(cont’d)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
Letter

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm
(a)

Gauged
Thk.
mm
(b)
P

S

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

SECOND TRANSVERSE SECTION AT FRAME NUMBER
No.
or
Letter

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

S

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

Page 43 of 52

Ren.
Thk.
mm

Gauged
Thk.
mm
(b)

(a)

P

S

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

S

THIRD TRANSVERSE SECTION AT FRAME NUMBER
No.
or
Letter

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm
(a)

Gauged
Thk.
mm
(b)
P

S

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

NOTES – See Reverse

IACS Req. 1990/Rev.29 Corr.1 2024S

Z7 Annex II (NSD)

Z7(cont’d)NOTES TO REPORT TM2-G(NSD) (i)1.

This report may be used for recording the thickness measurement of:Strength deck plating and sheerstrake plating transverse sections:One, two or three sections within the cargo length area, comprising of thestructural items.

2.

Only the deck 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 remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall be renewed,
and the mark “R” is to be indicated in the right-hand column. If the result is between 0
and substantial corrosion allowable limits (according to the individual classification
Society’s Rules), the structure in way shall be additional gauged, and the mark “S” is to
be indicated in the right-hand column.

Page 44 of 52

IACS Req. 1990/Rev.29 Corr.1 2024

Z7 Annex II (NSD)Z7

TM2-G(NSD) (ii) Report on THICKNESS MEASUREMENT OF SHELL 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
Letter

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm
(a)

Gauged
Thk.
mm
(b)
P
S

SECOND TRANSVERSE SECTION AT FRAME NUMBER

Remaining Corr.
Addition, mm
P(b)-(a)No.
orLetter

S

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

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

Page 45 of 52

Ren.
Thk.
mm
(a)

Gauged
Thk.
mm
(b)
P
S

THIRD TRANSVERSE SECTION AT FRAME NUMBER

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

No.
orLetter

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm
(a)

Gauged
Thk.
mm
(b)
P
S

Remaining Corr.
Addition, mm
P(b)-(a)NOTES – See Reverse

IACS Req. 1990/Rev.29 Corr.1 2024S

Z7 Annex II (NSD)

Z7(cont’d)NOTES TO REPORT TM2-G(NSD) (ii)1.

This report may be used for recording the thickness measurement of:Shell plating transverse sections:One, two or three sections within cargo length area comprising of the structural
items.

2.

The bottom area comprises keel, bottom and bilge plating.

3.

The exact frame station of measurement is to be stated.

4.

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

5.

The remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall be renewed,
and the mark “R” is to be indicated in the right-hand column. If the result is between 0
and substantial corrosion allowable limits (according to the individual classification
Society’s Rules), the structure in way shall be additional gauged, and the mark “S” is to
be indicated in the right-hand column.

Page 46 of 52

IACS Req. 1990/Rev.29 Corr.1 2024

Z7 Annex II (NSD)

Z7(cont’d)TM3-G(NSD)

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.

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm
(a)

Sheet 7

Gauged
Thk.
mm
(b)
P

S

SECOND TRANSVERSE SECTION AT FRAME NUMBER

Remaining Corr.
Addition, mm

Item
No.

(b)-(a)P

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

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

S

Ren.
Thk.
mm
(a)

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

Page 47 of 52

Gauged
Thk.
mm
(b)
P

S

THIRD TRANSVERSE SECTION AT FRAME NUMBER

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

S

Item
No.

As
Built
Thk.
mm

Vol.
Thk.
Add.
mm

Ren.
Thk.
mm
(a)

Gauged
Thk.
mm
(b)
P

S

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

NOTES – See Reverse

IACS Req. 1990/Rev.29 Corr.1 2024S

Z7 Annex II (NSD)

Z7(cont’d)NOTES TO REPORT TM3-G(NSD)
1.

This report may be used for recording the thickness measurement of:Longitudinal Members at transverse sections:One, two, or three sections within the cargo length area, comprising of theappropriate structural items.

2.

The exact frame station of measurement is to be stated.

3.

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

4.

The remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall be renewed,
and the mark “R” is to be indicated in the right-hand column. If the result is between 0
and substantial corrosion allowable limits (according to the individual classification
Society’s Rules), the structure in way shall be additional gauged, and the mark “S” is to
be indicated in the right-hand column.

Page 48 of 52

IACS Req. 1990/Rev.29 Corr.1 2024

Z7 Annex II (NSD)

Z7(cont’d)TM4-G(NSD)

Report on THICKNESS MEASUREMENTS OF TRANSVERSE BULKHEADS

Ship’s name.........................

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

LOCATION OF STRUCTURE:

Sheet 8
Report No. ........................

FRAME NO.:STRUCTURAL COMPONENT (PLATING/STIFFENER)
STRUCTURAL COMPONENT(PLATING/STIFFENER)

As Built
Thicknessmm

Voluntary
Thickness
Additionmm

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

Page 49 of 52

RenewalThicknessmm(a)Gauged Thickness
mm
(b)
P
S

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

NOTES – See Reverse

IACS Req. 1990/Rev.29 Corr.1 2024

Z7 Annex II (NSD)

Z7(cont’d)NOTES TO REPORT TM4-G(NSD)
1.

This report form may be used for recording the thickness measurement of cargo holdtransverse bulkheads.

2.

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

3.

The remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall be renewed,
and the mark “R” is to be indicated in the right-hand column. If the result is between 0
and substantial corrosion allowable limits (according to the individual classification
Society’s Rules), the structure in way shall be additional gauged, and the mark “S” is to
be indicated in the right-hand column.

Page 50 of 52

IACS Req. 1990/Rev.29 Corr.1 2024

Z7 Annex II (NSD)

Z7(cont’d)

TM5-G(NSD)

Report on THICKNESS MEASUREMENT OF MISCELLANEOUS STRUCTURAL MEMBERS

Ship’s name.........................

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

Sheet 9

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

STRUCTURAL COMPONENTSKETCHLOCATION OF STRUCTURE:
Description

As
Built
Thk.
mm

Voluntary
Thickness
Additionmm

RenewalThicknessmm(a)GaugedThickness
mm
(b)

P

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

Page 51 of 52

S

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

NOTES – See Reverse

IACS Req. 1990/Rev.29 Corr.1 2024

Z7 Annex II (NSD)

Z7(cont’d)NOTES TO REPORT TM5-G(NSD)
1.

This report may be used for recording the thickness measurement of miscellaneous
structural members.

2.

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

3.

The remaining corrosion addition is to be recorded with result of gauged thickness
minus renewal thickness. If the result is negative, the structure in way shall be renewed,
and the mark “R” is to be indicated in the right-hand column. If the result is between 0
and substantial corrosion allowable limits (according to the individual classification
Society’s Rules), the structure in way shall be additional gauged, and the mark “S” is to
be indicated in the right-hand column.

End ofDocument

Page 52 of 52

IACS Req. 1990/Rev.29 Corr.1 2024