NES 729 Part 3 Requirements for Non-Destructive Examination Methods

Ministry of Defence Defence Standard 02-729 (NES 729)

Issue 1 Publication Date 01 April 2000

Incorporating NES 729 Category 2

Issue 2 Publication Date December 1991

Requirements For Non-DestructiveExamination Methods

Part 3Eddy Current

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) 729 Part 3 Issue 2 dated December 1991.

Ministry of Defence

Naval Engineering Standard

NES 729 Part 3 Issue 2 (Reformatted) December 1991

REQUIREMENTS FOR NON-DESTRUCTIVEEXAMINATION METHODS

PART 3

EDDY CURRENT

This NES Supersedes

NES 729 PART 3 ISSUE 1

Record of Amendments

AMDT INSERTED BY DATE

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iNAVAL ENGINEERING STANDARD 729

REQUIREMENTS FOR NON-DESTRUCTIVE EXAMINATION METHODS

PART 3

ISSUE 2 (REFORMATTED)

EDDY CURRENT

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 729Part 3

Issue 2 (Reformatted)

iii

SCOPE

1. This part of NES 729 defines the minimum requirements for methods of detection of surfaceand near-surface discontinuities in electrically conductive materials, which may beferromagnetic or non-ferromagnetic, using eddy current examination techniques.

2. The requirements for the use of manually operated portable eddy current instrumentsdesigned specifically for the detection of surface-breaking cracks in welds are included.

3. The requirements of this NES are applicable to all items for which specifications, standards,drawings, refit or repair instructions require eddy current examination.

4. The NES is also applicable to the Quality Assessment of Examining Authorities who performeddy current examination.

5. This NES does not cover:

a. the extent to which eddy current examination is required. This requirement is to bestated in relevant Contract;

b. acceptance criteria for defects;

c. the examination of nuclear plant and machinery.

NES 729Part 3Issue 2 (Reformatted)

iv

NES 729Part 3


v

FOREWORD

Sponsorship

1. ThisNaval Engineering Standard (NES) is sponsored by theProcurement Executive, Ministryof Defence, Director Naval Architecture (Submarines) (DNA(SM)), Section NA 133.

2. It is to be applied as required by any Procurement Executive, Ministry of Defence contract forthe Non-Destructive Examination of Metals and is applicable to Surface Ships andSubmarines.

3. This NES comprises:

Requirements for Non-Destructive Examination Methods

Part 1 Radiographic

Part 2 Magnetic Particle

Part 3 Eddy Current (This Part)

Part 4 Liquid Penetrant

Part 5 Ultrasonic

4. 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(Surface Ships) (DNA(SS)), Section NA 145.

5. 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.

6. No alteration is to be made to this NES except by the issue of an authorized amendment.

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

8. 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.

9. This NES has been reissued to reflect the changes in nomenclature and technicalrequirements in line with current policy.


vi

Conditions of Release

General

10. 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.

11. 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.

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

MOD Tender or Contract Process

13. 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.

14. 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.

15. 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

16. 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.

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.

NES 729Part 3


vii

Health and Safety

Warning

19. 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.

Safety

20. All equipment involving the use of main electrical supply is to conform to the relevantstatutory requirements and safety regulations.

21. All examinations referred to in this NES are to be carried out with due regard to the applicablestatutory requirements, safety regulations and Codes of Practice.


viii

NES 729Part 3


ix

CONTENTSPage No

TITLE PAGE i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SCOPE iii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FOREWORD v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sponsorship v. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Conditions of Release vi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

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

Warning vii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Safety vii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

SECTION 1. ACCEPTANCE STANDARDS 1.1. . . . . . . . . . . . . . . . .

SECTION 2. GENERAL 2.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.1 Limitations 2.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.2 BS 3889 Parts A and B 2.1. . . . . . . . . . . . . . . . . . . . . . . .

SECTION 3. EXAMINATION PROCEDURE REQUIREMENTS 3.13.1 Personnel Requirements 3.1. . . . . . . . . . . . . . . . . . . . . .3.2 Procedures and Inspections 3.1. . . . . . . . . . . . . . . . . . . .3.3 Production Eddy Current Testing, Techniques

and Reporting 3.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .FIGURE 3.1 EDDY CURRENT INSPECTIONREPORT 3.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 4. EQUIPMENT 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.1 General 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.2 Test Coils 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.3 Driving Mechanism 4.1. . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 5. CALIBRATION STANDARDS 5.1. . . . . . . . . . . . . . . . .TABLE 5.1 REFERENCE STANDARD HOLEDIAMETERS 5.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 6. EQUIPMENT CALIBRATION 6.1. . . . . . . . . . . . . . . .6.1 Acceptance Level 6.1. . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 7. EXTENT OF EXAMINATION 7.1. . . . . . . . . . . . . . . . .

SECTION 8. SURFACE CONDITION 8.1. . . . . . . . . . . . . . . . . . . . . .


x

SECTION 9. PRODUCTION EXAMINATION TECHNIQUES 9.1.9.1 Testing Speed 9.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9.2 Manual Testing 9.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9.3 Sensitivity Level 9.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .9.4 Defect Indications 9.1. . . . . . . . . . . . . . . . . . . . . . . . . . . .9.5 Additional Tests 9.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 10. RECORDS 10.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

ANNEX B. DEFINITIONS AND TERMS B.1. . . . . . . . . . . . . . . . . .

ANNEX C. PROCUREMENT CHECK LIST C.1. . . . . . . . . . . . . . .

ALPHABETICAL INDEX

NES 729Part 3


1.1

1. ACCEPTANCE STANDARDS

a. The standards for acceptance of defect indications detected by eddy currentexamination are to be as specified in the Contract Documents.


1.2

NES 729Part 3


2.1

2. GENERAL

2.1 Limitations

a. Eddy current effects are susceptible to physical and chemical changes inmaterials. Eddy current methods used for flaw detection are therefore mosteffective for the examination ofmaterials which have a homogeneous structure,low permeability and precisely controlled sectional dimensions. Slightvariations in these parameters which in themselves are within the permittedtolerances may influence the results of this method of examination.

2.2 BS 3889 Parts A and B

a. Unless specified otherwise herein, mandatory requirements of BS 3889,Parts 2A and 2B are to apply to eddy current testing of ferrous and non-ferrouspipes and tubes, required by any MOD(PE) contract for Surface Ships orSubmarines. These standards may be also used for guidance, whereverapplicable, in the eddy current testing of other forms of material.

b. It is not the intent of this NES to exclude proven eddy current inspectionprocedures which can be demonstrated to the satisfaction of the MOD(PE) tomeet the quality requirements. Prior approval is to be obtained before suchprocedures are used.


2.2

NES 729Part 3


3.1

3. EXAMINATION PROCEDURE REQUIREMENTS

3.1 Personnel Requirements

a. The examining authority is to ensure that all personnel associated with eddycurrent examination have been trained and certificated to the level appropriateto their responsibilities. This certification is to relate to a National orInternational Accreditation Scheme, eg Personnel Certification inNon-Destructive Testing (PCN).

b. A register of approved personnel is to be kept by the examining authority.

3.2 Procedures and Inspections

a. Eddy current examination is to be performed in accordance with a writtenexamination procedure. Each Examining Authority is to certify that theprocedure is in accordance with thisNES and is to submit each procedure to theMOD QAR for written approval.

b. Separate procedures are to be written to cover the requirements of the eddycurrent inspection of welding or wrought products.

c. The relevant contract is to define the extent of eddy current examination andthe appropriate acceptance standard.

d. Inspection to eddy current procedures are to be carried out by approvedpersonnel certified in accordance with Clause 3.1a.

e. Procedures are to reference all relevant documents, specifications andacceptance standards. The procedures are to be recorded and maintained byexamining authorities for audit purposes.

f. Eddy current procedures are to cover all prerequisites and technicalrequirements associated with the application and are to contain specificguidance information including the following, as applicable:

(1) (a) Material type and descriptive details of the item to be testedincluding size and shape.

(b) For weldments: the type of weld, location and surface condition.

(2) Equipment description

(a) Make/Model.

(b) Details of monitoring and recording method.

(c) Type of test coils or probes, size and current frequency.

(3) Details of the technique to be used:

(a) Coil or probe arrangement.

(b) System used, eg absolute, differential or combined mode.

(c) Saturation (if used).

(d) Speed of test.

(e) Probe scanning method or grid to be used.

(4) Description of the calibration procedure and sensitivity checks including:

(a) Full details of the calibration test pieces.

(b) Method of frequency of production sensitivity checks.

(5) Method of recording the results of tests.


3.2

3.3 Production Eddy Current Testing, Techniques and Reporting

a. Eddy current inspections are to be recorded in an eddy current report. Thereport is to include the following information:

(1) relevant eddy current inspection procedure;

(2) name/s of operator/s;

(3) description of component or weld, material and location;

(4) contract number and details;

(5) eddy current inspection technique;

(6) inspection coverage;

(7) date and time of examination;

(8) results of the examination.

A specimen eddy current inspection report showing the minimum informationto be recorded is shown at FIGURE 3.1.

NES 729Part 3


3.3

Procedure No . . . . . . . . . . . . . . . . Issue No . . . . . . . . . . . . . . . . Date . . . . . . . . . . . . .

Company . . . . . . . . . . . . . . . . . . . . Procedure draft by . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . Approved by . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . Examination conducted by . . . . . . . . . . . . . . . . . . . .

COMPONENT DESCRIPTION

Title . . . . . . . . . . . . . . . . . . . . . . . Material Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MOD . . . . . . . . . . . . . . . . . . . . . . . Material Spec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Contract/Order No . . . . . . . . . . . . Drawing No . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Method of manufacture: Casting/Forging/Weld/Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Area(s) examined . . . . . . . . . . . . . Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Surface Condition . . . . . . . . . . . . . Surface Preparation . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Acceptance Standard Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TECHNIQUE DETAILS

1. EquipmentMake/Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Method of monitoring/recording . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Type of test coils/probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Size of test coils/probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Frequency test coils/probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2. Technique

Coils/probes arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

System used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Saturation (if used) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Speed of test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Probe scanning method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .or grid used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3. Calibration

Details of calibration standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Calibration procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Method of production checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Frequency production checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Method of recording results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Add supplementary information and sketches as necessary to show the coverage of the itemunder test.4. Results of the Examination

FIGURE 3.1 EDDY CURRENT INSPECTION REPORT


3.4

NES 729Part 3


4.1

4. EQUIPMENT

4.1 General

a. Depending upon the application, eddy current examination is to be performedusing approved automated or manually operated equipment and methods.Manually operated equipment that has been designed specifically for thedetection of surface-breaking cracks in ferromagnetic and non-ferromagneticwelds is to be used only for the intended purpose.

b. Preferably, the required coverage is to be achieved by automatic methods withpositive control of:

(1) coil/material configuration;

(2) speed of scanning;

(3) scanning helix, where applicable (see Clause 4.3a.).

4.2 Test Coils

a. The equipment is to be capable of energizing test coils with alternating currentsof suitable frequencies and of sensing the changes in the electricalcharacteristics of the test coils.

b. The test coils are to be capable of inducing current in the item under test andof sensing changes in the electrical characteristics of the item. Coils may beencircling types or probe types depending upon the application.

4.3 Driving Mechanism

a. In automated or semi-automated systems, means are to be provided for passingthe item through the test coil system or for transversing the test coil systemacross the item, at a uniform speed with minimum vibration of the coil systemand of the item under test and formaintaining the item substantially concentricwith the test coil system. The equipment is to be capable of imparting relativemovement which is rotational and/or translational, thereby permitting a helicaltest pitch to be obtained.


4.2

NES 729Part 3


5.1

5. CALIBRATION STANDARDS

a. Test pieces are to be prepared from suitable lengths of material which simulatethe item to be tested with regard to sectional dimensions, material type,metallurgical condition and surface finish. Reference standards(see Clause B.1) are to be incorporated in the test pieces, in the form of holes,notches or slits. When using manually operated equipment, a flaw-freecalibration test piece (see Clause B.1) of the same material type as that underexamination is to be additionally provided for reference.

b. For tubing, the reference standards are to be either:

(1) internal and/or external notches aligned either longitudinally ortransversely as appropriate and whose dimensions are:

Length: 25mm nominal

Depth: t/20 or 0.1mm whichever is greater

Width: 1.6mm maximum

where t is the nominal wall thickness of the tube being examined.

The notches in thematerial surfaces are to be separated in such away thatthey can be clearly and individually resolved under production conditions;

(2) three holes of the same nominal diameter drilled through the tube wallperpendicular to the surface and displaced circumferentially 120 degreesfrom each other; axial separation from each other and the ends of thecalibration test piece is to be such that the holes can be resolved clearlyand individually under production conditions; the hole diameter is to bein accordance with TABLE 5.1 unless otherwise agreed between theDesign Authority and the Inspection Organization.

TUBE NOMINAL ODmm

HOLE NOMINAL DIAMETERmm

over 6.3 up to and including 19 0.65 max

over 19 up to and including 25 0.80 max






TABLE 5.1 REFERENCE STANDARD HOLE DIAMETERS

c. Calibration test pieces for welded tubing are to contain reference standards inthe weld method and additionally in the parent metal when both materials areto be examined.

d. For barmaterial, notches or slits are to be cut in thematerial surface and spacedas for tubes.

e. The reference standard disposition, dimensions, orientation and numbers forcomponents other than tubes or bars are to be as agreed between the DesignAuthority and the Examining Authority. The reference standards are to bespaced such that they can be clearly and individually resolved under productionconditions.


5.2

f. The introduction of the reference standards into the calibration test piecewhether by drilling, spark erosion or other methods, is to be carried out undercontrolled conditions in order to minimize disturbance in adjacent material.

g. The preferred methods of introducing the reference targets are respectively:

(1) holesdrilling;

(2) notchesspark erosion or by thin cutting wheel.

h. The accuracy of the calibration test piece, and reference standard dimensionsand positions, is to be verified to the satisfaction of the MOD(PE).

i. Calibration test pieces are to be frequently examined for signs of damage whichmay impair performance and are to be renewed accordingly.

NES 729Part 3


6.1

6. EQUIPMENT CALIBRATION

a. The equipment is to be calibrated immediately prior to any test or series of teststo ensure that sensitivity is adequate and that the equipment is functioning ina consistent and stable manner. The calibration is to be in accordance withmanufacturers recommendations.

b. A test piece containing a reference standard(s) is used to calibrate theequipment, to establish the test sensitivity and to execute routine calibrationchecks and re-calibration.

c. The calibration test piece is to be passed through the test unit or the test unitis to traverse the test piece at the same relative speed and in the same directionand manner as that to be used in the production examination.(See Clause 9.1a.).

d. The selected current frequency for production examination is to produce clearand distinctive indications in the test unit by all the reference standards in thecalibration test piece.

e. Where specified, a battery check is to be carried out prior to the calibration ofportable manually operated test units used for the examination of weldments.If a low battery condition is indicated, the batteries are to be replaced orrecharged.

6.1 Acceptance Level

a. To set the equipment to the agreed acceptance level (see Clause 1.a.) theappropriate calibration test piece is to be subjected to the procedure inClause 6.c. The trigger/alarm or monitor level is then to be adjusted until theacceptance standard will just indicate rejection.


6.2

NES 729Part 3


7.1

7. EXTENT OF EXAMINATION

a. Items to be examined are to be completely examined wherever practicable sothat all significant defects are detected irrespective of their orientation.

b. When complete coverage cannot be obtained, the actual extent of that achievedis to be stated on the record of test. Examination of weldments is to be asspecified in the Contract. (See SCOPE 5.).


7.2

NES 729Part 3


8.1

8. SURFACE CONDITION

a. Unless otherwise specified in the Contract, acceptance inspection is to beperformed on an item in the final surface condition and the final heat treatedcondition.

b. All surfaces to be examined are to be free frommetallic particles, loose scale andother foreign matter. Methods used for surface preparation are not to bedetrimental to the material or the surface finish.

c. Surface preparation of weldments to be examined by instruments designed forthe purpose, is to be limited to the removal of loose scale, paint and corrosionproducts from the areas to be traversed by the search probe.

d. Surface coatings of a conductive nature, eg electroplating, metal spraying oraluminizing, may give misleading results and make balancing of certaininstruments impossible and consequently prevent detection of defects in thebase metal. In such cases, it is first to be verified by examination of a similarlycoated test sample, with due consideration of the equipment manufacturersrecommendations, that meaningful results can be obtained.


8.2

NES 729Part 3


9.1

9. PRODUCTION EXAMINATION TECHNIQUES

9.1 Testing Speed

a. The relative speed between the item and the test coil is not to vary from thatused during the calibration procedure by more than 10%.

b. The speed of test as applied to the examination of weldments using equipmentwithmeter indication and hand held probes is not to exceed 1metre perminute.Where LED indication and gate circuits are provided, probe speed may beincreased to 3 metres per minute.

9.2 Manual Testing

a. The probe is to be held at a constant attitude to the contact surface and movedin a path parallel to the weld and adjacent to it. Rocking of the probe and theplacing of the probe near to the edge of the workpiece are to be avoided as bothmay cause spurious indications which may be misinterpreted as defects.

9.3 Sensitivity Level

a. The specified sensitivity level is to be assured and maintained under allprevailing examination conditions for the full duration of the examination ofthe complete area.

b. A sensitivity check system is to be applied before production examinationbegins, at intervals of approximately 2 hours as examination proceeds andagainon conclusion, using the appropriate calibration test piece. Manually operatedequipment is to be checked frequently throughout the examination of theweldsto ensure the correct sensitivity is being maintained and to take account of anylocal variations in response to eddy currents in the material.

c. An indicated sensitivity reduction of more than 2dB will necessitate bothre-calibration and the re-examination of all the material examined since themost recent satisfactory check.

9.4 Defect Indications

a. All defect indications are to be evaluated in accordance with the specifiedacceptance standard. (See Clause 1.a.)

9.5 Additional Tests

a. Areas containing defect indications observed during the examination offerromagnetic weldments are to be additionally tested by magnetic particleexamination in accordance withNES729, Part 2, in order to verify the relevanceof these indications and extent of confirmed defect.


9.2

NES 729Part 3


10.1

10. RECORDS

a. All records of eddy current examinations are to be sufficiently detailed and incompliance with the agreed procedure in order to permit proper application ofthe specified standard of acceptance. Details of retest and additional tests, asrequired in Clause 9.5a., are to be included with the records.


10.2

NES 729Part 3


A.1 ANNEX A.

ANNEX A.

RELATED DOCUMENTS

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

See Clause

BS 3683 Glossary of terms used innon-destructive testing:

B.2

Part 5: Eddy current flaw detection

BS 3889 Methods for non-destructive testing ofpipes and tubes:

2.2a.

Part 2A: Automatic eddy currenttesting of wrought steel tubesPart 2B: Eddy current testing ofnon-ferrous tubes

NES 729 Requirements for Non-DestructiveExamination Methods:

9.5a.

Part 2: Magnetic particle


A.2ANNEX A.

NES 729Part 3


B.1 ANNEX B.

ANNEX B.

DEFINITIONS AND TERMS

B.1 Definitions

Calibration Test Piece A conveniently sized sample of material of similarelectromagnetic properties to the item to be testedand in which reference standards are located.

Design Authority That section or group within the MOD that hasoverall responsibility for the material, item,structure, or vessel concerned.

Examining Authority The Company, Organization, Establishment orNaval Base that carries out eddy currentexamination within the scope of this Part.

Reference Standard An artificially produced imperfection ofpredetermined dimensions, usually a notch or ahole, used for the sole purpose of establishing thetest sensitivity of the eddy current equipment.

Trigger/Alarm Level The level at which the electronic equipment isrequired to differentiate between acceptable andsuspect items.

B.2 Terms

BS 3683 Part 5 is to apply to the terms used in this Part.


B.2ANNEX B.

NES 729Part 3


C.1 ANNEX C.

ANNEX C.

PROCUREMENT CHECK LIST

Notes:1. This Check List is to ensure that certain aspects of this Naval Engineering

Standard are consulted when preparing a Statement of TechnicalRequirements for a particular application.

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

3. Each item is to be marked either

! = included

NA = not applicable

CHECKNo CHECK CLAUSE No ! or NA

1 Extent of eddy current examination SCOPE 5.

2 Standards for acceptance of defect indications 1.a.

3 Battery check before calibration 6.e.

4 Examination of weldments to be specified 7.b.

5 Surface condition and heat treatment condition 8.a.


C.2ANNEX C.

NES 729Part 3


INDEXINDEX.1

ALPHABETICAL INDEX

AAcceptance standards, iii, 1.1, 6.1, 9.1, C.1

Additional tests, 9.1

Aluminized surfaces, 8.1

Attitude, probe, 9.1

Automatic methods, 4.1

BBar material, 5.1

Battery check, 6.1, C.1

CCalibrationequipment, 6.1reference standard hole diameter, 5.1procedure, 9.1standards, 5.1, 5.2test piece, 5.2, 6.1, 9.1, B.1procedure, 9.1

Conditions of issue, vi

Corroded surfaces, 8.1

Cracks, surface-breaking, iii

DDefect indications, 9.1

Definitions, B.1

Design authority, 5.1, B.1

Driving mechanism, 4.1

EElectroplated surfaces, 8.1

Equipment, 4.1calibration, 6.1driving mechanism, 4.1general, 4.1test coils, 4.1

Examination procedure requirements, 3.1, 3.2

Extent of examination, iii, 7.1, C.1

Examining authority, 5.1, B.1

FFrequency, current, 6.1


INDEX INDEX.2

HHealth and safety, vii

Heat treatment condition, 8.1, C.1

Holes, reference standard, 5.1, 5.2

Helical test path, 4.1

IInspection procedures, iii, 8.1

Introduction, v

Issuing authorities, A.1

LLimitations, 2.1

MMagnetic particle examination, 9.1methods, 4.1, 6.1, 9.1

Metal sprayed surfaces, 8.1

NNotches, reference standard, 5.1, 5.2

Nuclear plant and machinery, iii

PPainted surfaces, 8.1

Personnel requirements, 3.1

Pipes, iii

Procedures and inspections, 3.1

Procurement check list, C.1

Production examination techniques, 9.1additional tests, 9.1defect indications, 9.1sensitivity level, 9.1testing speed, 9.1

QQuality assessment, iii

NES 729Part 3


INDEXINDEX.3

RRe-calibration requirement, 9.1

Records, 7.1, 10.1

Reference standards, 5.1, 5.2, 6.1, B.1

Related documents, A.1

SSafety, vii

Scope, iii

Semi-automated systems, 4.1

Sensitivitycheck, 9.1level, 6.1, 9.1

Slits, reference standard, 5.1

Speed of scanning, 4.1

Spurious indications, 9.1

Surface coatings, conductive, 8.1

Surface condition, 8.1, C.1

Surface preparation, 8.1

TTest procedure, 3.3

Test coils, 4.1

Test piece, calibration, 5.1, 5.2, 6.1, B.1

Test sensitivity, 6.1

Testing speed, 9.1

Trigger/alarm level, 6.1, B.1

Tubes, iii, 5.1

WWeldments, 6.1, 7.1, 8.1, 9.1, C.1


INDEX INDEX.4

Inside Rear Cover

Crown Copyright 2000

Copying Only as Agreed with DStan

Defence Standards are Published by and Obtainable from:

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File Reference

The DStan file reference relating to work on this standard is D/DStan/69/02/729.

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 SafetyWarningSafety

1. ACCEPTANCE STANDARDS2. GENERAL2.1 Limitations2.2 BS 3889 Parts A and B

3. EXAMINATION PROCEDURE REQUIREMENTS3.1 Personnel Requirements3.2 Procedures and Inspections3.3 Production Eddy Current Testing, Techniques and ReportingFIGURE 3.1 EDDY CURRENT INSPECTION REPORT

4. EQUIPMENT4.1 General4.2 Test Coils4.3 Driving Mechanism

5. CALIBRATION STANDARDSTABLE 5.1 REFERENCE STANDARD HOLE DIAMETERS

6. EQUIPMENT CALIBRATION6.1 Acceptance Level

7. EXTENT OF EXAMINATION8. SURFACE CONDITION9. PRODUCTION EXAMINATION TECHNIQUES9.1 Testing Speed9.2 Manual Testing9.3 Sensitivity Level9.4 Defect Indications9.5 Additional Tests

10. RECORDSANNEXESANNEX A. RELATED DOCUMENTSANNEX B. DEFINITIONS AND TERMSANNEX C. PROCUREMENT CHECK LIST

ALPHABETICAL INDEX