What is commonly used to prevent corrosion of metals? Eg piping, metal storage vessels
Cathodic protection
What is the transfer of one or more electrons from one atom to another called
Redox reaction
OIL is an acronym for?
Oxidation is loss of electrons
RIG is an acronym for?
Reduction is a gain in electrons
What 4 components need to be present for corrosion to occur?
Acme
Anode
Cathode
metallic path
Electrolyte
What is the process of metal detariasion because of a chemical reaction that occurs in the environment?
Corrosion
Buried steel has a potential around?
-550 mV
The two most common types of cathodic protection systems are?
Galvanic (sacrificial) anode
Impressed current
How does galvanized anode cathodic protection prevent corrosion?
Where is it most commonly used?
It uses sacrificial anode
Hot water tanks
What three materials are most commonly used for sacrificial anode systems?
What makes them good material?
Zinc
Aluminum
Magnesium
Their higher electrical potential
How does the impressed current cathodic system stop corrosion?
It uses manufactured anodes and an external power source
What gives the impressed current system an advantage over the galvanized system?
Their adjustability and longevity
What are the three impressed current cathodic systems?
Potential controlled
Voltage controlled
Current controlled
What section in the code book is for cathodic protection?
80
Cathodic protection conductors shall be connected to tanks by the use of?
Thermit welding
Who are often responsible for the initial power up of cathodic protection systems?
Electricians
Can branch circuits that supply the rectifier of a cathodic protection system share with other loads?
No
How do galvanic cathodic protection systems allow for testing between the structure and a test reference electrode installed in the ground?
They have preinstalled test stations
Structures protected by cathodic protection shall be ____
Marked
Lightning arresters used in impressed current cathodic protection systems provide a ___ ____ ____to divert high-voltage surges safely to ground
Low impedance path
In an impressed current system, the anodes would see?
DC current
In a corrosion cell what location allows for ions to flow?
Electrolyte
Impressed current cathodic protection systems deliver a ___ ___ to the anodes.
Controlled Current
