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Discussion Forums - The Hendrix Group
HomeHomeDiscussionsDiscussionsOil Refinery Co...Oil Refinery Co...CP at high temperatureCP at high temperature
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11/18/2009 9:00 AM
 
CP structure( tank bottom plate ) -to-soil potential is minimum -850 mv at 25C (77F). But if the tank is steam coiled to maintain a crude at 90C what could be the minimum protection potential ? regards
 
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11/18/2009 9:00 AM
 
Even though you maintain 90 C inside the tank but actual temperature experienced by the bottom plate is still lower due to heat dissipation. Further it depends on whether the underside of bottom plate is coated or not. Up to 80 C the -850mv protection is holds good and if it is exceeds to 80 C then the safe limit would be around -1.1 mv .If you keep more than this value there is a chance of excess hydrogen evolvation which may damage the system.
 
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11/23/2009 9:00 AM
 
dear krish, thanks do you mean to say if T> 80C the minimum CP potential should be -1.1V ( i.e. - 1100 mv ? ) ? or U mean to say that the maximum CP potential should nt exceed -1.1V ( i.e. -1100mV) in case T> 80C ? Pl. clarify . My question is if bottom plate T >80C what is the minimum level of CP potential ? >Even though you maintain 90 C inside the tank but actual >temperature experienced by the bottom plate is still lower >due to heat dissipation. Further it depends on whether the >underside of bottom plate is coated or not. > >Up to 80 C the -850mv protection is holds good and if it is >exceeds to 80 C then the safe limit would be around -1.1 mv >.If you keep more than this value there is a chance of >excess hydrogen evolvation which may damage the system.
 
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12/6/2009 9:00 AM
 
-1.1 mv is the safe limit considering the adequacy of protection as well as avoiding H2 evolution.
 
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