Want this as a site license? Changes from the previous issue A redline edition is available for this document, with all changes visible. Ask Document Center Inc. Scope 1. The two fundamental properties are electrode oxidation potential and ampere hours Ah obtained per unit mass of specimen consumed. The calcium sulfate, magnesium hydroxide test electrolyte simulates the long term environment around an anode installed in the gypsum-bentonite-sodium sulfate backfill.
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People often say to us, magnesium is magnesium — what is the difference. Herein lies the problem. The largest stakeholders in the entire process is often not exactly sure what they are buying. For all they know, there could be a large rock inside the bag. The purpose of a magnesium anode is to protect a piece of valuable equipment from corrosion.
The quality of magnesium directly relates to the value of protection afforded by the Cathodic Protection system. When you take a look at the below budget for installing magnesium anodes, it is clear that paying a couple cents more up front for quality anodes that meet the amp hours standard of the ASTM G97 test pays for itself even before the first year of service.
Below is a sample budget for a 50 anode installation, taking 3 men one day to complete 24 man hours. This value was chosen for illustrative purposes only, and in no way claims any one manufacturer consistently manufactures anodes of this quality. So what does this tell us? Of these charges, the difference in price between an anode meeting the industry requirement of 1. The next step is calculating the life of the equipment being protected.
During that 20 year life span the magnesium anodes would likely have to be replaced about 2 times, once after 7 years and again after 14 these are only estimates and soil types and other surrounding conditions will cause this to vary. If the first installation uses unacceptable anodes, you almost certainly will have to replace the anodes at least 3 times during the life of the equipment. Now this may be a very rudimentary calculation, but the basic principle will always hold true.
For a more detailed analysis, please view this PDF which breaks the process down further G97 Explained Write a Comment Your email address will not be published.
More G The degree of correlation between this test and service performance has not been fully determined. A method of ensuring that identical test specimens are being evaluated is to retest a test specimen. The surface of the test specimen should be smoothed by machining before retesting. The new diameter should be measured and the test current adjusted so that the retest current density is 0. It is unlikely that field results of Ah per unit mass consumed would ever be greater than those measured in this test.
Magnesium Quality – G97 Test Explained