Cathodic Protection Flashcards Preview

Intro To Corrosion > Cathodic Protection > Flashcards

Flashcards in Cathodic Protection Deck (24)
Loading flashcards...
1

Limitations of CP

Internal surfaces not protected Above ground surfaces not protected Electrical Shielding Stray Current Attenuation (gradual loss of current)

2

Produce small amounts of current Cannot be adjusted No power source needed

Galvanic System

3

Galvanic System Anodes

Aluminum, Zinc and Magnesium

4

Produce any amount of current Can be adjusted Power source is needed

Impressed Current System

5

Impressed Current Anodes

Graphite, High Silicone Cast Iron, Scrap Steel, Mixed Metal Oxide (MMO), Titanium-Niobium, Platinum, Lead-Silver

6

Impressed Current Power Sources

Rectifiers Photovoltaic Solar Panels Thermo-Electric Gen Engine Generators Fuel Cells Wind Mill Power
Closed Cycle Vapor Turbo Gen Batteries

7

Anode Backfill

Lowers contact with resistance to Earth; Enables anodes to consume uniformly; Lengthens the life of Impressed Anodes; Holds moisture for galvanic anodes; Must be designed to fit the ground-bed

8

Reference Electrodes

Copper Copper/Sulfate Hydrogen Zinc Calomel Silver Silver/Chloride Antimony

9

The positive terminal of an ICCP must be attached to the .....?

Ground bed

10

Most common reference cell used for CP?

Copper/Copper-Sulfate

11

What measurements are used most commonly as a criterion of protection for CP?

Potential

12

Coated pipe lines polarize very ......; the better the coating the ....... the polarization?

Rapidly; Faster

13

The lower the resistivity; the ...... will be the corrosivity?

Higher

14

The Wenner 4 pin test is used to measure ....... which is then utilized to calculate .........

Voltage (potentials), resistivites

15

In tankers tanks that are filled with salt water for ballast after discharging cargo are suseptible to severe corrosion; ........ anodes are widely used to prevent corrosion?

Galvanic

16

Metal that provides sacrificial protection to another metal that is more noble when electrically coupled in an electrolyte?

Galvanic Anode

17

Ratio of an anode weight sacrificed for CP divided by total theoretical amperes hours or capacity of the material used.

Galvanic Anode Efficiency

18

Ground bed anodes are not depended upon as a source of electrical energy. An external source of DC power is connected between ground bed anodes and structure.

Impressed Current CP (ICCP)

19

Device that is powered by electrical utility system which converts high voltage AC to low voltage DC by means of step-down transformers.

Rectifier

20

Change from open-circuit potential as a result of current across the electrode/electrolyte interface

Polarization

21

3 Sources of DC stray current

DC Railway systems; Mining operations using DC power; DC welding Operations

22

Closed interval potential survey is to record the potential profit of a pipeline over its entire length by taking potential readings at intervals of approximately M

CIPS

23

Pearson Survey and DCVG survey have in common?

They are tests designed to locate coating defects in buried pipelines.

24

Pearson Survey and DCVG survey are different?

Pearson Survey - no trailing wires and the defect gives a signal. No signal in DCVG means a defect.