nes 743 pipe manipulation

Ministry of Defence Defence Standard 02-743 (NES 743)

Issue 1 Publication Date 01 April 2000

Incorporating NES 743 Category 2

Issue 1 Publication Date April 1989

Pipe Manipulation

Part 5Brazing

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) 743 Part 5 Issue 1 dated April 1989.

Ministry of Defence

Naval Engineering Standard

NES 743 Part 5 Issue 1 (Reformatted) April 1989

PIPE MANIPULATION

PART 5

BRAZING

This NES Supersedes

DGS/PS/9019.1

Record of Amendments

AMDT INSERTED BY DATE

1 Incorporated

2 Incorporated

3

4

5

6

7

8

9

10

i

NAVAL ENGINEERING STANDARD 743

PIPE MANIPULATION

PART 5

ISSUE 1 (REFORMATTED)

BRAZING

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 743Part 5

Issue 1 (Reformatted)

iii

SCOPE

1. This NES defines the requirements for design and production of capillary brazed joints forpiping systems in Surface Ships and Submarines. It does not apply to reactor plant primarysystem pipework.

2. It covers only the material combinations listed. The general requirements of the NES may beapplied to other materials approved by MOD but not yet included in the NES.

3. The design temperature for piping systems with brazed joints covered by this NES is not toexceed 220 C (see Annex B.)

NES 743Part 5Issue 1 (Reformatted)

iv

NES 743Part 5


v

FOREWORD

Sponsorship

1. ThisNaval Engineering Standard (NES) is sponsored by theProcurement Executive, Ministryof Defence, Chief Naval Architect (CNA) Section NA 133.

2. It is to be applied as required by any Ministry of Defence contract for brazing piping systemsand is applicable to Surface Ships and Submarines.

3. This NES comprises:

PIPE MANIPULATION

Part 1 Bending of Pipes

Part 2 Extrusions

Part 3 Swaging

Part 4 Welding

Part 5 Brazing

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 Chief Naval Architect (CNA), NA 145for Ship Systems and Equipment.

5. Any user of this NES either within MOD or in outside industry may propose an amendmentto 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 a formal amendment.

7. Unless otherwise stated, reference in this NES to approval, approved, authorized or similarterms, means by the 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.

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.


vi

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 743Part 5

Issue1 (Reformatted)

vii

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

CONTENTS vii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 1. GENERAL REQUIREMENTS 1.1. . . . . . . . . . . . . . . . .1.1 Drawings 1.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2 Production 1.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 2. DESIGN REQUIREMENTS 2.1. . . . . . . . . . . . . . . . . . .2.1 General 2.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.2 Joint Design 2.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.2.1 General 2.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.2.2 Clearances 2.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FIGURE 2.1 JOINTS USING ALLOY INSERTRINGS 2.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .FIGURE 2.2 FACE FEED JOINTS 2.3. . . . . . . . . . . . .FIGURE 2.3 BRAZED FLANGE JOINTS 2.4. . . . . . .

2.2.3 Ultrasonic Examinations 2.5. . . . . . . . . . . . . . . . . . . . . .2.2.4 Surface Finish 2.5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.3 Heat Treatment 2.5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.4 Brazing Alloys and Fluxes 2.5. . . . . . . . . . . . . . . . . . . . .

SECTION 3. QUALIFICATION REQUIREMENTS 3.1. . . . . . . . . .3.1 General 3.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.2 Qualification of Brazing Alloys, Fluxes and

Combinations thereof 3.1. . . . . . . . . . . . . . . . . . . . . . . . .3.3 Brazing Procedure Information 3.2. . . . . . . . . . . . . . . .3.4 Changes in Brazing Procedures 3.3. . . . . . . . . . . . . . . .3.5 Automatic Brazing Equipment 3.3. . . . . . . . . . . . . . . . .3.6 Personnel 3.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.7 Qualification Approval 3.4. . . . . . . . . . . . . . . . . . . . . . .3.8 Requalification 3.4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.9 Responsibilities of the Organization 3.4. . . . . . . . . . . . .3.10 Qualification Test Pieces 3.5. . . . . . . . . . . . . . . . . . . . . .3.10.1 Qualification of Procedures 3.5. . . . . . . . . . . . . . . . . . . .

TABLE 3.1 PROBABLE NUMBERS OF TESTPIECES REQUIRED FOR EACH POSITION(HORIZONTAL AND VERTICAL) 3.5. . . . . . . . . . . . .

NES 743Part 5Issue1 (Reformatted)

viii

TABLE 3.2 EXTENT OF QUALIFICATION 3.5. . . .3.10.2 Qualification of Personnel 3.6. . . . . . . . . . . . . . . . . . . . .3.10.3 Retests 3.6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.10.4 Qualification of Automatic Brazing Equipment 3.6. . .3.11 Requirements for Qualification Tests 3.6. . . . . . . . . . . .

FIGURE 3.1 QUALIFICATION TEST PIECES 3.7. .FIGURE 3.2 QUALIFICATION TESTARRANGEMENTS FOR RESTRICTED ACCESS 3.8

3.12 Examination of Completed Test Pieces 3.9. . . . . . . . . . .

SECTION 4. BRAZING REQUIREMENTS 4.1. . . . . . . . . . . . . . . . .4.1 General 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.2 Brazing Processes 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . . .4.3 Fittings 4.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.4 Brazing Alloys and Fluxes 4.1. . . . . . . . . . . . . . . . . . . . .4.5 Preparation of Fittings 4.1. . . . . . . . . . . . . . . . . . . . . . . .4.6 Preparation of Pipes 4.3. . . . . . . . . . . . . . . . . . . . . . . . . .4.6.1 Cutting 4.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.6.2 Sizing 4.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.6.3 Clearances 4.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.7 Cleaning 4.4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.8 Fluxing 4.4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.9 Assembly 4.5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.10 Brazing of Valves 4.5. . . . . . . . . . . . . . . . . . . . . . . . . . . .4.11 Nitrogen Purge 4.6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.12 Tacking 4.6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.13 Heating 4.6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.14 Priming 4.6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.15 Face Feeding 4.6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.16 Cooling 4.7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.17 Marking of Joints 4.7. . . . . . . . . . . . . . . . . . . . . . . . . . . .4.18 Heat Treatment after Brazing 4.7. . . . . . . . . . . . . . . . . .4.19 Cleaning after Brazing 4.7. . . . . . . . . . . . . . . . . . . . . . . .4.20 Examination of Brazed Joints 4.7. . . . . . . . . . . . . . . . . .4.21 Repair of Joints 4.7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.21.1 General 4.7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.21.2 Repair Techniques 4.8. . . . . . . . . . . . . . . . . . . . . . . . . . .4.21.3 Examination 4.8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.21.4 Recording of Repairs 4.8. . . . . . . . . . . . . . . . . . . . . . . . .4.21.5 Heat Treatment of Repairs 4.8. . . . . . . . . . . . . . . . . . . .4.22 Reuse of Fittings 4.8. . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.23 Reuse of Pipe 4.8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 5. INSPECTION AND TEST REQUIREMENTS 5.1. . . .5.1 General 5.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.2 Pre-Braze Inspections 5.1. . . . . . . . . . . . . . . . . . . . . . . . .5.2.1 Joint Components 5.1. . . . . . . . . . . . . . . . . . . . . . . . . . . .5.3 Ultrasonic Examination of Fittings before Brazing 5.15.3.1 General 5.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

NES 743Part 5

Issue1 (Reformatted)

ix

5.3.2 Setting Up 5.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.3.3 Search Sensitivity 5.2. . . . . . . . . . . . . . . . . . . . . . . . . . . .5.3.4 Examination 5.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.3.5 Assessment 5.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.3.6 Report 5.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.3.7 Gas 5.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.3.8 Brazing Procedure 5.2. . . . . . . . . . . . . . . . . . . . . . . . . . .5.4 Inspections during Brazing for Joints using Insert

Rings 5.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.5 Inspection of Completed Joints 5.3. . . . . . . . . . . . . . . . .5.5.1 Visual Examination of Brazed Joints 5.3. . . . . . . . . . . .5.6 Ultrasonic Examination of Brazed Joints 5.3. . . . . . . .5.6.1 General 5.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.6.2 Method, Search Sensitivity and Calibration 5.3. . . . . .5.6.3 Examination of Joints with External Hexagonal

Configuration 5.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.6.4 Radiographic Examination of Brazed Joints 5.3. . . . . .5.7 Inspection of Used Fittings Salvaged for Reuse 5.4. . . .5.7.1 Inspections before Reuse 5.4. . . . . . . . . . . . . . . . . . . . . .5.7.2 Inspections after Brazing 5.4. . . . . . . . . . . . . . . . . . . . . .5.8 Inspection of Used Pipe Salvaged for Reuse 5.4. . . . . .5.8.1 Inspections before Reuse 5.4. . . . . . . . . . . . . . . . . . . . . .5.9 Inspection of Qualification Test Pieces 5.4. . . . . . . . . . .5.9.1 General 5.4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.9.2 Prebraze Inspections 5.4. . . . . . . . . . . . . . . . . . . . . . . .5.9.3 Inspections During Brazing for Joints with Insert

Rings 5.4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.9.4 Visual Examination of Completed Test Pieces 5.5. . . . .5.9.5 Bond Assessment 5.5. . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.10 Ultrasonic Examination 5.5. . . . . . . . . . . . . . . . . . . . . . .5.10.1 General 5.5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.10.2 Peel Tests 5.5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.11 Additional Tests required only for Qualification of

Procedures 5.6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.12 Hydraulic Testing 5.6. . . . . . . . . . . . . . . . . . . . . . . . . . . .

FIGURE 5.1 MECHANICAL PEEL TESTSPECIMENS AND REDUCED SECTIONTENSILE TEST SPECIMENS 5.7. . . . . . . . . . . . . . . . .FIGURE 5.2 FULL SECTION TENSILE TEST 5.8. .

SECTION 6. ACCEPTANCE STANDARDS FOR BRAZED PIPEJOINTS 6.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.1 Faying Surfaces of Pipes 6.1. . . . . . . . . . . . . . . . . . . . . .6.2 Faces of Joints using Insert RingsBefore Face

Feeding 6.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.3 Faces of Joints after Face Feeding 6.1. . . . . . . . . . . . . .6.4 Joint Geometry 6.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.5 Ultrasonic Examination of Brazed Joints 6.1. . . . . . . .6.5.1 General Fittings 6.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.5.2 Special Fittings 6.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

NES 743Part 5Issue1 (Reformatted)

x

TABLE 6.1 BOND ACCEPTANCE STANDARDS 6.16.6 Fittings Salvaged for Reuse 6.2. . . . . . . . . . . . . . . . . . . .6.6.1 Visual Examination 6.2. . . . . . . . . . . . . . . . . . . . . . . . . .6.6.2 Dye Penetrant Examination 6.2. . . . . . . . . . . . . . . . . . .6.7 Pipe Salvaged for Reuse 6.2. . . . . . . . . . . . . . . . . . . . . . .6.8 Qualification Test Pieces 6.2. . . . . . . . . . . . . . . . . . . . . .6.8.1 Faces of Joints using Insert Rings, before Face

Feeding 6.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.8.2 Ultrasonic Examination 6.2. . . . . . . . . . . . . . . . . . . . . . .6.8.3 Peel Tests 6.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TABLE 6.2 MINIMUM ACCEPTANCESTANDARDS FOR PERCENTAGE BOND INPEEL TESTS 6.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.8.4 Tensile Tests 6.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

ANNEX B. ABBREVIATIONS AND DEFINITIONS B.1. . . . . . . .

ANNEX C. MATERIALS FOR WHICH DATA IS INCLUDEDIN THE ANNEXES C.1. . . . . . . . . . . . . . . . . . . . . . . . . .TABLE C.1 MATERIAL COVERED IN THEANNEXES C.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ANNEX D. FLUXES AND BRAZING ALLOYS D.1. . . . . . . . . . . .TABLE D.1 FLUXES D.1. . . . . . . . . . . . . . . . . . . . . . . .TABLE D.2 BRAZING ALLOYS D.2. . . . . . . . . . . . . .

ANNEX E. HEAT TREATMENT E.1. . . . . . . . . . . . . . . . . . . . . . . . .TABLE E.1 HEAT TREATMENT OF FITTINGS E.1

ANNEX F. CLEARANCES FOR CAPILLARY BRAZEDJOINTS F.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .TABLE F.1 RADIAL CLEARANCES AT ROOMTEMPERATURE FOR PIPES USED WITHINTERNAL FITTINGS F.2. . . . . . . . . . . . . . . . . . . . . . .TABLE F.2 RADIAL CLEARANCES AT ROOMTEMPERATURE FOR PIPES USED WITHEXTERNAL FITTINGS F.3. . . . . . . . . . . . . . . . . . . . . .

ANNEX G. CONSUMABLES AND CLEARANCES FORALUMINIUM NICKEL SILICON BRASS(AlNiSi BRASS) PIPING USED WITHALUMINIUM SILICON BRONZE(AlSi BRONZE) FITTINGS G.1. . . . . . . . . . . . . . . . . .TABLE G.1 BRAZING ALLOYS AND FLUXESFOR USE WITH AlSi BRONZE FITTINGS ANDAlNiSi BRASS PIPES G.2. . . . . . . . . . . . . . . . . . . . . . .TABLE G.2 CLEARANCES (RADIAL) AT ROOMTEMPERATURE (AlNiSi BRASS PIPING WITHAlSi BRONZE FITTINGS) G.2. . . . . . . . . . . . . . . . . . .

SECTION H. HEALTH PROTECTION AND SAFETYPRECAUTIONS H.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ALPHABETICAL INDEX

NES 743Part 5


1.1

1. GENERAL REQUIREMENTS

1.1 Drawings

a. The drawing or contract is to state the method and extent of anynon-destructive examinations required, and the acceptance standards.

1.2 Production

a. Organizations working to this NES are responsible for meeting allrequirements in the NES.

b. Any conflict between this NES, the drawings, the procedures and the contractis to be referred in writing to the QAR.

c. Approval is required for any deviation from the requirements of this NES.

d. The QAR is to be given access and facilities at all reasonable times to ensure thatthe requirements of this NES are being met.

e. The QAR has the right to reject any production work which cannot be provedto meet the requirements of this NES.


1.2

NES 743Part 5


2.1

2. DESIGN REQUIREMENTS

2.1 General

a. It is not intended that this NES should exclude any design, manufacturingprocedure, material or process that can be proved to meet the qualityrequirements. Approval must be obtained before any design, procedure etc notcovered by this NES is issued for production.

b. Drawings are to indicate the location of each brazed joint, the level of thesystem and, when appropriate the approved brazing procedure. The varioussystem levels are defined in Annex B.

c. Each brazed joint is to be designed so that with a perfect braze but with themaximum end clearances allowed (see FIGURE 2.1, FIGURE 2.2 andFIGURE 2.3) the joint, under axial loads, is 1.8 times as strong as the weakerof the pipe and fitting and is also sufficiently strong to carry any bending loadswhich may be applied.

d. A realistic rule of thumb is:

(1) The total length of faying surfaces are to be between three and four timesthe thickness of the thinner component, with aminimum practical lengthof 3mm and a maximum length of 20mm for each faying surface, ie whenone alloy insert ring is used, the total faying surface can consist of twolengths of 20mm, one on each side of the insert ring groove. When facefeeding is used, the total faying surface is not exceed 20mm in length;

(2) Under normal conditions, silver brazing alloy will not flow more than20mm through a capillary gap.

e. Systems containing brazed joints are to be designed so that wherever possible,brazing is carried out in the workshop. Brazing in situ is to be kept to aminimum.

f. Adequate access is to be allowed for assembly, brazing, inspection and repair.Particular care is required to facilitate any brazing in situ.

2.2 Joint Design

2.2.1 General

a. Permanent joints in brazed piping systems are to be socket or sleeve joints asshown in FIGURE 2.1 and FIGURE 2.2.

b. Sleeve and socket joints are to use alloy insert rings unless specific approval foran alternative design has been obtained. Any sleeve or socket joint which is notdesigned to use pre-inserted alloy rings is to be individually identified as suchon the drawings.

c. Fittings designed for face feeding are not to be machined to take insert ringswithout approval.

d. Joints in brazed piping systems which may need to be dismantled are to beflanged joints as shown in FIGURE 2.3.

2.2.2 Clearances

a. The clearances required at the brazing temperature vary from alloy to alloy andare usually specified by the alloy manufacturers. This variation and thevariation inmelting temperatures between different alloysneed to be taken intoaccount when calculating the cold clearances required to give the correctclearances at brazing temperatures. It is also necessary to allow for differentialexpansion when pipe and fitting are of different materials.


2.2

Notes:

1. Dimensions in mm.

2. For pipe below 25mm OD, G is not to exceed 1mm. For pipe 25 OD and over, G isnot to exceed 3mm.

FIGURE 2.1 JOINTS USING ALLOY INSERT RINGS

NES 743Part 5


2.3

Notes:


2. For pipe below 25mm OD, G is not to exceed 1mm. For pipe 25 OD and over, G isnot to exceed 3mm.

FIGURE 2.2 FACE FEED JOINTS


2.4

Note: For flange and pipe materials and for design requirements, refer to BR 3013(1) forImperial sizes and BR 3013(2) for Metric sizes.

FIGURE 2.3 BRAZED FLANGE JOINTS

NES 743Part 5


2.5

b. Fittings are to be designed for the largest diameter of pipe which could besupplied, within the limits of the pipe specification, for the nominal pipe sizecalled up. The bore of the pipe recess is to allow acceptable clearances, asspecified in Annexes F. and G., with the largest pipe that can be supplied againstthe nominal pipe size called up.

Note: In production, the ends of pipes below the maximum diameter will beenlarged before brazing to give the correct clearance.

c. Joint design is to be checked to ensure that correct cold clearances can beobtained by acceptable enlargement of any diameter of pipe which could besupplied within the limits of the pipe specification for the nominal size calledup. The enlargement is not to exceed 1 per cent for pipes over 25mm OD or0.5mm for pipes of 25mm OD or less.

d. Where cold clearances are to be specified on a drawing and Annexes F. and G.do not contain the required information, any proposed clearances are to beproved by qualifying a brazing procedure as laid down in Section 3.

2.2.3 Ultrasonic Examinations

a. Fittings for use with pipe of 12mm OD or larger are to be designed to allow fullultrasonic examination of the faying surfaces as laid down in Section 5.

Note: Ultrasonic examination of a brazed joint is practicable only when the:

(1) pipe OD is not less than 12mm;

(2) pipe wall is not less than 1.5mm;

(3) fitting is cylindrical adjacent to the pipe, concentric with it, not less than15mm OD extending to at least 6mm beyond the end of the pipe with asurface finish on the OD equivalent to 6.3 micrometres or better and freefrom waviness or burrs.

b. To allow accurate assessment of the results of ultrasonic examinations of brazedjoints, it is necessary to carry out an ultrasonic examination of the fitting beforebrazing, as laid down in Section 5., in order to locate any defects in the fittingwhich could hamper or prevent adequate ultrasonic examination of thecompleted joint. Ultrasonic examination of brazing fittings is to be specified onthe drawing. The examinationmay be carried out by themanufacturer providedthat he meets the requirements in Section 5.

2.2.4 Surface Finish

a. The faying surfaces of brazing fittings are to be fine turned as this finishproduces a better joint than smooth or polished surfaces. Cold drawn surfacesalso produce satisfactory joints.

2.3 Heat Treatment

a. Drawings are to contain adequate instructions and sufficient information toensure that the required heat treatment is correctly carried out as laid down inAnnex E.

2.4 Brazing Alloys and Fluxes

a. Brazing alloys or fluxes specified on the drawing, are to be selected from the listof approved brazing materials in Annex D.

b. Materials not listed are not to be used without specific approval. Tests may berequired to prove and qualify the materials and the brazing procedure beforeapproval is given.


2.6

NES 743Part 5


3.1

3. QUALIFICATION REQUIREMENTS

3.1 General

a. Organizations working to this NES are to establish and maintain control ofprocedures, equipment and personnel which form part of production, repair,inspection, or required safety precautions. Equipment, essential processingenvironments, procedures and personnel qualifications are to be subject toapproval or certification to the satisfaction of the QAR.

b. All brazing is to be carried out by suitably qualified brazers in accordance withwritten brazing procedures.

c. Manual brazing equipment will not normally require qualification tests.Automatic brazing equipment is to be qualified by practical qualification testsas detailed later in this Section.

d. All brazing equipment, when used by qualified personnel working to approvedprocedures, is to be capable of consistently producing joints to the requiredstandards. Equipment is to be regularly inspected and tested as part of anapproved planned maintenance programme.

e. Brazers will normally qualify by producing test pieces which meet the specifiedAcceptance Standards as laid down in Clauses 3.6a.3.11c.

f. Personnel currently qualified to meet the brazing requirements of a recognizedauthority may, at the discretion of the QAR, be granted exemptions in respectof brazer qualification. The QAR will state clearly in writing the extent of anyexemption granted.

g. A brazing procedure is qualified by proving that acceptable sample joints canbe produced on standard test pieces, using the procedure. The test pieces are tobe prepared, examined and tested as described later in this Section. The testresults and, if requested, test pieces and test specimens are to be submitted andapproved by an Authority acceptable to the QAR. The test results may be in theform of a laboratory report. Qualification of the procedure automaticallyqualifies the person who brazed the test piece and the equipment used for thetest.

h. Organizations may be exempted from procedure qualification tests if, duringthe previous three years, brazed pipe joints similar to those covered by thisStandard have been successfully brazed to an acceptable quality. Supportingdocumentation such aswritten procedures, test data, letters of approval, etc areto be made available to the QAR on request.

3.2 Qualification of Brazing Alloys, Fluxes and Combinations thereof

a. Brazing alloys, fluxes and combinations of these already approved for brazingto this Standard are listed in Annex D. Details of other approved consumablesmay be obtained from NA 133.

b. If the proposed alloy/flux combination specified in the brazing procedure is notalready approved, it is to be tested and approved before use in production. Incertain cases long term corrosion tests may be necessary. Proposals forqualification of newmaterials or material combinations are to be submitted, inwriting, to the QAR.


3.2

3.3 Brazing Procedure Information

a. Each brazing procedure is to include the following information whereapplicable:

(1) Base metals:

(a) Pipe material, wall thickness and thermal condition;

(b) Fitting type, material and thermal condition;

in addition, brazing qualification procedures are to indicate clearly therange of wall thickness qualified by each test piece;

(2) Brazing materials:

(a) Brazing alloy type, specification and brand;

(b) Flux type, specification and brand;

(3) Brazing process and details:

(a) torch brazing: fuel gas;type of flame;

(b) furnace brazing: atmosphere;

(c) induction brazing: frequency and source of highfrequency current.

(4) Brazing position (brazing qualification procedures only);

(5) Safety precautions against:

(a) solvents used for cleaning;

(b) brazing materials;

(see Annex H.)

(6) Joint design;

(7) Joint fit-up:

(a) clearances (see Annexes F. and G.);

(b) reference marks (see Section 4.);

(8) Placement of brazing alloy: insert ring or face feed;

(9) Jigs and fixtures;

(10) Cleaning of faying surfaces and adjacent areas:

(a) extent of cleaning;

(b) cleaning methods and equipment;

(c) degreasing methods and agents;

(11) Method of cooling;

(12) Post-braze cleaning requirements;

(13) Post-braze heat treatment requirements;

(14) Non-destructive examinations and acceptance standards;

(15) Destructive tests (normally only in qualification procedures) andacceptance standards.

NES 743Part 5


3.3

3.4 Changes in Brazing Procedures

a. Any alteration in a brazing procedure is to be covered by an authorized changeto the procedure issued in writing.

b. Any change in items in Clause 3.3a.(8) to 3.4b.(7) will normally require a newprocedure and qualification of the new procedure and personnel except:

(1) in production procedures, changes of pipe wall thickness within the rangealready qualified;

(2) changes in consumables where the new consumable is supplied to thesame specification as the original;

(3) changes in fuel gas;

(4) changes in frequency or source of high frequency current for inductionbrazing;

(5) changes in fit-up clearances which do not allow the clearances to exceedthe limits laid down in Annexes F. and G.;

(6) changes affecting only the reference marks;

(7) changes where one material is replaced by another which, although notidentical, has similar characteristics and its use without requalificationis approved by the QAR.

3.5 Automatic Brazing Equipment

a. Automatic or mechanized brazing equipment is to be qualified by test brazes inaccordance with an approved, preliminary or proposed brazing procedure.

b. The Organization is required to demonstrate the reproducibility of machinebrazed joints. The production brazing procedure is to state the level andfrequency of any additional inspections necessary to meet this requirement.

3.6 Personnel

a. The Organization is responsible for qualifying each brazer and for ensuring thathe is capable of working strictly to brazing procedures and of brazing underproduction conditions to the specified acceptance standards.

b. Personnel currently qualified to meet the brazing requirements of a recognizedauthority may, at the discretion of the QAR, be granted exemptions in respectof brazer qualification. The QAR will state clearly in writing the extent of anyexemption granted.

c. A brazer who carries out a satisfactory brazing procedure qualification test alsoqualifies himself for production brazing using that procedure.

d. An unqualified brazer may qualify by producing acceptable sample brazed testpieces using an approved brazing qualification procedure. The procedure is toinclude the inspection requirements and acceptance standards. The test piecesare to be examined and tested as described later in this Section.

e. If a brazer is required to braze pipe joints in locations where access is difficultor restricted, he is first to qualify for brazing under conditions of restrictedaccess as laid down later in this Section.


3.4

Notes:

1. Access is defined as restricted when a panel or other surface passeswithin 150mm of the joint, the surface extending for 70 or more aroundthe joint and obstructing the access for the torch or brazing rod.

2. A typical case of restricted access occurs when a joint is required in a piperun close to an inside corner. This condition is used later in this Sectionin qualification tests for brazing with restricted access.

3.7 Qualification Approval

a. The procedures, test reports and, if requested, test pieces and test specimens areto be submitted to the QAR for approval. The test results may be in the formof a laboratory report. Test pieces and specimens are to be retained until writtenapproval is obtained.

3.8 Requalification

a. To avoid needless expense the Organization must apply to the QAR for a waiverwhen a proposed change is considered not to require requalification.

b. Requalification is not required for subsequent components or order, providedthat:

(1) the QAR is satisfied that the approved conditions are unchanged;

(2) the QAR is satisfied that the brazing equipment is producing acceptablewelds;

(3) requalification is not required for any other reason.

c. Requalification of brazers is required if:

(1) the QAR or Approving/Certification Authority has reason to believe thatthe production workmanship is not consistently of the required standard;

(2) aperiod of sixmonths has elapsed since the brazer was last engaged on thiswork.

d. Subject to the approval of the QAR, in exceptional circumstances, qualificationor requalification tests may be modified or waived for selected brazers subjectto full non-destructive examination of the first production braze, or asotherwise specified by the QAR.

3.9 Responsibilities of the Organization

a. Each Organization working to this NES is to carry out all necessaryqualification tests at its own expense. The QAR will require adequate notice ofeach test so that the tests may be witnessed.

b. The Organization is to certify that tests are conducted in accordance with thepreliminary, proposed or approved brazing procedure. When a test is intendedto qualify simultaneously any combination of procedure, equipment andpersonnel, this must be clearly stated when notifying the QAR and again whensubmitting details for approval.

c. The Organization is to keep up-to-date records of qualifications. The records areto include details of all tests carried out including failures as well as passes. Therecords are to include at least the following information:

(1) Brazer identification;

(2) Date of test and result;

(3) Procedure;

NES 743Part 5


3.5

(4) All test reports;

(5) Letter or other signed form of approval.

d. Records for personnel qualifications are to be retained until the person leavesthe Organization.

e. Records for procedure and equipment qualifications are to be retained inaccordance with the Contract Documents.

3.10 Qualification Test Pieces

a. The same test piece is used for qualification of brazers, procedures andequipment.

3.10.1 Qualification of Procedures

a. To qualify a brazing procedure, a minimum of two test pieces are to be brazed,one in a vertical position and one in a horizontal position, as shown inFIGURE 3.1. The test pieces are to be fixed so that the pipes cannot rotate oncebrazing has started.

b. To ensure that sufficient test specimens can be produced to meet theexamination requirements in Section 5., it is often necessary to braze more thanone test piece in each position. The actual number of test pieces to be brazed ineach position will depend on the size of pipe selected for the test pieces.TABLE 3.1 gives some guidance on the probable minimum numbers required.The exact requirements will depend on the method of preparation of the testspecimens and are to be decided by the responsible Organization before the testscommence.

Test Pieces required for Tests foreach position No of Test Pieces to be Brazed in

each positionPipe OD A B or C

each positionp

TensileTests

MechanicalPeel Tests

MachinedPeel Tests

TestsA+B

TestsA+C

TestsA+US

75 max 2 1 1 3 3 2

Over 75 to110 1 1 1 2 2 1

Over 110 One test piece can provide all of thetest specimens 1 1 1

Note: Peel tests are not required if the brazed joints are ultrasonically (US)examined before the destructive tests.

TABLE 3.1 PROBABLE NUMBERS OF TEST PIECES REQUIRED FOR EACHPOSITION (HORIZONTAL AND VERTICAL)

c. Successful qualification of a procedure using pipe of wall thickness t willqualify the brazer, the equipment and the production procedure for use with arange of pipe wall thicknesses defined in TABLE 3.2. The qualification coverspipe of any diameter.

Wall thickness t of pipe brazed in TestPiece

Range of pipe wall thickness covered byqualification

Up to and including 9mm 0 to 2t

Over 9mm to 18mm inclusive 9mm to 2t

Over 18mm 18mm to 2t

TABLE 3.2 EXTENT OF QUALIFICATION


3.6

3.10.2 Qualification of Personnel

a. To qualify a brazer a minimum of two test pieces are to be brazed, one in avertical position and one in a horizontal position, as shown in FIGURE 3.1 orFIGURE 3.2. The test pieces are to be fixed so that the pipes cannot rotate oncebrazing has started.

b. For normal qualification of brazers, the test piece arrangement shown inFIGURE 3.1 is to be used, but if the brazer is required to be qualified for brazingwhere access is restricted, then the test piece arrangement shown inFIGURE 3.2 is to be used.

c. A successful qualification test using pipe of wall thickness t will qualify thebrazer for brazing pipes with a range of wall thicknesses defined in TABLE 3.2.

3.10.3 Retests

a. If a brazer qualification test piece fails tomeet the acceptance standards, retestsare permitted as follows:

(1) One retest may be made for each test piece that failed without furthertraining;

(2) A second retest may be made for each test piece that failed provided thatbefore the retest, the brazer receives at least eight hours of training orpractice designed to prevent the defects which caused the failures.

If the brazer fails the second retest he is not to be retested for brazing to thisstandard until he has undergone a full retraining programme approved by theQAR.

3.10.4 Qualification of Automatic Brazing Equipment

a. To qualify automatic equipment, aminimum of two test pieces are to be brazed,one in a vertical position and one in a horizontal position, as shown inFIGURE 3.1 or FIGURE 3.2.

b. A successful qualification test using pipe of wall thickness t will qualify theequipment for brazing pipes with a range of wall thicknesses defined inTABLE 3.2.

3.11 Requirements for Qualification Tests

a. These requirements are to be read in conjunction with Section 4. In addition tothe requirements described below, the requirements of Section 4. are to be met,omitting any requirement of Section 4. which is not compatible with therequirements of this section.

b. Repair of test pieces is not permitted.

c. Supplementary face feeding and filleting are not permitted in qualification testsusing automatic brazing systems unless face feeding would always be possibleunder production conditions.

d. In qualification tests for manual brazing using fittings with alloy insert rings,supplementary face feeding and filleting are permitted only after an inspectionof the joint has shown that the braze resulting from the melting of the insertrings meets the appropriate acceptance standards in Section 6.

NES 743Part 5


3.7

Notes:

1. H is to be not less than 150mm. It is necessary to check that the dimension H issufficient for any tensile tests required.

2. Test pieces to be fixed to prevent rotation.

FIGURE 3.1 QUALIFICATION TEST PIECES


3.8

Notes:


2. To be read in conjunction with FIGURE 3.1.

FIGURE 3.2 QUALIFICATION TEST ARRANGEMENTS FOR RESTRICTED ACCESS

NES 743Part 5


3.9

3.12 Examination of Completed Test Pieces

a. After brazing, the test piece is to be heat treated, if required, in accordance withAnnex E. as specified in the brazing procedure and then examined as laid downbelow.

b. Examinations are to be carried out as required in Section 5. under Inspectionof Qualification Test Pieces. Inspection and testing are to be fully detailed in thequalification brazing procedure or in associated procedures called up in thebrazing procedure.


3.10

NES 743Part 5


4.1

4. BRAZING REQUIREMENTS

4.1 General

a. Whenever practicable, brazing is to be carried out in the workshop.

4.2 Brazing Processes

a. Brazing may be carried out by one of the following processes:

(1) Manual torch brazing;

(2) Mechanical torch brazing.

b. Approval is required for the use of any other process.

4.3 Fittings

a. The following types of fitting may be used:

(1) Socket and sleeve types as shown in FIGURE 2.1 and FIGURE 2.2;

(2) Flange types as shown in FIGURE 2.3.

b. All brazed fittings other than flange types are to be designed for use withpre-inserted alloy rings unless otherwise specified on the drawing.

c. Fittings designed for face feeding are not to be modified to take insert rings.

4.4 Brazing Alloys and Fluxes

a. The brazing alloy and flux, where not specified on the drawing, are to be selectedfrom the approved materials listed in Annex D. as suitable for use with the pipeand fitting material combination.

Note: The fluxes listed have a limited life at brazing temperature. When a jointis heated above 600 C the effective working life of the listed fluxes is about25 minutes.

4.5 Preparation of Fittings

a. Before brazing, wrought fittings are to be annealed and cast fittings are to bestress relieved. Fittings are normally purchased annealed or stress relieved, asappropriate. Should the certification not cover this (see Section 5.) the fittingsare to be heat treated as laid down in Annex E.

b. If a suitable certificate of ultrasonic examination is not supplied with any fittingfor use with pipe of 12mm OD or larger, (see Clauses 5.2.1a.5.2.1c.), anultrasonic examination is to be carried out before brazing, as laid down inSection 5.

c. In order to permit satisfactory ultrasonic examination, the outer surface of thefitting is to be smooth and uniform. If the outer surface is not suitable, thefitting is to be rejected unless a concession and repair procedure has beenapproved to allow machining of the fitting.

d. If fittings are to be plated before brazing, carry out the plating as laid down inthe Brazing Procedure and in Annex G.


4.2

4.6 Preparation of Pipes

4.6.1 Cutting

a. Pipe ends are to be square, free from burrs, parallel and within specifieddimensional limits before expansion. Care is required when cutting to avoidreducing the pipe wall thickness and forming a taper on the end of the pipe.

4.6.2 Sizing

a. Pipe ends are to be cylindrical andmay be enlarged, using suitable parallel pipeexpanders, to eliminate ovality and obtain the required clearances.

b. Pipe ends are to be sized to provide a joint clearance that will promote capillaryflow of the molten brazing alloy in the gap between the pipe and fitting at thebrazing temperature.

4.6.3 Clearances

a. The clearances required at the brazing temperature vary from alloy to alloy.This variation and the variation in melting temperatures between differentalloys need to be taken into account when calculating the cold clearances to givethe correct clearances at the brazing temperatures. It is also necessary to allowfor any differential expansion between pipe and fitting.

b. Clearances required at brazing temperatures are normally recommended by themanufacturers of the alloys. Recommended cold clearances are listed inAnnexes F. and G. Clearances for combinations and sizes not listed in theseAnnexes are to be proved by qualifying the proposed brazing procedure as laiddown in Section 3.

Note: Radial clearances are quoted in the tables in Annexes F. and G., whereaschecking is normally and most easily carried out by measuring thediametrical clearance with feeler gauges when the fitting and pipe are incontact diametrically opposite the point at which the measurement istaken.

c. The maximum diametrical enlargement of pipes resulting from the use of pipeexpanders or other devices is not to exceed 0.5mm for pipes up to 50mm OD or1% of the diameter for pipes over 50mm OD.

d. Pipes with tapered ends may be used only if the taper is insufficient to cause theclearances to be outside the specified limits anywhere along the faying surfaces.To check for taper, the pipe may be inserted about 3mm into the fitting and theclearance measured with feeler gauges, followed by a second measurement withthe pipe fully inserted.

e. Where clearances are excessive, brazing alloy may still enter the jointadequately due to gravity provided that the joint orientation is suitable. Suchjoints are uneconomic, the joint strength is usually lower than that of a similarcapillary fed joint and they are to be avoided. If, nevertheless, a gravity fedbrazed joint is proposed, it is to be qualified, together with the proposed brazingprocedure, as laid down in Section 3.

NES 743Part 5


4.3

4.7 Cleaning

a. Before brazing, the faying surface, the end face and the insert ring groove of thefitting, the brazing ring if used, the outside of the pipe and the end of the pipeare to be cleaned to bright metal. The end of the pipe is to be cleaned over alength equal to not less than twice the maximum depth of insertion of the pipeinto the fitting to allow for filleting and to avoid unnecessary degradation of theflux. The insert ring, if fitted, is to be removed to facilitate cleaning of ring andgroove. Any brazing rods to be used for face feeding are also to be similarlycleaned.

b. Cleaning will generally involve the following processes although somecommercial cleaning solutionsmay provide satisfactory cleaning in one process:

(1) Degrease with acetone, alcohol or other approved degreasing agent;

(2) On fittings which are not copper plated for brazing, remove scale, oxidesand other firmly adhering contaminants by the use of abrasive cloth,stainless steel wire brushes or stainless steel wire wool. Cleaning of copperplated fittings is limited to (1) and (3);

(3) Finally wipe clean with lint-free wipers soaked in degreasing agent ordamped with water.

Note: Cleaned surfaces are not to be touched with bare hands and are not to beallowed to come into contact with the skin or any other source ofcontamination. Natural body oils and acids transferred during contactwith the skin will seriously affect the quality of the brazed joint.

4.8 Fluxing

a. After cleaning, the faying surfaces are to be fluxed before brazing. If the surfacesare not fluxed within eight hours of cleaning, they are to be recleaned as laiddown above before fluxing.

b. Brazing flux is to be applied evenly to the faying surfaces in the form of a smoothstiff paste. If the joints are not assembled immediately, the fluxed surfaces areto be protected so that the flux is neither contaminated nor inadvertentlyremoved. If the flux dries before the joint is assembled, the old flux is to beremoved and fresh flux applied.

c. If the joint is in a system or at a location where soaking and flushing cannot beused to clean the joint after brazing, only sufficient flux to make a proper jointis to be applied. The flux is to be applied evenly to the faying surfaces not morethan five minutes before the joint is due to be assembled. Non-faying surfacesare to be wiped clean either before or after assembly, depending on accessibility.Excess flux is to be removed. During brazing a nitrogen purge is required asdescribed later.


4.4

4.9 Assembly

a. To facilitate assembly and inspection, where the inside of a joint will not beaccessible after brazing, a reference mark is to bemade on the outside of the pipeat a distance of 2L+10mm, say, from the end to be brazed, where L is the socketdepth or half of the sleeve length as shown in FIGURE 2.1 and FIGURE 2.2.(The figure of 10mm is only a suggestion and may be altered if required). Thedistance from the end of the pipe to the reference mark is to be measured andrecorded. The reference mark is to be located so that it is clearly visible afterbrazing and may be used for measurement on final inspection. The method ofmarking is to be such that the mark will not act as a stress raiser. In cases wherethe pipe bends too close to the joint to allow the mark to be located as suggestedabove, it may be located closer to the joint provided that it meets all of the otherrequirements.

b. When assembling a socket-type joint, the pipe end is to be inserted into thesocket so that nowhere does the distance between the end of the pipe and thebottom of the socket exceed the limits laid down in FIGURE 2.1.

c. The radial clearance between the pipe and socket is to be within the limits laiddown in Annex F. and G., or in an approved brazing procedure.

d. When assembling a sleeve-type joint, the pipe ends are to be inserted into thesleeve so that:

(1) the pipes are located within the limits laid down in FIGURE 2.2;

(2) nowhere does the distance between the ends of the pipes inside the sleeveexceed the limits laid down in FIGURE 2.2.

e. The radial clearance between each pipe and the sleeve is to be within the limitslaid down in Annex F. and G., or in the approved brazing procedure to be used.

f. Before brazing, the pipe supports are to be checked to ensure that they areadequate and sufficiently flexible to accommodate the expansion andcontraction resulting from the heating and cooling. Supports which are too rigidcan impose excessive stresses on the pipes and joint during the brazing cycle.

4.10 Brazing of Valves

a. Before brazing connection to valves, the valves are to be dismantled if possibleand all separable parts removed, particularly soft seats, packings, seals etc,which are easily damaged by heat. Non-removable items, (eg fixed valve seats,seat housings, integral threads etc) are to be protected from oxidation byapplying a film of flux or other protective medium.

b. Valves which are to be brazed while still assembled are to be kept as cool aspossible, particularly the bonnets. Before brazing, the valve is to be fully openedand then closed by a quarter of a turn. Gaskets, O rings, seals and packingswhich could be damaged by the heat are to be removed. Controlled heating andcooling techniques are to beused. Proprietary heat protective paste is to beused.

NES 743Part 5


4.5

4.11 Nitrogen Purge

a. If the joint to be brazed is in a system or at a location where soaking and flushingcannot be used to clean the joint after brazing, a nitrogen supply is to beconnected to one end of the system and sufficient nitrogen blown through thesystem to remove all the air. After the initial purge has removed the air, thenitrogen flow is to be reduced until the nitrogen emerging from the dischargeend can just be felt with the palm of the hand. The purge is to be maintainedduring brazing and until the joint has cooled below 120 C. When the purge isremoved the ends of the system are to be sealed to maintain an inertatmosphere.

4.12 Tacking

a. Tacking of joints is permitted only with specific approval of the QAR for eachapplication. If tacking is to be used, the brazing alloy used is to be the same asthat in the insert ring or that to be used in final assembly of face fed joints.Tacking is to be limited to the minimum required to maintain alignment. Nomore than 4 tacks are to be used, evenly distributed around the joint. Heatingis to be uniform to reduce the possibility of cracking.

4.13 Heating

a. Brazing torches are to be oxy-fuel gas types. The sulphur content of any fuel gasused is not to exceed 0.009 gram per cubic metre. The flame is not to be applieddirectly to the brazing alloy or flux. Only the outer envelope of the flame is tobe applied. The inner cone of the flame is not to come into contact with theassembly. The torch is to have sufficient capacity and the flame is to be adjustedto neutral or slightly reducing.

b. Overheating is to be avoided. Fittings of gunmetal and phosphor bronze inparticular are not to be heated above 800 C. Heating and cooling rates are tobe controlled to prevent cracking.

c. Temperatures may be measured with contact thermometers, or opticalpyro-meters.

d. Heat input is to be carefully controlled to ensure even distribution of heataround the joint.

e. Before brazing, large, thick walled fittings are to be preheated by raising thetemperature slowly anduniformly to 500 C inorder tominimize thermal shock.

f. The temperature of the assembled pipes and fitting is to be raised uniformly tothe brazing temperature to optimize the capillary flow of the molten brazingalloy.

4.14 Priming

a. Priming with flux of pre-inserted alloy joints is permitted, provided that allother requirements have been met. Priming with brazing alloy is NOTpermitted, as it will prevent any check of the brazing alloy flow round the jointcircumference.

4.15 Face Feeding

a. When the initial flow of the brazing alloy from the insert ring has been checkedby the Inspector it is recommended that the joint should be face fed, while stillhot, to complete the joint, make up for any recession of the brazing metal oncooling and ensure that a small circumferential fillet of alloy is present whenthe joint has cooled.


4.6

Note: Large fillets are unnecessarily expensive and do not increase the jointstrength.

4.16 Cooling

a. After completion of the joint, the assembly is to be allowed to cool in still air.

4.17 Marking of Joints

a. Where required, completed joints are to be marked to identify the brazer.

4.18 Heat Treatment after Brazing

a. Some materials are to be heat treated after brazing. These materials and theheat treatment required are listed in Annex E.

4.19 Cleaning after Brazing

a. After cooling, all accessible surfaces are to be cleaned to remove scale and fluxresidues. Internal surfaces are to be soaked for a minimum period of 12 hoursin cold water, or for two hours in hot water (at least 60 C). Subject to theapproval, some material combinations may be cleaned by soaking in hot toboiling caustic soda solution (10% by weight) for at least one hour. For thestandard of cleanliness required for particular systems in submarines seeNES 341.

b. Brazed joints made in situ are to be cleaned with water. The system is to besoaked for a period of at least twelve hours, and flushed in accordance with therequirements for that system. Where soaking and flushing is not permitted ina particular system, a nitrogen purge is used for brazing and the system is to befilled with nitrogen and sealed as Clause 4.11a.

4.20 Examination of Brazed Joints

a. After completion of the brazing, the newly brazed joints, together with anyother brazed joints within 75mm of a new joint are to be examined as laid downin Section 5. and are to meet the acceptance standards for brazed joints inSection 6.

4.21 Repair of Joints

4.21.1 General

a. Unless otherwise approved by the QAR, the brazing alloy used for repairs is tobe the same as that originally used in brazing the joint.

b. Before starting any repair, the end face of the fitting adjacent to the fayingsurfaces and the adjacent pipe surface are to be cleaned to bright metal andfluxed as laid down in Clauses 4.7a.4.8c.

c. Repairs are not permitted if the joints have been exposed to fluids other than:

(1) clean water;

(2) approved cleaning solutions;

(3) nitrogen;

(4) pure refrigerant.

If the joint has been exposed to refrigerant which cannot be guaranteed pure,the joint is not to be repaired.

NES 743Part 5


4.7

4.21.2 Repair Techniques

a. Repairs to improve the percentage bond, repair leaks, or to correct thealignment may be carried out by reheating the joint until the brazing alloymelts, rotating the fitting or pipe if required, followed by addition of flux, facefeeding of alloy and filleting as required.

b. No more than two attempts at repair are permitted on any one joint.

4.21.3 Examination

a. After completion of the repairs, all brazed joints within 75mm of a repair,together with the repaired joints, are to be examined as laid down in Section 5.and are to meet the acceptance standards in Section 6.

4.21.4 Recording of Repairs

a. Each repair attempt is to be recorded, either bymarking up the ships drawingsor by marking the fitting in accordance with the Contract Documents.

b. Where required, repaired joints may be marked also to identify the brazercarrying out the repair. The method of marking is to be in accordance with theContract Documents.

4.21.5 Heat Treatment of Repairs

a. Some materials are to be heat treated after repair. These materials and the heattreatment required are listed in Annex E.

4.22 Reuse of Fittings

a. Fittings may be reused, provided that the fittings are examined as laid down inSection 5. and meet the acceptance standards in Section 6.

b. If necessary the faying surfaces of the fitting and any insert ring grooves maybe machined, provided that the dimensions of the fitting after machining arestill within the specific limits. Hand grinding is not permitted.

c. Reference marks used for previous ultrasonic examinations need not beremoved.

d. Brazing procedures for joints made with reused fittings are to be the same asfor joints made with new fittings but, if required, insert rings may be slightlyrounded on the outer corners to fit the insert grooves.

e. Reused fittings are to be marked or records kept to show that they have beenre-used. Where the location and reuse of the fitting is to be recorded on the shipsdrawings, provided that the number of previous heatings is also recorded,marking of the fitting may be omitted.

4.23 Reuse of Pipe

a. Pipes of materials other than 70/30 CopperNickel (Cu Ni), 90/10 Cu Ni andAluminium NickelSilicon brass (AlNiSi brass) may be reused withoutformal inspection unless otherwise specified.

b. Pipes of 70/30 Cu Ni, 90/10 Cu Ni and AlNiSi brass are to be inspected aslaid down in Clause 5.10.2a. and are to meet the acceptance standards inSection 6.

c. Pipes to be reused are to be prepared for reuse as laid down in Clauses4.6.1a.4.8c.

d. Should pipe ends be oversize when the clearances are checked, the pipe ODmaybe reduced with emery paper, used carefully to avoid causing ovality, providedthat the pipe wall is not reduced below the specified minimum thickness.


4.8

NES 743Part 5


5.1

5. INSPECTION AND TEST REQUIREMENTS

5.1 General

a. Inspections are to be carried out in accordance with NES 729.

b. The extent of examination and testing required on any brazed system is to berelated to the level of the system. The level of each system or part of a systemis to be stated in the contract or on the relevant drawing which will specify alsothe required examinations and acceptance standards. The various system levelsare defined in Annex B.

c. Crack detection is to be carried out using dye penetrant examinationtechniques.

d. Dye penetrant and ultrasonic examinations are to be carried out by qualifiedpersonnel using approved equipment and working to approved procedures.

5.2 Pre-Braze Inspections

5.2.1 Joint Components

a. Before brazing, each pipe and fitting is to be inspected to check that:

(1) the materials of the pipe and fitting are as required by the drawing andthe approved brazing procedure;

(2) the fittings have been correctly heat treated as laid down in Annex E.;

(3) fittings for 12mm OD pipe and over are suitable for ultrasonicexamination after brazing and have been ultrasonically examined asrequired by Section 4. and as laid down later in this Section;

(4) the distance from the end of each pipe to the reference mark, if required,has been accurately measured and recorded;

(5) when pipe and fitting are assembled, the joint clearances are within thelimits laid down in Annexes F. and G., the drawing or approved brazingprocedure for the materials and alloy combination being used.

b. The faying surfaces of each pipe plus an adjacent pipe length of at least 10mmare to be examined using dye penetrant. The surfaces are tomeet the acceptancestandards in Section 6.

c. The brazing alloy is to be checked to ensure that it meets the requirements ofthe drawing and the brazing procedure.

5.3 Ultrasonic Examination of Fittings before Brazing

5.3.1 General

a. Ultrasonic examination of brazed joints using external fittings is practicableonly when pipes are 12mm OD or over and used with fittings of wall thickness1.5mm or over. When internal fittings are to be used, the fitting is to be 12mmOD or over and the pipe wall is to be 1.5mm or over. The following clauses arewritten to cover external fittings.Where internal fittings are to beused, the pipewall is to be examined before brazing instead of the fitting. The procedure isidentical.

b. In order to obtain reliable results from ultrasonic examinations of brazed jointsit is necessary to carry out an ultrasonic examination of each fitting beforebrazing, in order to locate and record sub-surface defects which could interferewith ultrasonic examinations after brazing.


5.2

5.3.2 Setting Up

a. The ultrasonic equipment is to be calibrated and qualified as laid down inNES 729.

b. Probes are to be combined double compressional wave of test frequency 5MHz.Where the material of the fitting has a high attenuation factor, probefrequencies down to 2.5MHz may be used. Full probe details are to be includedin the ultrasonic examination report.

c. Focussed probes are to be preferred where material thickness permits.

d. All examinations are to be made using a couplant whose film integrity is to bemaintained at all times.

e. The reject control is to be adjusted to the minimum setting consistent with aclean trace.

5.3.3 Search Sensitivity

a. The examination is to be carried out with the attenuator set to give 100% fullscale deflection (FSD) for the first back wall echo (BWE).

5.3.4 Examination

a. The search scan is to be along parallel lines separated by not more than 90% ofthe diameter of the probe crystal, to ensure complete coverage of the fayingsurfaces.

5.3.5 Assessment

a. Any fitting containing defects which would interfere with the ultrasonicexamination of the joint after brazing is unacceptable and is to be rejected.

5.3.6 Report

a. The ultrasonic examination report is to be included with the paperwork for thefitting and form part of the certification.

5.3.7 Gas

a. The certification of the gas to be used for torch brazing is to be checked to ensurethat the sulphur content does not exceed the limit laid down in Section 6.

5.3.8 Brazing Procedure

a. The brazing procedure is to be checked to ensure that only approved proceduresare used for production.

5.4 Inspections during Brazing for Joints using Insert Rings

a. After the alloy insert ring has been melted and capillary flow has taken place,the joint is to be inspected before any face feeding is permitted, in order to checkthat adequate capillary flow has occurred. The joint is to meet the acceptancestandards for capillary flow in Section 6.

NES 743Part 5


5.3

5.5 Inspection of Completed Joints

5.5.1 Visual Examination of Brazed Joints

a. After brazing or repair each joint is to be inspected for:

(1) evidence of brazing alloy at the face of the fitting;

(2) correct depth of insertion and correct clearance between the end of eachpipe and the bottom of its socket in socket-type fittings, or between theends of the pipes in sleeve-type fittings;

Note: When the inside of the joint is inaccessible, the insertion depth andclearances can be checked by measuring the distance from the face of thefitting to the reference mark placed on the pipe before assembly;

(3) Correct alignment to drawing.

b. Each joint is to meet the acceptance standards in Section 6. In multi-socketfittings each joint is to be similarly re-examined after completion of the lastbrazing operation on the fitting.

c. After completion or repair of a joint, every other brazed joint within 75mm isto be similarly re-examined.

5.6 Ultrasonic Examination of Brazed Joints

5.6.1 General

a. The extent of ultrasonic examination required is to be stated in the contract ordrawing. When the requirement is not stated, the extent of ultrasonicexaminations is to be as follows:

Level 1 systems 100%;Level 2 systems 100%;Level 3 systems 10% minimum;Level 4 systems Nil.

Where part of a system has a different level from the rest, the two parts are tobe treated as separate systems for the purpose of deciding the extent ofultrasonic examination.

Note: Ultrasonic examination of brazed joints is feasible only when the pipe is12mm OD or over and the wall thickness of the fitting is 1.5mm or over.All fittings for use with pipes of 12mm OD or over are to be suitable forultrasonic examination as laid down in Section 2.

5.6.2 Method, Search Sensitivity and Calibration

a. To be in accordance with NES 729.

b. The average percentage bond is to be calculated for each joint and this is tomeetthe acceptance standards in Section 6.

5.6.3 Examination of Joints with External Hexagonal Configuration

a. Each of the six sides is to be examined and the average percentage bondcalculated. The percentage bond is to meet the acceptance standards forhexagonal fittings in Section 6.

5.6.4 Radiographic Examination of Brazed Joints

a. When radiographic examination of joints is specified in the drawing or contractas a check of fit-up, unless otherwise specified, a minimum of 2% of the jointsare to be radiographed by qualified personnel using approved equipment andworking to an approved procedure.


5.4

5.7 Inspection of Used Fittings Salvaged for Reuse

5.7.1 Inspections before Reuse

a. Each fitting is to be inspected to check that:

(1) sufficient of the old brazing alloy has been removed tomeet the acceptancestandards in Section 6.;

(2) the dimensions meet the acceptance standards in Section 6.;

(3) the fitting has not been heated more than twice before, for brazing orrepairing. If there are no markings on the fitting, the drawings are to bechecked for the information.

b. The fitting is to be inspected using dye penetrant examination and is to meetthe acceptance standards in Section 6.

c. The fitting is also to be fully inspected as laid down earlier in this Section underPre-braze Inspections.

5.7.2 Inspections after Brazing

a. Each reused fitting is to be inspected to check that the fitting has been markedto show the additional brazing operation due to its reuse. Where approval hasbeen obtained to record the reuse on the ships drawings, these are to beinspected to check that the location and reuse have been recorded and that thetotal number of previous reheats is also recorded.

5.8 Inspection of Used Pipe Salvaged for Reuse

5.8.1 Inspections before Reuse

a. Before reuse, the ends of used pipes of 70/30 Cu Ni, 90/10 Cu Ni and AlNiSibrass are to be inspected using dye penetrant examination over a minimumlength P where P is equal to the socket depth plus 50mm. The areas inspectedare to meet the acceptance standards in Clause 6.1a. This inspection may beomitted for pipes of other materials.

5.9 Inspection of Qualification Test Pieces (See Clause 3.12b.)

5.9.1 General

a. Qualification test pieces are to be examined and tested as laid down in Clauses5.9.2a. to 5.11d. and are to meet the acceptance standards for qualification testpieces in Section 6.

5.9.2 Prebraze Inspections

a. Before brazing, qualification test pieces are to be inspected as stated in Clauses5.2.1a.5.2.1c.

5.9.3 Inspections During Brazing for Joints with Insert Rings

a. After the insert ring has melted and capillary flow has taken place, each jointis to be inspected before any face feeding is permitted, in order to check thatadequate capillary flow has occurred.

Notes:

1. Face feeding is not permitted during qualification tests using automaticbrazing on joints with insert rings unless face feeding would always bepossible under production conditions.

2. Repairs to test pieces are not permitted.

NES 743Part 5


5.5

5.9.4 Visual Examination of Completed Test Pieces

a. After completion, qualification test pieces are to be inspected as stated inClause5.5.1a.

5.9.5 Bond Assessment

a. The bond in qualification test pieces is to be assessed either by ultrasonicexamination or by peel tests as laid down in Clauses 5.12a.5.12b. Ultrasonicexaminations are not feasible on pipes below 12mmODand for these pipes, peeltests are to be carried out.

5.10 Ultrasonic Examination

5.10.1 General

a. When ultrasonic examination is specified, every test piece produced for aparticular qualification is to be examined as stated inClauses 5.6.1a. and 5.6.2a.

5.10.2 Peel Tests

a. Peel tests are to be carried out using one of the two methods described below:

(1) Method 1. Mechanical Peel Test:

(a) Peel test specimens are to be as shown in FIGURE 5.1. When thepipe is 51mm OD or larger, the test specimens are to be 40mmwide,measured round the OD of the pipe outside the joint. When the pipeis less than 51mm OD, each test specimen is to be a 90 segment ofthe test piece;

(b) The specimens are to be separated along the line of the brazing alloyby peeling the filling material from the pipe or vice versa. Tofacilitate separation, the test specimen may be heated to 550 C or,after removing the fillet of alloy from the face of the fitting, thespecimen may be cooled with dry ice or liquid nitrogen. The totalarea of defects, unbrazed areas and flux inclusions is to bemeasuredand recorded.

(2) Method 2. Peel Test by Machining.

(a) The fitting is to be parted off just clear of the end of the pipe. Thetest specimen is then to be prepared by machining the OD until thewall of the fitting remaining is 0.2 to 0.3mm thick. Then with thetube set true in a lathe the fittingwall is to be turned down carefully,taking successive cuts of 0.010.05mm. After each cut the surfaceis to be inspected carefully for bubbling of themetal surface causedby separation of the fitting from the brazing alloy or by separationof the brazing alloy from the pipe. All areas of separation are to beplotted on one scale plan, together with areas of flux inclusions andother defects. Continue machining until all of the brazing alloy hasbeen removed;

(b) The total unfused area is to be taken as the sum of the areas plottedon the scale plan, with any overlapping areas counted only once.

b. The percentage bond is to be calculated for each joint as follows:


5.6

(1) Mechanical Peel Test:

For each joint, calculate the total area of faying surface of the fitting in thetwo test specimens (F). Calculate also the total defective area in the twotest specimens (A):

Then percentage bond = FAF 100

The percentage area examined (E) is to be calculated as follows:

E= FTotal area of faying surface of socket

100

(2) Peel Test by Machining:

Calculate the total area of faying surface in the socket (F):

Percentage bond= FAF 100 where A is the total unfused

area determined earlier.

5.11 Additional Tests required only for Qualification of Procedures

a. For qualification of procedures, two tensile tests are to be carried out on testspecimens from both the horizontal and vertical brazing positions (four tests inall).

b. Tensile test specimens are to be full section as shown in FIGURE 5.2 when thePipe is less than 75mm OD. When the pipe is 75mm OD or larger, reducedsection tensile test specimens are to be prepared as shown in FIGURE 5.1.

c. The load at failure and the location of the break are to be recorded for eachtensile test.

d. The extent of the qualification obtained bya test is to be as shown inTABLE 3.2.

5.12 Hydraulic Testing

a. Hydraulic testing of brazed pipe systems is to be carried out in accordance withpressures given in the relevant systemNaval Engineering Standard or ContractDocuments.

b. All leaks are to be repaired.

NES 743Part 5


5.7

Notes:


2. For test pieces brazed in the horizontal position, AA is to be the horizontal axis.

3. For pipes below 51 OD, peel test specimens are to be 90 segments.

4. For pipes over 75OD, all test specimens for one brazing position may be taken fromthe same joint, provided that the specimens are taken from the correct positionsas shown.

FIGURE 5.1 MECHANICAL PEEL TEST SPECIMENS AND REDUCED SECTION TENSILETEST SPECIMENS


5.8

FIGURE 5.2 FULL SECTION TENSILE TEST

NES 743Part 5


6.1

6. ACCEPTANCE STANDARDS FOR BRAZED PIPE JOINTS

6.1 Faying Surfaces of Pipes

a. All faying surfaces and adjacent areas of pipe are to be inspected using dyepenetrant and are to be free from cracks, linear defects and similar faults.

6.2 Faces of Joints using Insert RingsBefore Face Feeding

a. Capillary flow of alloy from themelted insert ring is acceptable when, before anyface feeding of alloy has taken place, alloy can be seen at the face of the fitting,extending round at least 75% of the circumference of the joint.

6.3 Faces of Joints after Face Feeding

a. The joint face is acceptable when a small fillet of alloy is visible round the wholeof the circumference of the joint.

6.4 Joint Geometry

a. In joints using socket-type fittings, the depth of insertion of each pipe into itssocket is to be such that the clearance between the end of the pipe and thebottom of the socket does not exceed the limit specified in the drawing or inFIGURE 2.1.

b. In a joint using sleeve-type fittings, the depth of insertion of each pipe into thesleeve and the clearance between the end of the pipes are to be within the limitsspecified in the drawing or in FIGURE 2.1 and FIGURE 2.2.

c. The alignment of the pipes and joints is to be as shown on the drawing.

6.5 Ultrasonic Examination of Brazed Joints

6.5.1 General Fittings

a. The average bond of new joints is not to be less than50%. Jointswhich have beenin service and on inspection are found to have an average bond of 40% orgreater are acceptable for further service. For Nuclear Submarines refer toDPT1306 Specification.

6.5.2 Special Fittings

a. TABLE 6.1 acceptance standardsmay be used for fittingswhich are not suitablefor full ultrasonic examination of the faying surfaces and for the use of whichspecial approval has been obtained from the QAR.

b. Fittings with cylindrical exterior surfaces which are too small to allowexamination of all of the faying surfaces are to meet the acceptance levels inTABLE 6.1. Where the area available for examination lies between the valuesquoted in the table, use the lower area figure in the table (which will require ahigher acceptance standard).

Percentages of faying surfacesexamined

Acceptable % Bond

50 80

60 75

70 70

80 65

90 55

100 50

TABLE 6.1 BOND ACCEPTANCE STANDARDS


6.2

c. For fittings with hexagonal exterior surfaces the average bond for the joint isto be not less than 80%.

6.6 Fittings Salvaged for Reuse

6.6.1 Visual Examination

a. The fittings are to be clean and free from brazing alloy except that traces of alloyremaining in the corners of the insert ring groove may be allowed to remain.

b. The dimensions of the fitting are to be within the limits laid down in thedrawings except that a small increase in the interior diameter of the fayingsurfaces is acceptable provided that it does not require an unacceptable degreeof enlargement of the pipe to provide the correct clearances for brazing (seeSection 4.) The radius of the internal corners of the insert ring groove is to benot less than 0.4mm.

6.6.2 Dye Penetrant Examination

a. The fitting is to be free from cracks, linear defects and similar faults.

6.7 Pipe Salvaged for Reuse

a. The pipe ends and adjacent areas are to be free from cracks, linear defects andsimilar faults.

6.8 Qualification Test Pieces

6.8.1 Faces of Joints using Insert Rings, before Face Feeding

a. Capillary flow of alloy from themelted insert ring is acceptable when, before anyface feeding of alloy has taken place, alloy can be seen at the face of the fitting,extending round at least 75% of the circumference of the joint and any gap inthe brazing alloy around the circumference is less than 10% of thecircumference.

6.8.2 Ultrasonic Examination

a. The average percentage bond for any joint is to be not less than70%. ForNuclearSubmarines refer to DPT 1306 Specification.

6.8.3 Peel Tests

a. When mechanical peel tests are used the percentage bond for any joint is to benot less than stated in TABLE 6.2. Where the percentage area examined fallsbetween the figures listed in the table, use the acceptance standard for the nextlower figure of percentage area examined.

Percentage Area Examined Minimum Average Bondg%

g%

50 80

40 90

30 or less 100

TABLE 6.2 MINIMUM ACCEPTANCE STANDARDS FOR PERCENTAGE BOND INPEEL TESTS

b. When peel tests are carried out bymachining, the percentage bond for any jointis to be not less than 70%.

NES 743Part 5


6.3

6.8.4 Tensile Tests

a. If the failure occurs in the brazing alloy, the stress in the pipe at failure is to benot less than the minimum ultimate tensile stress for the annealed pipe.

b. If the pipe or fitting fractures then the stress in the fractured material at failureis to be not less than 90% of the minimum ultimate tensile stress for annealedmaterial.


6.4

NES 743Part 5


A.1 ANNEX A.

ANNEX A.

RELATED DOCUMENTS

A.1 Reference is made to:

Referred to inClause, Fig andAnnex

BS 499 Welding terms and symbolsPt 1 Glossary for welding, brazing andthermal cutting

Annex B.

BS 1845 Filler metals for brazing Annexes D.and G.

BS 2874 Copper and copper alloys, rods andsections (other than forging stock)

Annex C.

BS 3072 Nickel and nickel alloys: sheet and plate Annex C.

BS 3073 Nickel and nickel alloy: strip Annex C.

BS 3074 Nickel and nickel alloy: seamless tube Annex C.

BS 3075 Nickel and nickel alloy: wire Annex C.

BS 3076 Nickel and nickel alloy: bar Annex C.

NES 341 Requirements for the Cleaning of ItemsComponents and Equipment for FluidSystems

4.19a.

NES 729 Requirements for Non-DestructiveExamination Methods

5.1a., 5.3.2a.,5.6.2a.

NES 749 Requirements forAluminiumNickelSilica BrassPt 3: Tubes

Annex C.,Annex E.

NES 779 Requirements for 90/10 CopperNickelAlloy MaterialPt 3: Tubes

Annex C.,Annex E.

NES 780 Requirements for 70/30 CopperNickelAlloy MaterialPt 3: Tubes

Annex C.,Annex E.

BR 3013 Admiralty Pipework Standard FIGURE 2.3

DPT 1306 Nuclear Submarines Acceptance(Specification Issue 2 1974) Standards forThe Ultrasonic Inspection of BrazedJoints

6.5.1a., 6.8.2a.


A.2ANNEX A.

NES 743Part 5


B.1 ANNEX B.

ANNEX B.

ABBREVIATIONS AND DEFINITIONS

B.1 Brazing nomenclature and definitions are to conform generally to BS 499, Part 1withthe additions below.

B.2 For the purpose of this NES the following additional abbreviations and definitionsapply:

ADQA/IND Assistant Director Quality Assurance/Industry;

Approval Written approval from the QAR or other authorizedMOD local representative acting on behalf of and inconsultation with the Design Authority;

Approved Having written approval;

Brazer An individual who is producing brazed joints;

Brazing Procedure A written instruction containing the essentialinformation for brazing to this standard;

Capillary Flow The phenomenon which causes molten brazing alloy tobe drawn along the gap between the faying surfaces;

Clearance The radial gap between pipe and fitting when locatedconcentrically;

Consumables Brazing alloy and flux;

Design Authority The section within MOD(PE) Sea Systems Controlleratewhich carries overall responsibility for the systemconcerned;

Design Temperature The maximum temperature for which the piping systemis designed, which is not to be exceeded;

External Fitting A fitting designed so that the pipe is inserted into asocket in the fitting and brazed into place;

Face Feeding Manual addition of brazing alloy at the intersection offitting and pipe;

Faying Surfaces Machined surfaces of fitting that will form the capillaryjoint with the pipe;

Filleting Addition of brazing alloy at the intersection of fittingand pipe after the initial brazing operation to ensurethat a fillet of alloy is present around the inter-section;

Fitting A pressure-containing component of a piping systemsuch as a tee, elbow etc or a valve, flange, strainer, sleeveetc;

Insert Rings Rings of brazing alloy for insertion, before assembly ofthe joint, into a groove prepared in the fitting walladjacent to the faying surfaces;

Internal Fitting A fitting designed to be inserted into the pipe bore andbrazed into place;

Level See System Levels;

Organization The Contractor or responsible Authority at the sitewhere brazing to this standard is to be carried out;

Peel Test A destructive test to allow a visual assessment of thebonded area in a joint;


B.2ANNEX B.

Priming Manual addition of a small amount of flux at theintersection of fitting and pipe to help break surfacetension and promote alloy flow from the insert ring;

Qualified Approved as required by this standard;

QAR The MOD local Quality Assurance Representative orother authorized MOD representative usuallyADQA/IND;

Repairing Reheating the joint to melt the brazing alloy in order toseal leaks, improve percentage bond or correctalignment. Includes supplementary face feeding whererequired;

Special Fittings These fittings have an undesirable profile and require analternative U/T examination and % bond acceptancestandard. Examples being hexagon and two land jointswhere only one land joint is accessible;

Supplementary FaceFeeding

Addition of brazing alloy at the intersection of fittingand pipe after the initial brazing operation. Usually usedwith insert rings;

System Levels:Level 1 A system in which failure of brazed joints could lead to

uncontrollable flooding, immobilization of the vessel orserious hazard to personnel;

Level 2 A system in which failure of brazed joints could lead tosevere but controllable flooding, serious disruption ofweapon systems, main propulsion machinery orimportant auxiliaries;

Level 3 A system in which failure of brazed joints does notconstitute an immediate significant hazard;

Level 4 A system in which failure of brazed joints does notconstitute a hazard.

NES 743Part 5

Issue 1

nes 743 pipe manipulation

Documents

reformattedbrazingthe

ministry of defence

pipe manipulationpart

ministry of defencesea

ministryof defence

particular contract

daterevision notethis

historical recordthis