Understanding Corrosion Testing Procedures

Corrosion can result in irreversible damage to the material and function of your cooling towers. This damage is not only expensive to repair, but can also cause a drop in production and possibly safety risks. It’s important to find your equipment’s corrosion rate to ensure you avoid excess damage. In this blog, we will discuss the following topics relating to corrosion testing procedures:

  • What is corrosion testing?

  • What is a corrosion coupon?

  • Coupon test periods

  • Coupon removal and evaluation

What is Corrosion Testing?

Corrosion testing is a set of standardized procedures and evaluations that are performed to help owners know how resistant their equipment is to corrosion. If your cooling tower material is corroding earlier than its expected life-cycle, you may consider switching to a new material or model. Corrosion testing can also help compare the durability of two different materials if you’re deciding which route you want to take in the construction process. The standard way to perform corrosion testing is with corrosion coupons.

What is a Corrosion Coupon?

Corrosion coupons are small metal strips that get mounted in a coupon rack — a pipe system designed to hold the coupons. These are used to estimate the rate of metal corrosion by comparing the initial weight of the equipment with the weight after a period of exposure to the water in the cooling tower. Corrosion coupons are an accurate and cost-effective method of conducting corrosion testing.

Coupon Test Periods

In order to get the most accurate test results, it’s best to leave your coupons installed for a specific period of time, usually 30 to 90 days. You may inspect your coupons during this time, but it’s important that you do not touch or remove them before the test period is over. For environments with low corrosivity, a longer test period is suggested.

Coupon Removal and Evaluation

After the specified test period, the coupons should be removed for evaluation. Notations should be made if any of the coupons are loose or off-center in the rack, as this could affect the test results. Once removed, gently dry with a paper towel, and then begin your evaluation. Weigh, take photos of, and record the appearance of the coupons. Finally, plug the weights into the following formula to find the corrosion rate (CR):

How Can CTI Assist With Your Cooling Tower Needs?

Cooling Technology Institute has published a plethora of papers about various cooling topics. CTI is also an advocate in promoting the use of environmentally responsible Evaporative Heat Transfer Systems (EHTS), cooling towers, and cooling technology for the benefit of the public. Additionally, CTI is an independent, third-party thermal performance testing to help participating manufacturers and owners/operators achieve the best performance from their cooling towers. Visit our website today for more information on cooling technologies!

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