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A number in parentheses indicates the year of last reapproval. A superscript epsilon e awtm an editorial change since the last revision or reapproval. It is based on experience in use of the method with standard by cm 4- by 6-in.
It has been used also for rating similar panels that have been subjected to accelerated tests such as those covered by Practice B wstm, Method BTest Method Band Test Method B It is not intended for use with anodic sacri? Current edition approved Oct. Originally approved in Last previous edition approved in as B — 70 Basis of Procedure 3.
ASTM B537 – 70(2013)
Although these functions overlap, they can be evaluated separately and it is frequently desirable to do so. Accordingly, this practice assigns separate ratings to 1 appearance as affected by corrosion of the substrate and 2 appearance as affected by b5377 of the coating itself. Original adjunct produced in Types of Defects 4. Assignment of Protection Rating 6. Peeling of the coating from the substrate, or of one coat from another, is the principal such defect.
ASTM B (Reapproved )e1_图文_百度文库
Preparation for and Manner of Inspection NOTE 4—It may be desirable to expose panels for test even though they are defective in certain respects before exposure.
In that case, an inspection should be made and recorded before the panels are exposed. Lighting during inspection should be as nearly uniform as possible; direct re? If dirt, salt deposits, and so forth, make it impractical to inspect them, panels may be sponged with a mild soap solution followed by water rinse; but no pressure should be exerted in this procedure such as would tend to upgrade the rating by, for example, cleaning off rust or rust stain. Panels should be allowed to dry before inspecting them.
R is rounded off to the nearest whole number, leading to the tabulation given in Table 1.
Rating 10, accordingly, is arbitrarily b57 to a panel with no defects, and the equation operates at ratings 9 and below. Fractional ratings below 9, although normally not especially useful, may be assigned if desired. These photographs and charts4 are 10 by 15 cm 4 by 6 in. The standards represent as nearly as possible the maximum amount of corrosion permissible for a given rating; there is a standard for each asfm 1 through 9.
A panel worse than the standard for rating 1 would rate 0. Typical decorative deposits exposed to marine atmospheres often tend to fail by crater rusting, whereas in industrial atmospheres, they are more likely to exhibit pinpoint rusting; and the latter atmosphere also tends to be more severe with regard to degradation of the coating system but somewhat less awtm with regard to basis metal corrosion. For this reason, the same standard comparison photographs or charts are not suitable for use at both types of locations; photographs are more helpful in assessing panels exposed to marine atmospheres, whereas dot charts can be used for industrial locations Appendix X2.
Similarly contact and rack marks, mounting holes, and so forth, should be disregarded. Such procedure shall be con? One method of facilitating this comparison is to remove individual panels from their racks and place them beside other panels. It may be advisable to physically arrange all of the panels in order to merit. Assignment of Appearance Rating 7. Therefore, the appearance rating cannot be assigned with the same degree of precision as can the protection rating.
Since corrosion of the substrate also detracts from appearance, the appearance rating can be no higher than the protection rating. If there are surface defects not accounted for in the protection rating, the appearance rating will be one or more asttm lower than the protection rating. Guidelines are given below, but judgment factors inevitably enter into the decision.
One point is assessed if the defects can be classi? NOTE 6—If fractional rating was used for the protection number, this would result in a fractional appearance rating; in that case the fractional appearance rating may be retained, or rounded off to the nearest whole number, provided, however, that the appearance rating may not be higher than the protection rating.
For example, surface pits that begin to detract from re? Difficulties may be encountered in attempting to rate severely corroded panels. For example, if a panel rates as low as 4 for protection, it may be difficult to assess any additional appearance defects. At the option of the inspector, this difficulty may be handled as follows: For example, it may asfm agreed that any panel with a protection rating of 5 is so unacceptable that an appearance rating has no meaning.
Such panels may arbitrarily be assigned one of two appearance ratings: Permanent or massive type of basis metal corrosion such as that in pinholes, bare, or?
Corrosion pits probably not extending through to the basis metal—that is absence of obvious basis metal corrosion products bleeding therefrom. Users of this standard are expressly advised that astn of the validity of any such patent ashm, and the risk of infringement of such rights, are entirely their own responsibility.
This standard is subject to revision at any time by the responsible technical committee and must be reviewed every? Your comments are invited either for revision of this standard or for additional standards atm should be addressed to ASTM International Headquarters. Your comments will receive careful consideration astn a meeting of the responsible technical committee, which you may attend.
If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm.