Anode Spacing for Pipelines

[usarathy]

Hi Engineers!
I have designed a cathodic protection system for pipelines using bracelet anodes (as per DNV-RP-F103) and spaced them such that current requirement is met for the spacing length suggested (max 300m). Now I realize I need to consider and justify the potential attenuation at half length which I'm unable to calculate. I understand I need to consider metallic linear resistance along the pipeline and transverse pipe-to-seawater insulation resistance. My pipeline is just FBE coated with 0.45mm thk. Could anybody suggest how to estimate the insulation resistance (ohm-m2)? or a ball point figure conservatively from experience?

Thanks in Advance.
Cheers,
Uday
Pipeline Engineer

 

[SJones]

NACE SP0607, Annex A, A.10, Example 1

Steve Jones
Materials & Corrosion Engineer

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