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1 and done. > Anodes > Flashcards

Anodes Flashcards

1
Q

Galvanic anodes are permitted to mandatory dry-dock inspection at or less than how many years?

A

3 years.

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2
Q

Can you use magnesium anodes in sea water?

A

No, because of rapid loss of anode material and overprotection to the structure due to high driving voltage and low resistivity.

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3
Q

Sacrificial anodes are marked with a _____ letter designation.

A

3

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3
Q

What types of anodes can NOT be used in salt water?

A

Magnesium

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4
Q

Magnesium anodes are used in what type of water? Greater than ______ ohm/cm.

A

Brackish or fresh water. Resistivity of the electrolyte is relatively high, greater than 500 ohm/cm.

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5
Q

Aluminum anodes have a ____% service life.

A

30%

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6
Q

Can magnesium anodes be used on aluminum hulls?

A

No, aluminum is subject to deterioration by both acid and basic solution.

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7
Q

On steel surfaces, what type of lockwashers should be used?

A

Two star-type washers.

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8
Q

Where velocity exists, at least _______ the number of zinc anodes calculated for quiscent areas shall be installed.

A

Twice

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9
Q

What determines the frequency of an inspection?

A

Is the inspection surface or underwater, what is the expected rate of deterioration/damage?

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10
Q

All surface ships that are not protected by an impressed current system shall be protected by what?

A

Galvanic anodes, located amidships and aft.

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11
Q

Install twice as many anodes in velocity conditions greater than how many knots?

A

5 knots

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12
Q

With whose authority can you use magnesium on aluminum hulls?

A

NAVSEA

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13
Q

Copper alloys are known to benefit from the presence of ____ ____ in the water.

A

Iron ions

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14
Q

Reference electrodes are generally located on each side of the hull approximately ____ ____ between anode sites.

A

Half way.

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15
Q

A reference electrode is a silver/silver ____ type constructed of a silver mesh screen that has been treated with silver ______.

A

Chloride.

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16
Q

Sacrificial anodes on exterior on hull and appendages directed having _____ to _____ year cathodic protection.

A

2-3 year

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17
Q

Are galvanic anodes permitted on small boats?

A

Yes. ICS is not feasible.

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18
Q

What is the preferred install method of anodes?

A

Weld-on.

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19
Q

When are bolt-on anodes used?

A

If periodic maintenance and replacement is done without use of industrial facility.

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20
Q

Iron alloys have been used as anodes to enhance corrosion resistance of what alloys?

A

Copper

21
Q

How often are reference electrodes usually replaced?

A

10-12 years.

22
Q

Each seachest or other area of dissimilar metal found in larger aluminum huls. Place anode within ______ feet of dissimilar metal junction.

A

2 feet.

23
Q

Can magnesium anodes be used on aluminum hulls?

A

No

24
Q

Magnesium anodes have a half cell potential at approximately negative _____ volts.

A

1.5 volts seawater.

25
Q

Is there a hazard using magnesium anodes?

A

Yes

26
Q

On Aluminum surfaces, what type of lock washers should be used?

A

CRES Star type lockwashers and CRES Locknuts. Apply anti-seize to threaded surfaces of the studs.

27
Q

Is a dielectric shield needed with zinc anodes?

A

No due to low voltage; however zinc anodes will not be installed over bare metal.

28
Q

Are anode surfaces ever painted?

A

No, apply coating system before zinc anodes are installed.

29
Q

When using aluminum anodes, you must seek guidance from who?

A

NAVSEA

30
Q

Stagnant areas or areas subject to low velocity flow conditions (under ____ knots) shall be provided with _____ square feet of anode surface for each ______ square feet of bare metal surface.

A

Under 5 knots, 1sqft, 50sqft

31
Q

What are common sacrificial anode materials for cathodic protection systems.

A

Magnesium, zinc, aluminum.

32
Q

The threshold for a ship installed with an ICS is what percent?

A

10%

33
Q

Anodes of appropriate type shall be installed at ______ of dissimilar metals, bilge pump, strainers, valves and piping that are immersed in or frequently flooded with seawater (more than 25% of the time)

A

Junctions

34
Q

Metal that is listed in the galvanic series as more Electro (neg/pos) than another may provide cathodic protection for the more electro (neg/pos) metal. This is the basis for anode cathodic protection.

A

Negative (or active) Positive (noble).

35
Q

Can sacrificial anodes be used on a tank interior?

A

Yes

36
Q

What is the half cell potential for Zinc?

A

Negative 1.04VDC

37
Q

What is the half cell potential for Aluminum?

A

Negative 1.06V

38
Q

What is the half cell potential for Low-voltage aluminum?

A

Negative .8 to .85 VDC

39
Q

What is the half cell potential for Magnesium?

A

Negative 1.55VDC

40
Q

What anode is effective in polarizing steel or aluminum surfaces?

A

Zinc

41
Q

For anode attachment on steel surfaces what shall the studs and nut be fabricated form?

A

Medium or mild steel, galvanized steel, or corrosion resistant steel.

42
Q

When would a magnesium anode be used?

A

In fresh water where resistively is greater than 500 ohm.

Never in enclosed spaces. Never on aluminum alloy surfaces. Never in salt water.

43
Q

Why were low voltage aluminum anodes (gallium) developed?

A

To provide cathodic protection to materials that are susceptible to hydrogen embrittlement at zinc and aluminum operating potentials.

44
Q

What do the 3 letters on a sacrificial anode designate?

A

1: Metal type
A: Aluminum, L: Low voltage aluminum, Z: Zinc
2: Shape or use
3: Core

45
Q

What are the platinum anodes, used in ICS and surrounded by dielectric shields?

A

Tantalum anodes

46
Q

On steel hulls: In the midships area, install ___% of the calculated quantity of anodes for full protection.

A

60%

47
Q

Steel hull: In the stern area, ___% of anodes necessary for the complete hull system shall be butted end to end.

A

40

48
Q

Each bilge compartment in which seawater is held more than ____% of the time SHALL have cathodic protection.

A

25%

49
Q

Any anode showing ____ or greater deterioration should be replaced.

A

50%

1 and done. (22 decks)

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