NES 155 PART 2

Ministry of DefenceDefence Standard 02-155 (NES 155)

Issue 1 Publication Date 01 April 2000

Incorporating NES 155 Part 2 Category 2

Issue 3 Publication Date July 1992

Requirements For Structural PracticesIn Steel Surface Ships

Part 2Requirements For Survey And Repair

Of Steel Surface Ships

DStanDStan is now the publishing authority for all Maritime Standards (formerly NESs). Any reference to any other publishing authority throughout this standard should be ignored.Any queries regarding this or any other Defence Standard should be referred to the DStan Helpdesk as detailed at the back of this document.

AMENDMENT RECORD

Amd No Date Text Affected Signature and Date

REVISION NOTE

This standard is raised to Issue 1 to update its content.

HISTORICAL RECORD

This standard supersedes the following:

Naval Engineering Standard (NES) 155 Part 2 Issue 3 dated July 1992.

Ministry of Defence

Naval Engineering Standard

NES 155 Part 2 Issue 3 (Reformatted) July 1992

REQUIREMENTS FOR STRUCTURAL PRACTICESIN STEEL SURFACE SHIPS

PART 2

REQUIREMENTS FOR SURVEY AND REPAIROF STEEL SURFACE SHIPS

This NES Supersedes

NES 155 PART 2 ISSUE 2

Record of Amendments

AMDT INSERTED BY DATE

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iNAVAL ENGINEERING STANDARD 155

REQUIREMENTS FOR STRUCTURAL PRACTICES IN

STEEL SURFACE SHIPS

PART 2

ISSUE 3 (REFORMATTED)

REQUIREMENTS FOR SURVEY AND REPAIR

OF STEEL SURFACE SHIPS

The issue and use of this Standard

is authorized for use in MOD contracts

by MOD(PE) Sea Systems and

the Naval Support Command

ECROWN COPYRIGHT

Published by:

Director of Naval ArchitectureProcurement Executive, Ministry of DefenceSea Systems, Foxhill, Bath BA1 5AB

NES 155Part 2

Issue 3 (Reformatted)

iii

SCOPE

1. Part 2 of this NES covers the survey and repair requirements for steel surface ships andfloating docks designed to MOD standards and the practices to be adopted when carrying outthe surveys, repairs, and preparation of safety certification for structural strength of MODships and floating docks.

2. It includes atAnnexC. details of theReport of SurveySurface Ships that has to be completed.

3. This NES is not applicable to steel ships and floating docks maintained in class with aClassification Society.

NOTE: The requirements and practices described herein are common to varioustypes of ship. For information regarding structure peculiar to a particulartype of ship, the Design Authority for that ship is to be consulted.

NES 155Part 2Issue 3 (Reformatted)

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NES 155Part 2


v

FOREWORD

Sponsorship

1. ThisNaval Engineering Standard (NES) is sponsored by theProcurement Executive, Ministryof Defence, Director Naval Architecture (Surface Ships) (DNA(SS)), Section NA 123, Foxhill,Bath.

2. NES 155 Requirements for Structural Practices in Steel Surface Ships comprises:

Part 1 General Requirements

Part 2 Requirements for Survey and Repair of Steel Surface Ships (this part).

3. If it is found to be technically unsuitable for any particular requirement the Sponsor is to beinformed in writing of the circumstances with a copy to Director Naval Architecture (SurfaceShips) (DNA(SS)), Section NA 145.

4. Any user of this NES either within MOD or in industry may propose an amendment to it.Proposals for amendments which are:

a. not directly applicable to a particular contract are to be made to the Sponsor of theNES;

b. directly applicable to a particular contract are to be dealt with using existing proceduresor as specified in the contract.

5. No alteration is to be made to this NES except by the issue of a formal amendment.

6. Unless otherwise stated, reference in this NES to approval, approved, authorized or similarterms, means by the Ministry of Defence.

7. Any significant amendments that may be made to this NES at a later date will be indicatedby a vertical sideline. Deletions will be indicated by 000 appearing at the end of the lineintervals.

8. This NES has been reissued to reflect the changes in policy, practices and technicalrequirements. In particular the following:

a. Requirement of a Professional Officer.

b. Replacement of the D171 by a new Report of SurveySurface Ships at Annex C.

c. Schedule of Key Survey and CSSS Issue of Events for short repair periods at TABLE 3.2.

Conditions of Release

General

9. This Naval Engineering Standard (NES) has been prepared for the use of the Crown and ofits contractors in the execution of contracts for the Crown. The Crown hereby excludes allliability (other than liability for death or personal injury) whatsoever and howsoever arising(including but without limitation, negligence on the part of the Crown, its servants or agents)for any loss or damage however caused where the NES is used for any other purpose.


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10. This document is Crown Copyright and the information herein may be subject to Crown orthird party rights. It is not to be released, reproduced or published without written permissionof the MOD.

11. The Crown reserves the right to amend or modify the contents of this NES without consultingor informing any holder.

MOD Tender or Contract Process

12. ThisNES is the property of the Crown and unless otherwise authorized in writing by theMODmust be returned on completion of the contract, or submission of the tender, in connectionwith which it is issued.

13. When this NES is used in connection with aMOD tender or contract, the user is to ensure thathe is in possession of the appropriate version of each document, including related documents,relevant to each particular tender or contract. Enquiries in this connection may be made ofthe local MOD(PE) Quality Assurance Representative or the Authority named in the tenderor contract.

14. When NES are incorporated into MOD contracts, users are responsible for their correctapplication and for complying with contracts and any other statutory requirements.Compliance with an NES does not of itself confer immunity from legal obligations.

Related Documents

15. In the tender and procurement processes the related documents listed in each section andAnnex A can be obtained as follows:

a. British Standards British Standards Institution,389 Chiswick High Road,London W4 4AL

b. Defence Standards Directorate of Standardization and Safety Policy,Stan 1, Kentigern House, 65 Brown Street,Glasgow G2 8EX

c. Naval Engineering Standards CSE3a, CSE Llangennech, Llanelli,Dyfed SA14 8YP

d. Other documents Tender or Contract Sponsor to advise.

Note: Tender or Contract Sponsor can advise in cases of difficulty.

16. All applications to Ministry Establishments for related documents are to quote the relevantMOD Invitation to Tender or Contract Number and date, together with the sponsoringDirectorate and the Tender or Contract Sponsor.

17. Prime Contractors are responsible for supplying their subcontractors with relevantdocumentation, including specifications, standards and drawings.

Health and Safety

Warning

18. ThisNESmay call for the use of processes, substances and/or procedures thatmay be injuriousto health if adequate precautions are not taken. It refers only to technical suitability and inno way absolves either the supplier or the user from statutory obligations relating to healthand safety at any stage of manufacture or use. Where attention is drawn to hazards, thosequoted may not necessarily be exhaustive.

NES 155Part 2


vii

PersonnelFreshwater Tanks (FOOT)

19. Personnel engaged onwork inFWT are tomeet the health and hygiene requirements laid downin NES 763.

Tanks, Void Spaces and Compartments

20. The appropriate health and safety precautions are to be taken before entering and workingin tanks, void spaces and compartments, eg, gas-free certificates are to be issued before entry.


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NES 155Part 2


ix

CONTENTSPage No

TITLE PAGE i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SCOPE iii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .FOREWORD v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sponsorship v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Conditions of Release v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MOD Tender or Contract Process vi. . . . . . . . . . . . . . . . . . . . . . . . . .

Related Documents vi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Health and Safety vi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Warning vi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .PersonnelFreshwater Tanks (FOOT) vii. . . . . . . . . . . . . . . . . . . . . .Tanks, Void Spaces and Compartments vii. . . . . . . . . . . . . . . . . . . . . .

CONTENTS ix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 1. GENERAL 1.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.1 Doubler Plates 1.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2 Insert Plates 1.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.3 Cathodic Protection 1.1. . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 2. SAFETY CERTIFICATION 2.1. . . . . . . . . . . . . . . . . . .2.1 Introduction 2.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.2 Certificate of SafetyStructural Strength (CSSS) 2.1.2.3 Professional Officer 2.1. . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 3. HULL SURVEY 3.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.1 Preparation of Survey 3.2. . . . . . . . . . . . . . . . . . . . . . . .3.2 Conduct of Surveys 3.2. . . . . . . . . . . . . . . . . . . . . . . . . . .

TABLE 3.1 SCHEDULE OF KEY SURVEY ANDISSUE EVENTS (STANDARD REPAIR PERIOD) 3.3TABLE 3.2 SCHEDULE OF KEY SURVEY ANDISSUE EVENTS (SHORT REPAIR PERIOD) 3.4. . . .

3.3 Plates, Frames (etc) 3.5. . . . . . . . . . . . . . . . . . . . . . . . . .3.4 Tanks 3.5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.5 Fuel Tanks 3.5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.6 Fresh Water Tanks 3.5. . . . . . . . . . . . . . . . . . . . . . . . . . .3.7 Galleys, Serveries, Sculleries etc 3.6. . . . . . . . . . . . . . . .3.8 Passageways 3.6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.9 Bathrooms 3.6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.10 Watertight Doors, Hatches, Scuttles and Manhole

Covers 3.7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.11 Pipes and Trunks 3.7. . . . . . . . . . . . . . . . . . . . . . . . . . . .3.12 Fitted Ballast 3.7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.13 Inlets and Discharges 3.8. . . . . . . . . . . . . . . . . . . . . . . . .3.14 Hull Plating 3.8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.15 Rudder and Stabilizer Fins 3.9. . . . . . . . . . . . . . . . . . . .3.16 Ropeguards and Eddy Plates 3.9. . . . . . . . . . . . . . . . . . .3.17 Shaft Brackets 3.9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.18 Weatherdecks 3.9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.19 Machinery Spaces 3.9. . . . . . . . . . . . . . . . . . . . . . . . . . . .

FIGURE 3.1 blanking of drain holes 3.10. . . . . . . . . . . .3.20 Miscellaneous 3.11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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SECTION 4. REPORT OF SURVEY 4.1. . . . . . . . . . . . . . . . . . . . . . .4.1 Drawings and Sketches 4.1. . . . . . . . . . . . . . . . . . . . . . .4.2 Distribution 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.3 Hull Survey Record Sheets 4.1. . . . . . . . . . . . . . . . . . . .

SECTION 5. CORROSION 5.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.1 Description 5.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.2 Corrosion in a Ship Environment 5.1. . . . . . . . . . . . . . .5.3 Recording Corrosion Defects on Survey Record

Sheets 5.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.4 Thickness Gauging and NDE of Corroded Structure 5.25.5 Repair of Primary and Secondary Structure

Corrosion 5.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.6 Repair of Other Structure 5.2. . . . . . . . . . . . . . . . . . . . .

TABLE 5.1 CORROSION REPAIRREQUIREMENTS FOR PLATE ANDSTIFFENERS 5.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 6. CRACKING 6.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.1 Description 6.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.2 Repair of Cracks 6.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.3 Prevention of Further Cracks 6.2. . . . . . . . . . . . . . . . . .

SECTION 7. DEFORMATION 7.1. . . . . . . . . . . . . . . . . . . . . . . . . . . .7.1 Description 7.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TABLE 7.1 MAXIMUM ALLOWABLEDISTORTION 7.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 8. TESTING OF STRUCTURES 8.1. . . . . . . . . . . . . . . . .

ANNEX A. RELATED DOCUMENTS A.1. . . . . . . . . . . . . . . . . . . .

ANNEX B. ABBREVIATIONS AND DEFINITIONS B.1. . . . . . . .FIGURE B.1 DOUBLER PLATES B.4. . . . . . . . . . . . .FIGURE B.2 PLATE INSERTS B.5. . . . . . . . . . . . . . . .

ANNEX C. REPORT OF SURVEYSURFACE SHIPS C.1. . . . . .

ALPHABETICAL INDEX

NES 155Part 2


1.1

1. GENERAL

a. The Repair Yard is to adhere to the materials, scantlings and sizes of structuralcomponents specified in the Contract Documents and no unauthorizeddeparture from the approved arrangements is to be made.

b. All welding is to be in accordance with NES 706. The acceptance standards forthe welds is to be in accordance with DGS G10000B.

c. Any alterations made to existing structures are to be in accordance withNES 155, Part 1.

d. Lifting arrangements for Auxiliary Machinery and other Equipment are to bein accordance with NES 155, Part 1 and NES 113, Parts 1 to 11.

e. All new structure added to the ship is to meet the requirements of NES 154 andNES 155, Part 1.

f. When carrying out repairs to structure every effort is to be made to avoidnotches, sharp corners and discontinuities. Inserted material is to be alignedwith existing materials in accordance with NES 147.

1.1 Doubler Plates

a. The fitting of doubler plates is not permitted on Primary Structure. They maybe used to repair secondary structure but are to be considered temporary andare to be replaced at the earliest opportunity unless otherwise specified byDirector Naval Architecture (Surface Ships), DNA(SS). (See FIGURE B.1).

1.2 Insert Plates

a. Insert plates fitted into the hull or ship structure are to be at least the samethickness and quality as the original design material requirement. All cornersof the insert are to be radiused in accordance with NES 706. (See FIGURE B.2).

1.3 Cathodic Protection

a. Attention is drawn to NES 704, Parts 14 regarding the inspection and test ofcathodic protection systems.


1.2

NES 155Part 2


2.1

2. SAFETY CERTIFICATION

2.1 Introduction

a. Although the safety of a ship in service is ultimately the responsibility of theCommanding Officer, in some specific areas heneeds the assurance ofMOD(PE)that the ship meets the necessary safety standards.

b. The responsibility for establishing these standards and for auditing theircorrect application has been delegated within MOD(PE) to the DNA(SS), andto achieve this a package of safety certificates is issued providing assuranceagainst failures which could lead to a potential loss of ship or life. The documentoutlining the policy for CSSSs is CNA Technical Memorandum 1/92.

c. Certificates are issued on the basis of supporting evidence supplied by the repairyard and cover the safety of an undamaged vessel. They provide a formal andregularly updated record of DGSSs endorsement of the safety of critical aspectsof a ships design and material state.

2.2 Certificate of SafetyStructural Strength (CSSS)

a. The Warship Project Manager (WPM) has responsibility for, among otherthings, the structural strength of designated surface vessels. To ensure thatvessels maintain adequate structural strength throughout their lives the WPMassesses their condition after refits, etc and if appropriate recommends toDGSS, via DNA(SS), the issue of a CSSS. The section charged with auditingCSSS applications and preparing certificate documentation is Section NA 123(Surface Ship Structures).

b. This certificate states that, subject to any specific caveats, the structuralstrength of the ship is adequate for unrestricted operation. The validity of thecertificate is based on the WPMs assessment of the vessels structuralcondition. Despite the expiry date on a CSSS, the CSSS will be required to berenewed on the completion of every DED and refit. The certificate can bewithdrawn or amended at any time in that period in the event of changes ordefects being reported which significantly affect structural integrity.

c. The certificate is based on information received on the structural state of theship prior to the Refit or DED, the result of the survey, subsequent remedialaction undertaken and any other pertinent information. It is the responsibilityof the WPM to present a case to DGSS via DNA(SS) for the issue of a CSSS inorder to ensure that a certificate is available when a vessel is due to sail.

d. The procedures for survey and repair specified herein are applicable to all MODvessels except as excluded by SCOPE 3. A CSSS is issued for all MOD SurfaceShips or as required by DNA(SS), on the completion of build and is updated andreissued after each Refit or DED.

2.3 Professional Officer

a. The repair yard is to designate a Professional Officer who will be responsible forensuring that the survey has been conducted in accordance with therequirements of the contract and this standard. The name and qualifications ofthe Professional Officer are to be submitted to the WPM prior to refit start. Inorder to fulfil his responsibilities theProfessional Officer is to be associated withthe survey planning and execution, repair proposals, the quality of the repairsetc and satisfy himself by personal audit that the required standards have beenmet. It is also the Professional Officers responsibility to ensure that thesurveying officer is competent to perform the survey.


2.2

b. A qualified Classification Society Surveyor may be designated the ProfessionalOfficer for Category B or C vessels where the repair period is less than 10weeksduration.

NES 155Part 2


3.1

3. HULL SURVEY

a. The object of a hull survey is to assess the material condition of all structure andhull fittings in a vessel and it plays an integral part in the continuousassessment of the hull material state. It is the principal source of theinformation on which the CSSS is based. A hull survey is to comment on thestructural condition of all compartments and structural elements both withinand comprising compartment boundaries. In addition comment must be madeon other areas eg, masts, fittings etc.

b. It is recognized however that it will not be possible to inspect some areas of thehull. In the case of primary structure, or structure whose failure would seriouslyjeopardize the operational effectiveness of the ship, sufficient resources are tobe allocated to ensure that the survey is only limited by inaccessibility. In allcases, required equipment removals are to be scheduled and appropriatetechnology, eg endoscopes and fibrescopes used to reduce the amount ofinaccessible structure to a minimum.

c. Structure hidden from view by any form of covering material (paint, lagging,linings, tiles etc) is to be surveyed by removing sufficient material to allow aprofessional assessment of the structure beneath. Where problems areuncovered their full extent is to be established eg, by further removal ofmaterial.

d. A full survey is to be carried out during refit periods. Any reduction in thisrequirement is to be agreed by the Design Authority, in consultation withDNA(SS). A partial survey is conducted at DEDs, the extent of which is to beagreed with the Design Authority. The partial survey must, as a minimum,include all primary structure, known defects from earlier surveys and ship classdefects.

e. During the refit, those structures identified in the contract for survey thatcannot be surveyed are to be listed with reasons for lack of survey. This list isto be presented to those attending the Hull Survey Assessment Meeting(HSAM) for consideration prior to the meeting as scheduled in accordance withTABLE 3.1 or TABLE 3.2, as applicable. If the reasons are agreed concessionswill be granted by the Design Authority.

f. The repair yard is to be represented at the HSAM by the Professional Officer.

g. A list of all compartments andmajor structural elements is to be maintained bythe Design Authority for all ships. This list is to note the last date of survey, thenext scheduled survey date, and any structural components of particularimportance. Areas of concern to individual classes are to be designated on asurveillance plan.

h. It is the responsibility of the Warship Project Manager to specify thosecompartments and structural elements that are to be surveyed at each DED orRefit. When specifying surveys the WPM will account for ship, class oradministrative anomalies.

i. The Schedule in TABLE 3.1 is to be followed to ensure the timely rectificationof defects discovered during the refit, and subsequent issue of the CSSS.Whererepair periods are less than 10 weeks duration the WPM may specify anabbreviated schedule be adopted. In such cases the schedule in TABLE 3.2 isprovided for guidance. The final schedule shall be agreed with the DesignAuthority prior to the start of the repair period.


3.2

3.1 Preparation of Survey

a. The following clauses discuss the surveying of ships structures in generalterms. Adequate and early preparation of compartments is necessary forsatisfactory survey to be undertaken. The removal of bunks, stores, lockers,machinery and services, etcmust be scheduled at an early stage in order to allowtime for rectification of any defects discovered. Tanks and compartments are tobe cleaned and lit to a standard that will facilitate an accurate survey. Tanks,compartments and void spaces are to be certified gas-free before entry.

b. Any cleaning of the outer bottom must be programmed early in the dockingperiod so that a complete survey can be undertaken. Loose, flaking or blisteredpaint must be removed using an approved technique, to allow a full survey ofthe structure underneath. The area of coating removed must extend into aregion where the bond between the coating and underlying structure is sound.

3.2 Conduct of Surveys

a. Compartments and structural elements to be surveyed will be specified by theDesign Authority. They are to be examined paying particular attention to thefollowing: corrosion, distortion, welding, local damage and cracking asdescribed in the following clauses of this NES. The inclusion of a structuralelement such as decks or bulkheads in the survey requirement implies that theelement will be surveyed at all locations in the shipwhere the element is presentunless otherwise instructed. To this end decks and bulkheads, for example, areto be surveyed from both sides.

b. The following Clauses 3.3a.3.20a. indicate typical areas where defects may bediscovered and where special action is to be taken. The list not intended to becomprehensive. It is the responsibility of the Professional Officer to ensure thatsurveys are conducted in a professional and competent manner and that steps,including those described in Clause 3.b., 3.c. are taken in order to ensure thatthe survey report is an accurate and reliable description of the vesselsstructure. To this end surveys are to be extended where defects are found toestablish the boundaries of the defect.

NOTE: It may be necessary to conduct air, hose or water testing in support of asurvey. (See NES 155 Part 1 for testing requirements).

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3.3

NUMBER EVENT SCHEDULE DETAILS

1 PREFIT ASSESSMENT BYFOSF(ME) (1)

AS SPECIFIED BY FOSF(ME)(1)

NIL

2 DGSS SPECIFIES EXTENTOF SURVEY

NO LATER THAN 50 WEEKSBEFORE START DATE

REQUIREMENTS TO BE FORWARDED TO DGSR INFO FOSF(ME) (1). THESURVEY LIST SHOULD BE PRODUCED WHEN REVIEWING THE PREVIOUSREPORT OF SURVEY

3 RECONCILIATIONMEETING

AS REQUIRED BY DGSR(2) CALLED BY DGSR(2). ATTENDANCE REQUESTED FROM FOSF(ME), DGSSAND VESSEL. FINAL REFIT SPEC TO BE FORWARDED TO WPM

4 CONTRACTOR COMPLETESSURVEY OF PRIMARYSTRUCTURE

BY MID-DOCKING SURVEY LIMITED TO THAT SPECIFIED (2) AND IN CONTRACT DOCUMENTS

5 HULL SURVEYASSESSMENT MEETING(HSAM)

ON COMPLETION OF ITEM4

PRELIMINARY SURVEY RESULTS ARE TO BE FORWARDED TO MEMBERS 2WKS PRIOR TO THE MEETING FOR A REFIT AND 1 WK PRIOR FOR A DED.CHAIRED BY DGSR (2). ATTENDED BY DGSS, FOSF(ME), SHIP ANDCONTRACTORS REPRESENTATIVE (CL 3.e., 3.f.). ATTENDEES TO AGREE ONREPAIR OF EMERGENT WORK NOT PREVIOUSLY APPROVED. ATTENDEESARE TO VIEW THE SHIP BEFORE THE MEETING

6 CONTRACTED SURVEYCOMPLETED

AS REQUIRED BY DGSR(2) TWO WEEKS AFTER COMPLETION, FULL SURVEY RESULTS ARE TO BEFORWARDED TO MEMBERS OF THE HSAM. THESE RESULTS MAY TAKE THEFORM OF A DRAFT REPORT OF SURVEY WHERE THE SURVEY ANDPROPOSED ACTION COLUMNS OF THE SURVEY RECORD SHEETS AREFILLED IN

7 FINAL HSAM AS AGREED BY HSAMMEMBERS

CALLED TO DISCUSS REPAIRS AND FULL SURVEY RESULTS IF REQUESTEDBY ONE OR MORE MEMBERS OF THE HSAM

8 ICSSS REQUEST BY DGSS ON COMPLETION ITEMS 6+ 7

WHEN ISSUED ICSSS IS VALID FROM RFSD TO RFSD PLUS 10 WEEKS

9 REPORT OF SURVEYPRODUCED

BY 2 WKS BEFORE RFSD (OREQUIVALENT)

DISTRIBUTE AS PER CL 4.1a., ONE OF THE WPM COPIES TO CPG VIADNA(SS)

10 COMPLETION OFREFIT/DED

AS REQD BY DGSR(2) NIL

11 CSSS REQUEST BY RFSR PLUS SEVENWEEKS

DGSS REVIEWS REPORT OF SURVEY ETC AND REQUESTS CSSS. ALSOSTARTS LISTING FOR NEXT SURVEY

12 DNA(SS) ISSUES CSSS.ICSSS EXPIRES

BY RFSD PLUS 10 WEEKS DGSS FORWARDS COPY OF CSSS TO SHIP AND FOSF(ME) (1)

TABLE 3.1 SCHEDULE OF KEY SURVEY AND ISSUE EVENTS (STANDARD REPAIR PERIOD)

1. AND OPERATING AUTHORITY WHERE DIFFERENT FROM FOSF(ME)

2. ALTHOUGH DGSR IS THE MOD CONTRACTING AUTHORITY FOR THE MAJORITY OF REPAIR PERIODS,THERE MAY BE OTHERS (EG FMRO PORTSMOUTH)

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3.4

NUMBER EVENT SCHEDULE DETAILS

1 WPM SPECIFIES EXTENTOF SURVEY

APPROX 6 MONTHSBEFORE REFIT DATE

REQUIREMENTS TO BE FORWARDED TO DGSR(2) AND FOSF(ME) (1)

2 WORK PACKAGE MEETING AS REQUIRED BY DGSR(2) CALLED BY DGSR(2)

3 MEETING WITHPROFESSIONAL OFFICER

BEFORE REFIT START DATE AT DISCRETION OF WPM. MEETING WITH DGSS, DGSR(2) ANDPROFESSIONAL OFFICER

4 CONTRACTOR COMPLETESSURVEY OF PRIMARYSTRUCTURE

AS AGREED AT ITEM (3) SURVEY LIMITED TO THAT SPECIFIED (2) AND IN CONTRACT DOCUMENTS

5 HULL SURVEYASSESSMENT MEETING(HSAM)

ON COMPLETION OF ITEM(4) (IF REQUIRED)

AT DISCRETION AF WPM. ATTEDED BY DGSR, DGSS, SHIPREPAIRER,FOSF(ME) AND SURVEYOR. TO REVIEW THE SURVEY AND OUTSTANDINGACTIONS. PRELIMINARY RESULTS TO BE AVAILABLE DAY OF MEETING

6 COMPLETE SURVEY AS REQUIRED BY DGSR, NOLATER THAN 1 WEEKPRIOR TO RFSD

FULL SURVEY RESULTS ARE TO BE FORWARDED TO DGSS AND DGSR PRIORTO RFSD. THESE RESULTS MAY TAKE THE FORM OF A DRAFT REPORT OFSURVEY WHERE THE EXTENT OF SURVEY AND PROPOSED ACTIONCOLUMNS ARE FILLED IN

7 ICSSS ISSUED BY WPMAFTER CONSULTATIONWITH DNA(SS)

ON COMPLETION OF 6 WHEN ISSSUED ICSSS IS VALID FRO0M RFSD UNTIL RFSD PLUS 10 WEEKS

8 SURVEYOR TO INSPECTREPAIRS

SURVEYOR TO COMPLETE ACTIONS TAKEN COLUMN ON THE REPORT OFSURVEY

9 COMPLETION OF REFIT

10 FULL REPORT OF SURVEYPRODUCED

BY THREE WEEKS AFTERRFSD

REPORT OF SURVEY DISTRIBUTED

11 CSSS REQUESTED BY RFSD PLUS SEVENWEEKS

WPM REVIEW COMPLETED REPORT OF SURVEY COPY OF CSSS TO SHIPAND FOSF(ME) (1)

12 DNA(SS) SUPPORT ISSUEOF CSSS AND DGSS SIGNS

BY EXPIRY OF ICSSS

TABLE 3.2 SCHEDULE OF KEY SURVEY AND ISSUE EVENTS (SHORT REPAIR PERIOD)

1. AND OPERATING AUTHORITY WHERE DIFFERENT FROM FOSF(ME)

2. ALTHOUGH DGSR IS THE MOD CONTRACTING AUTHORITY FOR THE MAJORITY OF REPAIR PERIODS,THERE MAY BE OTHERS (EG FMRO PORTSMOUTH)

NES 155Part 2


3.5

3.3 Plates, Frames (etc)

a. The surfaces of plates and the exposed surfaces of boundary bars, frames andlongitudinals are to be examined for pitting, cracking and corrosion. Specialcare is to be taken to ensure the survey identifies the corrosion in both depthand area, using ultrasonic thickness gauging as required, so that repair actionas per TABLE 5.1 Section 5. can be initiated.

b. Dormant pools of water or oil in crevices, especially at the extreme bottom ofa compartment or lying on longitudinals are to be treated with suspicion.Pockets of sludge may harden and be mistaken for a weld. In all compartmentsbeing surveyed any pools of water, oil in crevices and pockets of sludge are to beremoved so that the underlying structure canbe properly surveyed. All drainageholes are to be cleaned to ensure they are not blocked.

c. Welding runs are to be examined for undercutting which can lead to crackingand severe corrosion, especially in areas where liquid can accumulate eg wells,sumps, gutters, etc. Particular attention should be paid towelds near structuraldiscontinuities, eg corners of openings or ends of superstructure. Arepresentative sample of scallop holes in longitudinal stiffeners and welds ofstiffener or transverse beam intersections is to be examined in the upper decksand bottom structure near midships.

d. Oil slicks in compartments adjacent to fuel tanks indicate damaged structurewhich must then be examined. Similarly, rust stains on other structureparticularly where the other side of the boundary is exposed to the weather orthe sea is to be further examined.

e. Protective coatings are to be examined for any signs of breakdown, lifting,bubbling or roughness. Suspect areas are to be chipped away to reveal the fullextent of any pitting or corrosion, and the steel work under examined,remembering that paint can hide pitting and that rust can spread even underan apparently sound-looking coating. All debris is to be removed to allowinspection of the underlying structure.

3.4 Tanks

a. Drainage holes are not to be drilled or cut in tanks. Old holes are to be repairedas stated in Clause 3.14d.

b. Tank tops are to be inspected in accordance with Clause 3.2a.

3.5 Fuel Tanks

a. Deteriorated protective coatings in fuel tanks, especially those that are watercompensated are to be repaired in accordance withNES 761. Coatings that haveexceeded their design lifetimes are to be replaced unless otherwise instructedby the Design Authority. (The design life of an epoxy paint is approximately8 years).

3.6 Fresh Water Tanks

a. Protective coatings are to be examined for any signs of breakdown, lifting ordiscolouration. Defective areas are to be chipped away and structure undersurveyed. On completion of any repair the tank is to be represerved inaccordance with NES 763. Consideration is to be given to replacing the entirepreservation system if either the design lifetime is approaching, or breakdownis widespread.


3.6

3.7 Galleys, Serveries, Sculleries etc

a. Experience has shown that steel decks can suffer from accelerated corrosion ifcovered by tiles or coatings. Sample areas of deck coverings are to be removedto allow survey of the deck underneath. Areas most likely to have deterioratedare where the deck coverings are defective and it is in these areas wherecoverings are to be removed initially. The sources of any rust stains are to beidentified and a full survey of the area carried out with equipment removed asnecessary. Areas where rust stains may be seen include scuppers, beneathboiling coppers and behind built-in equipment. See Clause 3.c.

3.8 Passageways

a. Because of the amount of cleaning in passageways the deck and the first fewinches of boundary bulkheads are vulnerable to corrosion, thereforepassageways are to be checked in accordance with Clause 3.c. to determinewhether any repair action is needed.

3.9 Bathrooms

a. Examine deck covering for worn or damaged patches and for signs of stainingand lifting, especially at corners or along boundaries. Such areas should takepriority when removing coverings for initial survey. See Clause 3.c.

b. Select areas near valves, vent trunking and pipes, remove any linings and surveystructure underneath. See Clause 3.c.

3.10 Watertight Doors, Hatches, Scuttles and Manhole Covers

a. These are essential to thewatertight integrity of the ship and are to be examinedfor any sign of corrosion, or compression, indentation or hardening of therubber seal. The door fastenings are also to be examined for signs of corrosionor stiffness. Chalk tests are to be used as required and action taken to ensureresults meet the required standard. Door frames and securing mechanisms areto be examined for cracks.

3.11 Pipes and Trunks

a. During Refits or DEDs sections of services are to be surveyed in accordance withthe planned maintenance schedules. Also, areas of structure adjacent to pipeand trunk penetrations are to be surveyed, especially on decks where watermaybe trapped.

b. Any defects to pipes or trunks identified in the course of the survey are to bepromptly reported to the Professional Officer.

3.12 Fitted Ballast

a. Due to the potential seriousness of allowing the ingress of water ormoisture intoinaccessible areas, great importance is placed on the regular inspection ofstructure concealed by fitted ballast. All outer bottom plating in the way ofballast is to be examined using ultrasonic thickness gauging while the ship isin dock for refit. In addition the ballast and interior of the hull are to beinspected as described below. The choice of area to be removed is to be based onouter hull NDE results and a visual inspection of the ballast itself. Areasshowing the most signs of deterioration or water permeation are to be givenpriority.

(1) Strapped Ballastat least one complete bay of ballast is to be removedand structure surveyed.

NES 155Part 2


3.7

(2) Bituminous Grouted Ballastbituminous grouting is to be visuallyinspected for signs of deterioration or moisture permeation. Sample areasof grouting and ballast are also to be removed to allow survey of thestructure underneath.

(3) Cemented Ballasta thorough survey of the cement used to secure theballast is to be undertaken, particular attention being paid to any areasof loose or cracked cement and rust stains. The extent of any removal ofballast will be dependent on the condition of the cement skin and this andany further removals are to be agreed with the Design Authority.

A record of ballast removed, state of the structure, ultrasonic gauging resultsand any remedial action undertaken is to be included in the Report of Survey.

3.13 Inlets and Discharges

a. From inside the ship each sea connection and sea tube, main inlet and dischargeis to be surveyed, in accordance with the contract. Particular attention is to bepaid to the neck, just below the valve where corrosion can be expected. Propersurvey of seatubes, inlets and discharges can only be achieved with the seavalve(s) removed. Work lists calling up the survey of these items are thereforeto include the requirement to remove (and subsequently replace and test), thehull valve(s) together with the requirement to clean the inner surface of the seatube.

b. Sea connections less than 75mm in diameter are difficult to coat internally andmust be thoroughly checked for soundness. Any areas where soundness isuncertain are to be further examined using appropriate NDE techniques.

c. In addition, all inlets and discharges are to be surveyed externally paying specialattention to the area adjacent to the valve where corrosion can be expected. Thesecurity of sacrificial anodes and the state of the grating studs is to be assessed.

3.14 Hull Plating

a. The hull plating is to be inspected both internally and externally for signs ofdamage to protective coatings, and for corrosion and pitting of plating or welds.

b. On each occasion of docking, opportunity is to be taken to inspect areas in wayof dock blocks, particularly where the dock blocks are closely spaced or wherepast survey or divers examination suggests that the keel is likely to havedeteriorated. Previous copies of Reports of Docking Form D495 (S238) andReport of Survey are to be examined and the aim is to be for phased blockremovals to occur over a succession of docking periods. Where possible Ships areto be docked at alternative positions, in accordance with the Docking Plan, andNES 850, at each docking to allow keel area to be properly surveyed andpreserved. During refits all closely cribbed dock blocks in way of the after cutup are to be removed, one by one, to inspect underlying structure.

c. Ultrasonic gauging of plate thickness is to be conducted in the following areas:

(1) Onprimary and secondary structure where wastage is judged to be greaterthan 10% of original thickness.

(2) In areas where internal examination of the plating is not possible,including all plate under fitted ballast.

It is stressed that corrosion can occur on both the inside and outside of the sameplates so reducing the thickness appreciably. This is especially true for internalstiffeners and therefore early detection is essential.


3.8

d. No hole is to be drilled or cut in the hull without express permission of theDesign Authority. This permission is to be in the form of a contract requirementor a concession. Any such holes are to be repaired by insert in accordance withNES 706. In the case of a drain plug a repair as shown in FIGURE 3.1 may beemployed if doing so is considered economical.

3.15 Rudder and Stabilizer Fins

a. Plating, portable plates and fastenings are to be examined for corrosion, andloose or missing screws are to be noted for replacement.

3.16 Ropeguards and Eddy Plates

a. These are to be examined for corrosion, particularly at edges of flanges andaround fastenings. Any missing fastenings are to be replaced.

3.17 Shaft Brackets

a. The whole of the surface of the arms and barrel is to be examined for corrosion.Severe pitting is not uncommon in these areas, and is to be reported for eitherweld reinforcement or replacement of the brackets. TABLE 5.1 Section 5. maybe used as guidance for deciding the appropriate repair.

3.18 Weatherdecks

a. Experience has shown that steel decks can suffer from accelerated corrosion ifcovered by wooden decks. Sample areas of wooden decks are to be removed toallow survey of the deck underneath. See Clauses 3.c. and 3.7a.

b. Where aluminium has been used and may have been affected by a rise intemperature, as in a fire, particular attention is to be given to any distortionfound as this may mean the mechanical properties of the material have beendegraded. If this is suspected laboratory testing is to be carried out to determinewhether the material properties of the aluminium are still acceptable.

c. In addition, aluminium is vulnerable to fatigue cracking. Where it is usedstructurally it is to be carefully examined for signs of cracking.

3.19 Machinery Spaces

a. These are areas where problems can arise from loose oil andwater, highambienttemperatures and humidity. Areas requiring close examination are:

(1) bilges (OB plating, framing and longitudinals);

(2) inside machinery seating;

(3) lower areas of bulkheads at the bulkhead, shell and deck joint;

(4) stabiliser wells;

(5) beneath evaporators, boilers and condensers;

(6) ships sides and deckheads.

Preservation coatings are to be examined for deterioration and represerved inaccordance with NES 765.

NES155

Part2Issue

3(Reform

atted)

3.9

FIGURE3.1

BLANKINGOFDRAIN

HOLES


3.10

3.20 Miscellaneous

a. Areas that require special attention are:

(1) Decks in the vicinity of holes cut for uptakes, downtakes and other largeopenings.

(2) Decks adjacent to scuppers, beneath lockers and fixed fittings.

(3) Decks and structural connections in the way of breaks in thesuperstructure.

(4) Where dissimilar materials are used eg, aluminium superstructure joinedto steel decks.

(5) Interior of funnels at deck join.

(6) Uptakes on steam ships.

(7) Watertight door frames.

(8) Mast structures including diaphragm plates.

(9) Bulkhead/deck connections in passageways, wet spaces, or on the upperdecks.

(10) Bilge keels.

(11) Class defects not included in these defined areas.

NES 155Part 2


4.1

4. REPORT OF SURVEY

a. The Report of Survey (see Annex C.) is a detailed record of the survey of shipstructure, WT doors and hatches including state of preservation etc conductedby the Contractor including air and water tests and repair action taken. It playsan important part in assessing the material state of the ship for authorizationof the CSSS and is to include all of the following:

(1) Name and location of all compartments and structural elements surveyed,irrespective of survey results.

(2) Name and location of all compartments and structural elements notsurveyed with reasons for such.

(3) Extent of survey within compartments and of structural elements.

(4) Comprehensive details of the condition of the structure highlighting anydefects found.

(5) Full details of the remedial action required to rectify defects found.Statements such as repair as required are not to be used.

(6) Full details of the actual repairs undertaken.

(7) Where defects have not been rectified it is important that these arehighlighted giving reasons and recommendations for future repair action.

(8) Professional Officers Certificate (POC) and Summary (POS).

b. Instructions for the completion of the Report of Survey are given on the reverseof the Report of Survey Cover Sheet in Annex C.

4.1 Drawings and Sketches

a. Clear and accurate drawings and sketches to show the extent of survey, defectsfound and positions of ultrasonic readings or drill test holes are to be used toprovide clarification. Such drawings are to be forwarded with the Report ofSurvey.

4.2 Distribution

a. The Report of Survey is to be completed and forwarded as follows:

(1) Original plus 1 copy to the Warship Project Manager.

(2) 1 copy to FOSF(ME).

(3) 1 copy to the Ships Commanding Officer.

(4) 1 copy to DGSR (if applicable).

(5) 1 copy to the Shipyard or Naval Base Manager.

(6) 1 copy to Operating Authority if different from FOSF(ME).

4.3 Hull Survey Record Sheets

a. All hull survey record sheets are to be signed by the surveyor who conducts thesurvey, the survey controller who reviews proposed actions, and the repairyards Ship Project Manager who confirms the action is completed.


4.2

NES 155Part 2


5.1

5. CORROSION

5.1 Description

a. Corrosion is a chemical or electro-chemical attack on the surface of ametal, andon the steel structure of a ship is the oxidation, or rusting, of metallic iron toform oxide (or rust). Aluminium and other metals can also corrode but in shipsthis is usually only due to electro-chemical bi-metallic effects. Stainless steel,in an anaerobic salt water environment, is also vulnerable to crevice corrosion.

b. Rusting occurs only in the presence of both water and oxygen and occurs in airwhen unprotected steel is exposed to moisture. The rate of rusting is increasedwhen the structure is subjected to heat; in salty atmospheres particles of dry saltand drops of water saturated by salt also aid corrosion.

c. The severity of rusting under water depends mainly on the oxygen content.Differences in the oxygen content can cause changes in the rate of corrosion, egthe corrosion of a ships underwater hull is worse at the waterline where ahigher oxygen concentration is found.

5.2 Corrosion in a Ship Environment

a. The environment in which a ship operates is highly corrosive. Externally, partof the hull is immersed in salt water while the atmosphere is usually salty andliquids such as dieso, lube oils and hot and cold water can attack protectivecoatings and aid corrosion.

b. In practice, severe corrosion of the main hull outside the ship above thewaterline is rare. However, it can be found externally at the wind and waterregion (See Clause 5.1c.), the stern and forefoot where abraded by the anchorand cable, fastenings to portable plates and sacrificial anodes, keel plating inway of dock blocks, in the plating on the rudder and stabiliser fin and ininaccesible areas and under defective coverings on exposed decks.

c. More serious corrosion occurs inside the ship in areas which are difficult tomaintain, subject to heat andmoisture, or frequently submerged by bilge water.These include fuel tanks (especially those that are water compensated), ballasttanks, sewage tanks, areas below permanent ballast, decks beneath defectivedeck coverings that bound wet compartments such as galleys, sculleries, headsand bathrooms, passageways and especially in machinery spaces and areasaround machinery seatings.

d. The most common form of corrosion found in a warship is pitting which occursvery rapidly in areas where protective coatings have broken down. If leftunattended, it can spread rapidly and lead to general wastage.

5.3 Recording Corrosion Defects on Survey Record Sheets

a. Corrosion, or pitting defects are to be recorded in hull survey record sheets anddescribed by its depth and area covered as follows:

(1) Depthas the average percentage reduction of the original thickness ofmaterial to the nearest half millimetre where the reduction is less than10% of the original thickness the term surface pitting is to be used. Themaximum depth is also to be quoted, if this varies by more than 50% fromthe average.

(2) Area as a percentage of a specified plate or stiffener web affected, usingthe term localized if less than 5% or scattered if less than 25%, andextensive if greater than 25%.

Sketches or NDE print-outs are to be provided for clarity and for subsequentmonitoring.


5.2

5.4 Thickness Gauging and NDE of Corroded Structure

a. The followingmethods ofmeasuring pitting or plate thicknessmaybe usedwithdue care taken to remove the loose rust and scale so as to maintain the level ofaccuracy required:

(1) Callipers to measure thickness of frames or ends of plates.

(2) Straight edge placed across pitted area and depth of pitting measured bydepth gauge.

(3) Plate thickness by ultrasonics. This process requires access to one side ofthe plate only and can be performed afloat or in dock. Only techniqueslisted in NES 729, Part 5 may be employed.

(4) Drill test to measure plate thickness. This may only be used on the OuterBottom plating when authorized by the DesignAuthority, and as it entailswelding to repair, can only be carried out during docking periods.

All structure on which thickness measurements are to be taken is to be well lit,and unless the system used does not require it, cleaned back to bright metal.

b. When taking thickness measurements the depths of all identifiable pits are tobe determined first. If on completion of this action the proper repair for theentire plate, in accordance with TABLE 5.1, is not established then a uniformlyspaced grid of readings is to be taken over the entire area.

c. In order to ensure adequate accuracy a minimum of 36 regularly spacedreadings per square metre are required. This equates to a maximum distancebetween readings of 20cms. If the readings result in a wide range of thicknesses(sample variance is greater than 50%of the sample mean) then further readingsare to be taken until a professional decision as to the correct repair action, asspecified by TABLE 5.1, can be taken.

d. The requirements of Clauses 5.4b. and 5.4c. apply to both plating and the websof frames and stiffeners.

e. If ultrasonic or drill tests are used, detailed records of the positions andthickness readings are to be kept including a check list of holes drilled andconfirmation they have been filled in accordance with NES 706.

5.5 Repair of Primary and Secondary Structure Corrosion

a. All cases of severe corrosion must be reported to the Design Authorityimmediately. In all cases repair of corroded primary or secondary structure isto be as specified in TABLE 5.1, unless agreed otherwise by Design Authorityin consultation with DNA(SS). It is to be noted that the requirements ofTABLE 5.1 refer to plates and both the webs and tables of stiffeners.

b. Inserts in plates and longitudinals are to be fitted in accordance with NES 706.The minimum number of welds in or to the hull are to be used.

5.6 Repair of Other Structure

a. Repair action for other structure is to be determined such that the structuresfunctions are maintained. If uncertain as to these functions advice is soughtfrom the Design Authority.

NES155

Part2Issue

3(Reform

atted)

5.3

TABLE5.1

CORROSIO

NREPA

IRREQUIREMENTSFO

RPL

ATEANDST

IFFENERS


5.4

b. Appendages to the outer bottom (eg A brackets, rudders etc) suffer fromcorrosion. In some cases severe pitting may be found and the defective area isto be repaired in accordance with NES 745, Part 2 and DG Ships PS/9011.

NES 155Part 2


6.1

6. CRACKING

6.1 Description

a. As a material, steel has been found to be very tolerant to misuse in service.However, when used in the fabrication of a structure, the local stressconcentrations and the number of cycles experienced mean that it has a finitefatigue life. This is particularly so in a structure as large and complex as awarship and will show itself in the form of cracking.

b. Cracking found on warships can be of two types, brittle and fatigue. Brittlecracks are normally caused as a result of rapid loading such as an explosion orcollision and will run rapidly following initiation. Under such circumstancescracks in welds are also common.

c. Fatigue cracks should only occur after many years of service, and in ductilematerials will start from a defect (a crack initiator which may be any smalldiscontinuity such as a rough flame-cut edge or a poor, but otherwise acceptable,weld) on the surface of the material before propagating through the thicknessand spreading. This process may take several years to become apparent anduntil the crack becomes large is invisible to the naked eye. As a result fatiguecracks can escape detection until serious damage occurs. Problems of fatigue areto be resolved with reference to the design requirements of NES 154.

d. As stated in Clause 6.1c., a crack needs an initiator to start and no matter howgood the design or the standard of Quality Control andNDE, defects will alwaysbe present in a steel structure. Cracking can be minimized by designing toensure average stresses are kept low, but at local concentrations, such holes orat discontinuities such as welds, stresses will always be high. Unfortunately, itis these areas where constructional defects are most likely to occur.

e. Cracking can also result from any of the following factors:

(1) poor structural continuity;

(2) discontinuities near holes without adequate compensations;

(3) poor detailing at local stress concentrations;

(4) welds at points of stress concentrations.

These are on the whole, design problems but they are all exacerbated by poorwelding and will require attention during surveys.

f. It is to be noted that not all cracks endanger the safety of the ship but they canbe a nuisance, particularly when the crack is in a water-tight boundary andleaks occur. Cracks can also jeopardise citadel integrity.

6.2 Repair of Cracks

a. All repairs to material subject to cracking must involve the tracing of the source(or initiator), removing it and replacing all damaged material with new.

b. Cracks in welds are to be completely removed by pneumatic chipping orgrinding and repaired in accordance with the requirements for the repair ofweld defects quoted in NES 706. Arc air gouging may be used; however, areassubject to this method are to be finished by grinding.


6.2

c. Where a plate in primary or secondary structure is found to be cracked, thedefective area is to be removed and replaced with an insert piece having similarbut not less strength and thickness as the defective plate when new. The insertplate shape, location and welding procedures are to be in accordance withNES 706 and sized to extend at least 75mm beyond the determined ends of allcracking. Use of higher strength or thickness inserts must be approved by theDesign Authority. Cracks in minor structure may be arrested, gouged out andrewelded unless there is evidence that the crack has recurred or will recur inwhich case assistance of the Design Authority is to be sought.

d. Defective stiffeners are to have all the defective area removed and replaced witha new length of the same dimensions. Inserts in longitudinals are to be at leastone frame space long. Butts are to be at least one third of a frame spacing awayfrom frames. Where adjacent longitudinals require part renewals in the sameframe spaces, then the butts are to be staggered. The location of stiffener insertbutts and weld procedures are to be in accordance with NES 706.

e. Cracks in plates and stiffeners in primary structure are not to be repaired by thefitting of a doubler or by gouging out and refilling with weld metal. Doublersmay be fitted temporarily in secondary structure only if approved by theDesignAuthority.

f. Where a crack is found to have started due to poor alignment of structure, aninsert may be fitted to improve alignment and so reduce stress concentrations.Such an alteration is to be approved by the Design Authority.

6.3 Prevention of Further Cracks

a. To assist in the prevention of further cracks, the following practices are to beadopted during the course of repair work.

(1) The number of holes, including those for temporary access, cut instructure is to be kept to a minimum.

(2) All holes that are cut must be authorised by the Design Authority andhave corners with a radius not less than 12% the width of the openingor 75mmwhichever is the greater. The longest side is to be in the directionof greatest stress. Holes less than 600mm across are to be circular. Theedges of the holes must be ground smooth.

(3) Shapes or sizes of existing holes must not be altered without the approvalof the Design Authority.

(4) Cuts and welded attachments are to be smooth and continuous.

(5) Lugs or fittings attached temporarily are to be removed so as to leave asmooth, continuous surface. On no account is scaffolding to be welded tothe vessel.

NES 155Part 2


7.1

7. DEFORMATION

7.1 Description

a. Deformation or distortion of structure can consist of dents or buckling and,although mainly found in plating, can also affect stiffeners.

b. Deformation can occur as a result of poor design or workmanship or can becaused as a result of damage (eg collision). Distortion can also occur when holesare cut in previously completed and unaffected structure and is due to thebuilt-in stresses being released from the structure.

c. Details, and guidance on prevention of distortion caused by welding are givenin NES 706.

d. Unless a higher standard of flatness is required for operational requirements,TABLE 7.1 gives the maximum distortion permissible for various parts of thestructure. These tolerances are suitable when the distortion is gradual and islocal in extent.

e. Where distortion of structure has taken place that extends over more thaneither one frame spacing or two longitudinals, but is less than the allowancesgiven in TABLE 7.1, then it is to be thoroughly examined and a description ofthe problem forwarded to the Design Authority for advice on proper correctiveaction.

f. Welds in areas of distortion are to be carefully examined using Eddy CurrentCrack Detection. Any cracks discovered are to be repaired either as part of thelarger insert, or by gouging out and filling with weld material.

g. Any distortion greater than that given in TABLE 7.1 is to be corrected.

MAXIMUM PERMISSIBLEAREA OF STRUCTURE PLATING BETWEEN

STIFFENERS STIFFENERS

PRIMARYAND

SECONDARY

DECKSHULL

WHICHEVER ISGREATEST:

FRAME SPACING/100or

35mm or 6t

S/100

SECONDARY

BULKHEADSWHICHEVER ISSMALLER:35mm or 6t

35mm BETWEENDECKS

ALL OTHER STRUCTUREWHICHEVER ISSMALLER:45mm or 8t

35mm BETWEENSUPPORT

STRUCTURE

t = PLATE THICKNESS S = LENGTH OF SELECTION BETWEENADJACENT STIFFENERS

TABLE 7.1 MAXIMUM ALLOWABLE DISTORTION


7.2

NES 155Part 2


8.1

8. TESTING OF STRUCTURES

a. All airtight, oiltight and watertight structures, tanks and compartments thathave been subjected to structural work are to be tested on completion inaccordance with the requirements of NES 155, Part 1.

b. The MOD is to be given the option of viewing all structures before filling andtesting. Similarly the option is to be given for final inspection of tanks,compartments and structures prior to closing up.


8.2

NES 155Part 2


A.1 ANNEX A.

ANNEX A.

RELATED DOCUMENTS

A.1 The following documents and publications are referred to in this NES:

See ClauseNES 113Parts 111

Mechanical Handling 1.d.

NES 147 Building Accuracy during Constructionof Surface Ships

1.f.

NES 154 Design Standards for Surface ShipStructures

1.e., 6.1c.

NES 155 Part 1 Requirements for Structural Practicesin Steel Surface Ships.Part 1: General Requirements

1.c., 1.d., 1.e.,3.2b., 8.a.

NES 704 Parts 14 Requirements for Cathodic Protection 1.3a.NES 706 Welding and Fabrication of Ships

Structure1.b., 1.2a.,3.14d., 5.4e.,5.5b., 6.2b.,6.2c., 7.1c.

NES 729 Part 5 Requirements for Non-DestructiveExaminationUltrasonic

5.4a.

NES 745 Parts 12 Classification, inspection requirementsand acceptance standards of steel andcopper based alloy castings

5.6b.

NES 761 Preparation and Painting of Fuel andHydraulic Oil Tanks

3.5a.

NES 763 Preservation and Painting ofCompartments in Surface Ships

Foreword 19.,3.6a.

NES 765 Requirements for Painting of MachineryCompartments in Steel Hulled SurfaceShips

3.19a.

DGS/G10000B(NES 773*)

WeldsMinimum Acceptance Standards 1.b.

NES 850 Requirements for the Dry Docking,Slipping or Lifting of MOD Vessels

3.14b.

DG Ships PS/9011(NES 711*)

Welding of Copper Based Alloy Castings 5.6b.

FORMD237A(S339A)

Reporting completion of Defects,Alterations and additions

Annex B.

FORM D495(S238) Report of the Docking and State of thecompositions of HM Ships

3.14b.

REPORT OFSURVEY

SCOPE 1.,3.14b., 4.a.,TABLE 3.1&TABLE 3.2,Annex C.

CNA TM 1/92 Certificate of SafetyStructuralStrength

2.1b.

*In course of preparation.


A.2ANNEX A.

NES 155Part 2


B.1 ANNEX B.

ANNEX B.

ABBREVIATIONS AND DEFINITIONS

B.1 Abbreviations

CAD Contract Acceptance Date

CSSS Certificate of SafetyStructural Strength

CFS Chief of Fleet Support

DED Docking and Essential Defects

DGSR Director General Ship Refitting

DNA(SS) Director Naval Architecture (Surface Ships)

DGSS Director General Surface Ships

FMRO Fleet Maintenance and Repair Organization

FOSF(ME) Flag Officer Surface Flotilla (Marine Engineering)

HSAM Hull Survey Assessment Meeting

ICSSS Interim Certificate of Safety Structural Strength

NDT Non-Destructive Testing

POS Professional Officers Summary

RFSD Ready for Sea Date

WPM Warship Project Manager

B.2 Definitions

a. For the purpose of this NES, the following definitions apply:

Category A Vessels All major warships, high value MODvessels, vessels required to withstandshock and vessels for cold weatheroperation as specified by the DesignAuthority.

Category B Vessels Vessels over 50 metres in length butexcluding Category A vessels.

Category C Vessels All other MOD owned vessels not includedin Category A or B.

Certificate of SafetyStructuralStrength (CSSS)

Certificate authorised by the DirectorGeneral Surface Ships (DGSS) and issuedby the Warship Project stating that,subject to any specific caveats, the vesselis structurally adequate for unrestrictedoperation.

Contract Acceptance Date (CAD) The date at which after inspection it isagreed that repair work is complete in allrespects (except for any work which isagreed shall be completed at a later stage)and that the contractor has fulfilled allobligations under the Contract (for an RNvessel this will be at the formal reading ofthe Form D237A (S339A)).


B.2ANNEX B.

Design Authority The Design Authority is the WarshipProject Manager who is the nominatedAuthority within the MOD charged withthe control of the ship or class of shipsduring the lives of those ships. Forcontracted repair periods, if, as requiredby this NES, the contractor requiresadvice or agreement from the DesignAuthority, the contractor shall seek suchadvice or agreement through theappropriate MOD contract representative.

Docking and Essential Defects(DED)

A programmed period of support when theship is given a routine intermediatedocking and when essential defectsdirectly affecting fighting and seagoingefficiency and primary structural strengthwhich cannot wait until the next refit arerepaired.

Doubler Plate Overlap plate, fillet welded over holes orwastage in structure (See FIGURE B.1).

Insert Plate Plate fitted to blank holes cut in structureas a result of removing redundantequipment or shipping machinery or forrepair of damaged or corroded structure orship structure. (See FIGURE B.2).

Interim Certificate of SafetyStructural Strength (ICSSS)

The Certificate issued on completion ofthe hull survey during DED or refit foruse until a CSSS is issued. It is issuedprior to RFSD and is valid for 10 weeksafter RFSD. (See TABLE 3.1 andTABLE 3.2).

Minor Structure That structure which does not contributeto either structural strength or watertightintegrity eg, Partition Bulkheads,Platforms etc.

Primary Structure That structure which contributes to themain structural strength of the ship (eg,Hull Plate, Frames, Longitudinals,Principal Decks, Main TransverseBulkheads, Main Longitudinal Bulkheads)and any other structures as specified bythe Design Authority.

Principal Deck Any deck as defined by the DesignAuthority which significantly contributesto the longitudinal strength of a ship.

Professional Officer The Professional Officer is a NavalArchitect of Chartered Engineer statusdesignated by the Repair Yard to supervisethe Contract survey work.

NES 155Part 2


B.3 ANNEX B.

Ready for Sea Date (RFSD) The date by which all work by MODpersonnel and that specified in thecontract is complete, all refitting yardtrials (including basin and specifiedharbour trials) are complete and allpainting is complete. The ship is in allrespects ready for sea trials.

Refit A refit is a programmed period ofDockyard Support when corrective andpreventative maintenance is carried out bycontract labour and ships staff inaccordance with specifications. Approvedalterations and additions may also beundertaken.

Secondary Structure That structure which does not contributeto the main structural strength but doescontribute to the watertight integrity andsupport of local loading, and as specifiedby the Design Authority.

Structural Element An area of structure having particularstructural significance. They are definedfor each Ship Class by the DesignAuthority. Typical examples are:HULL STRENGTHENING GIRDERSCARBON FIBRE PATCHESSPONSONSSHEER STRAKESCRITICAL LONGITUDINALS


B.4ANNEX B.

NOTES:

1. The fitting of doubler plates is not permitted on primary structure.They may be used for temporary repair of secondary structure asdescribed in Clause 1.1a.

2. The doubler is to be of a quality and thickness that are at least equalto those of the parent plate.

3. The doubler is to overlap sound material on all edges by at least10cm.

4. Where obstructed by other structure or a lack of space for weldingthe overlap should be as large as possible in accordance withNES 706.

FIGURE B.1 DOUBLER PLATES

NES 155Part 2


B.5 ANNEX B.

NOTE: Size, location, shape and welding procedures are to be in accordancewith NES 706.

FIGURE B.2 PLATE INSERTS


B.6ANNEX B.

NES 155Part 2


C.1 ANNEX C.

ANNEX C.

REPORT OF SURVEYSURFACE SHIPS

COVER SHEET

INTRODUCTION

1. THIS REPORT OF SURVEY FORM (RSF) COMPRISES:

COVER SHEET

INSTRUCTIONS FOR COMPLETION OF HULL SURVEY RECORD SHEETS

PROFESSIONAL OFFICERS CERTIFICATE (POC)

PROFESSIONAL OFFICERS SUMMARY (POS)

PART I REPORTS OF STRUCTURE, W/T DOORS, HATCHES, ETC ANDHULL PLATING AND APPENDAGES.

PART II REPORTS OF AIR/WATER TEST OF TANKS ANDCOMPARTMENTS.

References

NES 155 PART 1 Requirements for Structural Practices in Steel Surface Ships

NES 155 PART 2 Requirements for Survey and Repair of Steel Surface Ships

HMS.....................................................

*REFIT/DED/AMP at............................................. START DATE........................

*delete as applicable


C.2ANNEX C.

1. Instructions for Completion of Report of Survey

A Report of Survey is to be raised for all Surface Ship surveys other than those carried outby Ships Staff. The Report of Survey is to consist of a POC, POS, Part IReport of Structureand Part IIReport of Air/Water Tests.

2. Professional Officers Certificate (POC).

The POC is to be completed by a Naval Architect of Chartered Engineer status. In order tofulfill his responsibilities the Professional Officer is to be associated with the survey planningand execution, repair proposals, the quality of the repairs, etc and satisfy himself by personalaudit that the required standards have been met. It is the Professional Officersresponsibility to ensure that the surveying officer is competent to perform the survey.

3. Professional Officers Summary (POS).

The POS is to give a professional assessment of the overall structural condition of the vessel.The summary is to include lists of defects that have not been rectified in accordance with theapplicable NESs and concessions arising from the survey in general. The summary isnecessary to assist the Warship Project Manager (WPM) in forming his assessment of thevessel and therefore must be presented in a frank and forthright manner. The POmust stateany areas of doubt or concern together with any suggestions he may have for surveyingparticular areas in the future. The PO must give his opinion of the fitness of the structureuntil the next normal survey opportunity (ie the next plannedDED or Refit) or hemust statethe requirements for any intermediate survey or repair.

PART IREPORT OF STRUCTURE

4. The index is to list every compartment in the vessel and those structural elements identifiedby the MOD to be surveyed. Each compartment or element surveyed is to have a uniquesurvey record sheet which is to be numbered to align with the compartment or element indexnumber. A large compartment such as a machinery space may be surveyed using severalrecord sheets. Where this is the case, each sheet is to be given a sequential page number. Eachelement is to be individually signed for.

5. The Survey Record Sheets in Part I are to be preceded by a pictorial description of the surveyundertaken; the extent of survey should be marked on A3 or A4 size shell expansion, deckplan, and bulkhead drawings. The marking convention used should be as follows:

a. vertical hatch for survey of non-stiffened side of structure;

b. horizontal hatch for survey of stiffened side of structure; and

c. cross hatch for survey of both sides.

Any part of the vessel deemed to require special attention during the next survey is to beindicated. Survey record sheets are to be accompanied by sketches where their use wouldprovide clarification.

6. Part I will contain Survey Record Sheets each of which is to be completed in full. If part ofa record sheet is not appropriate to the compartment or structural element concerned thisis to be stated; blank spaces are not acceptable. Defects discovered but not rectified inaccordance with NES 155, Part 2 are to be clearly marked for inclusion into the ProfessionalOfficers Summary (POS) and the compartments or structural elements affected are to beidentified with an asterisk (*) on the master index preceding the Survey Record Sheets.

NES 155Part 2


C.3 ANNEX C.

7. Where NDE is conducted results are to accompany the appropriate visual survey recordsheets.

8. Survey Record Sheets are important documents and should not have entries erased ormodified. However if modifications are made to the RSF after the initial Hull SurveyAssessment Meeting (HSAM) these are to be clearly identified, dated and explained.

PART IIREPORTS OF AIR/WATER TESTS

9. Completion of Part II is self explanatory.

10. Completed Reports of Survey may be subject to audit at the MODs discretion.


C.4ANNEX C.


Professional Officers Certificate (POC)

Reference NES 155 Part 2 Issue ..............HMS.......................................................... Start date.............................*Refit/DED/AMP at..................................... Extent of Survey Full/Partial*Contract No..............................................

This certificate is to be signed by a Naval Architect of Chartered Engineer status.

I confirm that:

1. The vessels structure has been surveyed in accordance with the requirements of the contractand NES 155 Part 2 Issue......... All Survey Record Sheets are enclosed in Part I of the report.

2. Results of Air/Water tests are enclosed in Part II of the report (*).

3. The Survey Record Sheets, Survey Description, Index and the Professional OfficersSummary have been completed in accordance with the Instructions for Completion ofReportof Survey.

4. Defects discovered but not rectified in accordance with NES 155 Part 2 Issue......... are listedin my POS. Justification for such action is specified on the appropriate Survey Record Sheetand the index has been highlighted in accordance with the Instructions for Completion ofReport of Survey. All other defects have been made good as specified on the Survey RecordSheets.

5. I am satisfied that the report of the survey is complete and presents an accurate assessmentof the vessels structural state in the areas surveyed. The requirements of the reference havebeen met except as specified in my POS. I confirm that all significant structural defects inthe areas surveyed have been identified in my POS.

Signed........................................... Name..........................................

Date...........................................

Professional Qualification...........................................................................................

Position in the Company..............................................................................................


NES 155Part 2


C.5 ANNEX C.


Professional Officers Summary (POS)

1. This summary gives a professional assessment of the overall condition of the vessel, identifiesall significant defects discovered during the survey and lists defects not repaired inaccordance with NES 155 Part 2 Issue.........

HMS.............................................

Signed.............................................. Name...........................................

Date................................................. Status...........................................


C.6ANNEX C.


PART I

Reports of Structure, W/T Doors, Hatches, etc: Hull Plating and Appendages

Reference: NES 155 Part 2

HMS...............................................

at...................................................

Date of Last Survey.......................

Made at..........................................

NES 155Part 2


C.7 ANNEX C.


PART I

REPORTS OF STRUCTURE

Part IReports of Structure

HMS............................................

INDEX

Compartment/Element* Location SurveyedYes/No Index Number

*Element not repaired in accordance with NES 155 Part 2

NES155

Part2Issue

3(Reform

atte)

C.8

REPORT OF SURVEYSURFACE SHIPSHULL SURVEY RECORD SHEET

HULL SURVEY RECORD SHEET

HMS Compartment Index No

ZONE (if appl) Element Page No

Location and area of lining removed for survey (m2)

1.2.3.4.

Report in order the conditions of the following: Plating, Frames, Girders, Longitudinals, Beams, Ballast, Fittings, Coverings andLinings etc

Condition of structure*and or paint*

Proposed repair/remedial action iawNES 155 Part 1 Issue.........and Part 2 Issue.........

Action taken +. To be completedonly after repair has been effected

Contd+ see next sheet* delete as applicable

NES155

Part2Issue

3(Reform

atted)

C.9

Index No

Page NoContd

Condition of structure*and or paint*

Proposed repair/remedial action iawNES 155 Part 1 Issue.........and Part 2 Issue.........

Action taken +. To be completedonly after repair has been effected

DGSR Comment

Surveyor

Date

Signed

Survey Controller (HPTO or Equiv)

Date

Signed

Ship Manager

Date

Signed

+ if action taken is different from that an explanation is to be provided* delete as applicable


C.10ANNEX C.

REPORT OF SURVEYSURFACE SHIPSPART II

Reports of Air/Water Test of Tanks and Compartments

HMS....................................................................

*REFIT/DED/AMP at............................................. START DATE.............................

For guidance on completion of this form see Instructions for Completion of Report ofSurvey Form.

References

NES 155 Part 1NES 155 Part 2


NES155

Part2Issue

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atted)

C.11

REPORT OF SURVEYSURFACE SHIPSHULL SURVEY RECORD SHEET

HULL SURVEY RECORD SHEET

HMS Compartment Index No

ZONE (if appl) Element Page No

PARTICULARS OF AIR OR WATER TESTS OF W/T COMPARTMENTS INCLUDING GAS CITADEL(Minor defects made good during test need to be reported)

PARTICULARS ACTION TAKEN TO REMEDY

Contd

NES155

Part2Issue

3(Reform

atted)

C.12

Contd

Index No

Page No

PARTICULARS OF AIR OR WATER TEST OF W/T COMPARTMENTS INCLUDING GAS CITADEL (final sheet)(Minor defects made good during test need not be reported)

PARTICULARS ACTION TAKEN TO REMEDY

Surveyor

Date

Signed

Survey Controller (HPTO or Equiv)

Date

Signed

Ship Manager

Date

Signed

DGSR Comment

NES 155Part 2


INDEXINDEX.1

ALPHABETICAL INDEX

AAluminium, 3.10, 3.12

BBallast, 3.8bituminous grouted, 3.8cemented, 3.8fitted, 3.8strapped, 3.8

Bathrooms, 3.8

CCathodic Protection, 1.1

Certificate of SafetyStructural Strength, 2.1, 3.3, 3.5, B.1

Compartments, vii, 3.2

Conduct of Survey, 3.2

Contract Documents, 3.2

Controller (Survey), 4.1

Corrosionarea of, 5.1depth of, 5.1description, 5.1

Crackingprevention, 6.2repair, 6.1

DDeformation, 7.1

Discontinuities, 1.1

Distortion, 7.1

Doubler Plates, 1.1, B.1, B.4

Drawings, 4.1

EEddy Plates, 3.10

FFatigue Cracks, 6.1

Frames, 3.7

Fresh Water Tanks, vii, 3.7

Fuel Tanks, 3.7


INDEX INDEX.2

GGalleys, 3.8

Gas Free Certificates, vii

HHatches, 3.8

Health, vi

Hull Survey, 3.1

Hull Survey assessment meeting, 3.1preparation, 3.2

Hull Survey Record Sheets, 5.1

IInlets and Discharges, 3.9

Insert Plates, 1.1, B.1, B.5

Interim CSSS, 3.3, 3.5, B.1

LLagging, 3.1

Lifting Arrangements, 1.1

Linings, 3.1

MManhole Covers, 3.8

NNotches, 1.1

OOil, 3.7, 3.10

NES 155Part 2


INDEXINDEX.3

PPaint, 3.1

Passageways, 3.8

Personnel, vii

Pipes, 3.8

Pitting, 5.1, 5.2

Pitting measurement, 5.2

Plates, 3.7, 3.9thickness measurement, 5.2

Professional Officer, 2.1, 3.1, 3.2

Professional OfficersCertificates, 4.1, C.1Summary, 4.1, C.1

Protective Coatings, 3.7, 3.10

RReport of Survey, 3.3, 3.5, 3.9, 4.1, A.1

Rope Guard, 3.10

Rudder, 3.10

SSacrificial Anodes, 3.9

Safety, vi

Sculleries, 3.8

Scuttles, 3.8

Serveries, 3.8

Shaft Bracket, 3.10

Sketches, 4.1

Stabilizer Fins, 3.10

Structural Elements, B.1

Structureminor, B.1primary, B.1secondary, B.1

TTank Testing, 8.1

Tanks, vii, 3.2

Trunks, 3.8

UUltrasonic Testing, 3.9, 5.2


INDEX INDEX.4

VVoids, vii, 3.2

WWarning, vi

Weatherdecks, 3.10

Welding, 1.1, 3.7

Wind and Water Lines, 5.1

WT Doors, 3.8

Inside Rear Cover

Crown Copyright 2000

Copying Only as Agreed with DStan

Defence Standards are Published by and Obtainable from:

Defence Procurement AgencyAn Executive Agency of The Ministry of Defence

Directorate of StandardizationKentigern House65 Brown Street

GLASGOW G2 8EX

DStan Helpdesk

Tel 0141 224 2531/2 Fax 0141 224 2503

Internet e-mail [email protected]

File Reference

The DStan file reference relating to work on this standard is D/DStan/69/02/155.

Contract Requirements

When Defence Standards are incorporated into contracts users are responsible for their correctapplication and for complying with contractual and statutory requirements. Compliance witha Defence Standard does not in itself confer immunity from legal obligations.

Revision of Defence Standards

Defence Standards are revised as necessary by up issue or amendment. It is important thatusers of Defence Standards should ascertain that they are in possession of the latest issue oramendment. Information on all Defence Standards is contained in Def Stan 00-00 Standardsfor Defence Part 3 , Index of Standards for Defence Procurement Section 4 Index of DefenceStandards and Defence Specifications published annually and supplemented regularly byStandards in Defence News (SID News). Any person who, when making use of a DefenceStandard encounters an inaccuracy or ambiguity is requested to notify the Directorate ofStandardization (DStan) without delay in order that the matter may be investigated andappropriate action taken.

CONTENTSTITLE PAGESCOPEFOREWORDSponsorshipConditions of ReleaseGeneralMOD Tender or Contract Process

Related DocumentsHealth and SafetyWarningPersonnelFreshwater Tanks (FOOT)Tanks, Void Spaces and Compartments

1. GENERAL1.1 Doubler Plates1.2 Insert Plates1.3 Cathodic Protection

2. SAFETY CERTIFICATION2.1 Introduction2.2 Certificate of SafetyStructural Strength (CSSS)2.3 Professional Officer

3. HULL SURVEY3.1 Preparation of Survey3.2 Conduct of SurveysTABLE 3.1 SCHEDULE OF KEY SURVEY AND ISSUE EVENTS (STANDARD REPAIR PERIOD)TABLE 3.2 SCHEDULE OF KEY SURVEY AND ISSUE EVENTS (SHORT REPAIR PERIOD)3.3 Plates, Frames (etc)3.4 Tanks3.5 Fuel Tanks3.6 Fresh Water Tanks3.7 Galleys, Serveries, Sculleries etc3.8 Passageways3.9 Bathrooms3.10 Watertight Doors, Hatches, Scuttles and Manhole Covers3.11 Pipes and Trunks3.12 Fitted Ballast3.13 Inlets and Discharges3.14 Hull Plating3.15 Rudder and Stabilizer Fins3.16 Ropeguards and Eddy Plates3.17 Shaft Brackets3.18 Weatherdecks3.19 Machinery SpacesFIGURE 3.1 BLANKING OF DRAIN HOLES3.20 Miscellaneous

4. REPORT OF SURVEY4.1 Drawings and Sketches4.2 Distribution4.3 Hull Survey Record Sheets

5. CORROSION5.1 Description5.2 Corrosion in a Ship Environment5.3 Recording Corrosion Defects on Survey Record Sheets5.4 Thickness Gauging and NDE of Corroded Structure5.5 Repair of Primary and Secondary Structure Corrosion5.6 Repair of Other StructureTABLE 5.1 CORROSION REPAIR REQUIREMENTS FOR PLATE AND STIFFENERS

6. CRACKING6.1 Description6.2 Repair of Cracks6.3 Prevention of Further Cracks

7. DEFORMATION7.1 DescriptionTABLE 7.1 MAXIMUM ALLOWABLE DISTORTION

8. TESTING OF STRUCTURESANNEX A. RELATED DOCUMENTSANNEX B. ABBREVIATIONS AND DEFINITIONSFIGURE B.1 DOUBLER PLATESFIGURE B.2 PLATE INSERTS

ANNEX C. REPORT OF SURVEYSURFACE SHIPSALPHABETICAL INDEX

NES 155 PART 2

Documents

Transcript of NES 155 PART 2