1、BRITISH STANDARD BS 4129:1990 Specification for Welding primers and weld-through sealants, adhesives and waxes for resistance welding of sheet steelBS4129:1990 This British Standard, having been prepared under the directionof the Welding Standards Policy Committee, waspublished under the authorityof
2、 the Board of BSIandcomes into effect on 30November1990 BSI 04-2000 First publishedFebruary1967 Second editionNovember1990 The following BSI references relate to the work on this standard: Committee reference WEE/29 Draft for comment 88/77847 DC ISBN 0 580 18671 7 Committees responsible for this Bri
3、tish Standard The preparation of this British Standard was entrusted by the Welding Standards Policy Committee (WEE/-) to Technical Committee WEE/29, upon which the following bodies were represented: British Steel Industry Paintmakers Association of Great Britain Ltd. Railway Industry Association of
4、 Great Britain Society of Motor Manufacturers and Traders Ltd. Welding Institute Welding Manufacturers Association (BEAMA Ltd.) Coopted members Amendments issued since publication Amd. No. Date CommentsBS4129:1990 BSI 04-2000 i Contents Page Committees responsible Inside front cover Foreword ii 1 Sc
5、ope 1 2 Definitions 1 3 Classification 1 4 Coating procedures 1 4.1 Sampling 1 4.2 Mixing 1 4.3 Application of material to test specimen 1 4.4 Testing 2 5 Welding and test procedures 2 5.1 General 2 5.2 Test specimens 2 5.3 Application of coating 2 5.4 Measurement of surface coating 2 5.5 Type of ma
6、chine 2 5.6 Machine settings 2 5.7 Contact resistance tests 2 5.8 Electrical continuity tests 3 5.9 Weldability tests 3 5.10 Flammability tests 3 5.11 Toxicity/fume tests 3 6 Retests 5 7 Marking 5 Appendix A Contact resistance test 6 Figure 1 Current record test specimen 7 Figure 2 Circuit used for
7、detecting the onset of welding current flow 7 Figure 3 Chart record to indicate the onset of welding current flow 8 Figure 4 Typical weldability lobe 9 Figure 5 Test specimen assembly for spot welding flammability test with gun application 10 Figure 6 Test specimen assembly for spot welding flammabi
8、lity test with spray or brush application 10 Figure 7 Order of welding for spot welding flammability tests 11 Figure 8 Arrangements of potential pick-up points for measurement of resistance 12 Figure 9 Arrangement for static surface resistance measurement at steady current 13 Table 1 Recommended app
9、lied forces for contact resistance measurements 6 Publications referred to Inside back coverBS4129:1990 ii BSI 04-2000 Foreword This revision of BS4129 has been prepared under the direction of the Welding Standards Policy Committee and it supersedes BS4129:1967, which is withdrawn. This standard spe
10、cifies resistance welding requirements of welding primers and weld-through sealants, adhesives and waxes. It does not cover the protective properties of these materials. A series of tests, together with acceptance criteria, is also specified, covering the welding of these coatings on steel. If a wel
11、ding primer or weld-through sealant is to be applied to a preheated surface, compatibility with the pretreatment should be determined. Welding primers may or may not be over-coated after welding, but weld-through sealants, which are used for their gap-filling properties, are not normally a base for
12、a subsequent paint system. However, when welding primers or weld-through sealants do come into contact with a paint system, their compatibility should be determined. The Health and Safety at Work etc. Act1974 places a duty on manufacturers, designers and suppliers of substances and articles for use
13、at work to ensure, so far as is reasonably practicable, that they are safe and without risk to health when properly used. It is also the employers duty to take all reasonable measures to ensure the health and safety of persons at work. Welding primers and weld-through sealants, adhesives and waxes a
14、re substances as defined by Section6 of the Health and Safety at Work etc. Act1974. Sufficient information regarding the uses for which these coatings have been formulated and tested should be available at places of work. The composition of the welding primer or weld-through sealant, adhesive or wax
15、 should be such that it does not cause risk to health or discomfort to personnel during application or by thermal degradation while welding, when used in accordance with the manufacturers recommendations. The cooperation of the paint industry in drafting this standard is acknowledged. It has been as
16、sumed in the drafting of this British Standard that the execution of its provisions is entrusted to appropriately qualified and experienced people. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct
17、application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to14, an inside back cover and a back cover. This standard has been updated (see copyright da
18、te) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS4129:1990 BSI 04-2000 1 1 Scope This British Standard specifies requirements for the resistance welding characteristics of the following coatings: a) welding primers; b) weld-throu
19、gh sealants and adhesives; c) weld-through waxes. The resistance welding processes suitable for welding primers and weld-through sealants, adhesives and waxes are spot, seam and projection welding. NOTE 1This standard specifies requirements for resistance stud welding but does not cover arc stud wel
20、ding. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Standard, the following definitions apply. 2.1 welding primer a film material that is applied to an unpainted steel surface for protective purpo
21、ses which does not have to be removed prior to welding and does not prevent the making of an acceptable weld 2.2 weld-through sealant a mastic, gap-filling material that is applied prior to welding to an unpainted steel surface for non-pressure sealing purposes and does not prevent the making of an
22、acceptable weld 2.3 weld-through adhesive a polymer that is applied prior to welding to a primed or unpainted steel surface for the purpose of bonding but does not prevent the making of an acceptable weld 2.4 weld-through waxes a material composed of esterified fatty acids that is applied to afford
23、protection and act as a lubricant during pressing operations and which does not prevent the making of an acceptable weld 3 Classification The weldable coatings covered by this British Standard are classified into the following four basic types according to whether they remain weldable for an indefin
24、ite or a limited period. Type A. A primer, sealant, adhesive or wax that remains weldable after application for a limited period, usually less than24h under normal conditions. Type B. A primer, sealant, adhesive or wax that remains weldable after application for a period of1week storage under normal
25、 conditions. Type C. A primer, sealant, adhesive or wax that remains weldable after application for a period of6weeks storage under normal conditions. Type D. A primer, sealant, adhesive or wax that remains weldable after application for an extended period of storage under normal conditions, the sto
26、rage period being clearly marked. NOTEAny thermal treatment that is applied to a treated article may reduce the weldability of the welding primer or weld-through sealant, adhesive or wax whether of type A, B, C orD. 4 Coating procedures 4.1 Sampling 1) For examination for compliance with this Britis
27、h Standard, representative samples of the welding primer or weld-through sealant, adhesive or wax measuring not less than0.5L shall be drawn either at the filling stage or from one or more original and previously unopened containers. The samples shall be placed in suitable, clean, dry, air-tight con
28、tainers. The containers shall be so filled as to leave an ullage of not less than15% when closed. Each sample container so filled shall be marked with full details of the contents and the date of sampling. The samples shall be stored in accordance with the manufacturers recommendations. Where additi
29、onal activators, solvents, diluents, etc. are necessary, they shall be sampled at the same time and in a like manner to provide a suitable quantity for test purposes. 4.2 Mixing Before application, the primer, sealant, adhesive or wax shall be thoroughly mixed, where applicable, in accordance with t
30、he manufacturers recommendations. 4.3 Application of material to test specimen Adhesives that are generally stored at low temperatures prior to use in order to prolong shelf-life shall be brought to the working temperature prior to application. The material shall then be applied in accordance with t
31、he manufacturers instructions. NOTEThe primer may be applied by roller coating, brushing, dipping or spray techniques. 1) See also BS 3900-A1.BS4129:1990 2 BSI 04-2000 In all cases, the thickness of the material shall be measured. 4.4 Testing Test pieces shall be classified at the end of the weldabl
32、e period in accordance with clause3. 5 Welding and test procedures 5.1 General The following tests shall be carried out to demonstrate that the welding primer or weld-through sealant, adhesive or wax does not prevent production of satisfactory spot welds: a) contact resistance; b) electrical continu
33、ity; c) weldability: 1) weldability lobe; 2) consistency; d) flammability; e) toxicity/fume levels. NOTE 1For ease of assessment, spot welding is specified as it is the most widely used resistance welding technique and requires the most stringent application. NOTE 2The electrode should be checked to
34、 establish the number of welds that can be made before the weld quality falls below4 t (where t is the thickness of a single sheet (in millimetres) (see5.9.1). Two series of test shall be carried out: i) one series at the end of the drying or cure period, consisting of the tests for electrical conti
35、nuity, flammability, toxicity/fume levels and contact resistance; ii) the second series at the end of the weldable period, consisting of the tests for electrical continuity, contact resistance and weldability. 5.2 Test specimens Test specimens shall be of cold reduced sheet steel or strip of thickne
36、ss1.0mm, complying with CR1 or CR2 quality of BS1449 with a GP finish. Test specimens shall be free from rust and scale and shall be degreased with a suitable solvent prior to application of the primer, sealant, adhesive or wax. The dimensions of the test specimens for contact resistance, electrical
37、 continuity and weldability tests shall be as specified for the shear test specimen in BS1140. 5.3 Application of coating The welding primer or weld-through sealant, adhesive or wax shall be applied in a manner and to a thickness recommended by the manufacturer. Coated current record test specimens
38、shall consist of one piece coated on both sides and two outer pieces coated on the faying surfaces only (seeFigure 1). Coated shear test specimens shall be coated on the faying surfaces only. Specimens for the electrical continuity test shall be coated on both sides. 5.4 Measurement of surface coati
39、ng Appropriate instrumentation or techniques shall be used to measure the thickness of the coatings on the ferrous base to an accuracy of+3%. 5.5 Type of machine All tests shall be made on a single-spot, pedestal welding machine that is in accordance withAppendixA of BS1140:1980 and shall be equippe
40、d with a synchronous timing control. The welding electrodes shall be of copper alloy of sufficient cross-sectional area and strength to carry the welding current and electrode force without overheating, deformation or excessive deflection. The electrode material shall comply with the relevant requir
41、ements of BS4577. Electrode dimensions shall comply with BS4215 where applicable. For the test programme the electrodes shall be straight and the initial electrode tip diameter, D, shall be as given by the following equation: D = 5 t where: D is the initial tip diameter in mm; t is the single sheet
42、thickness in mm. 5.6 Machine settings The machine settings, which shall be checked before, maintained during and checked after welding the test specimens, shall be as follows: 5.7 Contact resistance tests In carrying out contact resistance measurements the test procedure shall be strictly adhered to
43、 and all electrical connections in the circuitry shall be secure. The contact resistance test shall be carried out in accordance withAppendix A. welding force : 1.4 kN welding current : 6.5 kA approximate a welding time : 9 cycles squeeze time : sufficient to achieve90% of electrode force hold time
44、: 10 cycles a The current given is for guidance only and may be adjusted in accordance with the application. The force and time should be set up as stated.BS4129:1990 BSI 04-2000 3 5.8 Electrical continuity tests 5.8.1 Test procedure and method The test shall be carried out as follows, using the arr
45、angement shown inFigure 1. a) Coat one panel on both sides and two more on one side only with the coating material under test, to a total thickness appropriate to the manufacturers recommendation for general usage. b) Allow the panels to dry or cure in accordance with the manufacturers recommendatio
46、ns. c) Assemble the panels into a “sandwich” with the double-coated panel in the middle. d) Spot weld the assembled “sandwich” together using a suitable instrument to record the following: 1) the initiation and magnitude of current; 2) the time and magnitude of welding current flow (seeFigure 2); 3)
47、 the point of thyristor or ignition excitation. e) Repeat steps a) to d) on a new test piece. 5.8.2 Acceptance criteria A trace similar toFigure 3 shall be obtained. The points A and B shown inFigure 3 shall be no more than1.5cycles apart. Weld time shall be measured from the point at which the curr
48、ent in any half cycle exceeds70% of the welding current. 5.9 Weldability tests 5.9.1 Weldability lobe NOTEA weldability lobe is a plot of the major welding parameters, i.e.current and time at a constant weld force, within which it is possible to guarantee weld quality as defined by arbitrary limits.
49、 A typical example of a weldability lobe is shown inFigure 4, the lower limit being represented by a minimum weld size of4t, where t is the thickness of a single sheet (in millimetres), and the upper limit by “interfacial splash” conditions. Using an electrode force of1.4kN, make a series of welds at weld times of5, 10, 15 and20cycles over a range of welding currents such that the upper and lower limits, as defined, can be established for each of the weld times. The width of the weldability lobe, obtained from these data, shall be at least1.5kA at a w
