Patrick Richards Corrosion Test
Corrosivity is defined as the ability of a material to cause damage to another material across time. This basic measure of material performance is essential in a variety of industries, most notably petroleum refining and manufacturing. Corrosivity can cause physical damage to products, products that are used in their own production, or the infrastructure they depend on. For the extraction and refining of resources, the failure of materials due to corrosion has both safety and economic consequences. To measure and account for corrosivity, the Patrick Richards corrosion test, or P-R Test, is employed.
The P-R Test was invented by Patrick Richard in 1972 and is now a commonly used test for industrial application in corrosion testing. The test measures the corrosiveness of material in question as a function of the materials electrical conductivity, temperature, and the electrochemical properties of the material. The test is conducted in a laboratory setting, using a reaction chamber equipped with a measure of the material in question. The material is then exposed to an aqueous solution and a controlled voltage, inducing a current between the two. For the duration of the test, the electrical conductivity, temperature and potential of the material is continuously monitored.
The Patrick Richards Corrosion Test is conducted over a period of time, ranging from a few hours to a few weeks. During this time, the electrical properties of the material are monitored and recorded. Corrosivity is expressed as an index, or those parameters used to establish the rating. The results of the test are then expressed in units of mass loss per area, charge transfer rate or open circuit potential. The results of this test can then be used to calculate the time to failure of the component, or how quickly corrosion will take place.
The P-R Test has also been used to predict and calculate various corrosion problems, such as localized corrosion, corrosion fatigue, and stress corrosion cracking. This testing method has been adopted by the American Society for Testing and Materials (ASTM) to evaluate the corrosivity of materials. It is also used as an assessment tool by industries such as aerospace and pharmaceutical to evaluate the corrosivity of their components. The Patrick Richards Corrosion Test is widely used around the world and has become a critical element in many industries.
