Cathodic protection of sets of pipelines

[Iskandarzade]

Hi all,

We have problem in managing cathodic protection of our oil and gas pipeline system. As we have dozens of pipelines in a large area with diameters mostly in the range of 4-inch to 8-inch. Some of them have been burried just several meters farther; some of them crossing each other; some of them are old; some of them are new; some others will be constructed in future. We cathodically protect each of them separately and when our local managers find it suitable we connect pipeline to each other using cad-weld and use one cathodic system for two or few pipelines. However, we have not comprehensive solution to manage our cathodic system. Do you know about any management method for such a situations?
Best

 

[Chumpes]

yo
there are CP probes (guns) made from a reference electrode and an electric contact with the item to be evaluated. It can be used to measure the protection potential of each item in the system vs. reference electrode.
I cannot remember the protection potential criteria but I guess it is something like -800mV / ECS for steel.
basic knowledge on CP is available online, you can start with
Link
regards

 

[brimmer]

How large of an area? Are we talking about in a facility yard? It is best to protect everything on a flood pattern, make everything electrically continuous, place groundbeds around the facility in strategic locations if possible. One CP system for multiple pipelines is fine, as long as current demand is calculated and the anode bed & rectifier(s) are sized properly. If you are speaking to pipelines that are miles long and not in a facility, then you may need to consider some other options, like separate CP systems, and placing them in different locations. Describe your scenario with more detail.

 

[Iskandarzade]

Thanks Brimmer for your reply.
Pipelines are lied in area of about 40 Km^2. Their length are vary from 3Km to 40Km. Currently, we have cathodically protected most of them,one by one. I mean, cathodic protection of each pipeline has been designed separately. But, according to the designer suggestion we have used one cathodic protection for multiple pipelines. But, we did not this tasks under a comprehensive procedure/plan or method. I am looking for a approved management method for optimal locating of CP facilities (groundbed, Rectifier, anodes..). Have you hear about such a management system?
Best

 

[brimmer]

Yes, you can use one cathodic protection system (ground bed & rectifier) to protect more than one pipeline, this is normally the case for onshore pipelines in a gathering system. I don't understand what you mean by management system for cathodic protection, this is different from cathodic protection design/best practice/standards. There are documents by NACE that speak to design & maintenance of cathodic protection for pipelines. NACE SP0572, NACE SP0169.

 

[SJones]

Call in an accredited CP engineering consulting agency to survey the system and recommend a solution with the necessary maintenance and monitoring activities.

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.