ASTM G_Laboratory Immersion Corrosion Testing of Metals – Free download as PDF File .pdf), Text File .txt) or read online for free. ASTM G Other ASTM procedures for laboratory corrosion tests are tabulated in the Appendix. NOTE 1—Warning: In many cases the corrosion product on the reac-. ASTM G Standard Practice for Laboratory Immersion Corrosion Testing of Metals_能源/化工_工程科技_专业资料. 暂无评价|0人阅读|0次.
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Cupric ions may also exhibit a passivating effect upon stainless steel coupons exposed at the same time. With borderline conditions, a prolonged test may be astk to permit breakdown of the passive?
Corrosion testing by its very nature precludes complete standardization. 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.
The most common testing periods are 48 to h 2 to 7 days.
If metallic contamination of the stamped area may in? 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.
A distinction should be made between those occurring underneath the supporting devices concentration cells and those on the surfaces that were freely exposed to the test solution see Guide G Scrubbing with a bristle brush and mild abrasive is the most popular of these methods. Therefore, at least duplicate specimens should normally be exposed in each test.
For example, lead exposed to sulfuric acid corrodes at an extremely high rate at? However, the absence of cracking should not be interpreted as indicating resistance see 4. 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.
It should be used as a reference to ensure that asym test will allow generation of data relevant to the application with the minimum of interferences.
The amount of possible contamination can be estimated from the loss in mass of the specimen, with proper application of the expected relationships among 1 the area of corroding surface, 2 the mass of the chemical product handled, and 3 the duration of contact of a unit of mass of the chemical product with the corroding surface.
A liquid atmospheric seal is required on the test vessel to prevent further contamination. The mass loss during the test period can be used as atsm principal measure of corrosion. Consequently, tests run for long periods are considerably more realistic than those conducted for short durations.
ASTM NACE / ASTMG31 – 12a Standard Guide for Laboratory Immersion Corrosion Testing of Metals
These changes should be determined if possible. The actual time of contact of the metal with the solution must also be taken into account. A method of electrolytic cleaning is described in Practice G 1. Circular specimens should preferably be cut from sheet and not bar stock, to minimize the exposed end grain. Solvents such as acetone, carbon tetrachloride, and alcohol are used to remove oil, grease, or resin and are usually applied prior to other methods of cleaning.
Proper ultrasonic procedures are an g13 alternate.
Using the above units for T, A, W, and D, the corrosion rate can be calculated in a variety of units with the following appropriate value of K: These factors include apparatus, sampling, test specimen, test conditions test solution composition, temperature, gas sparging, fluid motion, solution volume, method of supporting test specimens, duration of testmethods of cleaning test specimens, interpretation of results, and calculation of corrosion rates.
A number in parentheses indicates the year of last reapproval. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every? Measurement of percent elongation is a useful ast of embrittlement. A commercial surface may sometimes yield the most signi?
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. Originally approved in For relatively soft metals such y31 aluminum, magnesium, and copperscrubbing with abrasive powder is not always needed and can mar the surface of the specimen.
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 clad alloy specimens are to be used, special attention must be given to ensure that excessive metal is not removed. Molarity and normality are also helpful in de?
Active view current version of standard. G 31 — 72 The phenomenon of forming a protective? Oxygen saturation is a function of the partial pressure of oxygen in the gas. Last previous edition approved in as G 31 — 72 Warning—In many cases the corrosion product on the reactive metals titanium and zirconium is a hard and tightly bonded oxide that axtm In many such cases, corrosion rates are established by mass gain rather than mass loss.
Asm standard, rather than a standardized procedure, is presented as a guide so that some of the pitfalls of such testing may be avoided. F31 special cases for example, for aluminum and certain copper alloysa minimum of 24 h storage in a desiccator is recommended. 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.
For other degrees of aeration, the solution should be sparaged with air or synthetic mixtures of air or oxygen with an inert gas. This practice also emphasizes the importance of recording all pertinent data and provides a checklist for reporting test data. It is impractical to propose an in? Chemicals are chosen for application to a speci? A superscript epsilon e indicates an editorial change since the last revision or reapproval.
Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. Extraneous effects can be encountered if the air stream impinges on the specimens. This standard does not purport to address all of the safety concerns, if any, associated with its use.
Calculating Corrosion Rates Methods of Cleaning Specimens after Test 9.