1、BRITISH STANDARD BS 5245:1975 Incorporating Amendment No. 1 Specification for Phosphoric acid based flux for soft soldered joints in stainless steel ICS 25.160.50BS5245:1975 This British Standard having beenapproved by the Iron and Steel Industry Standards Committee, was published under the authorit
2、y of the Executive Board on 30September1975 BSI-05-1999 The following BSI references relate to the work on this standard: Committee reference ISE/66 andISE/66/1 Draft for comment 71/40639 ISBN 0 580 08755 7 Co-operating organizations The Iron and Steel Industry Standards Committee, under whose super
3、vision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: The organization marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted
4、with the preparation of this standard: British Cast Iron Research Association Institution of Mechanical Engineers British Constructional Steelwork Association (Automobile Division) British Ironfounders Association Institution of Production Engineers British Mechanical Engineering Institution of Stru
5、ctural Engineers Confederation Lloyds Register of Shipping British Steel Industry* Ministry of Defence British Steel Industry (Wire Section) National Association of Drop Forgers The Concrete Society and Stampers Council of Ironfoundry Associations Oil Companies Materials Association Department of Em
6、ployment, H.M. Chief Process Plant Association Inspector of Factories Royal Institute of British Architects Department of Industry N.P.L Shipbuilders and Repairers National Department of Trade (Marine Division) Association Engineering Equipment Users Association Society of Motor Manufacturers and Fe
7、deration of Civil Engineering Contractors Traders Ltd. Greater London Council Steel Castings Research and Institute of British Foundrymen Trade Association Institute of Marine Engineers Tin Research Institute British Gas Corporation Institute of Plumbing British Welded Steel Tube Manufacturers Natio
8、nal Water Council Association Water Companies Association Copper Development Association Amendments issued since publication Amd. No. Date Comments 10208 January 1999 Indicated by a sideline in the marginBS5245:1975 BSI 05-1999 i Contents Page Co-operating organizations Inside front cover Foreword i
9、i 1 Scope 1 2 References 1 3 Information to be supplied by the purchaser 1 4 Composition 1 5 Condition 1 6 Sampling 1 7 Solderability test 1 8 Retests 1 9 Inspection 1 10 Facilities for testing 1 11 Packaging 1 12 Marking 1 13 Manufacturers certificate 1 Appendix A Method for the determination of ha
10、logen content 2 Appendix B Solderability test 2 Figure 1 Jig for holding stainless steel test pieces 3 Figure 2 Area of solder spread 4 Publications referred to Inside back coverBS5245:1975 ii BSI 05-1999 Foreword This British Standard, authorized by the Iron and Steel Industry Standards Committee,
11、has been prepared at the request of the stainless steel industry. Because of the inadvisability in some cases of using acid chloride fluxes in making capillary joints in stainless steel tube, a decision was taken to prepare this standard for phosphoric acid based flux particularly for the applicatio
12、n of preparing soft soldered capillary joints in stainless steel tube in accordance with BS4127 “Light gauge stainless steel tubes”, Part 2 “Metric units”, with solder in accordance with BS EN29453 “Soft solder alloys Chemical composition and forms” and fittings of copper or copper alloy in accordan
13、ce with the relevant part of BS EN1254 “Copper and copper alloys plumbing fittings” or of stainless steel. It is intended to ensure that purchasers of phosphoric acid based flux for use in this application may be certain that such fluxes and their residues are safe, i.e.not corrosive in normal use,
14、towards the tube, fittings, or solder in the capillary joints after the joint has been made. The type of flux covered by this standard may, however, be used for other applications where soldered joints in stainless steel are involved. A British Standard does not purport to include all the necessary
15、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 cover, an inside front cover, pagesi andii, pages1 to4, a
16、n 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.BS5245:1975 BSI 05-1999 1 1 Scope This British Standard specifies requirements for phosphoric ac
17、id based flux for soft soldered joints in stainless steel. The flux is considered to be particularly suitable for making soft soldered capillary joints in stainless steel tube in accordance with BS4127-2, with solder in accordance with BSEN29453, and fittings of copper or copper alloy in accordance
18、with BS EN 1254, or of stainless steel. 2 References The titles of the British Standards referred to in this standard are listed on the inside back cover. 3 Information to be supplied by the purchaser The purchaser shall state on his enquiry and order the following information: a) if tests are requi
19、red (see clause 4 and clause 7); b) if a manufacturers certificate is required (seeclause 13); c) if it is the intention of the purchaser to inspect the material at the manufacturers works (seeclause 10). 4 Composition The principal active agent in the flux shall be phosphoric acid. The flux shall c
20、ontain not more than0.05% by mass of halogen, calculated as chlorine and determined by the method given in Appendix A. 5 Condition After any agitation recommended by the manufacturer and stated on the container, the flux shall be in a uniform viscous form and of a consistency suitable for applicatio
21、n to the surface to be soldered and subsequent retention within the gap of the capillary joint. 6 Sampling When tests are called for by the purchaser, one container of flux (seeclause11) shall be selected at random to represent one manufacturing batch. 7 Solderability test When tests are called for
22、by the purchaser, these shall be carried out in accordance with the method specified in Appendix B. The average of the results of ten tests shall give an area of solder spread of not less than3.0cm 2 . 8 Retests Should the sample of flux first selected fail to meet the requirements of clause 4 or cl
23、ause 7, two further samples from the same batch shall be selected for testing, unless the batch has been withdrawn by the manufacturer. Should both these additional samples meet the requirements of clause 4 or clause 7, the batch they represent shall be deemed to comply with this standard. Should ei
24、ther of these additional samples fail, the batch represented by the test samples shall be deemed not to comply with this standard. 9 Inspection The purchaser shall notify the manufacturer when placing the order if it is his intention to inspect the material at the manufacturers works. The manufactur
25、er shall afford the purchaser all reasonable facilities to satisfy himself that the material complies with the standard. For this purpose the purchaser or his representative may, by prior arrangement, attend to inspect the material, to select and identify the test samples for testing and to witness
26、the tests being made. 10 Facilities for testing The manufacturer shall furnish and prepare the necessary test samples and carry out the tests specified in this standard. If testing is done at his own works, the manufacturer shall supply the necessary labour and appliances. If there are not facilitie
27、s at his own works, the manufacturer shall arrange for the tests to be done elsewhere. 11 Packaging The flux shall be packaged in suitable durable containers with replaceable airtight closures so that the flux will continue to meet the requirements of clause 5. 12 Marking Each flux container shall b
28、e marked with the following information: a) the number of this British Standard; b) the name and address of the flux manufacturer; c) the batch number; d) any recommendations on use and storage temperature of the flux; e) a warning that the flux should be kept from contact with the skin and eyes. 13
29、 Manufacturers certificate When required by the purchaser and stated on the enquiry and order, the manufacturer shall certify that the flux complies with the requirements of this standard.BS5245:1975 2 BSI 05-1999 Appendix A Method for the determination of halogen content A.1 Principle. Oxalic acid
30、is added to complex the copper (if any) and ferric nitrate to complex the phosphate. The halogen content calculated as chlorine is then determined volumetrically with silver nitrate and ammonium thiocyanate. A.2 Solutions. The following solutions are required. A.2.1 Silver nitrate (0.02N) standard s
31、olution. Dissolve 3.40g of silver nitrate in water, transfer to a1litre volumetric flask, dilute to the mark and mix. A.2.2 Ammonium thiocyanate (0.02N approx.) Dissolve 1.6g of ammonium thiocyanate in water, transfer to a1litre volumetric flask, dilute to the mark and mix. A.2.3 Nitric acid (10% v/
32、v) Dilute 100ml of nitric acid d =1.42to1litre and mix. A.3 Procedure. Weigh10g of the flux, transfer to a100ml volumetric flask, add approx.70ml of water, stopper the flask and mix. Add2g of oxalic acid, dilute to the mark and mix well. Allow to stand for approx.10min and filter through a dry filte
33、r paper 1) . Transfer50ml of the filtrate to a125ml bottle, add15g of ferric nitrate (analytical reagent grade),5.0ml of the silver nitrate solution (0.02N) 2) , stopper the bottle and shake well. Titratethe excess silver nitrate with the ammonium thiocyanate solution (0.02N approx.) toa faint perma
34、nent orange-red end point. Carry out simultaneously a blank determination following the same procedure, and using the same quantities of reagents but omitting the sample. A.4 Standardization of the ammonium thiocyanate. Dissolve15g of ferric nitrate (analytical reagent grade) and1g of oxalic acid in
35、 70ml of the nitric acid (10% v/v), add5.0ml of silver nitrate (0.02N) solution and titrate with ammonium thiocyanate solution (0.02N approx.) to a faint orange-red end point. A.5 Calculation. 1ml of silver nitrate solution(0.02N) =0.000 709g of chlorine. Calculate the halogen content as chlorine us
36、ing the formula: where Appendix B Solderability test B.1 Principle of test. A standard volume of60/40 tin/lead solder is melted on the flat, horizontal surface of a piece of stainless steel strip in contact with the flux under defined conditions. The area to which the solder spreads and fully adhere
37、s to the stainless steel surface is taken as a measure of solderability. Heating is carried out by floating the stainless steel test piece in a bath of a molten low melting point alloy. B.2 Materials required B.2.1 Stainless steel. Ten flat 352mm squares shall be cut from0.71mm thick strip complying
38、 with the requirements of BS1449-4,302S17. Each square shall be prepared by first degreasing by immersion in a solvent such as acetone, followed by dry grinding by hand one surface to a180grit finish. After grinding, the squares shall be handled only with clean tweezers or tongs and shall be re-imme
39、rsed in a solvent such as acetone to wash off any particles of abrasive. B.2.2 Solder pellets. The composition of the solder pellets shall comply with the requirements of BS219 grade K (60% tin40% lead solder) and shall have a volume of20 1mm 3 . The pellets shall be blanked from strip not less than
40、1.5mm in thickness. B.3 Test apparatus B.3.1 Heating bath. The heating bath shall be either round, not less than75mm diameter, or rectangular, not less than75mm 75mm, and shall contain an alloy such as tin/lead solder, with a melting point not greater than200C, to a depth of not less than25mm. The t
41、emperature of the bath shall be maintained at3005C during the test. 1) Whatman no. 41 is suitable. 2) 2ml of nitrobenzene may be added to assist coagulation of the precipitate. %Cl 5 T () 0.0709 0.5 m - = T = volume (ml) of ammonium thiocyanate solution (0.02N approx.) used (corrected for blank) cal
42、culated in terms of a 0.02N solution m = mass (g) of sample taken.BS5245:1975 BSI 05-1999 3 B.3.2 Jig for holding stainless steel test pieces. Throughout the testing cycle the stainless steel test piece shall be maintained in a horizontal position. Means shall be provided for smoothly lowering it on
43、to the surface of the molten alloy and then raising it without vibration at the completion of the heating cycle. During the heating cycle, the test piece shall float freely on the molten alloy and shall not be in contact with any portion of the jig. The jig shall have a low heat capacity and should
44、preferably be made of thin gauge metal, which is not wetted by solder, such as titanium, aluminium or stainless steel. The design of jig shown in Figure 1 has been found to be suitable. B.4 Test procedure. A stainless steel square, prepared in the manner described in B.2.1 shall be placed in the jig
45、 with its ground face uppermost. The flux shall be applied as a circular layer,0.25mm to0.50mm thick and not less than25mm diameter, on the central region of the stainless steel square. (Such a layer is conveniently produced by the use of a0.25mm thick stainless steel template with a25mm diameter ap
46、erture, and a straight edged piece of metal, e.g.a razor blade. The template is placed on the stainless steel test piece, the circular cavity is filled with a slight excess of flux, the straight edge is drawn across the cavity to remove excess flux and the template is then removed.) After skimming a
47、ny dross off the surface of the molten metal in the heating bath, the square shall be lowered on to the surface of the molten metal under the conditions defined in B.3.2, where it shall remain floating for20s. A solder pellet, as defined in B.2.2, shall then be placed on the flux at the centre of th
48、e square and, after a further period of30s, the square shall be raised to a height sufficient to allow the solder on its upper surface to solidify. The square shall not be removed from the jig until the solder is completely solid, and any accidental vibration during cooling shall render the test inv
49、alid. Should any one test produce a solder patch that is very oval or irregular in shape, it may be discounted and repeated. This test procedure shall be repeated for a total of ten stainless steel squares. B.5 Measurement of area of solder spread. After washing off the flux residues in running water, the area of spread of the solder shall be measured. A transparent version of the grid shown in Figure 2 has been found to be a suitable means of measuring the area of solder spread. In cases of dispute, the area of
