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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Cupric ions may also exhibit a passivating effect upon stainless steel coupons exposed at the same time. asmt
After final preparation of the specimen surface, the specimens should be stored in a desiccator until exposure, if they are not used immediately. The density in the asmt K cancels out the density in the corrosion rate equation. Therefore, at least duplicate specimens should normally be exposed in each test.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. These factors include specimen preparation, apparatus, test conditions, methods of cleaning specimens, evaluation of results, and calculation and reporting of corrosion rates.
However, the calculations must not be based on mass loss except in qualification tests such as Practices Awhich is usually small but on microsections which show depth of attack. Location of deposits, variations in types of deposits, or variations in corrosion products are extremely important in evaluating localized corrosion, such as pitting and concentration cell attack.
The degree of lateral spreading of pits may also be noted. A wstm atmospheric seal is required on the test vessel to prevent further contamination. However, the absence of cracking should not be interpreted as indicating resistance see 4. Where required, the exhausted constituents should be added or a fresh solution provided during the course of the test. In many such cases, corrosion rates are established by mass gain rather than mass loss. Localized corrosion is reported separately.
However, there are cases where this assumption is not valid. Molarity and normality are also helpful in defining the concentration of chemicals in some test solutions. Size px x x x x NOTE 1—The flask can be used as a versatile and convenient apparatus to conduct simple immersion tests. 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.
G 31 — 72 Reapproved Standard Practice for Laboratory Immersion Corrosion Testing of Metals1 This standard is issued under the fixed designation G 31; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision.
G1-72 solutions corrosive to glass, suitable metallic or plastic kettles may be employed. Configuration of top to flask is such that more sophisticated apparatus can be added as required by the specific test being conducted.
A typical resin flask setup for g331-72 type test is shown in Fig.
ASTM G31 – 72() Standard Practice for Laboratory Immersion Corrosion Testing of Metals
This practice, rather than a standardized procedure, is presented as a guide so that some of the pitfalls of such testing may be avoided. A large surface-to-mass ratio and a small ratio of asstm area to total area are desirable. This guide also emphasizes the importance of recording all pertinent data and provides a checklist for reporting test data.
Warning—In many cases the corrosion product on the reactive metals titanium and zirconium is a hard and tightly bonded oxide that defies removal by chemical or ordinary mechanical means. If agitation is required, the apparatus can be modified to accept a suitable stirring mechanism, such as a magnetic stirrer.
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 ability of the cladding to protect cut edges in the test solution. 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. Most tests related to process equipment should be run with the natural atmosphere inherent in the process, such as the vapors of h31-72 boiling liquid.
ASTM NACE / ASTMG31 – 12a Standard Guide for Laboratory Immersion Corrosion Testing of Metals
Thank you for interesting in our services. In practice, only alloys of the same awtm type should be exposed in the testing apparatus. It is imperative to note that this usually occurs with no significant loss in mass of the test coupon, although certain refractory metals are an exception to these observations. Preferably, the use of a reflux condenser ordinarily precludes the necessity of adding to the original kettle charge.
Extraneous effects can be encountered if the air xstm impinges on the specimens. This standard does not purport to address all of the safety concerns, if any, associated with its use. We are a non-profit group that run this website to share documents. The values given in parentheses are for information only. Interpretation of Results adtm This can be done by chemical treatment picklingelectrolytic removal, or by grinding with satm coarse abrasive paper or cloth such as No.
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.
Determination of Metal Corrosion Rate by ASTM G31-72. Canadian Laboratory
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. Other procedures that require the removal of solid corrosion products between exposure periods will not measure accurately the normal changes of corrosion with time.
This can be accomplished by analysis of the solution after corrosion has occurred. The phenomenon of forming a protective film is observed with many corrosion-resistant materials. Care should be used to avoid the removal of sound metal.
Methods of Cleaning Specimens after Test 9. Consequently, tests run for long periods are considerably more realistic than those axtm for short durations. 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.