Marine Corrosion Pop Quiz #1

[JamesG161]

Can you pass with 7 correct?

1)Marine corrosion is ? ( trick question )
A) a Virus that spreads.
B) Never ending
C) Solely a Man made waste thing
D) Caused by solar dust.
D) None of the above.

2) Corrosion is increased by
A) Connecting two different metals in water
B) Polishing Stainless steel
C) Stray electrical currents in the marina
D) Scratching your aluminum boom.
E) All of the above

3) Grade 316 Stainless Steel is the best grade to stop crevice corrosion is sea water?
A) True
B) False

4) Is there corrosion on my Son’s all plastic, battery powered and remotely controlled sail boat, sailing in a distilled water kiddie pool? (trick question)
A) Yes
B) No

5) What is the correct name for series of chemical reactions associated with corrosion
A) Nobel Series
B) Noble Series

6) Plastics corrode.
A) True
B) False

7) A Galvanic cell is?
A) Solitary confinement on the Caribbean island of Galvan
B) Nick name for pop band leader’s cell phone
C) Part of a chemical battery.
D) None of the above

8) Sacrificial Zinc was named that way because?
A) Cost is way too high to install on boats.
B) Royalty gave up Zinc in preference to Gold.
C) Zinc sacrifices itself to protect more Noble metals in salt water
D) No such naming

9) Erosion is the same thing as corrosion.
A)True
B) False

10) Graphite is more Noble than Gold?
A) True
B) False



Answers to follow later.
Jim...

 

[Ken Cross]

I can pass them all with correct answers. One of those I just need an answer for first.

 

[JamesG161]

I can pass them all with correct answers. One of those I just need an answer for first.

Are you trying to be the "teacher's pet"?

Post your answers and I can score them in a PM.
But...
@Ken Cross I have read you corrosion advice and I would score those A+++
Jim...

 

[JamesG161]

@Ken Cross BTW I marked #1 & #4 as "trick questions" and on second thought, 6+ right will be a good score.
So, if you wanted to ask about those 2 trick questions, don't worry.
Jim...

 

[JamesG161]

Most people hate a pop quiz. Done for fun and a bit of info.
Here are the answers...

1. D. This was a trick question. Normally the answer would be B (Never ending) but when the item that is corroding disappears totally, corrosion ENDS.
2. E. B and D both remove the protective Oxide coating and increases the corrosion rate.
3. B. Alloy 20 stainless is one grade that resists this marine problem. I wondered why my keel bolts and rudder shaft are NOT made from a better grade.
4. A. It was trick because a battery is controlled Corrosion that we capture to make electricity. The plastic corrosion is so slow, it will normally last longer than the toy.
5. B. Alfred Noble, the inventor of dynamite, first documented the chemical reactions that produce electricity. Trivia: He hoped his dynamite would improve mankind but dedicated his wealth for the NOBLE PEACE PRIZE, from his guilt of warfare use of his dynamite.
6. A. They do corrode, albeit very very slowly.
7. C.
8. C. This is why it protects other metals in electrical contact with the zinc in water.
9. B. Erosion is an abrasive loss, while corrosion is a chemical reaction. Erosion does increase Corrosion rates.
10. A. Graphite is a special form of carbon, just like diamond. One of the reasons to avoid Graphite packings in a shaft stuffing box.

Jim..

PS: Did you get 10, @Ken Cross ?

 

[Charles Erwin]

Pretty good quiz overall but:

"B and D both remove the protective Oxide coating and increases the corrosion rate."

Are you sure on this one?

Certainly removing (by polishing) the surface oxides layer in any material results in exposure of the underlying alloy. However in the case of stainless anyhow that oxide layer essentially replaces itself in mili-seconds during the polishing process.

To the contrary in the case of stainless - polishing enhances resistance to crevice corrosion (the most threatening kind in stainless alloys) because polishing removes stress risers. In my opinion stainless is far better off polished because polishing makes a stainless part much more resistant to crevice corrosion.


Charles

 

[JamesG161]

Are you sure on this one?

Pretty sure, but I learned to have an open mind. (psssttt don't ask the Admiral that question)
Stress Corrosion Cracking for mariners...
1) Is normally in submerged, low dissolved Oxygen. exposed to Chlorides, like keel bolts.
2) Open air exposure normally has plenty of Oxygen to "corrode" and protect.
http://www.ssina.com/corrosion/stress-corrosion-cracking.html

Corrosion for metals, doesn't stop, but is slowed down to an acceptable rate for the designed service.

However in the case of stainless anyhow that oxide layer essentially replaces itself in mili-seconds during the polishing process.

This is why SS corrosion rate is acceptable, but it still loses metals to oxidation.
The chromium in the steel oxides and protects until you polish is off.
Don't worry that was allowed for in the design of your pretty winches.
Jim...

 

[Ken Cross]

I guess I missed #1 because I assumed corrosion never ends because if it isn't present one place it's present somewhere else.
Good point that it ends when there is no more but if it disappears 10% per year, it will never really be gone.
Ken

 

[druid]

On polishing SS: Depends on what it's polished WITH. If you use any type of metal, like a scouring pad or steel brush, it DOES make a difference. Tiny particles from the pad or brush will imbed in the SS, creating a place for corrosion to start.

druid

 

[JamesG161]

On polishing SS: Depends on what it's polished WITH. If you use any type of metal, like a scouring pad or steel brush, it DOES make a difference. Tiny particles from the pad or brush will imbed in the SS, creating a place for corrosion to start.

Guess what I use to brighten my pretty winches? Brass wool!!
That won't do what you suggest and the brass fibers corrode to stain your deck.

Good point that it ends when there is no more but if it disappears 10% per year, it will never really be gone.

Yeah yeah yeah You can't make a touchdown by 50% of the distance to the goal either.

The difference between an physicist and an engineer... (joke.. ready for it?)
If you take half the distance between you and a beautiful lady waiting to be kissed, each move...
the physicist thinks he will never get a kiss...
the engineer gets his kiss because he will get there "for all practical purposes".

Corrosion is rated by "mils of thickness loss/per year of exposure" and not percent of the change.

I did warn you it was a "Trick question".
Jim...

PS: @Ken Cross I am impressed you got question #4 right. If there was no battery the toy would have no corrosion.

The point I was trying to make, that corrosion is just like a battery operation. You have a positive and negative end of the battery.

Bonus Question: How does the US Navy reduce below water galvanic corrosion on iron hulls? Huge Zincs?
Ten point if you get this answer, even on a web search.

 

[Charles Erwin]

There is no better approach than a rated officer monitoring and managing an impressed current system.

Charles

ps By the way a serious polishing protocol for stainless - not the amateur methods so far mentioned - will reduce pitting and related crevice corrosion dramatically . Stainless corrosion resistance - particularly to pitting - will improve somewhere about 3 and 4 times.
Meanwhile, for example, my customers chain plates will be Aluminum Bronze because polishing anything is horrible, tedious, and boring to the extreme. Most important - stainless alloys offer no advantage and present serious risk of unannounced failure since corrosion occurs on the inside of the part and is essentially invisible
.
ce

 

[All U Get]

There is nothing as sad as a bunch of cold sailors watching metal rust. Hope you have an early spring. (Did I mention how nice it is in the Bahamas?)

All U Get

 

[JamesG161]

There is no better approach than a rated officer monitoring and managing an impressed current system.

I am IMPRESSED. ( pun intended ) 10 bonus points awarded!

I have been pointing out that corrosion is chemical battery. The Sailor's common one is a Lead/Acid battery. As the Lead corrodes in the battery container, we use it to give us electricity. How do we reverse that corrosion? We charge the battery.

The "impressed current system" means the Navy keeps their corrosion "battery charged"!
Jim...

PS: For Chlorides to cause SCC they must be dissolved in water. Standing rigging, under tensile stress (pulling), may be splashed with sea water, but the exposure time in minor. Once the salt dries, SCC stops. Rinsing down your rigging after a "gunnel awash" sail is good practice. Rain normally does the trick of salt removal.

 

[Ken Cross]

I have no navy experience, but one could counteract the problem with multiple efforts: Non conductive coating, and electrical charge to the hull. Just guessing in my case. It might also be interesting to know how they control marine growth.
Ken

 

[JamesG161]

electrical charge to the hull

I had to laugh at the vision I got of Disney's 20,000 Leagues Under the Sea movie and the dancing savages, on the electrified hull.
Maybe you could put on a "conductive coating" and pulse "charge it" to give algae/barnacles the "hot foot".
Very interesting thought!
Jim...

PS: Secretly writing it down to approach Patent Office.

 

[shemandr]

I got 9 out of 10, missing #1 which was a self announced trick question. I didn't see that coming. Your quiz, your rules, to paraphrase a popular mantra on this site.

 

[JamesG161]

missing #1 which was a self announced trick question

I thought about that one, a lot, kinda pointing at B, by the extreme of the other 3. (Tricky)

BTW I just disqualified Question #1, since it had 2- D) answers.

@shemandr et.al. give yourselves a ★GOLD STAR ★

The reason I did that one....
I have read so many discussions that people think that rust grows like a virus, by touching.

I was also trying help simplify corrosion by thinking about a battery.
Jim...

PS:I was wondering if should send @All U Get to the "time out" corner for his envious distraction.

 

[Scott T-Bird]

Jim, I think you get a -1 for Alfred Nobel, who did indeed invent dynamite and other explosives. I was puzzled by your statement that he first documented the chemical reactions which produces electricity, or the Noble Series. I can't find any reference to support that. BTW the Nobel Peace Prize is named after Alfred Nobel, not Alfred Noble. I suppose your answer (B) was correct for the question, but noting the wrong reference (so maybe just 1/2 off?).
My good friend was a corporate attorney for Dyno-Nobel, the Norwegian conglomerate, so I did have some familiarity.

 

[JamesG161]

was puzzled by your statement that he first documented the chemical reactions which produces electricity, or the Noble Series.

I forgot, Alfred Nobel, was the evil twin of Freddy Noble.

Well I learned that from my college Chemistry Professor (before wikipedia).
Dang...
What is said about Alfred Nobel, and the corrected Nobel Peace Prize was right!

Noble Series is right, but not for a namesake.

So with great humility, my reason for the Correct answer, was wrong.

It is Noble Series but not for Noble reasons.

Cough cough cough... @Scott T-Bird remember who is grading the test!

5) B. BUT NOT NAMED AFTER Alfred NobEL, the inventor of dynamite, first documented the chemical reactions that produced Nitroglycerine. Trivia: He hoped his dynamite would improve mankind but dedicated his wealth for the NOBEL PEACE PRIZE, from his guilt of warfare use of his dynamite.

Corrected reason to the right answer of #5
Jim...

PS: Sipping a martini wondering how to get a (-1) for getting the right answer to #5.

 

[All U Get]

PS:I was wondering if should send @All U Get to the "time out" corner for his envious distraction.

I laughed so hard my Bahama Mama squirted out my nose. They did retire my stool when I graduated at the age of 23.

All U Get