The paper is referring to a generalised galvanic corrosion cell. As posted above, normally the anode corrodes and the cathode is protected.
Steel is protected from corrosion under alkaline conditions which is why CP is widely used. What the paper is saying is that some other metals, notably...
You can buy these commercially, "Bathycorrmeter" or similar. A piece of sufficiently pure zinc would theoretically work, but to be useful it would require calibration against a 'real' reference electrode.
I would be very hesitant recommending any reinforced concrete mixed with salt water. My company did some research on sea water curing for a local port authority client, in the interests of reducing their water consumption. The findings were that use of sea water, just for curing the cast...
I doubt that it's an electrolysis / galvanic corrosion problem. Grounding it out is unlikely to help. Continuous hot seawater is too aggressive for 316 and as suggested a more highly alloyed stainles or cupro-nickel would be better.
Consider the liquid applied shrink wrap / goop (can't remember the brand name off the top of my head) used for storage and transportation of things like helicopters.
A photo would be worth 1000 words. The main issues though, sound like the wet chlorinated conditions and possibly the treated timber.
If the steel section loss is not excessive, you could refurbish by cleaning up and applying a suitable coating system.
Replacing with stainless will be very...
Hmm, about 48 deg.C. Careful using zinc at higher temperatures than this, 60-70 degrees C is the normal limit for zinc because of inversion of driving potential. Higher temperatures may affect anode efficiency too for other galvanic metals.
Regarding current densities, your numbers sound...
There is a fair bit of misinformation around these forums on CP. To answer some of the OP's questions:
1) Directly bonding copper earthing to the pipe will stop the CP working, yes. If external earth connections are required then DC decoupling devices should be used.
2) The power is provided...
Good design practice requires gas venting of deep well anodes. The bed will work, for a while, depending on how hard you're driving it. Then you will probably suffer 'gas blocking' where the combination of heat and chlorine dries out the backfill and creates voids around the anodes. No...
Hot dip galvanising is generally more durable and sturdy than mechanically applied zinc layers. You get the benefit of metallurgical bond and the iron-zinc intermetallics formed by dipping into molten zinc at high temperature.
Neither will be great for long-term marine exposure, I would...
Corrosion only on the one side, nearest the seawall, certainly sounds like an electrolysis problem to me. Get a CP engineer to do a hull potential survey. This will tell you what the anodes are doing and whether the hull is cathodically protected, as well as identify what might be causing your...
Bagged anodes are not normally used offshore in my experience; how impractical is it to achieve continuity?
Surely no more impractical than attaching separate anodes after driving skirt piles. Drill and bolt with air tools, wet weld tack, even a clamp and set screw would do it.
The potential difference between copper and aluminium is pretty much constant. What changes with distance from the shoreline is the presence of an electrolyte (salt) at the interface.
There are a number of standards around the world (ISO, Australian are the ones I use) which identify...
Under effective cathodic protection, external corrosion rates are negligible. You need to ensure the CP is appropriately monitored and maintained, of course.
