What Does Immersion Test Mean?
Immersion tests measure the progress of corrosion damage obtained from the immersion length within a corrosive environment, as well as other factors that can accelerate the corrosion process.
These tests can involve alternative drying or immersions, such as in cases of cyclical tests. Moreover, test instrumentations may be included throughout immersion like electrochemical instrumentation connections in order to facilitate the measurements.
Immersion tests are capable of generating uniform data for alloy corrosion and are utilized in industries subjected to immersion conditions.
Corrosionpedia Explains Immersion Test
Environmental conditions that should be created and the acceleration degree needed usually identify which laboratory tests should be used. Proper acceleration is obtained by the following:
- Prolonging the exposure to vital conditions which are believed to lead to corrosion damage. For instance, if a certain vessel is to undergo batch processing with a chemical for 24 hours, the corrosion exposure in the laboratory should be 240 hours.
- Making the conditions more intense in order to boost corrosion rates. This can be achieved by increasing one or more of the following: pressure, salt concentration, temperature or solution acidity.
When the conditions for the environment have been identified and the test has been created, this should be conducted again several times to verify whether this test meets the acceptable reproducibility standard.
Generally, immersion tests can be separated into these categories:
- Alternate immersion test - This immersion test involves a cyclic procedure that involves a specimen being immersed for a certain period of time. Then, the specimen is removed and undergoes drying prior to re-submerging to the cycle. Typically, about a hundred cycles are completed throughout the test.
- Simple immersion test - In this test, small batches of the material are subjected to the medium under testing, while loss of weight is being gaged for a particular period.
The immersion test remains the most reliable method in terms of screening. It also serves as the most simple and economical way to determine the most suitable material to protect against corrosion in certain environments.