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Associate

Join Date: May 2012
Posts: 25

### Calculation of Corrosion Allowance

06/16/2012 3:41 AM

Hi guys

Is there any standard about it?

thank you so much

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Guru

Join Date: Oct 2008
Location: 34° 34' 21.60" N, 92° 55' 42.28" W
Posts: 20962
#1

### Re: calculation of corrosion allowance

06/16/2012 9:18 AM

If you knew, How to Search the Internet

You could find Corrosion Allowance Calculator and many other wonderful things.corrosion allowances

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Associate

Join Date: May 2012
Posts: 25
#2

### Re: Calculation of Corrosion Allowance

06/17/2012 12:14 AM

Thank you

But I want to know the method of caculation basically.

I have faced two corrosion allowance for two part of a pipe line. The chemical composition of fluor and the material of pipe is same!

Guru

Join Date: Oct 2008
Location: 34° 34' 21.60" N, 92° 55' 42.28" W
Posts: 20962
#3

### Re: Calculation of Corrosion Allowance

06/17/2012 12:39 AM

I'm sorry, I don't believe you grasp the concept of "corrosion allowance".

The method of calculating the amount of material loss due to surface erosion is dependent on the materials involved, and is different in each case. The math is relatively simple once you understand this.

Corrosion allowances for most common materials are well known and only involve simple math to get results.

Don't try to re-invent the wheel.

__________________
Luck comes and goes. Skill is forever. Intelligence either is, or it ain't. lyn
Associate

Join Date: May 2012
Posts: 25
#4

### Re: Calculation of Corrosion Allowance

06/17/2012 1:10 AM

Thank you for attention

If I had enough experience to corrosion, I would never write the question and never help this site!

In our company, all of pipline is carbon steel but variety fluor flows in it from acids to bases. According to kind of fluor, corrosion allowance is determined. So, I get a result that corrosion rate determin corrosion allowance. But I face to a case which get me scruple. What is the reason two corrosion allowance for one corrosion rate?

Guru

Join Date: Jul 2007
Location: Commissariat de Police, Nouvions, occupied France, 1942.
Posts: 667
#5

### Re: Calculation of Corrosion Allowance

06/17/2012 3:52 AM

There are loads of materials compatibility databases on the web, Uncle. It may be that you are using a meterial that is totally incompatible with the fluids you are handling. For example, no-one would give a corrosion allowance for sulphuric acid in PVDF piping, because no corrosion takes place.

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Power-User

Join Date: Jan 2010
Location: Mineral wells Tx
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#6

### Re: Calculation of Corrosion Allowance

06/19/2012 5:56 AM

According to the compatibility chart Cole Parmer. CS is not recommended for this service

Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic molecules, F2. In stars, fluorine is rare compared to other light elements. In Earth's crust, fluorine is very common, being the thirteenth most abundant element.

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Guru

Join Date: Nov 2007
Posts: 512
#7

### Re: Calculation of Corrosion Allowance

06/19/2012 8:56 AM

Corrosion allowance is a company preference basically. It can vary from 0" to any thickness.

Basically, you calculate the required thickness and then pick a life expectancy. If you want to replace the pipe or vessel every 6 months that's your choice.

Get a corrosion handbook if you don't have expected corrosion rates and use that to predict the initial corrosion rate. Then follow whichever inspection code that applies (API 510, API 570, API 653, etc.).

And yes you can use carbon steel for acids and bases. It's actually better to use for some fluids than more corrosion resistant materials like stainless steel.

Associate

Join Date: May 2012
Posts: 25
#8

### Re: Calculation of Corrosion Allowance

06/20/2012 12:09 AM

Thank you cingold

you understand my question exactlly. Thank you so much.

But we don't have any hand book or corrosion rate.

Can you help me more? Do you have any document about corrosion rate?

Guru

Join Date: Nov 2007
Posts: 512
#9

### Re: Calculation of Corrosion Allowance

06/21/2012 8:26 AM

Unfortunately no. I don't remember what book we used at my last job to get corrosion rates. It was either the Metals Handbook or the Corrosion Handbook.

You could also contact NACE. I believe all of these options will cost money to get an answer but they should save money in the long run.