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1、- - - - - - - - - - - - - - - - - BRITISH STANDARD BS 1723-1: 1986 Brazing Part 1: Specification for brazing UDC 621.791.36 BS 1723-1:1986 This British Standard, having been prepared under the direction of the Welding Standards Committee, was published under the authority of the Board of BSI and com
2、es into effect on 28 February 1986 BSI 02-1999 First published, as BS 1723, March 1951 First revision March 1963 First published, as BS 1723-1, February 1986 The following BSI references relate to the work on this standard: Committee reference WEE/19 Draft for comment 84/77328 DC ISBN 0 580 14772 X
3、Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Welding Standards Committee (WEE/-) to Technical Committee WEE/19 upon which the following bodies were represented: BNF Metals Technology Centre British Association for Brazing and Solderin
4、g British Non-Ferrous Metals Federation Electricity Supply Industry in England and Wales Heating and Ventilating Contractors Association Joint Industry Board for Plumbing Mechanical Engineering Services in England and Wales Ministry of Defence Plumbing Trades Union Society of British Aerospace Compa
5、nies Limited Welding Institute Coopted member Amendments issued since publication Amd. No.Date of issueComments BS 1723-1:1986 BSI 02-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope 1 2Definitions1 3Information and requirements to be agreed and to be documented1 4Paren
6、t materials 2 5Processes2 6Brazing consumables2 7Joint design2 8Joint preparation3 9Jigging3 10Brazing procedure approval3 11Quality control3 12Testing procedure3 13Acceptance criteria3 14Requirements specific to the method of brazing4 Publications referred toInside back cover BS 1723-1:1986 ii BSI
7、02-1999 Foreword This Part of BS 1723 has been prepared under the direction of the Welding Standards Committee and supersedes BS 1723:1963 which is withdrawn. BS 1723 was originally published as one standard but this revision has been divided into four Parts as follows: Part 1: Specification for bra
8、zing; Part 2: Guide to brazing; Part 3: Destructive testing and non-destructive evaluation (in preparation); Part 4: Procedure and operator approval (in preparation). This format has allowed the aspects covered in the guide (see BS 1723-2) to be widened and approvals (both procedure and operator) an
9、d methods of testing are included for the first time. This is the first revision in which metric units have been used throughout. It has been assumed in the drafting of this British Standard that the execution of its provisions is entrusted to appropriately qualified and experienced people. A Britis
10、h Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front
11、cover, an inside front cover, pages i and ii, pages 1 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. BS 1723-1:1986 BSI 02-19991 1 Scop
12、e This Part of BS 1723 specifies requirements for the brazing of joints between any parent materials that are capable of being brazed by one of the processes listed in clause 5. In addition to the definitive requirements given, it also requires the items detailed in clause 3 to be documented. For co
13、mpliance with this standard, both the definitive requirements and the separately documented requirements have to be satisfied. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purpose of this British Standard the definitions g
14、iven in BS 499-1 apply together with the following. 2.1 brazing filler metal the metal added during brazing (or pre-applied during preparation) which is to flow between the faying surfaces (see 2.2) and complete the joint 2.2 faying surfaces1) the surfaces that are to be joined in an assembly 2.3 fi
15、llet1) the meniscus formed by the brazing filler metal at a joint edge 2.4 witness evidence of brazing filler metal flow as seen at a joint edge remote from the point of application 2.5 continuous fillet a fillet with no breaks or pores visible at low magnification (up to 5) 2.6 partial fillet a fil
16、let with pores or discontinuities NOTEA specification may limit the maximum length of any allowable discontinuity or pore, individually or in total. 2.7 percentage fill the percentage of nominal joint that is filled with brazing filler metal as judged by an agreed non-destructive test method NOTESee
17、 BS 1723-32). 2.8 lap joint1) overlapping faying surfaces 2.9 butt joint1) abutting faying surfaces 2.10 preform brazing filler metal fabricated into a suitable shape for pre-placement NOTEWire, foil, plastic bonded sheet and adhesive tape are suitable for manufacturing preforms. 2.11 loading groove
18、 (pre-placement groove) a formed groove to locate pre-placed brazing filler metal 2.12 brazing gap the separation between faying surfaces at the brazing temperature 2.13 fit-up the clearance between the faying surfaces at the assembly temperature. This becomes the brazing gap at the brazing temperat
19、ure 2.14 parent material the material(s) to be joined NOTEThe expression “base metal” is to be avoided because of danger of misconception when noble metal brazing filler metals are used. 2.15 liquation the selective separation at slow heating rates of low melting temperature filler metal phases 3 In
20、formation and requirements to be agreed and to be documented 3.1 Information to be supplied by the purchaser The following information to be supplied by the purchaser shall be fully documented. Both the definitive requirements specified throughout the standard and the documented items shall be satis
21、fied before a claim of compliance with the standard can be made and verified. a) The application standards to be used, if any, together with any supplementary requirements. b) Specification of the parent material. 1) This definition differs from that given in BS 499-1. 2) In preparation. BS 1723-1:1
22、986 2 BSI 02-1999 c) Types of test to be carried out on brazing filler metal. d) Whether a written brazing procedure is required (see clause 10). e) Types of tests to be carried out on brazed joints (see clause 12). 3.2 Requirements to be agreed The following items to be agreed between the contracti
23、ng parties, which are specified in the clauses referred to, shall be fully documented. Both the definitive requirements specified throughout the standard and the following documented items shall be satisfied before a claim of compliance with the standard can be made and verified. a) The brazing proc
24、ess to be used (see clause 5). b) The brazing filler metal to be used in the absence of a relevant application standard see 6.1 c). c) The joint design if it is not specified in a relevant application standard see clause 7 c). d) The brazed joint category, destructive and non-destructive tests and a
25、cceptance criteria (see clause 13). 4 Parent materials Parent materials shall be capable of being brazed see also 3.1 b). NOTEGuidance on the brazeability of parent materials using different brazing processes is given in BS 1723-2. 5 Processes The brazing process shall be one or more of the followin
26、g as agreed between the contracting parties: hand torch brazing mechanical flame brazing induction brazing resistance brazing furnace brazing (including protective atmosphere, vacuum and open furnace) immersion brazing infra-red brazing electron beam brazing laser brazing 6 Brazing consumables 6.1 F
27、iller metal The composition of the brazing filler metal shall: a) be in accordance with the relevant application standard; or b) comply with BS 1845; or c) be selected by agreement between the contracting parties in the absence of an application standard. NOTEGuidance on the selection of filler meta
28、ls is given in BS 1723-2. BS 1845 covers the following groups of filler metals: BS 1845 also covers particular requirements of filler metals for vacuum applications. Some filler metals are available in one specific form only, and this should be ascertained when joint design is considered. The availa
29、ble forms are wire, shim, strip, foil, powder, paste, clad sheet, preforms and deposited coatings. General information on the melting ranges of these types of filler metal is given in BS 1845. The minimum volume of brazing filler metal applied shall be 25 % in excess of that required to fill the wid
30、est gap possible with the permitted component tolerances. When using a composite filler material due allowance shall be made for the presence of a flux or a binding agent. 6.2 Flux NOTEFluxes may be gaseous, liquid, paste or powder in form. 6.2.1 Where a flux is used to assist in making a joint it s
31、hall be in accordance with the recommendations of the supplier of the filler metal. Special care shall be taken with fluxes, as many are corrosive and hygroscopic. NOTEThey should be stored according to the manufacturers recommendations. 6.2.2 Where a flux has been used, any active residue shall be
32、removed by chemical or mechanical means. NOTEGuidance on flux removal is given in BS 1723-2. 7 Joint design Joint designs shall be one of the following: a) in accordance with the relevant application standard; b) in accordance with the guidance given in BS 1723-2; or c) by agreement between the cont
33、racting parties, in the absence of an application standard. The fit-up of the parts to be joined shall lie between that which will permit adequate penetration by the molten brazing filler metal and that which will adequately retain it. NOTEThe fit-up will depend upon the parent material(s), the fill
34、er metal used, the brazing process to be applied and the properties required of the finished assembly. It is impracticable in this standard to specify limits of clearance to cover every case. Guidance is given in Table 2 of BS 1723-2:1986. Group ALAluminium brazing filler metals Group AGSilver brazi
35、ng filler metals Group CPCopper-phosphorus brazing filler metals Group CUCopper brazing filler metals Group CZCopper-zinc brazing filler metals Group HTNNickel and cobalt brazing filler metals Group PDPalladium bearing brazing filler metals Group AUGold bearing brazing filler metals BS 1723-1:1986 B
36、SI 02-19993 8 Joint preparation To ensure satisfactory brazing, all components shall be properly fitted and the faying surfaces shall be clean immediately prior to brazing. All surface scale, oxides, grease, oil, cleaning fluid and dirt shall be removed either by chemical or mechanical means which d
37、o not of themselves leave a residue. Cleaned parts shall not be contaminated during storage, assembly or application of the brazing filler metal. The shelf life of a cleaned part shall be determined and adequate controls established to provide re-cleaning when it is exceeded. When stopping-off agent
38、s are used to contain the flow of filler metal within the joint area the stopping-off agent shall be prevented from encroaching on the faying surfaces. Where pre-placed filler metal is not visible after assembly, verification of placement shall be made. Storage and handling of assembled components s
39、hall not affect filler metal placement or component alignment. 9 Jigging If used, jigs shall maintain the required brazing gap and shall not cause distortion during the heating or cooling cycle. NOTEThe thermal capacity of the jig should be taken into account when considering the method and rate of
40、heating. Recommendations on jigging are given in BS 1723-2. 10 Brazing procedure approval3) When a written brazing procedure is required it shall contain such of the following items as are appropriate: a) company identification; b) brazing procedure serial number; c) method of brazing; d) parent mat
41、erials specification; e) filler metal specification; f) flux; g) cleaning and preparation; h) fit-up (drawing/detail) and component tolerances; i) jigging; j) brazing cycle; k) post-brazing treatment (flux removal, heat treatment, etc.); l) any special features; m) testing procedures; n) quality con
42、trol procedures. 11 Quality control4) The manufacturer shall have a quality control system to ensure that all brazed joints supplied satisfy the requirements of this Part of BS 1723. The system shall be documented and provide for the ready detection of discrepancies and for timely and positive corre
43、ctive action. The system shall provide records such that the identification number of each batch shall provide references to the manufacturers own documented records. Tests and inspections shall be performed during manufacture so that continuous quality control of production is maintained and any de
44、parture from the accepted quality will be detected before despatch. From each batch of brazed joints a sufficient quantity of finished components or replica joints shall be taken to allow execution of the quality control tests defined in the manufacturers system. The contractor shall satisfy the pur
45、chaser that brazing operators are suitable for the work upon which they will be employed3). NOTEDetails of any approval obtained by the operators under any appropriate standard laying down approval tests may be submitted as evidence of their competence. The names of all operators approved in accorda
46、nce with this clause, together with particulars of any tests passed by each, should be recorded, and made available as and when required. 12 Testing procedure Tests on brazed joints shall be one or more of the following types as specified by the purchaser or his representative and carried out in acc
47、ordance with BS 1723-35): a) visual examination; b) non-destructive tests; c) destructive tests. 13 Acceptance criteria Brazed joint category (see clause 4 of BS 1723-2:1986) and acceptance criteria shall be agreed between the purchaser and the supplier at the time of placing the order. 3) Further i
48、nformation will be given in BS 1723-4 which is in preparation. 4) Further guidance on general principles may be obtained from BS 4891. 5) In preparation. BS 1723-1:1986 4 BSI 02-1999 14 Requirements specific to the method of brazing6) 14.1 Flame brazing 14.1.1 Hand torch brazing 14.1.1.1 The heat in
49、put from the flame shall be adequate to ensure rapid heating of the joint but overheating of parent material, brazing filler metal, or flux shall be avoided. 14.1.1.2 The components shall be heated to a temperature at which the brazing filler metal is able to flow through the joint before application of hand fed rod. NOTEWhere the comp