Different Corrosion Testing Methods

by Corinne Crawford

Corrosion testing is an important engineering function. It’s usually required when selecting the right materials for a specific application. Each type of alloy is exposed to different environments to see how they fare and better understand how and what makes them corrode. 

Corrosion testing can be done at the laboratory or in the field. Every setting has its advantages and drawbacks. Field testing makes it easier to predict potential issues at the workplace site or in real-world applications. On the other hand, laboratory testing can make it faster to achieve the desired environmental setting. 

Let’s talk more about different corrosion testing methods in this post.

  1. Visual examination. Corrosion levels can be determined through visual examinations. Devices, such as x rays and microscopes, are used to gather accurate measurements. When evaluating corroded surfaces, inspectors look at the density of pits – the number, depth, and thickness loss. There are also specific tools to help carry out these processes. 
  1. Immersion testing. During immersion testing, materials are submerged in water or different types of liquids to see how they respond. Other factors can also be monitored during the process. Immersion testing is known as one of the simplest types of corrosion testing. First, corrosive products or contaminants are removed before samples. Product resistance is determined by calculating the weight or thickness lost. Several factors can affect the results, such as the duration of exposure and the amount of area exposed to corrosives. 
  1. Fog testing. Fog testing is another commonly-used method to evaluate corrosion. How long samples can resist corrosion is measured to know more about their durability. They’re exposed to a salt or fog environment for a certain number of hours. If they pass the test, they may be used for production. If none of the samples meet the requirements, it’s a sign that there may be something wrong with the pre-treatment process. The longer samples are exposed, the larger the potential losses too. Overall, since the process is quicker and cheaper, it also helps manufacturers and engineers make quick comparisons between samples. One downside of this method, though, is it doesn’t simulate real-world conditions. Hence, it doesn’t offer much help in finding out how materials shall be delivered in actual situations.
  1. Electrical resistance. Electrical resistance testing is performed following the principle that electrical resistance can increase if the thickness of a material is reduced. Hence, changes in the electrical resistance of metals are monitored over time. This is a field test, and the electrical resistance (ER) probes and tools can also be used in various types of settings. The probes help measure metal loss due to corrosion and can be produced to fit the type of metal or environment being tested. Another advantage of probes is that they can be portable, which allows testing to be easily done in different locations.

There are several other corrosion testing methods available. It’s very important to perform this test to ensure product safety, improve efficiency, and reduce overall costs in your industry. It helps predict potential issues at the site, which, in turn, prevents damages, injuries, or accidents. Talk to a reputable controlled environment specialist for more information on proper corrosion testing methods.

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