Pharma Engineering

For Engineer By Engineer

• Wednesday, 18 November 2020

H
iii All ......!!!

Tested positive for Covid & back after a gap. Hope everyone is safe and healthy. Today i want to post related to corrosion and testing.
This is going to be a simple post and the corrosion rate estimator shall be included in our android app.
Hope everyone reading this has installed the app, if not get a copy at,

Let's get back into topic, estimating the corrosion rate through testing. Before that lets check out some of the vocabulary and the testing procedure.

What is Corrosion ?

Corrosion is a process where a pure metal will gain a stable form through a chemical reaction, mostly it can be oxidation or forming hydroxides / sulphides. This can be due to environmental effect, incompatibility etc. This will destroy the metal surfaces gradually.

What is the test for corrosion ?

Coupon test.

What is the testing procedure ?

Placing a piece of metal with known dimensions and weight in the medium to which we need to check the compatibility for certain period of time.

Let's start the calculation with some considered / assumed input:

Dimensions be: L - 0.8 cm; B - 0.6 cm; W - 0.6 cm;

Initial weight: 3.000 g, Final weight: 2.975 g;

Testing time: 3 days.

Calculation begins here:

Weight loss per day = (3.000 - 2.975) / 3 = 0.00833 g/day,

Total surface area = 2 x ( (0.8 x 0.6) + (0.6 x 0.6) + (0.6 x 0.8) ) = 2.64 cm2

Total volume = 0.8 x 0.6 x 0.6 = 0.288 cm3

Density = 3.000 / 0.288 = 10.42 g/cm3

Corrosion rate = (Weight loss / day) / (Total surface area x Density) = 0.00833 / (2.64 x 10.42)
= 0.000303 cm/day = 1.11 mm/year

Half of the job is done by now,

Remaining job is interpretation, which can be done based on below tabulation:

< 0.75        mm/year  - Acceptable;
0.75 - 1.53 mm/year  - Acceptable for short periods
> 1.53        mm/year  - Not Acceptable

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A
bout The Author

Hi! I am Ajay Kumar Kalva, Currently serving as the CEO of this site, a tech geek by passion, and a chemical process engineer by profession, i'm interested in writing articles regarding technology, hacking and pharma technology.