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1、BRITISH STANDARD BS ISO 11844-2:2005 Corrosion of metals and alloys Classification of low corrosivity of indoor atmospheres Part 2: Determination of corrosion attack in indoor atmospheres ICS 77.060 ? Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontrolled Copy,
2、(c) BSI BS ISO 11844-2:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 25 January 2006 BSI 25 January 2006 ISBN 0 580 47510 7 National foreword This British Standard reproduces verbatim ISO 11844-2:2005 and implements it as the UK nation
3、al standard. The UK participation in its preparation was entrusted to Technical Committee ISE/NFE/8, Corrosion of metals and alloys, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation,
4、 or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement i
5、nternational publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to i
6、nclude all the necessary provisions of a contract. Users are responsible for its 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, the ISO title page, pages
7、 ii to v, a blank page, pages 1 to 11 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontrol
8、led Copy, (c) BSI Reference number ISO 11844-2:2005(E) INTERNATIONAL STANDARD ISO 11844-2 First edition 2005-12-15 Corrosion of metals and alloys Classification of low corrosivity of indoor atmospheres Part 2: Determination of corrosion attack in indoor atmospheres Corrosion des mtaux et alliages Cl
9、assification de la corrosivit faible des atmosphres dintrieur Partie 2: Dtermination de lattaque par corrosion dans les atmosphres dintrieur BS ISO 11844-2:2005 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii Licensed Copy: sheffieldun sh
10、effieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 11844-2:2005 iii Contents Page Foreword iv Introduction v 1 Scope 1 2 Normative references 1 3 Principle1 4 Methods 1 Annex A (normative) Determination of corrosion rate by mass change measurement 4 Annex B (normati
11、ve) Determination of corrosion rate by electrolytic cathodic reduction .7 Annex C (informative) Determination of corrosion rate by resistance measurements .9 Bibliography 11 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 11844-2:2005
12、 iv 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
13、 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 mat
14、ters 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 circu
15、lated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. ISO 11844-2 was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys. ISO 11844 consists of the following parts, under the gen
16、eral title Corrosion of metals and alloys Classification of low corrosivity of indoor atmospheres: Part 1: Determination and estimation of indoor corrosivity Part 2: Determination of corrosion attack in indoor atmospheres Part 3: Measurement of environmental parameters affecting indoor corrosivity L
17、icensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI v Introduction This part of ISO 11844 describes standard specimens, their exposure and evaluation for the derivation of the indoor corrosivity categories. The determination of the corrosion atta
18、ck is, at the present state of knowledge, the most reliable way, and usually also an economical way, for evaluation of corrosivity taking into account all main local environmental influences. BS ISO 11844-2:2005 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontro
19、lled Copy, (c) BSI blank Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 1 Corrosion of metals and alloys Classification of low corrosivity of indoor atmospheres Part 2: Determination of corrosion attack in indoor atmospheres 1 Scope This pa
20、rt of ISO 11844 specifies methods for determination of corrosion rate with standard specimens of metals in indoor atmospheres with low corrosivity. For this direct method of evaluation of corrosivity, different sensitive methods can be applied using standard specimens of the following metals: copper
21、, silver, zinc and steel. The values obtained from the measurements are used as classification criteria for the determination of indoor atmospheric corrosivity. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, onl
22、y the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60654-4:1987, Operating conditions for industrial-process measurement and control equipment Part 4: Corrosive and erosive influences ANSI/ISA-S71.04:1985, Enviro
23、nmental conditions for Process, Measurement and Control Systems: Airborne Contaminants 3 Principle The corrosivity of the indoor location, e.g. control rooms, electric boxes, storage rooms, during transportation, in museums, etc., is determined from the corrosion rate calculated from the mass change
24、 or resistance change per unit area of standard specimens of metals after exposure for a certain time period. Different materials are sensitive to different environmental parameters or their combinations. 4 Methods The following methods described in Annexes A and B are available for evaluation of th
25、e corrosion attack: Determination of corrosion rate by mass change measurements (Annex A) Determination of corrosion rate by electrolytic cathodic reduction (Annex B) The method described in informative Annex C is suitable for continuous or periodic monitoring of the corrosion attack: Determination
26、of corrosion rate by resistance measurements (Annex C) BS ISO 11844-2:2005 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 Special features of the methods, such as sensitivity, possibility for continuous or periodic assessment of corrosion
27、 attack, available space, etc., should be considered when choosing the most suitable methods. Examples of suitable racks for exposure of specimens are given in Figure 1. Dimensions in millimetres Key 1 specimens 2 support 15 a) Sketch of a rack for sheltered exposure of specimens Figure 1 Examples o
28、f exposure racks with suggested dimensions BS ISO 11844-2:2005 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 3 Dimensions in millimetres Key 1 specimens 2 distance pins 3 plastic plates 4 open air flow 5 plastic screws b) Sketch of a mount
29、ing plate for unsheltered exposure of specimens Figure 1 (continued) BS ISO 11844-2:2005 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 Annex A (normative) Determination of corrosion rate by mass change measurement A.1 Principle Mass incr
30、ease measurements can be performed on all metals and comparatively large surfaces can be evaluated. The technique is relatively easy to operate. The mass loss determination gives a best estimate of the corrosion effect. The method is not yet applicable to all metals. Both mass increase and mass loss
31、 determination using an ultramicro-balance has a precision of about 10 mg/m2 with the method described below. Due to the difficulty of distinguishing corrosion effects from other surface-related phenomena, such as sorption and contamination by particulate matter, the specimens should preferably be e
32、xposed under shelter. A.2 Specimens It is preferable to use rectangular specimens in the form of flat sheets, as they can be readily weighed. A convenient specimen size is 10 mm 50 mm. Specimens may be larger provided that they can be accurately weighed. The specimen thickness may preferably be 0,5
33、mm. The materials used to prepare the specimens are of the following quality, Silver: 99,98 % min. Copper: ISO 1336-1337, Cu-DHP, 99,85 % min. Zinc: 99,45 % min. Carbon steel: ISO 3574, CR 1, max. 0,15 % C, max. 0,04 % P, max . 0,05 % S, max. 0,6 % Mn The specimens should, before weighing, be prepar
34、ed as follows: a) A hole with diameter 4 mm is cut at the upper side of the specimen. b) Abrading1) Silver and copper with silicon carbide paper to 1 200 P (600 grit). Zinc and carbon steel to 500 P (320 grit). c) Cleaning in deionised water. d) Degreasing in ethanol in an ultrasonic bath for 5 min.
35、 e) Drying. 1) To avoid risk of contamination, an abrading paper must not be used for polishing specimens of different metals. BS ISO 11844-2:2005 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 5 f) Store in plastic tubes with a hole in the
36、 top. The plastic tubes are placed in a desiccator or sealed into plastic bags with desiccant before and after the weighing and the exposure. After final surface cleaning before exposure, it is important that limited handling occurs. Before and after weighing, the specimens are placed in tubes and a
37、re only handled with a clean pair of tweezers. To avoid marking on the specimens, the identity of the specimens may preferably be marked on the tubes. A.3 Exposure The specimens shall be exposed vertically, either with or without a shelter against settling particles (see Figure 1). The specimens sha
38、ll be mounted between plastic plates or racks to permit free air circulation. A distance of a minimum of 10 mm between the surfaces and/or the surface and the mounting plate is recommended. The plastic racks or mounting plates are placed at a site with free air circulation, preferably at a height of
39、 1 m above the floor. The exposure should be performed in an area with airflow rates characteristic of the site. A map of specimen identity on the plastic rack, exposure date and location of the exposure rack should be established. The type of exposure, with or without a shelter, should be noted. Th
40、e test specimens (at least three) should be exposed preferably for one year but at least for six months. A.4 Mass increase The specimens shall be weighed on a micro-balance, with an accuracy of 0,1 g. Each test specimen is weighed twice in relation to a reference balance standard of stainless steel
41、having a similar mass to the specimen. The difference between the first mass of the test specimen m1 and the reference balance standard mr,1 is calculated as (mr,1 m1), and the difference between the second masses (mr,2 m2) is calculated in the same way. The mass of the test specimen is calculated i
42、n relation to the reference specimen as the average of the differences (m): r,11r,22 ()() 2 mmmm m + = where m is the mass of the test specimen in relation to the reference balance standard, in mg; m1 is the mass of the test specimen at first weighing, in mg; m2 is the mass of the test specimen at s
43、econd weighing, in mg; mr,1 is the mass of the reference balance standard at first weighing, in mg; mr,2 is the mass of the reference balance standard at second weighing, in mg. The same weighing procedure is performed both before and after the exposure of the specimens. After the exposure, the spec
44、imens should be carefully blown with oil-free compressed air or nitrogen to remove dust before the weighing. The rate of mass increase for each metal is given by the following equation: aebe mi mm r A t = BS ISO 11844-2:2005 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:39:50 GMT+00:00 2
45、006, Uncontrolled Copy, (c) BSI 6 where rmi is the rate of mass increase in mg/m2a mae is the mass of the test specimen in relation to the reference balance standard after exposure, in mg; mbe is the mass of the test specimen in relation to the reference balance standard before exposure, in mg; A is
46、 the surface area including both sides and edges, in m2; t is the exposure time; in years (with the unit symbol a). A.5 Mass loss The specimens shall be weighed on a micro-balance, with an accuracy of 0,1 g. The specimens are weighed in relation to a reference balance standard of stainless steel bef
47、ore exposure, see the description in Clause 3. After the exposure, the specimens are pickled in the following solutions: Silver: 750 ml hydrochloric acid (HCl, density = 1,18 g/ml). Distilled water to make up to 1 000 ml Copper: aqueous amidosulfonic acid (sulfamic acid) with a volume fraction of 5
48、% Zinc: saturated glycine solution Carbon steel: concentrated hydrochloric acid, 20 g/l Sb2O3, 50 g/l SnCl2. Measurement of the mass after repetitive cleaning cycles is the normal method for determining the mass loss of corroded specimens (see ISO 8407). In this part of ISO 11844, however, a simplif
49、ied procedure with the use of a blank is recommended, since the weighing of specimens on a micro-balance requires significant time compared to the usual weighing procedure. The pickling time depends on the severity of the corrosion attack but is usually 1 min to 2 min. The time should be long enough to ensure that the sample is clean and all corrosion products have been removed. During the pickling, an unexposed specimen (blank) of each materi