Skip to main content

Coupon test for corrosion inhibitors

Image
By

Concept

  • Coupon test is used to gauge a material's corrosion rate in a corrosive environment.
  • It is also used to test the efficiency of corrosion inhibitors.


Parameters

  • Material - The coupons are made from the same or similar material as that of the actual component
  • Electrolyte - The electrolyte for exposure is the same or similar to the actual environment. Sometimes, coupons are placed in the actual environment with the component, for example in the soil with submerged pipelines.


Steps

  1. Clean the coupon of any oil/grease/rust
  2. Measure the weight of original coupon - W
  3. Measure the Area of coupon to be exposed - A.
  4. Take photographs and/or optical micrographs of the coupon
  5. Immerse the coupon in the electrolyte without inhibitor
  6. Note the time of measurement - t. This is decided by the concerned parties or as per the standards followed.
  7. Take out the coupon after the time.
  8. Take photographs and/or optical micrographs of the coupon
  9. Clean the corrosion products off the coupon. DO NOT USE ROUGH POLISHING as it can remove the underlying pits and surface as well.
  10. Take photographs and/or optical micrographs of the coupon.
  11. Measure the final weight of the coupon again - Wf

To test the efficiency of an inhibitor, add the inhibitor to the electrolyte and then use a DIFFERENT COUPON.  Follow the above steps again.

Calculations

Weight loss Wo = Original weight W – final Weight Wf

corrosion rate C.R = weight loss W / Area A* time of exposure t

degree of surface coverage θ = (corrosion rate C.Ro without inhibitor– corrosion rate with inhibitor C.Rinhi) / corrosion rate without inhibitor C.Ro

inhibition efficiency (Einhi%) = (corrosion rate C.Ro without inhibitor– corrosion rate with inhibitor C.Rinhi) * 100 / corrosion rate without inhibitor C.Ro

For standard samples with the same Area A and time of exposure t, the C.R may be changed to weight loss W.


Watch the video here for detailed explanation!





😀Happy learning!😀

Labels:

Comments

Post a Comment

Welcome to the CORROSPECTIVE BLOG! Scroll along for more posts! Looking forward to your feedback!
P.S. Don't forget to check out the free quizzes!

Popular posts from this blog

Corrosion risk planning - 1 - Lead acid battery

By
Corrosion is a quality, environment, and safety issue. Hence, it has to come under the cope of integrated management system audits However at the moment, it is more or less considered a quality issue. As such, the general tendency is to solve corrosion issues as they come. Especially in new inventions, the foresight to look for potential corrosion risk gets lost in the attempt to focus and highlight the amazing qualities of the said inventions. Hence, I have initiated this series, where I will take a component and point out the potential corrosion and damage risk areas.  Here goes the first one - lead acid battery cell. (Source:https://opentextbc.ca/chemistry/chapter/17-5-batteries-and-fuel-cells/)  Protective casing -  effect of temperature + electrolyte + contamination in electrolyte on the polymer crevice corrosion at fixtures mechanical damage during handling leading to voids for moisture ingress and oxygen/electrolyte leakage Positive terminal - corrosion of the mate...
Post a Comment
Read more

CAREER OPTIONS IN CORROSION

By
  CAREER OPTIONS IN CORROSION The first time I studied corrosion was in 2009. The last 14 years have taught me one important thing - The path of a career in corrosion is not as straightforward as we are led to believe. Whether we are starting as a student of corrosion, or are entering the field after working as a non-corrosion person, there is always some career pathway that we are not aware of. There are research projects, certifications , audits, inspections , etc. EveryEng gave me the opportunity to share my learnings about the possible options in the field of corrosion . If you are someone who is starting or wants to switch to/between corrosion and its related fields, here is a short presentation for you! https://www.everyeng.com/mentor/course/view/3559864f 😀 Happy learning! 😀
Post a Comment
Read more