Cathodic protection for copper grounding grid.

[Okpower]

Hi all:

I work in the design of a new gas plant. Yesterday in a technical seminar, my boss proposed me to protect the grounding grid of the new plant with cathodic protection. I think it is unuseful, and not common practice. But I want to know your opinions in case that the proposal becomes in a instruction to action. Is it possible or common practice to protect grounding copper grid with impressed current cathodic protection?

Thanks in advance.

 

[SJones]

It is possible but probably not considered common practice. It may be that your boss is confusing the issue of trying to cathodically protect buried plant items or tank bottoms which are tied into the earthing system and dealing with the ensuing problems.

Steve Jones
Materials & Corrosion Engineer

http://www.oilandgaspeople.com/cv/11499664

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

 

[brimmer]

No, not a common practice. Copper obviously used for this task becasue it is a very good conductor, but also because of its natural corrosion resistance. I would agree with SJones and think your boss might be confused, cp used to protect plant sturctures with cp, not the grounding grid. In fact, you will want to isolate the grounding grid from your cp system, otherwise the current will be protecting the copper (which is unecessary) and not the steel structures.

 

[MJCronin]

Cathodic protection of a gounding grid..??

You realize, of course that there is a real risk of electrocution in a power generating facility if the grounding grid does not function properly ?

Does your boss have an MBA ?

This is why people die..... MBAs in an active technical role...

My opinion only

 

[Okpower]

MJCronin:


As Electrical Leader, I do think this is a serious issue to handle. I would prefer to have ground voltage just 0 Volts, not 10 or 15 volts (that would be the voltage that cathodic protection could put in grounding elements).

In any case, which are the solutions or the alternatives? I have investigated some in the internet and I learned that stainless steel is better if we consider corrosion topics.

By the way, my boss does have an MBA (but he is engineer).

 

[brimmer]

Apologies for butting in, but Okpower, I am not sure I understand you correctly, the way I intepret your comment you have thought this in a reverse manner. It is not the CP current from groundbeds that is causing the danger, it is that the grounding grid may dissipate large amounts of electrical current at some point, and if it is connected to the CP system, which is connected the pipelines or other structures at the gas plant, and someone touches a valve for example while this is occurring... they get zapped.

If you want an alternative to impressed current CP, you can use scrificial anodes to protect structures in the plant, no risk of electrocution here, but do not tie these into your grounding grid! (carbon steel, coatings in conjunction with cathodic protection is the norm, stainless steel is expensive, not really recommended to burry stainless steel).

The 10 or 15 volts you mention, to me this is what the grounding grid is sending to the plant structures if everything is bonded together, not what the CP system is putting on the grounding grid, this is impossible, CP systems typically induce approx 1 volt.