Cathodic Protection seashore

[garciaf]

Here is my issued:

I would like to know what is the right measurement value with reference electrode for a pipeline (pipe, api 5l grade b), please see attached image in order to watch the location. the value that has been taking the techinician is -200 mv, but I think that is not the right value for carbon steel (-850mv) in orden to protect the pipe that have a Zinck epoxy primer and polyurethane finish.
what are the recomensations. what other factor you recommended to me, there is a standard that tells me something about it. It is possible that reference electrode shows a wrong measurement due to sand o salinity.
please help.

 

[SJones]

ISO 15589-1 and NACE TM0497. Zinc rich coating with a polyurethane top coat would not be considered an appropriate choice for a buried shore crossing coating system.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[LittleInch]

That's a very simple diagram. where is the CP potential coming from?

Are there isolation joints?

Have you tried a different portable reference electrode?

You are correct in -200mv is not sufficient to have have effective CP.

There are many types of coatings so "polyurethane finish" is very vague. Thickness, application?
If you're asking for a code reference for a CP system tells me you're not a CP engineer. first find the design calculations and design documentation on the CP system and then see if it was all installed...

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