ASTM G_Laboratory Immersion Corrosion Testing of Metals. August 18, | Author: Description. Designation: G 31 – 72 (Reapproved ). Buy ASTM G() Standard Practice for Laboratory Immersion Corrosion Testing of Metals from SAI Global. Offering ASTM G31 corrosion testing + modified tests to fit your needs and budget . Rapid, high-quality service by experts.
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The total surface area of a circular specimen is given by the following equation: If clad alloys are exposed, special procedures will be required to ensure that only the cladding is exposed, unless the purpose is to test the asrm of the cladding to protect cut edges in the test solution. If agitation is required, the apparatus can be modified to accept a suitable stirring mechanism, such as a magnetic stirrer.
It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
We need your help to maintenance this website. A liquid atmospheric seal is required on the test vessel to prevent further contamination. A method of electrolytic cleaning is described in Practice G 1. Active view current version of standard.
There are a number of other special types of phenomena of which one must be aware in the design and interpretation of corrosion tests. The actual time of contact of the metal with the solution must also be taken into account. If the specific effects of high velocity are to be studied, special techniques must be employed to transfer the 2. These factors include oxygen concentration, temperature, rate of flow, pH value, composition, and other important characteristics of the solution.
The choice of a specific treatment must be considered on the basis of the alloy to be tested and the reasons for testing.
These factors include specimen preparation, apparatus, test conditions, methods of cleaning specimens, evaluation of results, and calculation and reporting of corrosion rates. Consequently, tests run for long periods are considerably more realistic than those conducted for short durations.
With a thickness of approximately 3 mm 0. These ratios can be achieved through the use of square or circular specimens of minimum thickness.
ASTM G_Laboratory Immersion Corrosion Testing of Metals – Free Download PDF
Generally, if cracking is observed on the coupon, it can be taken as positive indication of susceptibility, whereas failure to effect this phenomenon simply means that it did not occur under the duration and specific conditions of the test.
One purpose for this guide is to promote better correlation of results in the future and the reduction of conflicting reports through a more detailed recording of meaningful factors and conditions. Occasional exceptions, in which a large difference is observed, can occur under conditions of borderline passivity of metals or alloys that depend on a passive film for their resistance to corrosion. The procedures for determining these values are shown in detail in Test Methods E 8.
ASTM G31-72_Laboratory Immersion Corrosion Testing of Metals
The reporting of nonuniform corrosion is discussed below. It should be used as a reference to ensure that the test will allow generation of data relevant to the application with the minimum of interferences. However, there are cases where this assumption is not valid. For example, lead exposed to sulfuric acid corrodes at an extremely high rate at first, while building a protective film; then the rates decrease considerably so that further corrosion is negligible.
The corrosion rate can be calculated from the concentration of the matrix metal found in the solution and it can be compared to that determined from the mass loss of the specimens. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. For relatively soft metals such as aluminum, magnesium, and copperscrubbing with abrasive powder is not always needed and can mar the surface of the specimen.
This cannot be evaluated by mass loss alone. This guide also emphasizes the importance of recording all pertinent data and provides a checklist for reporting test data. It is necessary to evaluate this localized corrosion separately from the overall mass loss. Therefore, short tests on such materials would indicate a high corrosion rate and be completely misleading.
Most tests related to process equipment should be run with the natural atmosphere inherent in the process, such as the vapors of the boiling liquid. For solutions corrosive to glass, suitable metallic or plastic kettles may be employed. Excellent references for the use of statistics in corrosion studies include Ref. Size px x x x x It is impractical to propose an inflexible standard laboratory corrosion testing procedure for general use, except for material qualification tests where standardization is required.
Any necessary distortion of the test conditions must be considered when interpreting the results. These changes should be determined if possible.
Significance and Use 3. If clad alloy specimens are to be used, special attention asgm be given to ensure that excessive metal is not removed. In special cases for example, for aluminum and certain copper alloysa minimum of 24 h storage in a desiccator is recommended.
It is impractical to propose an inflexible standard laboratory corrosion testing procedure for general use, except for material qualification tests where standardization is obviously required.
Immersion Corrosion Testing According to ASTM G31 Standard
We need your help! This practice also emphasizes the importance of recording all pertinent data and provides a checklist for reporting test data. It should be observed, however, that galvanic corrosion can be greatly affected by the area ratios of the respective metals, the distance between the metals and the resistivity of the electrolyte.
For other degrees of aeration, the solution should be sparaged with air or synthetic mixtures of air or oxygen with an inert gas. For example, the accumulation of cupric ions in the testing of copper alloys in intermediate strengths of sulfuric acid will accelerate the corrosion of copper alloys, as compared to the rates that would be obtained if the corrosion products were continually removed.