TR3 Jointing of Copper and its alloys Preview

Guide to Good PracticeHeating and JOINTING OF Ventilating COPPER ANDContractors’ ITS ALLOYSAssociation Recommended practice and tests for competency TR3

JOINTING OF COPPER AND ITS ALLOYS TR3ACkNOwLEDGEmENTSMany thanks to the following for their valued input and time: -Nicholas Haykevin SteadJohn Thompsonmark JohnsonAlan keating – SecretaryThis publication has been written in conjunction with the above for the HVCA and has been reviewedby BSRIA, CIBSE, CIPHE, OFTEC, together with the HVCA Technical Committee for their time, input andvetting.The compilers of this publication record their appreciation of the courtesy of the British Standards In-stitution for permitting inclusion herein of extracts from various Standards.A list of the publications in this field can be found in Appendix 3.First Published in 1976 byHEATING AND VENTILATING CONTRACTORS' ASSOCIATION34 Palace Court, London W2 4JGTelephone: 0207 313 4900in conjunction withTHE ASSOCIATION OF PLUmBING & HEATING CONTRACTORS LTD.14 Ensign House, Westwood Way, Coventry, CV4 8JARevised 1990COPYRIGHT ©2010 by the Heating and Ventilating Contractors' AssociationAll rights reservedHeating and Ventilating Contractors' AssociationEsca House 34 Palace CourtLondon W2 4JGTel: 020 7313 4900 Fax: 020 7727 9268e-mail: [email protected]: www.hvca.org.uk X

JOINTING OF COPPER AND ITS ALLOYS TR3ForewordTHIS CODE OF PRACTICE is intended for use by employers and their operatives and by con-sulting engineers and other designers. It is complementary to the Code of Practice TR/5Welding of Carbon Steel Pipework.This publication has been compiled jointly by the Heating and Ventilating Contractors' Associ-ation and the Association of Plumbing & Heating Contractors Ltd (APHC). It is appropriatehere to record appreciation for the very considerable help in the compilation of this publica-tion given by UK Copper Board, the British Association for Brazing and Bronze Welding andthe Institute of Refrigeration.As the requirements and testing procedures set out in this publication are designed for theheating, ventilating, plumbing and refrigeration industries, the publication covers tube with amaximum diameter of 200 mm and wall thickness of 4.5 mm.The publication covers jointing of copper and cupro-nickel for refrigeration purposes, but doesnot cover fusion welding of copper and copper alloys. It deals with:(a) brazing and bronze welding for water, steam-condense and gas pressures up to and including 17.0 bar and/or temperatures from -20°C, up to and including 220°C and(b) refrigeration pipework with pressures of up to 28 bar and temperatures from -40°C up to and including 60°C and(c) soft soldering of copper pipework (see Table A for Working Pressures and Temperatures Appendix 1).The publication generally gives effect to good current practice and is in line with the relevantBritish Standards. (Some of these were undergoing revision when this book was being writ-ten, so care should be taken to consult the current British Standard in each case).The test methods and requirements set out herein are those accepted by the appropriate in-dustries. The composite test piece for copper pipe embodied in Figure 6 has been devised asa logical progression from the individual tests, but with a trend towards brazing. This compos-ite test piece effects a significant economy of material and fuel gases, as compared with thesame tests carried out individually.Attention is drawn to the appendix dealing with safety. The special precautions noted thereinare necessary to avoid danger to health.It has also been thought highly desirable to include an appendix dealing briefly with the cor-rosion of brazing alloys used in the heating, ventilating and plumbing industries. The compo-sition of town water has changed in recent years and this trend, by reason of the increasingincidence of recycling of water, can only continue. 1

JOINTING OF COPPER AND ITS ALLOYS TR3 CONTENTS FOREwORD Page 11 SCOPE Page 62 CONFORmITY wITH LAw AND REGULATIONS Page 6 Contractor is required to give supplier details of any statutory or other regulations relating to the pipe or sheet. Safety precautions are referred to (Appendix 1)3 TERmINOLOGY Page 6 Terms used in the publication are drawn from BS 499: Part 1 and are defined 3.1 Brazing Page 6 3.2 Braze welding Page 6 3.3 Bronze welding Page 6 3.4 Soldering Page 64 PARENT mETAL Page 6 Standards Page 65 FILLER mETALS FOR BRAZING, BRONZE wELDING Page 6 AND SOLDERING 5.1 General British Standards Page 6 5.2 Choice of material Page 7 Silver-copper-phosphorus alloys suitable for general Page 7 use; filler metals with high silver content for corrosive environments 5.3 Compliance with test requirements. Contractor to Page 7 ensure filler metals used make satisfactory joints suitable for the service conditions 5.4 Copper-phosphorus alloys (CP) Function and Page 7 suggested applications 5.5 Silver alloys for brazing (AG) Suitable filler for Page 7 metals and details of composition 5.6 Alloys for bronze welding Function and precautions to Page 8 be taken in use 5.7 Alloys for soldering Page 86 FLUXES AND PURGING Page 8 6.1 Function Purpose defined Page 8 6.2 Fluxes for brazing Procedure described Page 8 6.3 Fluxes for bronze welding Procedure described Page 8 6.4 Fluxes for soldering Page 9 6.5 Purging of refrigerant pipework Page 92

JOINTING OF COPPER AND ITS ALLOYS TR37 JOINTING TECHNIQUES Page 9 7.1 Methods of heating - General Heating methods to be Page 9 used in brazing and bronze welding Page 9 7.2 Methods of heating for brazing Uniformity of heating; heat sources; danger of local over-heating 7.3Methods of heating for bronze welding Oxy-acetylene and Page 9 flame control 7.4 Methods of heating for Soldering Page 108 JOINT DESIGN AND PREPARATION Page 10 8.1 General Page 10 8.2 Use of forming tools Page 10 Joint tolerances; manual forming and special tooling 8.3Joint design for brazing Page 10 8.3.1 Overlap Page 10 8.3.2 Accuracy of fit-up and choice of brazing alloy Page 10 8.3.3 Clearance for brazing alloys Extent of overlap alloys Page 10 importance of good penetration of filler alloy; optimum clearances; forming of joints9 FLANGES Page 10 Details of bi-metal and insert type flanges for brazing10 EXPANSION BENDS 10.1 General Page 10 Guidance in fabrication Page 10 10.2 Thermal expansion Page 10 Coefficients of expansion for copper, cupro-nickel and steel Page 1011 ANCHORS AND GUIDES Page 12 Directions on fabrication and attachment12 TESTING Page 12 12.1 Pressure Tests Page 12 12.1.1 General Page 12 12.1.2 Hydraulic test pressures Page 12 12.1.3 Period of test Page 12 12.1.4 Repair of leaks Page 12 12.1.5 Re-making of joints Page 12 12.1.6 Certification Page 12 12.2 Destructive tests Page 1213 PRESSURE TESTING OF REFRIGERATION PIPEwORk Page 12 3

JOINTING OF COPPER AND ITS ALLOYS TR3 13.1 Pressure tests Page 12 13.1.1 General Page 13 13.1.2 Test pressures Page 13 13.1.3 Duration of test Page 13 13.1.4 Tracer refrigerants Page 13 13.1.5 Leak testing equipment Page 13 13.2 Destructive testing Page 1314 SUPERVISION AND wORkmANSHIP Page 13 14.1 Supervisor Page 13 Competent supervisor to be employed Page 13 14.2 Certificates of Competency Operatives employed on pipework to hold Certificate of Competency 14.3 Staging Page 13 Staging and protection to be provided 14.4 Welding equipment Page 13 Welding equipment to be in safe and sound condition15 HVCA/APHC STANDARD TEST PROCEDURE Page 14 15.1 General Page 14 15.2 Brazing and bronze welding composite test piece-(pipe) Page 14 Specifies four tests for copper pipe Page 14 15.3 Bronze weld for copper sheet Specifies test (for plumbers only) 15.4 Materials to be provided for standard tests Page 14 Lists materials required to carry out standard test on pipe and sheet 15.5 HVCA/APHC standard tests Page 15 Describes detailed procedure for bronze welding and brazing of pipe; and for bronze welding of sheet 15.6 Brazing refrigeration pipework test piece Page 16 15.7 Materials to be provided for refrigeration pipework test piece Page 16 15.8 Test No. 6 refrigeration pipework test piece Page 1616 EXAmINATION OF JOINTS Page 18 16.1 Visual examination Page 18 16.1.1 Brazed joints Page 18 16.1.2 Bronze welded joints Page 18 Specifies visual examination procedure for brazed and or bronze welded joints 16.2 Destructive tests Page 18 16.2.1 Brazed joints Page 18 16.2.2 Bronze welded joints Page 18 Specifies destructive tests for brazed and for bronze welded joints 16.3 Acceptance levels and re-testing Page 184

JOINTING OF COPPER AND ITS ALLOYS TR3 16.3.1 Bronze welded joints (Test Nos. 1 and 2) Page 18 16.3.2 Brazed joints (Test Nos. 3, 4 and 6) Page 18 16.3.3 Re-testing Page 18 Gives procedure for judging acceptability of brazed and bronze welded joints; and for re-testing17 CERTIFICATES OF COmPETENCY Page 19 17.1 General Conditions of issue Page 19 17.2 Validity of Certificates of Competency Specifies conditions Page 19 of validityAPPENDICES Appendix 1 Page 19 Safety in brazing and bronze welding Draws attention to the requirements of the Health & Safety at Work Etc Act 1974, plus sets out briefly the main safety factors to be observed. Appendix 2 Page 20 Corrosion of brazing and bronze welding alloys in the mechanical services industry Describes corrosion hazards to be guarded against and suggests precautions to be taken. Page 22 Appendix 3 Bibliography Lists British Standards and other publications relevant to the brazing and bronze welding of copper pipe and sheet 5