mecha...

It has been my expereince that corrosion rates for carbon steel piping are not really calculated.....they are estimated based on lab test results.

Lets say that in a certain service the corrosion rate from experimental data is 2 mills per year (.002 inches) if we want about a thirty year piping life, we would specify an additional "corrosion allowance" of .0625 inches on the pipe wall thickness.

Corrosion allowances used in piping design typically range from 0.0 to 0.125 inches in most service.

If the corrosion rate causes a piping lifetime that is too short, switch to a more corrosion resistant material.

-My opinions only

-MJC

   

Mecha20,

Please review the posting policies on Eng-Tips.  It is contrary to the posting policies to cross post in multiple forums.  Thanks,

http://www.eng-tips.com/viewthread.cfm?qid=266900&page=1

Mecha20...corrosion rates are very specific to the use and environment of materials.  As MJCronin noted, they are usually estimated from lab or field data.  

Look at past performance of the material in similar applications and environment.   

Mecha20 Subtract your minimum thickness reading from the nominal thickness then divide by the amount of time in service. Will give you a general corrosion rate.

Mike