Sailboat Owner's Guide to Corrosion - Basic Theories (Collier 1-4)

[JamesG161]

The confusion in terms is mixing chemistry involved.

Example is Sodium Chloride.

When not in water or dry, is a crystal [does not pass an electrical current]

Put NaCl in water, it dissolves to form an Electrolyte. [Or will pass an electric current]

Na [-1] + Cl [+1] + H2O

So we need the Electrolyte to be part of the Galvanic Corrosion Electrochemical Circuit.

Jim...

PS: Distilled water has no electrolytes and will NOT pass an electric current.

 

[Will Gilmore]

PS: Distilled water has no electrolytes and will NOT pass an electric current.

So water is not conductive, as we were taught in school. Conductivity comes from the dissolved material, salts, metals? There's a lot of iron in my well water. Does that make it an electrolyte?

-Will (Dragonfly)

 

[dLj]

So water is not conductive, as we were taught in school. Conductivity comes from the dissolved material, salts, metals? There's a lot of iron in my well water. Does that make it an electrolyte?

-Will (Dragonfly)

Water becomes conductive through the ions that are dissolved in it. So sure, you likely have an electrolyte...

dj

 

[jssailem]

My book just arrived. A couple of days of reading and I will be up to speed.

 

[thinwater]

So water is not conductive, as we were taught in school. Conductivity comes from the dissolved material, salts, metals? There's a lot of iron in my well water. Does that make it an electrolyte?

-Will (Dragonfly)

In fact, there is very little iron in the water, depending on the pH. No more than a few ppm. What you see is precipitation when ferous oxidizes to ferric. Even in well water, it is tiny compared tothe contributions of sulfate, bicarbonate, chloride, sodium, and calcium.

I've always found these plots useful.

 

[Will Gilmore]

My book just arrived. I'll read this evening. Start posting soon.

-Will (Dragonfly)

 

[jssailem]

With such small amounts of FE in the water is is a wonder our tastebuds allow us to taste the iron when we drink the water.

 

[JamesG161]

Since blood chemistry requires Fe to attach Oxygen, @Will Gilmore needs very little vitamin Fe to prevent...

Iron Deficiency Anemia

Common in old fartz ...

Will, you are cured!!!
Jim...

 

[JamesG161]

If you want to remove the Fe from your well water, using Thinwater's charts...

Raise the pH to about 8 [ use baking soda] and let sit for a bit to see the FeOH settle out.
Filter it and then add back some lemon juice for taste and back to neutral.

No more Fe in you water.

Chemistry in action.
Jim...

PS: OMG don't do that, we add CO2 to the air!!
PSS: Guess you have that Fe tinge to your well water... dang it

 

[dLj]

With such small amounts of FE in the water is is a wonder our tastebuds allow us to taste the iron when we drink the water.

That's soluble iron. My water also has suspended iron in it. I'd have to dig out my water analysis, but it's got lots of iron in it...

dj

 

[JamesG161]

My water also has suspended iron in it

Don't drink a lot of it before sailing.

It might cause Steering Compass deflection!!!

Jim...

 

[thinwater]

That's soluble iron. My water also has suspended iron in it. I'd have to dig out my water analysis, but it's got lots of iron in it...

dj

FWIW, suspended iron is not going to contribute to conductivity.

In fact, precipiatating these metals to such low levels is not as easy as just changing the pH. The crystals that form are far too small to settle. But now we are wondering off-topic towards water treatment.

 

[dLj]

FWIW, suspended iron is not going to contribute to conductivity.

In fact, precipiatating these metals to such low levels is not as easy as just changing the pH. The crystals that form are far too small to settle. But now we are wondering off-topic towards water treatment.

Yeah, I have a small factory in my basement..

dj

 

[Will Gilmore]

I have this in my well:
"Iron-oxidizing bacteria are chemotrophic bacteria that derive the energy they need to live and multiply by oxidizing dissolved ferrous iron. They are known to grow and proliferate in waters containing iron concentrations as low as 0.1 mg/L. However, at least 0.3 ppm of dissolved oxygen is needed to carry out oxidation."

I'm not concerned because my water is the best tasting water I know. No iron flavor.
The Iron-oxidizing Bacteria may actually be relevant to a thread on marine corrosion since they encourage oxidation of ferrous material. May not be a problem in saltwater, but there are plenty of freshwater areas with this bacteria around here.

-Will (Dragonfly)

 

[JamesG161]

The crystals that form are far too small to settle

Not if you use a clarifying agent. I do it all the time in my swimming pool.
Jim...

 

[thinwater]

Not if you use a clarifying agent. I do it all the time in my swimming pool.
Jim...

Exaclty. In your case, a charged polymer that collects the particles until they are filterable.

 

[thinwater]

I have this in my well:
"Iron-oxidizing bacteria are chemotrophic bacteria that derive the energy they need to live and multiply by oxidizing dissolved ferrous iron. They are known to grow and proliferate in waters containing iron concentrations as low as 0.1 mg/L. However, at least 0.3 ppm of dissolved oxygen is needed to carry out oxidation."...The Iron-oxidizing Bacteria may actually be relevant to a thread on marine corrosion since they encourage oxidation of ferrous material. ...

-Will (Dragonfly)

In fact, this is a very significant concern in iron diesel fuel tanks, although those are scarce in boats. I'm guessing it is relevant to wooden boats.
Wiki re. Microbial Influenced Corrosion
Does it apply to aluminum tanks? The iron oxidation does not and I am not aware of an analogous reaction with aluminum, but fuel bugs do create acidity which can cause severe pitting of aluminum diesel tanks. Aluminum is NOT recomended by anyone, including the USCG, because numerous failures with ethanol gas have been noted within just a few years.

 

[dLj]

In fact, this is a very significant concern in iron diesel fuel tanks, although those are scarce in boats. I'm guessing it is relevant to wooden boats.
Wiki re. Microbial Influenced Corrosion
Does it apply to aluminum tanks? The iron oxidation does not and I am not aware of an analogous reaction with aluminum, but fuel bugs do create acidity which can cause severe pitting of aluminum diesel tanks. Aluminum is NOT recomended by anyone, including the USCG, because numerous failures with ethanol gas have been noted within just a few years.

MIC would be very bad in an aluminum tank. You'd particularly have problems with the sulfate reducing bacteria. They can get the sulphur from the fuel. Although modern fuels are quite low in sulphur, there is likely enough to have a problem if you were to use an aluminum tank.

dj

 

[Will Gilmore]

I read a little bit last night and it seems like there are some definitions that would be worth compiling for this endeavor. I had thought each election shell was called a valence, but Collier says only the outer shell is a valence. That is where covalent bonding happens.
The charge imbalance of an atom or molecule leads to bonding, the joining together of atoms to share outer electrons, or corrosion, the loss of electrons from one negatively charged atom or molecule to a positively charged atom or molecule.

-Will (Dragonfly)

 

[JamesG161]

the joining together of atoms to share outer electrons

Stable Molecule [no chemical reaction]
______

corrosion, the loss of electrons from one negatively charged atom

Chemical Reaction called Oxidation
______

[ corrosion ] positively charged atom

Chemical Reaction [opposite part] called Reduction.

Commonly referred to as RedOx

Jim....