Re: [PSUBS-MAILIST] Rainy day work

CP stands for cathodic protection, it can be measured using a silver/silver chloride half cell. What it does, basically, is to measure the potential between the steel and itself. If the steel is well protected it will show a potential reading of - 800 to - 1000 mV Poor protected steel will be between -650 and -800mV

ICC Impressed Current Cathodic protection is when you protect the steel by applying current to it. The anod, or node, as it called in these systems would be from the top of the galvanic series, not the bottom. Materials such as titanium, platinised niobiumm and lead/silver alloys are used. Noble metals, virtually non-consumable anodes, can be used in this system because in electrolytes of pH7 or less the anode reaction is the oxidation of water, rather than the metal dissolution.

On Jan 27, 2008 9:38 PM, <ShellyDalg@aol.com> wrote:

Thanks Oystein. I'm being very careful not to have any spaces that I can't get at for maintenance. The pressure vessel is smooth with almost no corners. Just a few welded tabs for attachment of front and rear bolted on structures. The soft ballast tanks will probably be fiberglass ( I'm looking at the odd shapes and thinking stainless will be too difficult to shape.)

The design is modular so the sub can be reconfigured as needed for different tasks.

I think with many small anodes, I can space them around the sub, see how well they're holding up, and how good they work.

The places where bolt-on connections are made will need to be removed from time to time to repaint, but I should be able to take the front or back sections off in just a few minutes. All the bolt connections will be isolated from each other by nylon blocks and bushings. I'm hoping that will reduce maintenance.

I prefer the stainless ballast tank plan, In case I hit something like a big rock. I was thinking stainless would dent rather than break, but it looks like a very difficult shape to make out of metal. The jury is still out on that one. I'll know better when I finish the structural frames and see exactly what kind of room/shape is available.

What is ''CP'' readings and ''ICC''

Sounds like something I need to know.

Thanks for the good advice. Frank D.

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