1、BSI Standards PublicationBS ISO 18069:2015Corrosion of metals and alloys Method for determinationof the uniform corrosion rateof stainless steels and nickelbased alloys in liquidsBS ISO 18069:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 18069:2015.The U
2、K participation in its preparation was entrusted to TechnicalCommittee ISE/NFE/8, Corrosion of metals and alloys.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Us
3、ers are responsible for its correctapplication. The British Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 79068 3ICS 77.060Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of the
4、Standards Policy and Strategy Committee on 30 June 2015.Amendments issued since publicationDate Text affectedBS ISO 18069:2015 ISO 2015Corrosion of metals and alloys Method for determination of the uniform corrosion rate of stainless steels and nickel based alloys in liquidsCorrosion des mtaux et al
5、liages Mthode pour la dtermination du taux de corrosion uniforme des aciers inoxydables et des alliages base de nickel dans les liquidesINTERNATIONAL STANDARDISO18069First edition2015-06-15Reference numberISO 18069:2015(E)BS ISO 18069:2015ISO 18069:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PRO
6、TECTED DOCUMENT ISO 2015, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without pri
7、or written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 180
8、69:2015ISO 18069:2015(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 15 Equipment . 26 Test solutions . 27 Specimens 38 Procedure. 39 Evaluation 610 Test report . 7Annex A (informative) Example of how to calculate the corrosion rate 8Bibliography
9、 9 ISO 2015 All rights reserved iiiContents PageBS ISO 18069:2015ISO 18069:2015(E)ForewordISO (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
10、 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 collaborate
11、s closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval crit
12、eria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document may be the subject o
13、f patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade nam
14、e used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technica
15、l Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 156, Corrosion of metals and alloys.iv ISO 2015 All rights reservedBS ISO 18069:2015ISO 18069:2015(E)IntroductionStainless steel and nickel based alloys generall
16、y show good corrosion resistance but uniform corrosion can occur in acidic and alkaline solutions. The uniform corrosion rate in aqueous solutions is usually considered to be a fairly stable process as long as the corrosive environment is constant with respect to chemical composition, temperature, a
17、nd flow conditions. The uniform corrosion resistance of stainless steels and nickel based alloys is thus often determined by short-term laboratory coupons immersion tests carried out under controlled conditions. However, in real applications, some variation in service conditions can occur which migh
18、t cause a temporary activation of the stainless steel or nickel based alloy surface. Temperature variations, fluctuation in the access of air or other oxidants, contact to less noble materials, e.g. mild steel, or to certain cleaning agents are all factors which under certain circumstances could cau
19、se activation.One important property to investigate is therefore the ability for the material to passivate after activation and accordingly, this method includes activation of the specimens. The corrosion rate determined by this test can be used as a basis for material selection and to estimate the
20、lifetime of the material. ISO 2015 All rights reserved vBS ISO 18069:2015BS ISO 18069:2015Corrosion of metals and alloys Method for determination of the uniform corrosion rate of stainless steels and nickel based alloys in liquids1 ScopeThis International Standard specifies the measurements of the c
21、orrosion rate of uniform corrosion for stainless steels and nickel based alloys in the intended liquids and the ability for the material to passivate after activation.This method is intended to be used for estimation of the uniform corrosion rate in liquids, under atmospheric conditions, for the che
22、mical industry under specific environmental conditions and not as a qualification test. It can also be used to determine iso-corrosion diagrams and at which temperature the corrosion rate exceeds 0,1 mm/a.This International Standard is not intended for excessive corrosion rates above 1 mm/a since an
23、 even higher corrosion rate indicates that the stainless steel is not suitable in the application.This International Standard is not intended to be used for solutions containing halides, especially chlorides, since these might cause localized corrosion.2 Normative referencesThe following documents,
24、in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applied. For undated references, the latest edition of the referenced document applies.ISO 3696, Water for analytical laboratory use Specification
25、and test methodsISO 8044, Corrosion of metals and alloys Basic terms and definitionsISO 17864, Corrosion of metals and alloys Determination of the critical pitting temperature under potientiostatic control3 Terms and definitionsFor the purposes of this document, the terms and definitions given in IS
26、O 8044 apply.4 Principle4.1 This method involves immersion of the material in the intended liquid after the required temperature has been reached. Mass measurements are carried out before and after each of three sequential periods, 24 h, 72 h, and 72 h of immersion.Period 1: 24 h of immersion in the
27、 liquid. When exposed to acid, the passive layer will change composition during this period. In addition, contaminations on the specimens will be removed during this period. For this reason, the first period is normally not accounted for when evaluating the corrosion rate.Period 2: 72 h of immersion
28、 in the liquid. This period determines the corrosion rate.Period 3: 72 h of immersion in the liquid with activation of the specimens. This period determines the corrosion rate of a specimen with an active surface and the ability to repassivate in the specific liquid.INTERNATIONAL STANDARD ISO 18069:
29、2015(E) ISO 2015 All rights reserved 1BS ISO 18069:2015ISO 18069:2015(E)4.2 The weight, before and after each period, is measured, the mass loss during each period is calculated, and the average corrosion rate is determined for periods 2 and 3.4.3 In the beginning of the third period, the specimens
30、shall be activated, according to the procedure described in 8.5, to investigate whether the material has the ability to repassivate in the specific conditions.4.4 Activation by a potentiostat or zinc shall be used, except in strongly oxidising solutions, such as nitric acids or ferrous sulfate where
31、 a hydrochloric acid solution shall be used.4.5 The test involves immersion of specimens in a test liquid, which is in open air. This implies that the oxygen in the aerated liquid can maintain the passive layer and the result shall therefore not be compared with results obtained in deaerated liquid.
32、5 Equipment5.1 Vessel, flask, or beaker of inert material to the test liquid.5.2 Specimen holder of inert material to the test liquid shall be used.5.3 Temperature controller with an accuracy of 1 C.5.4 In case of using potentiostatic activation, a potentiostat and a reference electrode is required.
33、 The potentiostat shall be capable of controlling the electrode potential to within 1 mV of a present value. If the liquid in the test vessel is heated, the reference electrode shall be maintained at ambient temperature external to the test vessel via a Luggin capillary probe (see ISO 17864) or elec
34、trode shall be suitable for higher temperatures and values shall be referred to as values at ambient temperature.5.5 Laboratory balance. The laboratory balance shall be able to measure with accuracy of 0,000 1 g or better.6 Test solutions6.1 Test solutions can be laboratory prepared or process solut
35、ion. If the solution is prepared in the laboratory, it shall be made from reagent-grade chemicals and high-purity water.6.2 Precautions shall be taken according to the chemical safety data sheet of the solution.6.3 It is necessary to be sure that the solution does not react with the vessel.If the so
36、lution contains hydroxides (e.g. NaOH) or fluorides (e.g. HF and wet phosphoric acid, WPA), the equipment shall be made of a resistant polymer material.6.4 If hydrochloric acid-solution is used for activation of the specimens, it shall be prepared by mixing 1 part of HCl, mass fraction 37 % by weigh
37、t HCl, with 2 parts high-purity water with a conductivity less than 1 S/cm (ISO 3696, grade 2).2 ISO 2015 All rights reservedBS ISO 18069:2015ISO 18069:2015(E)7 Specimens7.1 At least two specimens for each of the materials shall be tested in each environmental condition. Both welded and non-welded s
38、pecimens can be used.If materials of different alloy composition are tested in the same liquid, it should be verified that this does not influence the result.7.2 The surface area of each specimen shall be at least 20 cm2and influence from edges surfaces shall be minimized by minimizing the area of t
39、he edges as far as possible. The specimens dimensions shall be measured with an accuracy of 0,1 mm and the area shall be calculated. The specimen shall be orientated so the majority of the test area is representative of the surface of interest.7.3 The edges shall be ground down to a surface finish o
40、f at least P 120 grit paper. All the other surfaces shall represent the surface of interest. The specimens shall be left in air, at a temperature higher than the dew point temperature for at least 24 h before testing, to be able to form a stable passive film.NOTE Wet grinding is preferred but dry gr
41、inding can also be used if care is taken to avoid overheating of the surface.7.4 If welded specimens are used, the weld shall preferably be located in the middle of the specimens. Post weld cleaning shall be selected to be representative for the application of interest.NOTE Surface preparation such
42、as blasting or too rough grinding surfaces might affect the result.7.5 The specimens shall be cleaned immediately prior to immersion by degreasing, rinsing in high-purity water followed by ethanol or a similar solvent, and air drying. After degreasing, care shall be taken not to contaminate the test
43、 surface of the specimens.8 Procedure8.1 The specimens shall be weighed preferably at room temperature with an accuracy of 0,000 1 g or better. The weight prior to this testing shall be registered as mi. Weighing prior to and after testing shall be conducted at the same temperature.8.2 Examples of t
44、he experimental equipment are shown in Figures 1 and 2. In Figure 1, the equipment consists of a flask, a specimen holder, a reflux condenser, a stirrer, and a temperature controller. In Figure 2, the specimens are mounted on a specimen holder of glass and placed in the liquid. Covers of the beakers
45、 are used to avoid evaporation.8.3 The test solutions temperature shall be constant during the test with an accuracy of 1 C. Stirring shall be used if corrosion products are formed in the liquid.NOTE Slight stirring is used to avoid corrosion products on the specimens and temperature gradients in th
46、e liquid. ISO 2015 All rights reserved 3BS ISO 18069:2015ISO 18069:2015(E)Figure 1 Example of equipment and specimen holder4 ISO 2015 All rights reservedBS ISO 18069:2015ISO 18069:2015(E)Figure 2 Equipment consists of beakers in a thermostatic bath8.4 The liquid is poured into the vessel, flask, or
47、beaker. The required volume shall be at least 5 ml/cm2specimen area and the specimens shall be completely immersed. The temperature of the liquid shall be controlled with an accuracy of 1 C. In case of evaporation, a condenser shall be used to make sure that the volume is constant. ISO 2015 All righ
48、ts reserved 5BS ISO 18069:2015ISO 18069:2015(E)8.5 When the intended temperature has been reached and is stable, the specimens are placed in the liquid. The contact area between the specimens and the specimen holder shall be minimized. The measurements of mass loss are carried out after three sequen
49、tial periods 24 h, 72 h, and 72 h.8.6 After each test period, the specimen shall be rinsed in high-purity water (see ISO 3696). The specimens are immersed in ethanol, mass fraction 99 %, and dried in air. The weight mi+1after each test period shall be noted.NOTE i is the number of test period.8.7 New test solutions shall be used for each period. However, if the corrosion rate for all specimens from the first period is less than 0,01 mm/a, the same solution can be used for the second period.8.8 The specimens shall be weighed
