nes 872 part 3 procedures for first level nickel aluminium bronze castings - category 1

Procedures for First Level NickelAluminium Bronze Castings

Part 3

Revalidation

Ministry of Defence Defence Standard 02-872 Part 3

Issue 1 Publication Date 02 December 2002

Category 1

AMENDMENTS ISSUED SINCE PUBLICATION

AMD NO DATE OFISSUE

TEXT AFFECTED SIGNATURE &DATE

Revision Note

This Issue of this Standard has been prepared to incorporate changes to text and presentation. Thetechnical content has been updated in line with current practice.

Historical Record

DPT1312

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DEFENCE STANDARD 02-872

PROCEDURES FOR FIRST LEVEL NICKEL ALUMINIUM BRONZE CASTINGS

PART 3

ISSUE 1

REVALIDATION

This Defence Standard

is authorised for use in MOD contracts

by the Defence Procurement Agency

and the Warship Support Agency

Published By:

Defence Procurement AgencyAn Executive Agency of the Ministry of DefenceUK Defence StandardizationKentigern House65 Brown StGlasgow G2 8EX

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SCOPE

1. This specification is to be used for the revalidation of Submarine First Level & sea wettedcastings made of Nickel Aluminium Bronze manufactured to DGS 8520, DGS 348 orDefence Standard 02-747 Part 1, 2 or 4 which have had service use involving contact with seawater.

2. Revalidation in accordance with this specification is to establish the extent of any selectivephase corrosion, the acceptability of any weld repairs and the wall thickness following finaldressing to remove corroded regions. This information will allow the Design Authority todetermine the suitability of the casting for future use. It is additional to the normal inspectionsand tests applied to the Submarine First Level castings, e.g. radiography and surface dyepenetrant examinations.

3. Part 1 of this Defence Standard covers the policy for the recording and updating of NickelAluminium Bronze castings fitted in submarines to meet the First Level Quality Assurancerequirements in accordance with SSP 25.

4. Part 2 of this Defence Standard is to be used for the validation of all Submarine First Levelcastings made of Nickel Aluminium Bronze manufactured to Defence Standard 02-747 Part 1,2 or 4. It is to be used to establish a baseline of data for any weld repairs, wall thicknessmeasurements and the integrity of the casting at manufacture.

5. Part 4 of this Defence Standard is to be used for in-service inspections carried out outside ofthe Long Overhaul Period.

FOREWORDSponsorship

1. This Defence Standard (Def Stan) is sponsored by the Defence Procurement Agency,Ministry of Defence.

2. The complete Defence Standard 02-872 comprises of:

Procedures for First Level Nickel Aluminium Bronze castings.

Part 1: Policy

Part 2: Validation

Part 3: Revalidation

Part 4: Inspections Outside of Long Overhaul Period

3. If it is found to be unsuitable for any particular requirement the MOD is to be informed inwriting of the circumstances.

4. Any user of this Defence Standard either within MOD or in industry may propose anamendment to it. Proposals for amendments that are not directly applicable to a particularcontract are to be made to the publishing authority identified on Page 1 and those directlyapplicable to a particular contract are to be dealt with using existing procedures.

5. No alteration is to be made to this Defence Standard except by the issue of an authorisedamendment.

DEF STAN 02-872 Pt 3 / Issue 1

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6. Unless otherwise stated, reference in this Defence Standard to approval, approved, authorisedor similar terms, means the MOD in writing.

7. Any significant amendments that may be made to this Defence Standard at a later date will beindicated by a vertical side line. Deletions will be indicated by 000 appearing at the end of theline interval.

8. Extracts from British Standards within this Defence Standard have been included with thepermission of the British Standards Institution.

Conditions of Release

General

9. This Defence Standard has been devised solely for the use of the MOD, and its contractors inthe execution of contracts for the MOD. To the extent permitted by law, the MOD herebyexcludes all liability whatsoever and howsoever arising (including but without limitation,liability resulting from negligence) for any loss or damage however caused when the DefenceStandard is used for any other purpose.

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 Defence Standardwithout consulting or informing any holder.

MoD Tender or Contract Process

12. This Defence Standard is the property of the Crown. Unless otherwise authorized in writingby the MOD, it must be returned on completion of the contract, or submission of the tender, inconnection with which it is issued.

13. When this Defence Standard is used in connection with a MOD tender or contract, the user isto ensure that they are in possession of the appropriate version of each document, includingrelated documents, relevant to each particular tender or contract. Inquiries in this connectionmay be made to the Authority named in the tender or contract.

14. When Defence Standards are incorporated into MOD contracts, users are responsible for theircorrect application and for complying with contractual and other statutory requirements.Compliance with an Defence Standard does not of itself confer immunity from legalobligations.

Categories of Naval Defence Standard

15. The Category of the Naval Defence Standard has been determined using the followingcriteria:

a) Category 1. If not applied may have a Critical affect on the following:Safety of the Vessel, its complement or third partiesOperational performance of the vessel, its systems or equipment.


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b) Category 2. If not applied may have a Significant affect on the following;Safety of the Vessel, its complement or third partiesOperational performance of the vessel, its systems or equipment.Through life costs and support.

c) Category 3. If not applied may have a Minor affect on the following.MOD best practice and fleet commonality.Corporate experience and knowledge.Current support practice.

Related Documents

16. In the tender and procurement processes the related documents in each Section and Annex Acan be obtained as follows:

a) British Standards British Standards Institution389 Chiswick High Road,London, W4 4AL.

b) Defence Standards Defence Procurement AgencyAn Executive Agency of the MoDUK Defence Standardization,Kentigern House, 65 Brown Street,Glasgow, G2 8EX

c) Other documents Tender or Contract Sponsor to advise

17. 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.

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

Health and Safety

Warning

19. This Defence Standard may call for the use of processes, substances and procedures that maybe injurious to health if adequate precautions are not taken. It refers only to technicalsuitability and in no way absolves either the supplier or any user from statutory obligationsrelating to health and safety at any stage of manufacture or use. Where attention is drawn tohazards, those quoted may not necessarily be exhaustive.

20. This Defence Standard has been written and is to be used taking into account the policystipulated in JSP430: MOD Ship Safety Manual System Handbook.


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Use of ARDROX 160 and silver nitrate solution

21. Before using this Defence Standard in conjunction with Ardrox 160 and the silver nitratesolution, users should make themselves familiar with the precautionary measures set out inthis Section.

22. Care is to be taken to ensure that the silver nitrate etching solution does not come into contactwith the skin or eyes, e.g. a face mask and rubber gloves must be worn.

23. Protective clothing should be worn and other measures taken as necessary in handling thematerials referred to in this Defence Standard.

24. Ardrox 160 is a proprietary product and the manufacturers health and safety instructions mustbe followed.

Additional Information

(There is no relevant information)


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CONTENTS

Page No

TITLE PAGE 1

SCOPE 2

FOREWORD 2

Sponsorship 2

Conditions of Release 3

Categories of Defence Standard 3

Related Documents 4

Health and Safety 4

CONTENTS 6

SECTION 1. GENERAL REQUIREMENTS 81.1 Selection of Castings for Revalidation 81.2 Identification 81.3 Pre-requisites for Revalidation 9

SECTION 2. CLEANING OF CASTINGS 102.1 General 102.2 Opening Up Inspection 102.3 Cleaning & General Etching 102.3.1 Cleaning Method 1 112.3.2 Cleaning Method 2 112.3.3 General Etching Method 11

SECTION 3. ETCHING AND EXAMINATION FOR CORROSION 123.1 General 123.2 Visual Examination 123.3 Detection of Corrosion 123.3.1 Detailed Etching Method 133.3.2 Ultrasonic Examination 133.4 Removal of Corrosion 133.5 Post Dressing Thickness Gauging 133.6 Recording of Examination Results 14


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SECTION 4. ACCEPTANCE CRITERIA 154.1 Cleaning 154.2 Wall Thickness 154.2.1 90% Criterion 154.2.2 Finite Element Analysis (FEA) and Lifing 154.3 Handling of Rejected Components 164.4 Re-Stamping 164.5 Certification 164.6 Records 16

SECTION 5. RECLAMATION OF REJECTED CASTINGS 175.1 Policy on Weld Repair 175.2 Options for Casting Repair 175.3 Procedure for Weld Repair 175.4 Inspections 175.5 Re-Stamping 175.6 Certification 185.7 Records 18

ANNEX A. RELATED DOCUMENTS 19

ANNEX B. DEFINITIONS AND ABBREVIATIONS 20

ANNEX C. PROCUREMENT CHECK LIST 21

ANNEX D. CASTING RECORD OF REVALIDATION INSPECTION 22

ANNEX E. REVALIDATION CERTIFICATE FOR NAB CASTINGS 23

ANNEX F. CHECK LIST FOR DOCUMENTS TO BE INCLUDEDIN QA PACK FOR REVALIDATED CASTINGS 24

ALPHABETICAL INDEX 25


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1. GENERAL REQUIREMENTS

Related Documents: Def Stan 824, Def Stan 02-872 part 2, DGS 8520, see also Annex A

a. Extensive examinations have shown that the Nickel Aluminium Bronze (NAB)castings used since the early 1960s are, to varying degrees, susceptible to normal andselective phase attack by sea water which destroys the mechanical properties of thematerial without any obvious change in the appearance of the materials' surface.

b. To limit the effect of this corrosion problem, it is necessary to examine NAB castingsprior to fitting in critical positions, and to carry out periodic examinations duringtheir life. These examinations are termed 'Validation' and 'Revalidation' respectively.

1.1 Selection of Castings for Revalidation

a. A number of 'Higher Risk' NAB castings will be selected by WSA for examinationduring Docking Periods (DP) as considered necessary. Inspections are to be carriedout to the requirements of Part 4 of this Defence Standard. Reports of examinationare to be made to the Design Authority as early as possible to enable the results to beassessed and necessary actions to be undertaken during the DP.

b. At LOP(R) all NAB castings listed in the NAB Register are to be either revalidatedin accordance with Part 3 of this Defence Standard, or replaced with NAB castingsvalidated in accordance with Part 2 of this Defence Standard or Copper NickelChromium castings to Def Stan 02-824. Repair by welding will not normally beallowed on revalidation (see Section 5 of this Defence Standard).

c. If at any time during the revalidation process, the LOP(R) Contractor believes thatrevalidation is physically impossible or economically not viable for a casting DesignAuthority endorsement is required before the casting is rejected.

d. Non-critical castings (those not listed in the NAB Register) are to be replaced onlywhen defective.

NOTE: To ensure that the Design Authority is given sufficient time to answer individualqueries, it is essential that the Design Authority receives information on castings as earlyas possible, including accurate detailed information on defects. The reason for rejecting thecasting must be clearly stated, and be supported with detailed information. Defectinformation must as a minimum contain accurate positions, types, extent and depth ofcorrosion, together with detailed sketches.

1.2 Identification

a. Previously validated/revalidated castings should be stamped with a code whichuniquely identifies them. The code consists of the radiographic number which maybe preceded by the letters H or HA. The letters H and A indicate that the casting hasbeen heat-treated and weld repaired respectively. Castings manufactured tospecifications subsequent to DGS 8520 will have their specification indicated,followed by letters VAL and the date. The letters VAL and the date show that thecasting has been previously validated/revalidated on the date shown.

b. Where radiographs are preceded with other than H or HA such as UI they can belinked to the H/HA number via the QC495.


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1.3 Pre-Requisites for Revalidation

a. A casting examination control facility is required at the repair source, together with aregister of properly trained personnel who have the necessary experience to carry outthe procedures described in this Defence Standard. The Design Authority will definewhat level of training and experience is necessary.

b. The Revalidation Contractor is to demonstrate to the Design Authority thatprocedures necessary to control and document the application of this DefenceStandard are in place before work is carried out.

c. The Quality Assurance (QA) documentation from previous validation or revalidationis to be available to the personnel making the inspection. As a minimum these shallinclude:-

(1) drawings with dimensions and wall thickness

(2) all non conformance documentation (concessions etc) affecting casting integrity

(3) validation or revalidation certificate

If available -

(4) casting wall thickness maps

(5) weld repair maps

NOTE: If the QA documentation in (1) to (3) is not available, the Design Authority is tobe informed of the component description and details stamped on the component e.g.radiograph/unique number, validation/revalidation date. The Design Authority is to adviseaction to be taken.

d. Revalidation Contractors who find information on the castings which does notcorrespond to that on the QA documentation are to refer to the Design Authority forfurther action.

e. Non Destructive Examination (NDE) methods such as ZIPSCAN must be formallydefined and approved by the Design Authority before use. Factors such as training,limits, accuracy and archiving of results must be specified before approval to usethese techniques is granted.

WARNING: ZIPSCAN ~ Total reliability is not guaranteed under all conditions and untila fully approved method is available these techniques must be restricted to use a detectingcorrosion with confirmation of corrosion depth verified by an etch and grind process.


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2. CLEANING OF CASTINGS

Related Documents: Def Stan 68-188, Def Stan 80-20, see also Annex A

2.1 General

a. The sea water wetted surface of the castings will be covered with varying degrees ofbiofouling, calcareous deposits and redeposited copper that can be difficult toremove.

b. Any cleaning processes used are not to be detrimental to the casting. Special care isto be taken to protect machined surfaces. Approved methods of cleaning NABcastings include:

i). Hydrojetting with or without entrained abrasives.

ii). Dry blasting with alumina grit.

iii). Chemical Dip.

c. Metal will be removed with any blasting process and damage to the casting is to beprevented. The nozzle must be kept moving at all times, i.e. castings should be sweptblast and machined surfaces must be masked.

d. The casting is to be visually inspected for general condition and satisfactorycondition of seal faces and machined tolerances before the costly and timeconsuming effort of removal of all surface redeposited copper by abrasion is carriedout. If at any stage the casting is deemed to be unsuitable for revalidation, the processis to be stopped and Design Authority guidance is to be sought, as detailed in Clause1.1, as to whether the casting should be rejected or revalidation is continued.

e. Suitable methods of cleaning are described in Clauses 2.3.1 and 2.3.2. Thecontractors cleaning procedure and the training of operators must have DesignAuthority written approval.

f. Cleaning of castings must be carried out by staff who are suitably experienced.

2.2 Opening Up Inspection

a. The unique number stamped on the casting is to be read off and a check made toensure that it is listed in the NAB Register and that there are no concessions on thecasting that would make it undesirable to revalidate.

b. Where it is impractical or undesirable to revalidate a casting it is to be removed andreplaced as per the requirements of Part 1 of this Defence Standard.

c. It is important that data on the state of the casting when it is removed from serviceand prior to cleaning is established. Photographs should be taken when considerednecessary to add value to the survey report.

2.3 Cleaning & General Etching

a. The surfaces of the casting that have been in contact with sea water are to be cleanedby an approved method, as described below. Cleaning Method 1 should be used toremove all marine growth and surface corrosion products. This should be followedby Cleaning Method 2 to provide clean, degreased surfaces for etching.


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2.3.1 Cleaning Method 1

a. The surfaces of the casting that have been in contact with sea water are to be cleanedby an approved method to remove marine growth and surface corrosion products.Approved methods of mechanically cleaning NAB castings include hydrojetting withor without entrained abrasives and dry blasting with alumina grit.

b. Blasted surfaces are then to be lightly abraded with an emery disc or flap wheel toremove all surface redeposited copper where present. Note that the etching solutionused to detect selective phase corrosion will give a false indication if surfaceredeposited copper is still present.

NOTE: The machined surfaces are to remain protected.

2.3.2 Cleaning Method 2

a. The casting is to be degreased either in a hot water detergent or in a cold agitatedsolvent to Def Stan 68-188 or similar approved alternative for between 30 minutesand 1 hour, or as advised by the manufacturers instructions.

b. After degreasing, the casting is to be washed in hot fresh water until the degreasingsolvent is removed.

c. Paint can be removed by an additional dip in a chemical cleaner to Def Stan 80-20 orsimilar approved alternative for up to 8 hours after which the casting must again bewashed, this time in cold water.

2.3.3 General Etching Method

a. On completion of cleaning, the casting is to be dipped for between 1 and 10 minutesin an approved brightening solution, e.g. Ardrox 160 (available under NSN 99 2201162) or similar approved alternative. This process will etch the surface of thecasting, highlighting areas of weld repair, and selective phase corrosion, should theseexist. The solution must be sufficiently fresh not to contaminate the casting surfacewith redeposited copper. After removal from the dip bath, the casting is to bethoroughly washed in cold fresh water to remove all traces of the brighteningsolution.

b. In general, the appearance of the various exposed surfaces of the casting followingdipping in Ardrox 160 will be roughly as follows:

Weld metal - Dark Grey or BlackParent Metal - Mid GreyHAZ Corrosion - Greyish GreenPlug/Crevice Corrosion - Copper Colour or Greyish Green

c. A suitably experienced person (See clause 1.3a) is to check that the casting is freefrom surface redeposited copper before the etching and examination for corrosiondescribed in Section 3 is carried out. The suitably experienced person is to advisewhen the brightening solution requires changing, e.g. if it causes re-deposition ofcopper. See Defence Standard 02-341.

NOTE: Due to the toxicity of Ardrox 160, contractors may prefer to use an alternativegeneral etching chemical, e.g. ferric chloride. Where such a change is proposed, priorapproval should be obtained from the Design Authority.


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3. ETCHING AND EXAMINATION FOR CORROSION

Related Documents: Def Stan 02-872 Part 2, see also Annex A

3.1 General

a. The castings require immersion in the Ardrox 160 solution prior to the examinationdetailed in this Section to enable the location of the weld repairs and the areas ofplug/crevice corrosion to be established. It is only once these areas have beenidentified that the more searching etching techniques can be applied. Experience ofre-validating NAB valve bodies has revealed that the Ardrox 160 etchant is unable todetect selective phase attack in the form of a continuous uniform layer, rather thanthe plug type attack normally associated with this form of corrosion. Only 10%Silver Nitrate etchant is to be employed for the more detailed examination coveredby this Section of the specification. This is consistent with the method specified atClause 3.4b to ensure the complete removal of all corrosion.

b. The main corrosion mechanism causing concern with NAB castings is selectivephase corrosion which occurs under crevices and biofouling (plug corrosion) oraround weld repairs in the heat affected zone (HAZ corrosion). Selective phasecorrosion can penetrate the thickness of the casting at up to 1.1 mm per year with noapparent surface loss of metal. The purpose of the procedures described in thisSection is to detect and establish the depth of selective phase corrosion.

3.2 Visual Examination

a. The detailed visual examination after the etching described in this Section is to becarried out by staff meeting prerequisite in Clause 1.3a. The location of selectivephase corrosion will be around weld repairs and under biofouling and crevices. It isimperative that all welds on seawater wetted and non wetted surfaces are identifiedafter general etching, referring to Clause 2.3.3b. Previous QA documentation is to beconsulted to assist locating these weld repairs which are to be identified on thecasting using a felt tip marker.

b. Areas of plug and crevice corrosion are to be identified on the casting using a felt tipmarker.

3.3 Detection of Corrosion

a. HAZ corrosion is typified by a narrow band of corrosion around weld repairs. Thesurface must be dry abraded to a distance of at least 10mm all round the weldtypically with a flap wheel (80 grit) just prior to etching (i.e. within one hour). Weldson non-wetted surfaces can have HAZ's extending to wetted surfaces. If there is anydoubt these are also need to be identified and the seawater wetted surface preparedfor etching.

b. Areas of plug corrosion are visible following general etching (see Clause 2.3.3b) andcan be seen as dimples in the surface or patches of redeposited copper. To preparethe surface for etching, the surface must be abraded to a smooth even finish, typicallywith a flap wheel (80 grit), just prior to etching (i.e. within one hour).


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3.3.1 Detailed Etching Method

a. Areas of selective phase corrosion are to be identified by etching with fresh 10%silver nitrate solution stored in a dark bottle to prevent deterioration by light. Theetch is preferably to be applied using a fine spray to moisten the metal surface.Alternatively a soft brush may be used. Swabs may be used provided care is taken toavoid contamination which can cause spurious results, (this usually means that swabsare used only once on a single wipe). Etching is to be carried out within one hour ofdry abrading the surface, as the surface develops an oxide film resistant to etchsolutions after a period of time.

b. The silver nitrate etch will reveal regions of selective phase corrosion which turnblack. This is caused by silver depositing on any redeposited copper within theregions of selective phase corrosion. Note that care is required to ensure that allgeneral surface redeposited copper is removed as this will also turn black and can beconfused with selective phase corrosion.

c. Wash the etched areas thoroughly with fresh water to remove the etching chemicals.

d. Repeat etching will be required after removal of the corroded regions.

3.3.2 Ultrasonic Examination

a. The use of NDE such as ultrasonic methods for measuring wall thickness must besupported by written procedures to a specification approved by the Design Authority.

b. Ultrasonic NDE methods, e.g. ZIPSCAN, have been used with limited success tomeasure the depth of selective phase corrosion which has occurred at the HAZ. Totalreliability, however, is not guaranteed under all conditions and until a fully approvedreliable NDE method is available these techniques must be restricted to use as an aidfor detecting corrosion with confirmation of corrosion depth verified by an etch andgrind process.

3.4 Removal of Corrosion

a. Thickness mapping of the surface is required prior to commencing any grindingprocess. All areas where corrosion is present must be thickness gauged usingcallipers or an approved ultrasonic method in accordance with Clause 3.3.2.

b. Corroded areas identified in Clause 3.3 are to be ground out using suitable tooling,e.g. tungsten carbide burrs or grinding wheels, until further etching shows nocorrosion indications remaining. Not more than 1mm depth of metal shall beremoved prior to repeat etching with silver nitrate.

c. If corrosion removal has reduced the wall thickness to the minimum figure of 90% ofdrawing final machined dimension and further corrosion still remains, the casting isto be referred to the Design Authority for the suitability for life assessment to bedetermined; refer to Clause 4.2.

3.5 Post Dressing Thickness Gauging

a. All areas where corrosion was present must be thickness gauged using callipers or anapproved ultrasonic method in accordance with Clause 3.3.2.


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b. It is mandatory that the dimensions of all ground out areas are recorded as defined inClause 3.6.

3.6 Recording of Examination Results

a. A full report of the examination is to be submitted to the Design Authority. This is toinclude casting sketches showing the location of corrosion, referenced to the depth ofcorrosion penetration and casting wall thickness.

b. In addition, a Casting Record of Revalidation Inspection, an example of which is atAnnex D, should be filled in. A separate sheet should be filled in for each casting.This is used to supply the information required to carry out life assessment. Thefollowing information should be included in the Table:

(1) The casting description, unique number and previous QA document numbershall be logged at the top of the table.

(2) All weld repairs and other defects where corrosion has been removed using theprocedures in Clause 3.4 of this document are to be given a number which willbe marked on the casting using a felt tip marker and logged in column 1 of theTable. Note that all areas of corrosion are to be logged, including any groovingat 'O' seals. Grooving or pitting at 'O' seals is a special case to be referred to theDesign Authority.

(3) Details of weld repairs on sea water wetted surfaces, obtained from previousQA documentation, are to be entered in column 2 of the Table next to defectsidentified in column 1. Note that some weld repairs may not have resulted incorrosion but confirmation of this is required. A sketch or photograph of areasof corrosion, with identification numbers as referenced in column 1 of theTable, should accompany the Table. Gridded sketches for large headers, basedon Finite Element Analysis (FEA), can be obtained through the DesignAuthority.

(4) Grid based thickness scans for the larger NAB castings should be availablewith the QA documentation in accordance with Part 2 of this DefenceStandard. If these are not available then general wall thicknesses should bemeasured on a gridded sketch at a spacing to be agreed with the DesignAuthority. The measurements should give sufficient detail to provideconfidence on the general wall thickness. For guidance the grid spacing will betypically 70 mm to 100 mm.

(5) On the castings, measure the maximum straight surface length 'A' in any onedirection and the maximum depth 'B' for each ground out defect and recordthese on the Table in columns 4 and 5.

(6) Using a calibrated ultrasonic probe or callipers, measure the thinnest walladjacent to the defect, i.e. measure the wall thickness prior to the grinding outof the defect. This defect free wall thickness 'C' is to be recorded in column 6of the Table. Subtracting the defect depth 'B' from this will give the remainingwall thickness 'D', where D=(C-B), see column 7 of the Table. This can beconfirmed by measuring directly the remaining wall thickness 'D'.

(7) Complete columns 8 to 10 in the Casting Record of Revalidation InspectionTable.


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4. ACCEPTANCE CRITERIA

Related Documents: Def Stan 02-341, Def Stan 02-747 Parts 2 and 4, Def Stan 02-824, seealso Annex A

4.1 Cleaning

a. The casting has been satisfactorily cleaned when all fouling and redeposited copperhas been removed. Acceptance must be confirmed by suitably experiencedpersonnel.

4.2 Wall Thickness

4.2.1 90% Criterion

a. The 90% of the finished machined drawing wall thickness criterion is simple to useand complies with the requirements of Defence Standard 02-747 Parts 2 and 4. If aspecified life is required refer to life assessment in Clause 4.2.2.

b. All areas where corrosion was present must be thickness gauged to ensure that thefinished machined thickness given on the manufacturing drawing has not beenreduced by more than 10%.

c. Castings whose thickness has been reduced by more than 10% below the drawingthickness are to be REJECTED.

d. REJECTED castings with minimum pressure retaining wall thickness greater than14mm are to be referred to the Design Authority for suitability for life assessment tobe determined as identified in Clause 4.2.2.

e. Complete columns 8 to 10 in the Casting Record of Revalidation Table, see AnnexD.

4.2.2 Finite Element Analysis (FEA) and Lifing

a. It might be economic to carry out life assessment for rejected large castings to justifya further commission or to calculate a maximum justified life. The decision is to bemade by the Design Authority whether the full extent of the corrosion should beremoved to provide the required information for life assessment.

b. Life assessment methods developed include:-

(1) Probabilistic approach using NABWETLIFE, a MoD developed code

(2) Deterministic approach using FEA and Fracture Mechanics

c. The probabilistic approach is more suited to thinner wall castings which are includedin the NABWETLIFE submarine specific database and will identify which castingsand the timescale for inspection.

d. The deterministic approach is suitable for castings which are either not covered bythe probabilistic approach, i.e. those castings which are not included in the submarinespecific database, or for larger components where there are complex stress profilesunder shock conditions, e.g. major header castings.


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Data requirements for the deterministic approach are as defined in the Casting Record ofRevalidation Inspection Table, Annex D. All corrosion must be completely removed using theprocedures in Section 3.

e. Complete columns 8 to 10 in the Casting Record of Revalidation Inspection Table.

4.3 Handling of Rejected Components

a. Rejected castings are to be referred to the Design Authority who will advise scrap,life assessment or repair action. Reclamation will be in accordance with Section 5,life assessment will be in accordance with Clause 4.2.2.

b. All rejected castings, even those unsuitable for reclamation and life assessment, areto be collated in one batch as appropriate and referred to the Design Authority whomay decide to authorise full removal of the corrosion by separate contract action soas to provide useful data.

c. Castings which fail revalidation and are beyond economic repair are to be replacedwith castings validated in accordance with Part 2 of this Defence Standard, apreviously revalidated casting to this part of this Defence Standard, or a CopperNickel Chromium casting to Def Stan 02-824.

4.4 Re-Stamping

a. The suitably experienced personnel witnessing the stamping of the casting are to signthe validation certificate. A line is to be stamped through the previous validation dateand the new date stamped as a suffix to the original number.

NOTE: Pressure castings are not to be stamped on the highly stressed region e.g. CriticalTest Regions of the castings. The stamping should be positioned on low stress areas asindicated below:

i. Valve bodies - should be stamped at the edge of the cover flange or in the absenceof a prominent flange then as close to the cover position as possible. Failing thisanother flange should be stamped, but stamping on hull flanges is to be avoided.

ii. Flange fittings - to be stamped on a flange edge.

iii. Unflanged fittings - to be stamped on an area that is thicker that the minimumacceptable wall thickness.

4.5 Certification

a. All castings that are free of corrosion, or have defects which have all been assessedas safe in the Casting Record of Revalidation Inspection Table are to be re-stampedin accordance with Clause 4.4, and issued with a Revalidation Certificate in theformat of Annex E.

4.6 Records

a. A copy of the Revalidation Certificate, QA certificate of compliance and the full QArecords, as listed in Annex F, are to accompany the casting. These are to be held bythe Through Life Records Contractor when the casting is fitted to the vessel, and areto be available for future revalidations.


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b. On completion of installation the original documents held by the supplier/manufacturer are to be passed to the Through Life Records contractor to be held asmaster Records.

NOTE: The records should be of a suitable quality for scanning purposes.

5. RECLAMATION OF REJECTED CASTINGS

Related Documents: Def Stan 02-747 Parts 2 and 4, Def Stan 02-771, Def Stan 02-872 Part2, see also Annex A

5.1 Policy on Weld Repair

a. Weld repair is not normally to be carried out to reclaim rejected castings. There mayhowever be occasions when weld repair might be considered an appropriate action totake. If appropriate, weld repair will be approved by a production permit, issued bythe Design Authority. In these circumstances, the procedure in Clause 5.3 is to beapplied, provided the area is isolated and that the distortions caused by welding areacceptable.

5.2 Options for Casting Repair

a. Alternative methods of reclamation, such as sleeving, fillers and coatings may alsobe investigated, but use of these options is subject to Design Authority approval.

5.3 Procedure for Weld Repair

a. All weld repairs are to be carried out in accordance with Defence Standard 02-771.Where deep excavation is necessary the preparations for the weld repair should beangled to the surface whilst at the same time ensuring that the size of the repair iskept to a minimum. The potential corrosion path is through the HAZ and by anglingthe weld boundary, a longer corrosion path is provided.

b. Defence Standard 02-771 requires heat treatment of castings after weld repair, inorder to minimise HAZ corrosion. The Design Authority may waive this whenappropriate.

5.4 Inspections

a. A complete record of the weld repairs carried out is to be added to the Weld RepairRecording Sheet as per the requirements of Part 2 of this Defence Standard.

b. Reclaimed castings are to be fully inspected as per the requirements of DefenceStandard 02-747 Part 2 or 4.

5.5 Re-Stamping

a. The suitably experienced person witnessing the stamping is to sign the RevalidationCertificate. A line is to be stamped through the previous validation date and the newdate stamped as a suffix to the original number. Where a weld repair has been madeon a casting that has not previously been weld repaired then the letter 'A' is to bestamped as a prefix to the radiographic number.


18

NOTE: Pressure castings are not to be stamped on the highly stressed region e.g. CriticalTest Regions of the castings. The stamping should be positioned on low stress areas asindicated below:

i. Valve bodies - should be stamped at the edge of the cover flange or in the absenceof a prominent flange then as close to the cover position as possible. Failing thisanother flange should be stamped, but stamping on hull flanges is to be avoided.

ii. Flange fittings - to be stamped on a flange edge.

iii. Unflanged fittings - to be stamped on an area that is thicker that the minimumacceptable wall thickness.

5.6 Certification

a. On completion of the examination and weld repairs, a Revalidation Certificate is tobe completed in the format of Annex E.

5.7 Records

a. A copy of the Revalidation Certificate, QA certificate of compliance and the full QArecords, as listed in Annex F, are to accompany the casting. These are to be held bythe Through Life Records Contractor when the casting is fitted to the vessel, and areto be available for future revalidations.


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ANNEX A.

RELATED DOCUMENTS

A1. The following documents and publications are referred to in this Defence Standard:

JSP430 MOD Ship Safety Management System Handbook

Def Stan 02-341 Requirements for cleaning of items components and equipment for fluidsystems

Def Stan 02-747 Requirements for Nickel Aluminium Bronze Castings and ingots

Part 1 - Nickel Aluminium Bronze (Naval alloy) centrifugal castings andingots

Part 2 - Nickel Aluminium Bronze (Naval alloy) sand castings and ingots

Part 4 - Nickel Aluminium Bronze (Naval alloy) sand castings withwelding restricted to the non-wetted surface (Class I and II castings only)

Def Stan 02-771 Requirements procedure and inspection for weld repair of copper alloyand nickel alloy castings

Def Stan 02-824 Copper Nickel Chromium sand castings and ingots

Def Stan 02-872 Procedure for First Level Nickel Aluminium Bronze Castings

Part 1 - Policy

Part 2 - Validation

Part 4 - Inspections Outside of Long Overhaul PeriodDef Stan 68-188 Emulsifier for solvent cleaner

Def Stan 80-20 Cleaning compound, solvent, cold bath type, for metal (cresylic acid/dichloromethane)

DGS 348 Cast Nickel Aluminium Bronze (Superseded by Defence Standard 02-747 part 2)

DGS 8520 Cast Nickel Aluminium Bronze (Superseded by DGS 348)

SSP 25 Quality Assurance for Safety in Submarines


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ANNEX B.

DEFINITIONS AND ABBREVIATIONS

B1. For the purposes of this Defence Standard the following definitions and abbreviationsapply:

Design Authority Authority within MOD with design responsibility for the equipment

DDIN Departure from Design Intent

FEA Finite Element Analysis

First Level QualityAssured

Where the consequences of failure of a hull area, system or equipmentare such that it would lead to loss of the submarine, these areas, systemsand equipment's will be classified First Level and additional QualityAssurance measures will be implemented. SSP 25 refers.

HAZ Heat Affected Zone around a weld.

NAB Nickel Aluminium Bronze to DGS 8520, DGS 348 or Def Stan 02-747

NAB Register The document used to monitor and control the inspection andreplacement of First Level Quality Assured NAB castings which arenormally in contact with sea water and are fitted on HM submarines

NABWETLIFE MOD in-house code for determining the life of NAB castings based onstatistical analysis

NDE Non Destructive Examination

NSN NATO Stock Number

QA Quality Assurance

LOP(R) Long Overhaul Period(Refuel). This replaces the obsolete term refit.

LOP(R) Contractor Organization contracted to carry out the LOP(R) of the submarine.

Revalidation Examination of used NAB castings during their life to the requirementsof this Part of this Defence Standard to determine the castings fitness forfurther service

RevalidationContractor

Organization contracted to carry out the revalidation of the castings

RVI Remote Visual Inspection

Through Life RecordsContractor

Organization contracted to maintain the QA records for NAB castingsthrough life

Validation Examination of new NAB castings prior to fitting in critical positions tothe requirements of Part 2 of this Defence Standard

ZIPSCAN Proprietary time of flight ultrasonic examination technique developed byAEA which has been used for the detection of selective phase corrosion


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ANNEX C.

PROCUREMENT CHECK LIST

Notes:C.1 This check list is to ensure that certain aspects of this Naval Engineering

Standard are consulted when preparing a Procurement Specification for aparticular application.

C.2 Clauses where a preference for an option is to be used or where specific data isto be added are included in the Check List.

C.3 Each item is to be marked either:

= includedNA = not applicable

CHECKNo. CHECK

CLAUSENo.

orNA


ANNEX D.

CASTING RECORD OF REVALIDATION INSPECTION

Revalidation Date Material

Casting Unique RadiographicNumber

Previous Radiographic No. (ifdifferent)

Component Description

1 2 3 4 5 6 7 8 9 10

Defect Depth (mm)DefectID No

Radiographposition

numbers forweld repairs(see previous

QA documents)

Type ofDefect

e.g. HAZ,Plug,

O Seal

DefectLength(mm)

A

Ultrasonic Etch &Grind

B

Defect FreeWall

Thickness(mm)

C

RemainingWall

Thickness(mm)

D=(C-B)

DrawingWall -10%

(mm)

E

D>E =

D

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ANNEX E.

REVALIDATION CERTIFICATE FOR NAB CASTINGS

PART I - IDENTIFICATION

A. EQUIPMENT SERIAL No. F. PIL No (VSN/ )

B. UNIQUE RADIOGRAPH No. G. PIL LINE ENTRY No

C. COMPONENT DRAWING No. H. COMPONENT ADREFNO

D. SHIP FITTING No. (e.g. BS 123) I. MANUFACTURER

E. COMPONENT DESCRIPTIONMATERIALSPECIFICATION

PART II - REVALIDATION ACTION Signature

A. ALL PREVIOUS CONCESSIONS ASSESSED

B. CLEANED ETCHED AND GROUND TO DETECT CORROSION

C. THICKNESS RECORDS IN WAY OF CORRODED AREAS ATTACHED

D.CASTING RECORD OF REVALIDATION INSPECTION TABLE COMPLETED FORALL DEFECTS AND ATTACHED WITH SKETCH.

PART III - RECLAMATION AND REVALIDATION

A. PREVIOUS VALIDATION DOCUMENTATION SCRUTINIZED

B. SUBSEQUENT WELD REPAIR

C. COMPONENT RADIOGRAPHED AND DP EXAMINED

D. DIMENSIONAL CHECKS

E. WELD AREAS RE-MACHINED

F. INTERNAL WELD REPAIRS

Indicate action taken by signature (or NA if not applicable in appropriate box).

CONCESSION NOS

CONCESSIONS GRANTED FOR ABOVE COMPONENT

I certify that the above NAB casting has been revalidated in accordance with Def Stan 02-872

Part 3 and stamped *

SIGNATURE

NAME IN BLOCK LETTERS

AUTHORITY/DEPT

DATE

* CASTING IDENTIFICATION TO BE INSERTED


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ANNEX F.

CHECK LIST FOR DOCUMENTS TO BE INCLUDED IN QA PACK FORREVALIDATED CASTINGS

F.1. All certification and record sheets for the revalidated castings are to be annotated with theappropriate ship fitting number or pump serial number (as applicable), description, andunique radiographic number.

QA CERTIFICATE OF COMPLIANCE

CHEMICAL ANALYSIS RESULTS RECORD SHEET

MECHANICAL TESTS RESULTS RECORD SHEET

VISUAL INSPECTION RESULTS RECORD SHEET

LIQUID PENETRANT RESULTS RECORD SHEET

RADIOGRAPHY/ULTRASONIC RESULTS RECORD SHEET

HEAT TREATMENT CERTIFICATE

PRESSURE TEST RESULTS RECORD SHEET/ CERTIFICATE OF COMPLIANCE

GRIDDED SKETCH FOR WALL THICKNESSES

WALL THICKNESS RECORDING SHEET CROSS-REFERENCED TO GRIDDEDSKETCH

SKETCH/PHOTOGRAPH OF WELD REPAIRS

WELD REPAIR RECORDING SHEET CROSS-REFERENCED TO SKETCH/PHOTOGRAPH

REVALIDATION CERTIFICATE

CASTING RECORD OF REVALIDATION INSPECTION TABLE

All QA records complete: SIGNATURE

NAME IN BLOCK LETTERS

AUTHORITY/DEPT

DATE


25

AArdrox 160 5, 10, 12

BBiofouling 10, 12

CCasting

Copper Nickel Chromium 8, 15Nickel Aluminium Bronze 2, 8Rejected 10, 15, 17

CertificateRevalidation 8, 15, 17, 23, 24Validation 8, 16

Concessions 8, 10, 23Corrosion

Crevice 10, 12HAZ 10, 12, 17Plug 10, 12Selective Phase 2, 8, 10, 12

DDesign Authority 2, 8, 10, 12,

15, 17Deterministic approach 15Drawings 8, 12, 15

EEtching 10, 12

FFEA 12, 15Ferric Chloride 10

HHeat Treatment 8, 17

IIdentification number 12

LLife assessment 15LOP(R) Contractor 8

NNAB Register 8, 10NABWETLIFE 15

PPhotographs 10, 12Probabilistic approach 15

QQuality Assurance Documentation 8, 12

RRadiograph 8, 15Redeposited copper 10, 12, 15Revalidation Contractor 8

SSilver Nitrate 5, 12Sketches 8, 12

TThrough Life Records Contractor 15, 16, 17

UUltrasonic Examination 12

VValidation 2, 8

WWall Thickness 2, 8, 12, 15Weld map 8Weld repairs 17

ZZIPSCAN 8, 12

ALPHABETICAL INDEX(Note: Page Numbers are given)


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Inside Rear Cover

Crown Copyright 2002

Copying Only as Agreed with DStan

Defence Standards are Published by and Obtainable from:

Defence Procurement AgencyAn Executive Agency of The Ministry of Defence

UK Defence 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/69/02/872 Pt 3.

Contract Requirements

When Defence Standards are incorporated into contracts users are responsible for their correctapplication and for complying with contractual and statutory requirements. Compliance with aDefence 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 that users ofDefence Standards should ascertain that they are in possession of the latest issue or amendment.Information on all Defence Standards is contained in Def Stan 00-00 Standards for Defence Part 3 ,Index of Standards for Defence Procurement Section 4 Index of Defence Standards and DefenceSpecifications published annually and supplemented regularly by Standards in Defence News (SIDNews). Any person who, when making use of a Defence Standard encounters an inaccuracy orambiguity is requested to notify the Directorate of Standardization (DStan) without delay in orderthat the matter may be investigated and appropriate action taken.

CONTENTSSCOPEFOREWORDConditions of ReleaseCategories of Naval Defence StandardRelated DocumentsHealth and Safety1. GENERAL REQUIREMENTS2. CLEANING OF CASTINGS3. ETCHING AND EXAMINATION FOR CORROSION4. ACCEPTANCE CRITERIA5. RECLAMATION OF REJECTED CASTINGSANNEX A. RELATED DOCUMENTSANNEX B. DEFINITIONS AND ABBREVIATIONSANNEX C. PROCUREMENT CHECK LISTANNEX D. CASTING RECORD OF REVALIDATION INSPECTIONANNEX E. REVALIDATION CERTIFICATE FOR NAB CASTINGSANNEX F. CHECK LIST FOR DOCUMENTS TO BE INCLUDED IN QA PACK FOR REVALIDATED CASTINGSALPHABETICAL INDEX