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Industry engineers state that the ideal corrosion test should be simple, rapid, low cost and able to predict long-term service behaviour. The two most common techniques used which satisfy these requirements are corrosion coupons and probes.

The corrosion coupon is one of the most useful tools for monitoring corrosion. Coupons are of a predetermined shape, size and surface area, and are typically made of a metal of similar chemical composition to that of the process equipment. Their weight and surface preparation is recorded before insertion into the process stream, and they are then re-weighed and visually analyzed after a set exposure period. Lab analysis provides the corrosion rate (mpy), observations (before and after cleaning) and measurements regarding visual damage (such as pitting and scaling).

Corrosion coupons have many advantages. Coupons provide accurate results at a reasonable cost. They are simple to use and are able to provide general information that is both quantitative and visual on several types of corrosion, without relying on theoretical approximations. Coupons are also extremely versatile, as they can be used in any type of corrosive environment.

Corrosion coupon analysis usually forms the basis of any corrosion monitoring program.

To view the technical catalog sheet on Corrosion Coupons (Click here)
For more information on laboratory analysis of coupons (Click here)

There are various designs of probes that use proven scientific methods to measure corrosion. The most common types of probes are electronic. Linear Polarization Resistance and Electrical Resistance are two examples of widely used electronic probes. Other probes, such as hydrogen probes, measure hydrogen transmission or diffusion that can lead to mechanical damage, while sand probes measure erosion.

Almost all probes have electrical connections that allow them to connect to electronic instruments or remote monitoring systems.

The advantage of probes is that they typically provide faster response than corrosion coupons, allowing better identification of the moment that the corrosion rate changed. They also provide quantitative data on the rate of corrosion, which can be translated into impacts, such as wall thickness loss per annum.

To view the technical catalog section on Probes (Click here)