ISO-16151-2005.pdf

Reference number ISO 16151:2005(E) © ISO 2005 INTERNATIONAL STANDARD ISO 16151 First edition 2005-10-15 Corrosion of metals and alloys Accelerated cyclic tests with exposure to acidified salt spray, “dry” and “wet” conditions Corrosion des métaux et alliages Essais cycliques accélérés avec exposition au brouillard salin acidifié, en conditions «sèches» et en conditions «humides» Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 02:30:29 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16151:2005(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. © ISO 2005 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii © ISO 2005 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 02:30:29 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16151:2005(E) © ISO 2005 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references. 1 3 Test solution 2 3.1 Method A 2 3.1.1 Preparation of acidic 5 % sodium chloride solution. 2 3.2 Method B 3 3.2.1 Preparation of the mixed salt solution . 3 3.2.2 Preparation of the acidic solution. 3 3.2.3 Preparation of the acidified-salt solution. 3 4 Apparatus 4 4.1 Exposure cabinet 4 4.2 Humidity and temperature control 4 4.3 Spraying device 4 4.4 Air saturator 4 4.5 Collecting devices 4 4.6 Air dryer. 5 4.7 Exhaust system. 5 4.8 Drain system . 5 5 Test specimens. 5 6 Arrangement of the test specimens 5 7 Operating conditions 6 8 Continuity of tests 8 9 Duration of tests . 8 10 Treatment of specimens after test 8 11 Evaluation of results. 8 12 Test report . 9 Annex A (informative) Relationship between amount of acidic stock solution added to mixed salt solution and pH of the resulting acidified-salt solution . 10 Annex B (informative) Typical apparatus for accelerated cyclic tests with exposure to acidified salt spray, “dry” and “wet” conditions. 11 Annex C (informative) Method of evaluation of the corrosivity of the chamber 13 Bibliography. 15 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 02:30:29 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16151:2005(E) iv © ISO 2005 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO 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, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 16151 was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 02:30:29 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16151:2005(E) © ISO 2005 All rights reserved v Introduction Corrosion of metallic materials, with or without corrosion protection, is influenced by many environmental factors, the importance of which may vary with the type of metallic material and with the type of environment. It is impossible, therefore, to design accelerated laboratory corrosion tests in such a way that all environmental factors influencing resistance to corrosion are taken into account. Laboratory tests are, therefore, designed to simulate the effects of the most important factors, which enhance the corrosion of metallic materials. The accelerated corrosion-test methods described in this International Standard are designed to simulate and enhance the environmental influence on a metallic material to outdoor climates, where exposure to acid rain and to salt-contaminated conditions occur and may promote corrosion. It has been prepared by reference to technical papers and reports (see the Bibliography). The test methods involve cyclic exposure of test specimens to a mist of acidified-salt solution, to drying conditions, and to periods of high humidity. However, the methods are mainly intended for comparative testing and the results obtained do not permit far-reaching conclusions on the corrosion resistance of the tested metallic material under the whole range of environmental conditions in which they may be used. Nevertheless, the methods provide valuable information on the relative performance of materials exposed to salt/acid rain environments similar to those employed in the test. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 02:30:29 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 02:30:29 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 16151:2005(E) © ISO 2005 All rights reserved 1 Corrosion of metals and alloys Accelerated cyclic tests with exposure to acidified salt spray, “dry” and “wet” conditions 1 Scope This International Standard specifies two accelerated corrosion-test procedures, Methods A and B, for the comparative evaluation of metallic materials with or without permanent corrosion protection or temporary corrosion protection in outdoor salt/acid rain environments. It also specifies the apparatus used. The two tests involve cyclic exposure of the specimens to acidified salt spray, “dry” and “wet” conditions. The particular advantages of the two tests over conventional accelerated tests, such as the neutral salt spray test (NSS) as specified in ISO 9227 lie in their better ability to reproduce the corrosion that occurs in outdoor salt/acid rain environments. They are also useful for evaluating cosmetic corrosion. Method A applies to metals and their alloys, metallic coatings (cathodic), anodic oxide coatings, and organic coatings on metallic materials. Method B applies to steel coated with anodic coatings, and steel coated with anodic coatings covered with conversion coatings. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 4628-1:2003, Paints and varnishes Evaluation of degradation of coatings Designation of quantity and size of defects, and of intensity of uniform changes in appearance Part 1: General introduction and designation system ISO 4628-2:2003, Paints and varnishes Evaluation of degradation of coatings Designation of quantity and size of defects, and of intensity of uniform changes in appearance Part 2: Assessment of degree of blistering ISO 4628-3:2003, Paints and varnishes Evaluation of degradation of coatings Designation of quantity and size of defects, and of intensity of uniform changes in appearance Part 3: Assessment of degree of rusting Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 02:30:29 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16151:2005(E) 2 © ISO 2005 All rights reserved ISO 4628-4:2003, Paints and varnishes Evaluation of degradation of coatings Designation of quantity and size of defects, and of intensity of uniform changes in appearance Part 4: Assessment of degree of cracking ISO 4628-5:2003, Paints and varnishes Evaluation of degradation of coatings Designation of quantity and size of defects, and of intensity of uniform changes in appearance Part 5: Assessment of degree of flaking ISO 8407:19911), Corrosion of metals and alloys Removal of corrosion products from corrosion test specimens ISO 8993:1989, Anodized aluminium and aluminium alloys Rating system for the evaluation of pitting corrosion Chart method ISO 9227:19901), Corrosion tests in artificial atmospheres Salt spray tests ISO 10289:1999, Method for corrosion testing of metallic and other inorganic coatings on metallic substrate Rating of test specimens and manufactured articles subjected to corrosion tests ISO 11130:1999, Corrosion of metals and alloys Alternate immersion test in salt solution 3 Test solution The following clauses give instructions for the preparation and use of the solutions used in Methods A and B. 3.1 Method A 3.1.1 Preparation of acidic 5 % sodium chloride solution 3.1.1.1 Neutral 5 % sodium chloride solution A sufficient mass of sodium chloride shall be dissolved in distilled or deionized water, with a conductivity not higher than 20 µS/cm at 25 °C ± 2 °C, to produce a concentration of 50 g/l ± 5 g/l. The specific gravity range for a 50 g/l ± 5 g/l solution shall be 1,029 to 1,036 at 25 °C. The sodium chloride shall contain less than 0,001 % mass fraction of copper and less than 0,001 % mass fraction of nickel, as determined by atomic absorption spectrophotometry or another analytical method of similar sensitivity. It shall not contain more than 0,1 % mass fraction of sodium iodide, or more than a mass fraction of total impurities of 0,5 % calculated for dry salt. If the pH of the prepared solution, measured at 25 °C ± 2 °C, is outside the range 6,0 to 7,0, investigate the presence of undesirable impurities in the salt and/or the water. 3.1.1.2 Acidification The pH of the solution shall be adjusted to a value of 3,5 ± 0,1 at 25 °C ± 2 °C, by adding the following reagents to 10 litres of the prepared neutral 5 % sodium chloride solution as follows: 12 ml of nitric acid (HNO3, = 1,42 g/ml); 17,3 ml of sulfuric acid (H2SO4, = 1,84 g/ml); a sufficient quantity of 10 % mass fraction of sodium hydroxide (NaOH) solution, to adjust the pH of the solution to 3,5 ± 0,1 (about 300 ml will be required). 1) Under revision. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 02:30:29 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16151:2005(E) © ISO 2005 All rights reserved 3 3.2 Method B 3.2.1 Preparation of the mixed salt solution The mass of reagent shown in Table 1 shall be dissolved in distilled or deionized water, with a conductivity not higher than 20 µS/cm at 25 °C ± 2 °C, to produce a stock solution with a concentration of 36 g/l ± 3,6 g/l. It shall be diluted by 1:6 to produce a mixed salt solution with a concentration of 6,0 g/l ± 0,6 g/l. The composition of the stock solution is the same as a typical synthetic ocean water shown in ISO 11130:1999, Annex A, A.3 Test solution for simulating the corrosive effects of ocean water. Table 1 Composition and concentration of a stock solution for a mixed salt solution Reagents Concentration g/l NaCl MgCl2 Na2SO4 CaCl2 KCl NaHCO3 KBr H3BO3 SrCl2 NaF 24,53 5,20 4,09 1,16 0,695 0,201 0,101 0,027 0,025 0,003 WARNING Handling of SrCl2 and NaF can be hazardous and shall be resticted to skilled chemists or conducted under their control. 3.2.2 Preparation of the acidic solution To prepare the acidic solution, 16,2 g of concentrated nitric acid (HNO3, = 1,40 g/ml, with a mass fraction of HNO3 equal to 0,65) and 42,5 g of sulfuric acid (H2SO4, = 1,84 g/ml, with a mass fraction of H2SO4 equal to 0,96) shall be dissolved in water and diluted to a total volume of 1 litre to make 1 N acid solution with respect to nitric acid and sulfuric acid at an equivalent ratio of NO3/SO42 of 0,4. 3.2.3 Preparation of the acidified-salt solution The prepared acidic solution from 3.2.2 shall be added to the mixed salt solution from 3.2.1 to adjust the pH to 2,5 ± 0,1 at 25 °C ± 2 °C. NOTE The relationship between the amount of mixed acidic solution from 3.2.2 and the pH of the acidified-salt solution is shown in Annex A. This solution, with pH v