# Problem 19 in 6-Minute Solutions



## JoeysVee (Sep 6, 2009)

Does anyone know where the equation they use to solve problem 19 is in the MERM? It's The rate of corrosion loss and is found using the formula R=87,600 *m/(rho*A*t)? Where in the MERM will I find this formula? I would like to read up on this material and become familiar enough to use it during the exam.

Thanks!

BTW, I'm using edition 1 of the 6-Min Solutions.


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## MechGale (Apr 2, 2010)

I know this was an older post, but I am working through this book and have no idea where that equation came from either. Hopefully someone out there knows? I've looked through my MERM, along with my other reference materials (Materials book from college included) and can't find any mention of this equation anywhere. I don't know if that 87,600 is always used for corrosion loss, or if it is specific to nickel. Can anyone help with this? If something like this is on the exam, I will not be getting points for it without a lucky guess.


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## BrianC (Apr 2, 2010)

The only place I have been able to find that equation is in Mark's Handbook. Given are only two equations and each is based on the units desired.

(1) mils/yr = 534W/DAT

(2) micro-m/yr = 87,600W/DAT

Where:

W = weight loss [mg]

D = density [g/cm^3]

A = area [sq. inch or sq. cm]

T = exposure time


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## MechGale (Apr 5, 2010)

Good to hear, thanks for your help. I don't have Mark's handbook, but after seeing it mentioned here so often, I finally ordered a copy of it on Friday, and should be arriving tomorrow. If it helps with at least one exam question (like this one), then it is worth it. Plus sounds like a good reference to have regardless. Thanks again.


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## gaidox (Apr 5, 2010)

Its a good reference so its worthed even if you didnt used it in exam..

Photocopy the index as soon as you have it for quick search of what you needed.


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## John_NY (Apr 5, 2010)

If this is the problem I remember correctly, I solved it using the rate of corrosion found on the sample over 72 hours and multiplying by 365/3 (and also adjusting for size).

There was no MERM formula per se.


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## vittorio (Apr 8, 2010)

John_NY said:


> If this is the problem I remember correctly, I solved it using the rate of corrosion found on the sample over 72 hours and multiplying by 365/3 (and also adjusting for size).There was no MERM formula per se.


it's the formula for determination of corrosion rate based on weight loss. it's used for example when you use corrosion coupon in chemical plant.

http://www.caproco.com/catalog/pdf/Coupons...e-Procedure.PDF

http://www.corrosionist.com/corrosion_rate_conversion.htm

vittorio

corrosion &amp; rust protection


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