100% satisfaction guarantee Immediately available after payment Both online and in PDF No strings attached
logo-home
Summary NACE CP2 Study Guide Complete Solutions Verified Graded A+ $12.39   Add to cart

Exam (elaborations)

Summary NACE CP2 Study Guide Complete Solutions Verified Graded A+

 3 views  0 purchase
  • Course
  • Institution

Summary NACE CP2 Study Guide Complete Solutions Verified oxidation loss of electrons, positive charge atoms (anode) reduction gain of electrons, negative charged atoms (cathode) forms of corrosion uniform, crevice, galvanic (dissimilar metals) if two metals have to be couple then best...

[Show more]

Preview 3 out of 22  pages

  • April 21, 2024
  • 22
  • 2023/2024
  • Exam (elaborations)
  • Questions & answers
avatar-seller
Summary NACE CP2 Study Guide Complete
Solutions Verified
oxidation
loss of electrons, positive charge atoms (anode)


reduction
gain of electrons, negative charged atoms (cathode)


forms of corrosion
uniform, crevice, galvanic (dissimilar metals) if two metals have to be couple then best to couple
metals close together in the galvanic series, pitting, intergranular, selective leaching (dezincification,
graphitization), velocity phenomena, environmental cracking (corrosion fatigue, hydrogen
embrittlement, SCC (Carbonates/bicarbonates)


High PH
Low hydrogen, alkaline, easy polarization


Low PH
high hydrogen, acidic, harder to polarize


High oxygen/High Hydrogen concentration
harder to polarize, work at the cathode only, called cathodic depolarizers.


factors affecting corrosion
A. anything that affects polarization. (temp. etc...)
B. concentration cells (oxygen, temp, etc.) In an oxygen concentration cell, what is the anode? (i.e. the
area with more or less oxygen?) In a metal ion cell, which area is the anode (i.e. the area with the
greater of lower concentration)?
C. Anaerobic bacteria (MIC) Absence of oxygen, depolarizer


polarization
a. corrosion current reduces with polarization
b. polarization increases with CP current applied
c. Occurs at surface of both anode and cathode.


shielding
a. shorted casings
b. proximity of other structures
c. reinforced concrete


amphoteric materials
corrode at low and high pH


on potential
native + polarization + IR drop

,polarized potential (off)
native + polarization


kirchoff's laws
a. voltage (series circuits)
b. current (parallel circuits)


faraday's law
W=KIT
relates weight loss of metal in a corrosion cell with time and current flow.


rate of corrosion
directly proportional to current flow


cathodic protection limitations
-shielding issues
-attenuation
-interference
-excessive current density
-contact with other metals (shorts)


measurement methods
true voltage reading
voltmeter reading
% error calculations
effect of voltmeter resistance
IR correction methods


test stations
allow electrical connection to structure for potential measurements and bonds.
Spans allow current and direction (IR drop).
inistall during construction


pH
measure of acidity(hydrogen ion concentration)
high pH is alkaline
low pH is acid
pH is a log function therefore each increase in pH is a factor of 10.


RECTIFIER
- positive to anode
-negative to structure
- AC suppy
-AC circuit breaker
-Transformer (increase or decrease voltage)
-AC fuse
-rectifier bridge - diodes change AC to DC
-Voltmeter and Ammeter

, -Surge Protection
-Filters
Esecondary = (Eprimary x Secondary turns) / primary turns


Reference electrode location
the reference electrode should be placed as close to the structure as practical. (underground piping or
tanks- over the center of the structure, multiple readings along the structure as required)

internal surfaces of storage tanks, waterfront and offshore structures (as close to the wall as possible)


impressed current vs sacrificial
impressed current- higher current, better control

sacrificial- no power required, less maintenance, easy to install, less land


AC considerations
capacitance, inductance, and resistance

hazardous AC potential - 15 Vac

Safe method of connecting ground0 cable to ground then to pipe

arcing hazards

corrosion rates from AC (current density)

switching or pulse rectifiers


Reference cells
CuCuSO4- most common, (soil, fresh water)

AgAgCL - seawater

Calomel- lab

Hydrogen - standard (lab)

zinc- stationary


Cathodic Protection
protect the cathode

attempts to bring the cathode potential as negative as the anode potential

NACE criteria- what are the exceptions?
-high temperature
-bacteria
-sulfides
-acid environments
-dissimilar metals

The benefits of buying summaries with Stuvia:

Guaranteed quality through customer reviews

Guaranteed quality through customer reviews

Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.

Quick and easy check-out

Quick and easy check-out

You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.

Focus on what matters

Focus on what matters

Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!

Frequently asked questions

What do I get when I buy this document?

You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.

Satisfaction guarantee: how does it work?

Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.

Who am I buying these notes from?

Stuvia is a marketplace, so you are not buying this document from us, but from seller ACADEMICAIDSTORE. Stuvia facilitates payment to the seller.

Will I be stuck with a subscription?

No, you only buy these notes for $12.39. You're not tied to anything after your purchase.

Can Stuvia be trusted?

4.6 stars on Google & Trustpilot (+1000 reviews)

83100 documents were sold in the last 30 days

Founded in 2010, the go-to place to buy study notes for 14 years now

Start selling
$12.39
  • (0)
  Add to cart