ISO-6957-1988.pdf

IS0 6957 INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEXQJYHAPOAHAR OPTAHMSAMR l-l0 CTAHflAPTM3Aklkl Copper alloys - Ammonia test for stress corrosion resistance Alliages de cuivre - Essai i) l ammoniaque pour la rbsistance c) la corrosion sous contrainte First edition 1988-10-01 Reference number IS0 6957 : 1988 (E) IS0 6957 : 1966 (El Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees, Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting. International Standard IS0 6957 was prepared by Technical Committee ISO/TC 26, Copper end copper alloys. Annexes A and B of this International Standard are for information only. 0 international Organization for Standardization, 1999 0 Printed in Switzerland INTERNATIONAL STANDARD ISO 6957 : 1988 (E) Copper alloys - Ammonia test for stress corrosion resistance 1 Scope This international Standard specifies a test, using an am- moniacal atmosphere, for the detection of applied or residual stresses in copper alloy products which can cause failure of the material in service or storage through stress corrosion cracking. The method can also be used for testing assemblies and partial assemblies (of limited size). This method is relatively simple to carry out and its severity can be regulated by changing the pH value of the solution produc- ing the ammoniacal atmosphere. The appropriate pH-value for the test shall be specified in the product specification or agreed upon with respect to the alloy and its application. In annex A, recommendations are given for the choice of pH- values to be used for some frequently occurring applications. 2 Principle Exposure of test pieces to an ammoniacal atmosphere for 24 h, followed by examination for cracks at a magnification of x 10 to x 15. 3 Reagents and materials Use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 3.1 Ammonium chloride, 4 mol/l solution, for the prep- aration of the test solution. Dissolve 107 g f 0,l g of ammonium chloride (NH in case of dispute, the temperature shall be kept at 25 OC f 1 OC. The exposure time shall be 24 h. 9 Test report The test report shall include the following information: a) an identification of the sample, and the location of the test piece in the sample if the test was carried out on a test piece taken from the sample, rather than on the sample itself; b) the reference of the method used; c) the pH-value of the solution producing the ammoniacal atmosphere; d) the exposure temperature; e) the number of replicate test pieces tested; f) the test results: cracks or no cracks (as required in the appropriate product specification) ; g) any unusual features noted during the determination; any operation not included in this International Standard or regarded as optional; h) the date of the test. 2 -,-,- IS0 69!3 : 1988 (El Annex A (informative) Guidance for choice of the pH-value of the test solution On the basis of the known correlation between the behaviour of test pieces in the ammonia test and the behaviour of copper alloy products under service conditions, the following pH-values are recommended as being representative of atmospheres of different corrosiveness and corresponding to different safety requirements. Corrosiveness of atmosphere Low Indoor atmosphere under dry conditions Moderate Indoor atmosphere with risk of formation of condensation Outdoor atmosphere, temperate climate High Atmosphere with ammoniacal pollution, for example in stables pH-value Safety requirement Low High 9.3 93 9.5 10.0 92 10,o 10,o 10,5 Annex B (informative) Bibliography l AEFSI, F., Untersuchungen iiber die Spannungskorrosion von Alpha-Messing in Ammoniakdampf, Z. Mefallkunde 49 (1958, Heft 2, pp. 63-68. 2 Mn-sso, E., HOLM, Ft., and HASSEL, L., Ammonia test for stress corrosion resistance of copper alloys. STP 970, ASTM, Philadelphia, PA, USA (to be published). 131 LANDGREN, W., and MATTSSON, E., Stress corrosion of brass: Field test in different types of atmosphere, Br. Corros. J., 1976, Vol 11, No 2, pp. 80-85. 4 BS 2871: Part 3: 1972, Tubes for heat exchangers, sub-clause 12.2. 3 -,-,- IS0 6957 : 1988 (EI UDC 669.3 : 620.194.2 Descriptors: copper, copper alloys, copper products, tests, stress corrosion tests, determination, corrosion resistance. Price based on 3 pages -,-,-