Alternate-Immersion Test

Definition - What does Alternate-Immersion Test mean?

An alternate immersion test is a method for assessing the corrosion resistance of metals in salt solution. The test is particularly suitable for quality control during the manufacture of materials.

Immersion testing is the most frequently conducted test for evaluating the corrosion rates of metals in aqueous solutions. The alternate immersion test applies to metals and all kinds of metallic and organic coatings.

Corrosionpedia explains Alternate-Immersion Test

There are two types of immersion testing:

  • Simple immersion test: This involves immersing a test specimen in a corrosive solution for a period of time and then removing the specimen for examination. It is also known as a "quick and dirty" test.
  • Alternate immersion test: This is a cyclic test procedure where a test specimen is immersed for a period of time in a test environment, then removed and dried, and then examined for corrosion rates before being re-immersing it and continuing the cycle. This cycle is repeated a number of times based on the real-time conditions.

ASTM G31 is a Standard Practice for Laboratory Immersion Corrosion Testing of Metals which describes standard factors including:

  • Test specimen preparation
  • Testing apparatus
  • Test conditions
  • Methods for cleaning specimens
  • Result evaluation
  • Basic calculation
  • Reporting corrosion rate

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