Description. ASTM G Standard Practice for Calculation of Corrosion Rates and Related Information from Electrochemical Measurements. View more. ASTM G()e1. Standard Practice for Calculation of Corrosion Rates and Related Information from Electrochemical Measurements. ASTM-G Standard Practice for Calculation of Corrosion Rates and Related Information from Electrochemical Measurements – corrosion.
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Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk t102 infringement of such rights, are entirely their own responsibility.
See Refs for more information. Some approaches for estimating this information are given. The estimation of a B value for situations involving mixed control requires more information in general and is beyond the scope of this standard. This is equivalent to the calculation shown in 4. Although the conversion of these current values into mass loss rates or penetration rates is based ast, Faraday’s Law, the calculations can be complicated for alloys and metals with aetm having multiple valence values.
ASTM D standar It is best if an independent technique can be used to establish the proper valence for each alloying element. Another approach is to asgm or estimate the electrode potential of the corroding surface. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Other units may be used in this calculation.
NOTE 4—Electrodes exhibiting stable passivity will behave as if the anodic reaction were diffusion limited, except that the passive current density is not affected by agitation. The conversion of asstm results to either mass loss or penetration rates requires additional electrochemical information.
The capacitance charging effect will cause the calculated polarization resistance to be in error. Normally only elements above 1 mass percent in the alloy are included in the calculation.
Some typical values of equivalent weights for a variety of metals and alloys are astj. A sample calculation is given in Astmm X6. W 5 the atomic weight of the element, and n 5 the number of electrons required to oxidize an atom of the element in the corrosion process, that is, the valence of the element.
In the case of galvanic couples, the exposed area of the anodic specimen should be used. This practice is intended to provide guidance in calculating mass loss and penetration rates for such alloys.
ASTM G Standard Practice – Free Download PDF
NOTE 4— Eq 4 was used to make these calculations. Calculation methods for converting corrosion current density values to either mass loss rates or average penetration rates are given for most engineering alloys.
A sample calculation is given in Appendix X2 1. Originally published as G — Current edition approved Feb.
A superscript epsilon e indicates an editorial change since the last revision or reapproval. This will cause either the anodic or cathodic b value to appear smaller than the corrosion reaction above. Link to Active Adtm link will always route to the current Active version of the standard. In addition, some guidelines for converting polarization resistance values to corrosion rates are provided.
ASTM G102 Standard Practice
It is assumed that the current distributes uniformly across the area used in this calculation. Consider a unit mass of alloy oxidized. Astn approaches have been proposed based on analyses of electrode kinetic models. In general, Eq 7 and Eq 8 may be used, and the corrosion rate calculated by these two approximations may be used as lower and upper limits of the true rate.
A sample calculation is given wstm Appendix X1. In general, Tafel slopes are given by NOTE 2—Some of the older publications used inaccurate thermodynamic data to construct the diagrams and consequently they are in error.