ASTM B117-2018 Standard Practice for Operating Salt Spray (Fog) Apparatus.pdf

1、Designation: B117 16B117 18Standard Practice forOperating Salt Spray (Fog) Apparatus1This standard is issued under the fixed designation B117; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in p

2、arentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This practice covers the apparatus, procedure, and condition

3、s required to create and maintain the salt spray (fog) testenvironment. Suitable apparatus which may be used is described in Appendix X1.1.2 This practice does not prescribe the type of test specimen or exposure periods to be used for a specific product, nor theinterpretation to be given to the resu

4、lts.1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establ

5、ish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Princ

6、iples for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2B368 Test Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Test)D609 P

7、ractice for Preparation of Cold-Rolled Steel Panels for Testing Paint, Varnish, Conversion Coatings, and Related CoatingProductsD1193 Specification for Reagent WaterD1654 Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive EnvironmentsE70 Test Method for pH of Aqueous So

8、lutions With the Glass ElectrodeE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodG85 Practice for Modified Salt Spray (Fog) Testing3. Significance and Use3.1 This practice provides a controlled corrosive environment which has been utilized to produce r

9、elative corrosion resistanceinformation for specimens of metals and coated metals exposed in a given test chamber.3.2 Prediction of performance in natural environments has seldom been correlated with salt spray results when used as standalone data.3.2.1 Correlation and extrapolation of corrosion per

10、formance based on exposure to the test environment provided by thispractice are not always predictable.3.2.2 Correlation and extrapolation should be considered only in cases where appropriate corroborating long-term atmosphericexposures have been conducted.3.3 The reproducibility of results in the s

11、alt spray exposure is highly dependent on the type of specimens tested and theevaluation criteria selected, as well as the control of the operating variables. In any testing program, sufficient replicates should1 This practice is under the jurisdiction ofASTM Committee G01 on Corrosion of Metals and

12、 is the direct responsibility of Subcommittee G01.05 on Laboratory CorrosionTests.Current edition approved March 15, 2016Aug. 1, 2018. Published April 2016October 2018. Originally approved in 1939. Last previous edition approved in 20112016 asB117 11.B117 16. DOI: 10.1520/B0117-16.10.1520/B0117-18.2

13、 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to

14、provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof

15、the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1be included to establish the variability of the results. Variability has been observed when similar specimens

16、are tested in differentfog chambers even though the testing conditions are nominally similar and within the ranges specified in this practice.4. Apparatus4.1 The apparatus required for salt spray (fog) exposure consists of a fog chamber, a salt solution reservoir, a supply of suitablyconditioned com

17、pressed air, one or more atomizing nozzles, specimen supports, provision for heating the chamber, and necessarymeans of control. The size and detailed construction of the apparatus are optional, provided the conditions obtained meet therequirements of this practice.4.2 Drops of solution which accumu

18、late on the ceiling or cover of the chamber shall not be permitted to fall on the specimensbeing exposed.4.3 Drops of solution which fall from the specimens shall not be returned to the solution reservoir for respraying.4.4 Material of construction shall be such that it will not affect the corrosive

19、ness of the fog.4.5 All water used for this practice shall conform to Type IV water in Specification D1193 (except that for this practice limitsfor chlorides and sodium may be ignored). This does not apply to running tap water. All other water will be referred to as reagentgrade.NOTE 1Water used wit

20、h a conductivity 1.0 S/cm (or resistivity 1.0 Mcm) may cause damage to some equipment due to the reactive nature ofthe water. In addition, it may cause issues with stabilizing pH measurements.5. Test Specimens5.1 The type and number of test specimens to be used, as well as the criteria for the evalu

21、ation of the test results, shall be definedin the specifications covering the material or product being exposed or shall be mutually agreed upon between the purchaser andthe seller.6. Preparation of Test Specimens6.1 Specimens shall be suitably cleaned. The cleaning method shall be optional dependin

22、g on the nature of the surface and thecontaminants. Care shall be taken that specimens are not recontaminated after cleaning by excessive or careless handling.6.2 Specimens for the evaluation of paints and other organic coatings shall be prepared in accordance with applicablespecification(s) for the

23、 material(s) being exposed, or as agreed upon between the purchaser and the supplier. Otherwise, the testspecimens shall consist of steel meeting the requirements of Practice D609 and shall be cleaned and prepared for coating inaccordance with the applicable procedure of Practice D609.6.3 Specimens

24、coated with paints or nonmetallic coatings shall not be cleaned or handled excessively prior to test.6.4 Whenever it is desired to determine the development of corrosion from an abraded area in the paint or organic coating, ascratch or scribed line shall be made through the coating with a sharp inst

25、rument so as to expose the underlying metal beforetesting. The conditions of making the scratch shall be as defined in Test Method D1654, unless otherwise agreed upon betweenthe purchaser and the seller.6.5 Unless otherwise specified, the cut edges of plated, coated, or duplex materials and areas co

26、ntaining identification marksor in contact with the racks or supports shall be protected with a suitable coating stable under the conditions of the practice.NOTE 2Should it be desirable to cut test specimens from parts or from preplated, painted, or otherwise coated steel sheet, the cut edges shall

27、beprotected by coating them with paint, wax, tape, or other effective media so that the development of a galvanic effect between such edges and the adjacentplated or otherwise coated metal surfaces, is prevented.7. Position of Specimens During Exposure7.1 The position of the specimens in the salt sp

28、ray chamber during the test shall be such that the following conditions are met:7.1.1 Unless otherwise specified, the specimens shall be supported or suspended between 15 and 30 from the vertical andpreferably parallel to the principal direction of flow of fog through the chamber, based upon the dom

29、inant surface being tested.7.1.2 The specimens shall not contact each other or any metallic material or any material capable of acting as a wick.7.1.3 Each specimen shall be placed to permit unencumbered exposure to the fog.7.1.4 Salt solution from one specimen shall not drip on any other specimen.N

30、OTE 3Suitable materials for the construction or coating of racks and supports are glass, rubber, plastic, or suitably coated wood. Bare metal shallnot be used. Specimens shall preferably be supported from the bottom or the side. Slotted wooden strips are suitable for the support of flat panels.Suspe

31、nsion from glass hooks or waxed string may be used as long as the specified position of the specimens is obtained, if necessary by means ofsecondary support at the bottom of the specimens.8. Salt Solution8.1 The salt solution shall be prepared by dissolving 5 6 1 parts by mass of sodium chloride in

32、95 parts of water conformingto Type IV water in Specification D1193 (except that for this practice limits for chlorides and sodium may be ignored). CarefulB117 182attention should be given to the chemical content of the salt. The salt used shall be sodium chloride with not more than 0.3 % bymass of

33、total impurities. Halides (Bromide, Fluoride, and Iodide) other than Chloride shall constitute less than 0.1 % by mass ofthe salt content. Copper content shall be less than 0.3 ppm by mass. Sodium chloride that has had anti-caking agents added shallnot be used because such agents may act as corrosio

34、n inhibitors. See Table 1 for a listing of these impurity restrictions. Uponagreement between the purchaser and the seller, analysis may be required and limits established for elements or compounds notspecified in the chemical composition given above.8.2 The pH of the salt solution shall be such tha

35、t when atomized at 35C (95F) the collected solution will be in the pH rangefrom 6.5 to 7.2 (Note 4). Before the solution is atomized it shall be free of suspended solids (Note 5). The pH measurement shallbe made at 23 6 3C (73 6 5F) using a suitable glass pH-sensing electrode, reference electrode, a

36、nd pH meter system inaccordance with Test Method E70. pH measurement shall be recorded once daily (except on weekends, or holidays when the saltspray test is not interrupted for exposing, rearranging, or removing test specimens or to check and replenish the solution in thereservoir. The maximum inte

37、rval between pH measurements shall not exceed 96 h). Only diluted, reagent grade hydrochloric acid(HCl) or reagent grade sodium hydroxide (NaOH) shall be used to adjust the pH.NOTE 4Temperature affects the pH of a salt solution prepared from water saturated with carbon dioxide at room temperature an

38、d pH adjustment maybe made by the following three methods:(1) When the pH of a salt solution is adjusted at room temperature, and atomized at 35C (95F), the pH of the collected solution will be higher thanTABLE 1 Maximum Allowable Limits for Impurity Levels inSodium ChlorideA,B,CNOTE 1Ameasurable li

39、mit for anti-caking agents is not being definedas a result of how salt is manufactured. During salt manufacturing, it iscommon practice to create salt slurry from the raw salt mined. Acrystallization process then captures the pure salt from this slurry. Somenaturally occurring anti-caking agents can

40、 be formed in this process andare not removed from the resultant product. Avoid salt products whereextra anti-caking agents are added.Additionally, when doing an elementalanalysis of salt, there can be trace elements present that are either astand-alone element or part of an anti-caking agent. It is

41、 not economicallyfeasible to know where such elements came from due to the long list ofpossible anti-caking agents for which there would have to be testing.Therefore, a salt product that meets the impurity, halide, and copper limitswith no anti-caking agents added will be acceptable. The salt suppli

42、er canprovide an analysis of the salt with a statement indicating that anti-cakingagents were not added to the product.Impurity Description Allowable AmountTotal Impurities # 0.3 %Halides (Bromide, Fluoride and Iodide) excluding Chloride 99.9%, then the limits for halides can be ignored.This is due

43、to the fact that the halides cannot be $0.1% with a salt purity of99.9%. If the salt used is of lower purity, then test for halides.B117 183the original solution due to the loss of carbon dioxide at the higher temperature. When the pH of the salt solution is adjusted at room temperature, it istheref

44、ore necessary to adjust it below 6.5 so the collected solution after atomizing at 35C (95F) will meet the pH limits of 6.5 to 7.2. Take about a 50-mLsample of the salt solution as prepared at room temperature, boil gently for 30 s, cool, and determine the pH. When the pH of the salt solution is adju

45、stedto 6.5 to 7.2 by this procedure, the pH of the atomized and collected solution at 35C (95F) will come within this range.(2) Heating the salt solution to boiling and cooling to 35C (95F) and maintaining it at 35C (95F) for approximately 48 h before adjusting the pHproduces a solution the pH of wh

46、ich does not materially change when atomized at 35C (95F).(3) Heating the water from which the salt solution is prepared to 35C (95F) or above, to expel carbon dioxide, and adjusting the pH of the saltsolution within the limits of 6.5 to 7.2 produces a solution the pH of which does not materially ch

47、ange when atomized at 35C (95F).NOTE 5The freshly prepared salt solution may be filtered or decanted before it is placed in the reservoir, or the end of the tube leading from thesolution to the atomizer may be covered with a double layer of cheesecloth to prevent plugging of the nozzle.NOTE 6The pH

48、can be adjusted by additions of dilute ACS reagent grade hydrochloric acid or sodium hydroxide solutions.9. Air Supply9.1 The compressed air supply to the Air Saturator Tower shall be free of grease, oil, and dirt before use by passing throughwell-maintained filters (Note 7). This air should be main

49、tained at a sufficient pressure at the base of theAir Saturator Tower to meetthe suggested pressures of Table 2 at the top of the Air Saturator Tower.NOTE 7The air supply may be freed from oil and dirt by passing it through a suitable oil/water extractor (that is commercially available) to stop anyoil from reaching the Air Saturator Tower. Many oil/water extractors have an expiration indicator, proper preventive maintenance intervals should takethese into account.9.2 The compressed air supply to the atomizer nozzle or nozzles shall be conditio