1、DEUTSCHE NORM March 1997 I Metallic and other non-organic coatings Sulfur dioxide test with general condensation of moisture (IS0 6988 : 1985) Enalish version of DIN EN IS0 6988 IEN IS0 6988 ICs 25.220.30; 25.220.40 Descriptors: Metal coatings, non-organic coatings, sulfur dioxide, corrosion Metalli
2、sche und andere anorganische berzge - Prfung mit Schwefeldioxid unter allgemeiner Feuchtigkeitskondensation (IS0 6988 : 1985) This standard, together with DIN 50018, March 1997 edition, supersedes January 1995 edition testing. European Standard EN IS0 6988: 1994 has the status of a DIN Standard. A c
3、omma is used as the decimal marker. National foreword This standard has been published in accordance with a decision taken by CENiTC 262 to International Standard IS0 6988 as a European Standard. d without Iteration, The responsible German body involved in its preparation was Technical Committee Kor
4、rosion und Korrosionsschufz of the Normenausschu Materialprfung (Materials Testing Standards Committee). It should be noted that the previous edition of DIN 5001 8 has been superseded by a revised edition, issued in March 1997, in which exposure conditions are covered that are relevant to the German
5、 market but have not been dealt with in the present standard. Amendments In comparison with DIN EN IS0 6988, January 1995 edition, the Superseding note has been amended. Previous edition DIN EN IS0 6988: 1995-01. EN comprises 7 pages. O No part of this standard may be reproduced without the prior pe
6、rmission of DIN Deutsches Institut fur Normung e.V., Berlin. Beuth Verlag GmbH, Berlin, has the exclusive right of sale for German Standards (DIN-Normen). Ref. No. DIN EN IS0 6988: 1997-03 English price group 07 Sales No. 7 7 O7 10.97 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN IS0 6988 Oct
7、ober 1994 ICs 25.220.30; 25.220.40 Descriptors: Metal coatings, non-organic coatings, sulfur dioxide, corrosion testing. English version Metallic and other non-organic coatings Sulfur dioxide test with general condensation of moisture (IS0 6988 : 1985) Revtements mtalliques et autres revtements non
8、organiques - Essai au dioxyde de soufre avec condensation gnrale de lhumidit (IS0 6988: 1985) Metallische und andere anorganische berzge - Prfung mit Schwefeldioxid unter allgemeiner Feuchtigkeits- kondensation (IS0 6988 : 1985) This European Standard was approved by CEN on 1994-10-26 and is identic
9、al to the IS0 Standard as referred to. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such n
10、ational standards may be obtained on application to the Central Secretariat or to any CEN member. The European Standards exist in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and
11、notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Por- tugal, Spain, Sweden, Switzerland, and the Un
12、ited Kingdom. GEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels O 1994. CEN - All rights of exploitation in any form and by any means reserved worldwide for CEN national members. Ref. No.
13、EN IS0 6988: 1994 E Page 2 EN IS0 6988: 1994 Foreword International Standard IS0 6988: 1985 Metallic and other non-organic coatings - Sulfur dioxide test with general condensation of moisture, which was prepared by ISO/TC 107 Metallic and other inorganic coatings of the International Organization fo
14、r Standardi- zation, has been adopted by Technical Committee CENTTC 262 Protection of metallic materials against corrosion as a European Standard. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, and conflicting na
15、tional standards withdrawn, by April 1995 at the latest. In accordance with the CENKENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norwa
16、y, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. Endorsement notice The text of the International Standard IS0 6988: 1985 was approved by CEN as a European Standard without any modifica- tion. NOTE: Normative references to international publications are listed in Annex ZA (normative)
17、. O Introduction Page 3 EN IS0 6988: 1994 3 Apparatus and material 0.1 Moist air containing sulfur dioxide quickly produces easily visible corrosion of many metals in a form resembling that occurring in industrial environments. It is therefore a test medium well suited to detect pores or other sourc
18、es of weakness in protective coatings and deficiencies in corrosion resistance associated with unsuitable alloy composition or treatments. The results obtained in the test should not be regarded as a direct guide to the corrosion resistance of the tested materials in all environments where these mat
19、erials may be used. Simi- larly, performances of different materials in the test should not be taken as a direct guide to the relative corrosion resistance of these materials in service. 0.2 The exposure conditions may be varied by either proceeding continuously or in cycles of alternate exposure to
20、 the sulfur dioxide-containing atmosphere and to the ambient atmosphere. 0.3 The variant of the test to be used, the test duration, the type of test specimen and the criteria of failure are not specified in this International Standard. Such details are provided in appropriate material and product sp
21、ecifications. 1 This International Standard specifies a method for assessing the resistance of materials or products to condensed moisture containing sulfur dioxide. The method has been found to be suitable for testing metallic and non-organic coatings. Scope and field of application NOTE - For test
22、ing paints and varnishes, see IS0 3231, Paints and varnishes - Determination of resistance to humid atmospheres containing sulphur dioxide. 2 References IS0 1462, Metallic coatings - Coatings other than those anodic to the basis metal - Accelerated corrosion tests - Method for the evaluation of the
23、results. IS0 4540, Metallic coatings - Coatings cathodic to the substrate - Rating of electroplated test specimens subjected to corrosion tests. 3.1 Test cabinet, of preferred capacity 300 f 10 dm3, with a door capable of being closed hermetically, and fitted with the components specified in 3.2, 3.
24、3 and 3.4. Typical test cabinets are shown in figures 1 and 2. NOTE - Test cabinets of capacities other than 300 f 10 dm3 may be used, provided that the other test conditions to which the test specimens are submitted are the same. The details and instructions given in this International Standard are
25、, however, appropriate to test cabinets of the preferred capacity and will require corresponding modifications for other capacities. 3.1.1 Matarials of construction All the materials used in the construction of the test cabinet shall be resistant to the action of moist sulfur dioxide and shall thems
26、elves not emit any gas or vapour likely to influence corro- sion of the test specimens. The floor and lower parts of the walls shall be capable of being heated and shall be able to retain without leakage at least 2.5 dm3 of water containing dissolved sulfur dioxide, this volume being required to flu
27、sh the apparatus. Lead-clad con- struction material is suitable for these parts and for the framework and fittings of the cabinet, but the greater part of the walls and door should be made of transparent sheet, such as glass or suitable plastics material. A new cabinet shall be operated at least onc
28、e, without in- troduction of test specimens, following the procedure ap- plicable to an atmosphere containing 2 dm3 of sulfur dioxide, before it is brought into use for testing. This should reduce risks of contamination of the atmosphere by vapours from the materials of construction. 3.1.2 Shape Som
29、e variation in the shape of the test cabinet can be tolerated, but the roof should be shaped so that moisture con- densing on it does not fall on test specimens in the test cabinet. An inclination of the roof of about 12O to the horizontal pro- vides a suitable safeguard. 3.1.3 Ambient conditions Th
30、e test cabinet shall be installed in a room in which there is a clean atmosphere and shall be protected from large or rapid temperature fluctuations, strong direct sunlight and draughts. (See also 6.5.2.1 Page 4 EN IS0 6988: 1994 3.2 Temperature-regulating device, with its actuating ele- ment placed
31、 in the upper part of the test cabinet, and a ther- mometer capable of being read from outside the cabinet with its bulb 150 mm from the roof and door and 250 mm from a side. 3.3 Gas inlet tube, through which gas can be introduced into the test cabinet, placed about 50 mm above the base, a valve, by
32、 which excess pressure can be relieved, placed in or near the roof of the cabinet, and a drain-cock in the floor of the test cabinet. 3.4 Heating device. capable of heating the test cabinet to 40 f 3 OC in 1,5 h and of maintaining the interior at this temperature. (See 6.5.) A 1 kW electrically heat
33、ed hotplate is suitable for the preferred size of test cabinet. 3.5 Source of sulfur dioxide, and means of measuring the volumes of gas required for delivery into the test cabinet. A container of liquid sulfur dioxide is the usual source, but the gas may be generated externally in suitable apparatus
34、 from sodium sulfite and sulfuric acid. The volume of gas delivered into the test cabinet may be measured by any suitable method, for example : a) by means of a gas burette using viscous liquid paraffin as the pressure-controlling fluid. As the volume to be measured will usually be 0.2 dd, measures
35、shall be taken to avoid errors from causes such as air contained in delivery tubes between the burette and the chamber; b) dioxide and opened in the chamber; ci by means of a gas jar of known volume filled with sulfur by means of a calibrated flowmeter. 4 Test specimens 4.1 The number, type, shape a
36、nd dimensions of test specimens, shall be selected according to the specification for the coating or product being tested. When not so specified, details concerning the specimens shall be agreed between the interested parties. (See 5.3.) 4.2 Thoroughly clean the test specimens before testing. The cl
37、eaning method employed will depend on the nature of the surface and the contaminants, but shall not include the use of any abrasives or solvents which may attack the surface of the test specimens. Take care that the test specimens are not recontaminated, after cleaning, by excessive or careless hand
38、- ling. 4.3 If test specimens are cut from a larger coated article, the cutting shall be carried out in such a way that the coating is not damaged, especially in the area adjacent to the cut. Unless otherwise specified, the cut edges shall be adequately pro- tected by coating them with a suitable me
39、dium, stable under the conditions of the test, such as wax or adhesive tape. 5 Method of exposure of test specimens 5.1 Place the test specimens in the cabinet. The distance be- tween the test specimens shall be not less than 20 mm, the distance between the test specimens and the walls or roof of th
40、e test cabinet shall be not less than 100 mm. The distance between the lower edges of the specimens and the surface of the water in the base of the test cabinet shall be not less than 200 mm. The surface area of contact between a test specimen and its holder shall be as small as possible. 5.2 Arrang
41、e the test specimens so that any moisture conden- sing on any of them or on their supports does not fall on to other test specimens placed at lower levels. 5.3 The orientation of the exposed test surface is critical. In the case of flat surfaces, the angle of inclination to the vertical, unless othe
42、rwise specified, shall be 15 f 2 “. 5.4 The total exposed surface area of the test cpecimen(s) tested at any one time should be substantially the same and, unless otherwise agreed, shall be 0.5 k 0,l m2 for the test cabinet of preferred capacity (see 3.1) and proportionately more or less for differe
43、nt sizes of cabinet. 5.5 The supports for the test specimens shall be of non- metallic material such as glass, plastics material or suitably coated wood. Any material used to suspend the test specimens in the cabinet shall be of synthetic fibre or other inert insulating material; metallic materials
44、shall not be used. 6 Procedure 6.1 Introduce 2 k 0,2 dm3 of distilled water, having a con- ductivity of 500 pS/m or less, into the base of the test cabinet. NOTE - The quantity of water deDends on the size of the test cabinet. A proportional change is valid only for test cabinets of similar shape. 6
45、.2 the test cabinet hermetically. Place the test specimens in position and close the door of 6.3 through the inlet pipe. Introduce 0.2 dm3 of sulfur dioxide into the test cabinet 6.4 Switch on the heater and raise the temperature inside the test cabinet to 40 i 3 OC in about 1,5 h. Maintain heating,
46、 under control, so as to keep the temperature inside the test cabinet at 40 f 3 OC for the specified period. 6.5 One test cycle is 24 h, but this may be made up either by continuous exposure of the test specimens inside the test cabinet or by exposure inside the test cabinet for 8 h, followed by exp
47、osure to the ambient atmosphere for 16 h. For either form of test, replace the water in the test cabinet and the sulfur dioxide in the test cabinet atmosphere before a 24 h cycle begins. Page 5 EN IS0 6988: 1994 6.5.1 For a test of continuous exposure in the test cabinet for longer than 24 h, replac
48、e the water and sulfur dioxide after each 24 h period of test with minimum disturbance to the test specimens. 6.5.2 For test specimens exposed to ambient conditions for part of the test cycle, the ambient conditions shall be those described in 3.1.3, with a temperature of 23 * 5 OC and a relative hu
49、midity of less than 75 YO. 7 Test duration The test duration shall be as given in the specification for the material or product being tested or as agreed between the pur- chaser and supplier. 8 At the end of the test period, remove the test specimens from the cabinet. Before they are examined, allow them to hang freely in a normal indoor atmosphere until any liquid corrosion products have solidified. First examine them with all corrosion products in position. Any cleaning carried out shall depend on the criteria laid down for the evaluation of the results of the test.
