NACE 2008 Student Manual! CP2 START OF CHAPTER 1 Corrosion is an electrochemical process involving A) flow of protons and electrons B) flow of neutrons and ions C) flow of protons and ions D) flow of electrons and ions E) flow of resistance and resistivity d
Metal loss or corrosion occurs at the A) cathode B) anode C) electronic path D) metallic path b
What are the four parts of the corrosion cell A) anode, resistor, electrolyte, metallic path B) anode, cathode, electron, electronic path C) anode, cathode, electrolyte, metallic path c
True or False (t or f): Ions exist only in the electrolyte? t
Electrons flow in a corrosion cell by which of the following paths? A) anode to cathode via electrolyte B) cathode to anode via electronic path C) anode to cathode via electronic path c
At the cathodic surface in a corrosion cell, the electrons from the ____ meet ____ ions from the solution. A) cathode, hydrogen B) cathode, OHC) anode, hydrogen D) anode, OH-
c
Oxidation of the metal occurs at the ____ surfaces and reduction of ____ ions occurs at the ____. A) anodic, hydrogen, cathodes B) cathode, OH-, anodic C) anodic, OH-, cathodes D) cathode, anodic, electrolyte E) cathode, hydrogen, electrolyte a
True or false Is oxidation necessarily associated with oxygen? f
Current flow in a corrosion cell flows which path: A) anode to metallic path to cathode B) anode to electronic path to cathode C) cathode to metallic to anode D) cathode to electrolyte to anode E) anode to electrolyte to cathode Voltage is the measure of the electrochemical difference between two electrodes in an electrolyte e
_____ is the measure of the electrochemical difference between two electrodes in an electrolyte A) current B) resistance C) error D) ohms E) ohms-cm F) voltage f
The ________ represents the reversible work to move a unit charge from the electrode surface through the solution to the reference electrode A) current potential B) electrode potential
C) resistance potential D) ohms potential E) Faraday potential b
Metals occur in nature in the form of various chemical compounds referred to as ___ A) ores B) anodic metals C) cathodic metals D) carbohydrates a
The amount of energy required by a metal during the refining process determines the ___ or _______ of the metal. A) current, active state B) voltage, active state C) active resistance, voltage D) resistance, active state E) current, active resistance b
During the refining stage of metal the ____ the energy, the more ____ the metal and the more tendency it has to corrode. A) higher, inactive B) lower, active C) higher, active D) lower, inactive c
What is the most common iron ore? A) hemophite B) hematite C) magnesium D) calcium E) aluminum b
True or false Iron is considered thermodynamically unstable? t
True or false Gold is more noble than zinc? t
Which of the following metals is most active? A) magnesium B) copper C) iron D) nickel E) platinum a
Electromotive force (emf), is ____ in sign and magnitude to the electrode potential of the ___ less the electrode potential of the ____. A) unequal, cathode, anode B) unequal, anode, cathode C) equal, cathode, anode D) equal, anode, cathode d
The driving force for electrochemical corrosion is ____ A) current B) voltage C) resistance D) ohms E) siemens-cm b
In relation to a corrosion cell, ____ is the net transfer of electric charge per unit time A) current B) voltage C) resistance D) ohms E) siemens-cm a
If a metallic path connects two electrodes inside an electrolyte, the ____ difference will cause a ____ to flow between them A) current, voltage B) resistance, current
C) resistance, voltage D) voltage, current E) current, resistance d
The more useful method of organizing metals in order of their tendency to corrode is _____ A) emf series B) pgp series C) nuclear series D) electron series E) galvanic series e
The ____ expresses the exact electromotive force of a cell in terms of the activities of products and reactants of the cell A) Ernest Equation B) Faraday Equation C) Ohm's Law Equation D) Nernst Equation E) Uniform Equation d
Given the Nernst Equation, using the Valence of Common Metals Table, and using the partial Standard emf Series of Metals solve: What is the potential of zinc in a 0.01 molar zinc chloride solution at 25C? A) -0.892V B) -0.287V C) -0.827V D) -0.297V E) -0.889V c
E= -0.763 + (0.059/2) log (0.710.01/1) = -0.827V
Standard conditions for pure metals in the emf series are based on one unit activity of metal ions in the electrolyte at ___ C with no impurities in the metal or electrolyte and with reference to a standard ____ electrode. A) 25, hydrogen B) 35, hydrogen C) 25, CSE D) 35, CSE E) 25, SSC F) 35, SSC a
The ____ the concentration of metal ions in the electrolyte, the ____ the metal. A) lower, less active B) higher, less active C) lower, more active D) higher, less active b
In reference to the temperature in a corrosion cell, in most cases, electrode at the _____ temperature becomes the ____ A) lower, anode B) higher, cathode C) lower, cathode D) higher, anode d
During metal fabrication of structures, highly stressed areas of a metal will tend to be at ____ energy levels, thus more ____ than less stressed areas A) higher, active B) lower, active C) higher, inactive D) lower, inactive a
True or False (t or f): Corrosion cells may form because of differences in the electrolyte t
____ cells are responsible for much of the corrosion that take place in soils, particularly in bare or poorly coated pipe
A) concentration B) steady state C) carbon D) dynamic E) telluric a
In many cases in naturally occurring soils, a portion of pipe lying in the more _____ soil is the ____ and in the less ____soil is the ___. A) inductive, anode / inductive, cathode B) inductive, cathode / inductive, anode C) conductive, anode / conductive, cathode D) conductive, cathode /conductive, anode c
The two most common types of concentration cells involved in promoting corrosion are ____ and ____. A) oxygen, nonmettalic ion B) oxygen, calcium C) lack of oxygen, metal ion D) oxygen, metal ion d
What is the most common of the cathodic depolarizers, that can maintain and promote a cathodic reaction? A) CO2 B) oxygen C) carbon D) OHE) Hydrogen b
Most corrosion on pipelines is on the ____ portion of the pipe A) sides B) top C) bottom c
If a pipe is running through a section of pavement and through a section of non pavement: A) anode is the metal outside the pavement, the cathode is the metal under the
pavement B) anode is the metal under the pavement, the cathode is the metal outside the pavement C) cathode is the metal under the pavement, the anode is the metal outside the pavement b
In a metal ion concentration cell, the surface in contact with ____ concentration of metal ions acts as the ____ A) lower, anode B) lower, cathode C) higher, anode D) higher cathode a
Theoretically, the potential of a structure changes by about ____mV for each pH unit A) 40 B) 50 C) 20 D) 70 E) 60 e
The corrosion potential of a metal might be -500mV in an environment with a pH of 7, but the corrosion potential might be ____ at a pH of 8? A) -440mV B) -660mV C) -300mV D) -560mV d
True or false (t or f) an acidic pH can be harmful to concrete, such as reinforced concrete structures? t
A pH of less than ____ is considered to be harmful to concrete? A) 4 B) 6 C) 5 D) 2 E) 8 c
The rate of corrosion is directly ____ to ____ flow? A) inproporinate, current B) inproporinate, voltage C) proportional, voltage D) proportional, current d
If a 1 Amp CP system must last 40 years and the electrochemical equivalent for silicon chromium cast iron anodes is 0.75 lb/A-yr, how many pounds of anodes are needed? A) 50lbs B) 35lbs C) 25 lbs D) 45lbs E) 30lbs e
All things being equal, the greater the magnitude of the difference between two voltages of metals, the ____ the current flow and rate of corrosion A) higher B) lower a
True or False ( t or f) Magnesium will corrode at a slower rate when connected to steel rather than zinc? f
Which reference electrode is considered a primary reference electrode because it is used to determine the potential of other secondary reference electrodes that are better suited for field use? A) CSE B) Ag/AgCI C) Calomel D) Zinc E) SHE e
Most common used reference electrode for measuring potentials of underground structures? A) CSE
B) Ag/AgCI C) Calomel D) Zinc E) SHE a
True or false (t or f) The potential of a reference electrode in the sun can decrease from 10 to 50mV versus an electrode kept in the dark? t
Which reference electrode is mostly commonly used in seawater? A) CSE B) Ag/AgCI C) Calomel D) Zinc E) SHE b
Which reference electrode is mostly commonly used in concrete structures? A) CSE B) Ag/AgCI C) Calomel D) Zinc E) SHE b
Which of the following is primarily a laboratory electrode? A) CSE B) Ag/AgCI C) Calomel D) Zinc c
When doing a structure to electrolyte potential , the structure is connected via the _____ terminal and the reference is connected via the _____ terminal A) negative , positive B) positive, negative b
A potential of -0.810Vcse converted to Calomel (SCE) A) +0.306 sce B) -0.750 sce C) -0.735 sce c
A potential of -0.810Vcse converted to Ag/AgCI (SSC) A) +0.306 ssc B) -0.735 ssc C) -0.750 ssc c
A potential of -0.810Vcse converted to Zinc (ZRE) A) +0.306 zre B) -0.735 zre C) -0.750 zre a
True or False (t or f) The potential of a STATIONARY reference electrode should be checked from time to time with a portable reference electrode that is known to be accurate under "no current" conditions. t
As current is impressed on a metal over time, where does polarization occur? A) at the anode and the cathode B) at the anode C) at the cathode a
Polarization _____ the potential difference between the anode and the cathode and by Ohm's Law, the current ___ and the corrosion rate ____ until an equilibrium is reached A) lowers, drops, decreases B) increases, increases, decreases C) lowers, increases, decreases D) lowers, drops, decreases d
Depolarizers include: I dissolved oxygen II microbiological activity III water flow A) only I B) only II C) I and II D) I, II , III d
The name for the current that exists during the steady state of polarization is called the _____ of the system A) telluric current B) dynamic current C) corrosion current D) mixed potential current E) closed current c
The potential normally measured between the polarized cathode potential and the polarized anode potential A) mixed potential B) corrosion potential C) corrosion current D) open circuit potential a
_____ are the potentials of the cathode and anode when the corrosion current is zero A) mixed potentials B) corrosion potentials C) corrosion current potentials D) open circuit potentials d
______ is the result of the reaction steps at the structure/electrolyte interface including the actual transfer of charge A) activation polarization B) concentration polarization C) mixed polarization D) reactant polarization a
In concentrated acids, _______ polarization predominates A) activation polarization B) concentration polarization C) mixed polarization D) reactant polarization a
_______ is the result of reaction steps involving the diffusion of reactants up to the reaction products away from the reaction surface A) activation polarization B) concentration polarization C) mixed polarization D) reactant polarization b
Anything that causes a depletion of available reactants or a buildup of reaction products results in a ____ in the reaction rate and an _____ in concentration polarization. A) decrease, increase B) increase, decrease a
If the slowest step in the overall process involves waiting for arrival of reactants or the removal of reaction products, the reaction is under __________ control. A) activation polarization B) concentration polarization b
If the slowest step in the overall reaction process is is on the metal surface or in the charge transfer reaction the process is under _____ A) activation polarization B) concentration polarization a
__________ usually predominates in electrolytes where the concentration of the reactants is low, as with dilute solutions, or there is a buildup of reaction products from activation polarization or in stagnant environments.
A) activation polarization B) concentration polarization b
As polarization ____ , current _____ A) increases, decreases B) decreases, decreases C) increases, increases D) decreases, increases c
An increase in ions will result in a ____ in resistivity A) increase B) decrease b
The effect of current concentrated on a small area will be ____ than the effect of the same amount of current on a ____ area. A coated structure will polarize more rapidly than a bare structure A) larger, larger B) less, larger C) greater, smaller D) smaller, smaller E) greater, larger e
True or False (t or f) A small anode and a large cathode is desirable f
A(n) ____ in temperature has a tendency to ____ chemical reactions, which _____ the electrodes and _____ current A) increase, increase, depolarizes, increases B) increase, increase, depolarizes, decrease C) decrease, decrease, polarize, increase D) decrease, increase, polarize, decrease a
A(n) ____ in temperature results in a(n) ____ in polarization A) increase, decrease B) increase, increase
C) decrease, increase D) decrease, decrease c
____ movement results in a ____ in polarization and a(n) _____ in current A) decreased, decrease, decrease B) decreased, increase, decrease C) increased, increase, decrease D) increased, decrease, decrease E) increased, increase, increase d
A(n) _____ in the metal ion concentration of the anode metal results in a(n) ____ in polarization of the anode and a(n) ____ in current A) increase, decrease, decrease B) decrease, decrease, decrease C) decrease, increase, decrease D) increase, increase, decrease E) decrease, decrease, increase e
Polarization of the cathode can be affected by the concentration of cathodic reactants, such as _____ or _____ ions A) CO2, OHB) oxygen, OHC) carbon, OHD) oxygen, hydrogen d
In regards to cathodic reactants, a(n) _____ in the concentration of either of the reactants of oxygen or hydrogen will _____ polarization of the cathode and _____ current and vice versa A) increase, decrease, decrease B) decrease, decrease, decrease C) increase, decrease, increase D) increase, increase, decrease E) decrease, decrease, increase c
Passivity can be defined as the A) gain of chemical reactivity
B) polarization of chemical reactivity C) loss of chemical reactivity D) depolarization of molecular reactivity E) polarization of molecular reactivity c
The ____ region is when a slight increase in corrosion potential causes the corrosion current to increase A) transpassive B) passive C) nonpassive D) active d
The ____ region is when the corrosion potential increases to a certain point, however, the corrosion current suddenly decreases and remain essentially constant A) transpassive B) passive C) nonpassive D) active b
The ____ region occurs if the potential is increased sufficiently thus current again increases A) transpassive B) passive C) nonpassive D) active a
For the active (or nonpassivating) metal, as corrosion potential _____, corrosion current ____, more or less logarithmically (or linearly on a semilog graph). A) increases, increases B) decreases, decreases C) increases, decreases D) decreases, increases a
This type of film which forms naturally on most metals when they are exposed to the air, can provide substantial protection against further attack by many environments
A) ore B) oxide C) reductant D) selimum b
Type of corrosion with an even loss of metal over the entire area or a large area of the structure A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack g
This type of corrosion occurs where two tightly spaced surfaces - either two metals or a metal and nonmetal - are exposed to a corroding environment. Holes, gasket surfaces, lap joints, surface deposits, and crevices are likely places for this type of corrosion. A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack f
This corrosion occurs when two dissimilar metals are connected. The potential of the two metals creates a voltage difference, the driving force for corrosion. A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack a
Localized corrosion that occurs over a small area of the metal surface and leaves holes in the surface.
A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack e
This is a local corrosion attack at the grain boundaries of an alloy. It is caused by a difference in element composition near the boundaries, compared to the rest of the alloy. A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack b
This type of corrosion involves the certain removal of one of the elements from an alloy. A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack c
This corrosion is associated with rapid movement of a corrosive fluid over a metal, removing corrosion products. A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack d
results from the reaction of the metal with a corrosive environment and the presence of a stress
A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) environmental cracking F) crevice corrosion G) uniform attack d
In general, hydrogen is generated in neutral environments at ____ mV CSE A) 1,000 B) 1,044 C) 1,500 D) 1,200 b
For aluminum, the polarized potential must be kept below _____ mV CSE to avoid alkali corrosion A) 1,000 B) 1,044 C) 1,500 D) 1,200 d
For titanium, the maximum potential is ____ mV ssc to prevent hydriding A) 800 B) 700 C) 1,500 D) 1,200 b
For prestressed concrete, polarized potentials more negative than -____ mV should be avoided A) 1,000 B) 1,044 C) 1,500 D) 1,200 a
The cracking of a metal under an applied tensile stress in the presence of a corrosive environment A) stress corrosion cracking B) intergranular attack C) selective leaching D) velocity phenomena E) pitting a
Stress Corrosion Cracking occurs in a narrow potential range of ______ at a pH between ______ , and is more likely at ____ temperatures A) -525 to -725, 5 and 7, more B) -625 to -825, 7 and 9.5, less C) -525 to -725, 8 and 10.5, more D) -625 to 700, 8 and 10.5, less c
True or False (t or f) MIC exist under non anaerobic conditions (presence of great oxygen) f
In relation to MIC, consumption of _____ at the structure surface _____ the steel at cathodic areas and permits more rapid consumption of the metal by galvanic corrosion cells A) hydrogen, polarizes B) hydrogen, depolarizes C) OH-, polarizes D) OH-, depolarizes END OF CHAPTER 1 b
START OF CHAPTER2: Corrosion of the metal will cease once the applied cathodic protection current _______ the corrosion current. A) equals B) equals or exceeds C) falls below b
As the potentials of the ___ sites polarize toward the potentials of the ____ sites, corrosion current is ____.
A) anodic, cathodic, increase B) cathodic, anodic, reduced C) cathodic, anodic, increase D) anodic, cathodic, decrease b
Polarization occurs in a step-like manner with the more ____ or ____ sites polarizing first. A) positive, anodic B) positive, cathodic C) negative, anodic D) negative, cathodic b
To mitigate corrosion, all existing cathode sites must be electronegatively polarized to a potential ____ to the open circuit potential of the most ___ ____ potential existing on the structure. A) equal, inactive, cathode B) unequal, active, anode C) unequal, inactive, cathode D) equal, active, anode d
Polarization of the ____ to the ____ potential of the anodes is the true criterion for eliminating corrosion. A) cathodes, closed circuit B) anodes, closed circuit C) cathodes, open circuit D) anodes, open circuit c
Bare Pipe: What is the current required to protect an uncoated 30.48 cm (12 in.) diameter steel pipeline 1,524 m (5,000 ft) in length that is buried in soil with a resistivity of 10,000 Ω-cm? Assume experience has shown that adequate levels of cathodic protection can be achieved from 10.76 mA/m 2 (1 mA/ ft 2 ) of bare surface area. A) 16.8A B) 15.7A
C) 14.7A D 13.8A b
Coated Pipe: What is the current required to protect an uncoated 30.48 cm (12 in.) diameter steel pipeline 1,524 m (5,000 ft) in length that is buried in soil with a resistivity of 10,000 Ω-cm? Assume that 5 percent of the pipe contains holidays or defects in the coating A)0.8538A B) 1.785A C) 0.785A D) 2.754A c
For a cathodic protection system, a(n) ____ in the cathodic polarization is desired to _____ the current requirement for the structure. A) decrease, increase B) increase, increase C) decrease, decrease D) increase, decrease d
The current required for cathodic protection generally is _____ in low pH (acids) than in high pH (basic) and neutral environments. A) lower B) greater b
What two phenomena account for the increase in CP current requirement in low pH environments? A) shift in the negative directions of the structure's open circuit cathode potential / a flattening of cathodic polarization curve for the structure B) shift in the positive direction of the structure's open circuit cathode potential / a flattening of cathodic polarization curve for the structure b
The structure's cathodic polarization slope is flattened with _____ acidity because of the increased concentration of reducible _____ ion
A) increasing, hydrogen B) decreasing, hydrogen C) increasing, OHD) decreasing, OHa
True or False (t or f) The pH of an electrolyte (soil or water) is USUALLY a neutral 7 f
_______ (an acid salt) used as a fertilizer tends to decrease pH of the soil. A) calcium sulfate B) ammonium sulfate C) carbon sulfate D) magnesium sulfate b
_____ in temperature has a depolarizing effect A) increase B) decrease a
When the rate of reduction reaction is ____, it ____ the level of polarization and _____ the cathodic protection current requirement A) increased, increases, increases B) increased, decreases, decreases C) increased, decreases, increases D) decreased, increases, decreases E) decreased, decreases, decreases c
Increased temperature will ____ ionization A) increase B) decrease a
As ionization _____, the electrolyte's conductivity _____, which _____ corrosion current and the amount of cathodic protection current required for adequate protection. A) increases, increases, increases B) increases, decreases, decreases
C) increases, decreases, increases D) decreases, increases, decreases E) decreases, decreases, decreases a
Oxygen or other oxidizers ____ the current requirements as a result of flattening the cathodic polarization slope A) increase B) decrease a
True or False (t or f) structures in well aerated soils, such as sand and gravel, require more cathodic protection current than structures surrounded by relatively deaerated soils, such as clay. t
A(n) _____ in the relative movement between the electrolyte and the structure causes a(n) _____ in current requirement A) increase, decrease B) increase, increase C) decrease, increase D) decrease, decrease b
True or False (t or f) a ship under way requires less cathodic protection current than a ship at rest f
To reduce the residual corrosion current to zero, cathodic protection current must be _______ A) disproportionately increased B) disproportionately decreased C) proportionately increased D) proportionately decreased a
The relationship between applied cathodic protection current and corrosion rate is ____ A) proportional
B) disproportional C) logarithmic c
In regards to amphoteric metals: The formation of ____ ions at the cathode causes the pH of the electrolyte next to the cathode to become ____. A) hydroxyl, aciditic B) hydrogen, aciditic C) hydroxyl, aciditic D) hydroxyl, alkaline d
For pipeline coatings, polarized potential values more negative than ____ mV CSE should be avoided. A) -1000 B) -1500 C) -1200 D) -850 c
Control of External Corrosion on Underground or Submerged Metallic Piping Systems A) SP0170 B) SP0169 C) SP0007 D)SP0175 b
True or False (t or f) The potential of interest when determining adequate cathodic protection is the polarized potential across the structure/electrolyte interface t
Figure 2.15 E true = A) Structure to electrolyte potential B) Reference-to-earth resistance C) Pipe-to-earth resistance a
Figure 2.15 R r,e = A) Structure to electrolyte potential B) Reference-to-earth resistance C) Pipe-to-earth resistance b
Figure 2.15 R p,e = A) Structure to electrolyte potential B) Reference-to-earth resistance C) Pipe-to-earth resistance c
Figure 2.15 (a) Electrical Schematic of the Structure to Electrolyte Measurement Circuit A) Vm = Rm/Rt * Etrue B) Vm= Rt/Rm * Etrue C) Vm = Rt/Etrue * Rm D) Vm = Rm/Etrue *Rm a
Do you want high or low impedance on your internal circuit of your meter? A) low B) high b
The IR drop across the electrolyte can be reduced to near zero by placing the reference electrode ____ the structure coating holiday or by ____ the current flow A) far, allowing B) near, interrupting b
The criterion for cathodically protecting aluminum based on NACE Standard SP0169 is a minimum of ___ mV of polarization as measured between the structure surface and a stable reference electrode contacting the electrolyte. A) 50 B) 75 C) 100 D) 25 c
True or false (t or f) Aluminum is NOT amphoteric f
Aluminum corrodes under ____ conditions A) both acid and alkaline B) acidic only C) alkaline only a
The criteria for the cathodic protection of copper based on NACE Standard SP0169 is a minimum of 100 mV of polarization as measured between the structure surface and a stable reference electrode contacting the electrolyte. A) 50 B) 75 C) 100 D) 25 c
NACE Standard ____, "Cathodic Protection of Reinforcing Steel in Atmospherically Exposed Concrete Structures," A) SP0169 B) SP0250 C) SP0290 D) SP1000 c
True or False (t or f) The second criterion for reinforced concrete structures is that that the polarized potential be at least as negative as the potential at the base of the Tafel Slope on an E-Log I curve. t
In relation to reinforced concrete structures: The E-Log I test is performed by incrementally ____ the cathodic protection current from the installed system. At each interval, the _____ potential of the steel reinforcement is measured relative to a stable reference electrode.
A) decreasing, IR drop B) increasing, IR drop b
In relation to reinforced concrete structures: The third criterion in this standard is that the ____ potential is statistically more ____ than the statistical standard deviation of the native potentials. A) depolarized , positive B) depolarized, negative C) polarized, positive D) polarized, negative d
Minimum voltage for anerobic soils or soils containing SRB A) -850mV B) -900mV C) -950mV D)-1000mV c
In relation to E log I: Data for the curve are obtained by applying test currents of ____ magnitude and measuring the structure's ____ potential at each discrete test current value A) increasing, depolarized B) increasing, polarized C) decreasing, depolarized D) increasing, polarized b
In relation to E log I: True or False: The time interval between measurements and the current increments should be kept as consistent as possible to eliminate distortions due to the change of polarization with time t
In relation to E log I: The range of test current must be ___ than the estimated current required for protection
A) greater B) less a
In relation to E log I: The measured potential must be corrected for ____ error to obtain a polarized potential (Instant Off). A) IR drop B) current drop C) signal drop a
Figure 2.17 _____ is considered as an adequate potential for cathodic protection under the E log I method. A) Icp B) Ecorr C) Tafel Slope D) Ecp END OF CHAPTER 2 d
START OF CHAPTER 3 True or false (t or f) Pure forms of anode metals are best because they do not undergo too much "self corrosion?" f The pure forms of the metals are often not suitable as anodes because they undergo too much "self corrosion" in the environment and do not stay active.
A Magnesium Standard Alloy ______ A) is used for use in low-resistivity soils and water B) provides a higher driving voltage than the standard alloy a
A Magnesium High-Potential Alloy A) is used for use in low-resistivity soils and water B) provides a higher driving voltage than the standard alloy b
Zinc anode MIL-A-18001 or ASTM B418 Type I is _______ A) for use in low-resistivity soils and water B) provides a higher driving voltage than the standard alloy b
Zinc anode MIL-A-18001 or ASTM B418 Type II is _______ A) high purity for underground and fresh water use B) for salt water and brackish water use a
Aluminum ally anodes are used primarily in ______ applications A) dry soil B) fresh water C) seawater c
True or False (t or f) Aluminum anodes are not used in fresh water, except as impressed current anodes t
Galvalum I A) contains zinc and mercury for use in saline mud B) contains zinc and mercury for use in seawater C) contains zinc and indium for use in seawater, brackish water, and saline mud b
Galvalum II A) contains zinc and mercury for use in saline mud B) contains zinc and mercury for use in seawater C) contains zinc and indium for use in seawater, brackish water, and saline mud
a
Galvalum III A) contains zinc and mercury for use in saline mud B) contains zinc and mercury for use in seawater C) contains zinc and indium for use in seawater, brackish water, and saline mud c
True or False (t or f) The consumption of any metal is directly proportional to the amount of current discharged from its surface t
Anode efficiency is the ratio of _____ producing useful cathodic protection ____ to the total metal consumed. A) metal added, current B) voltage, current C) metal added, voltage D) metal consumed, current d
Magnesium anode efficiency is ___ A) 90% B) 80% C) 50% D) 25% c
Zinc anode efficiency is _____ A) 90% B) 80% C) 50% D) 25% a
Anode backfill provides a _____ resistivity environment around the anode? A) low B) high C) medium a
_____ can be added to anode backfill to lower resistivity A) sodium lithium B) chloride sulfate C) sodium sulfate D) chloride calcium c
The most common backfill material contains 75% _____ A) bentonite clay B) hydrated gypsum C) sodium sulfate D) chloride b
Zinc anodes can also be packaged in a backfill consisting of 50% ____ and 50% ______ A) sodium sulfate, chloride B) hydrated gypsum, bentonite clay C) sodium sulfate, hydrated gypsum b
Impressed current anodes are manufactured from materials that are consumed at ____ rates A) high B) low b
_____ anodes are used in soils, flowing seawater, mud, and are practically immune to chlorine attack A) Magnesium B) Zinc C) Galvalum D) Aluminum E) Graphite F) High-Silicon Chromium-Bearing Cast Iron e
Which of these anodes is known for being brittle A) Magnesium B) Zinc
C) Graphite D) Aluminum E) Galvalum F) Magnetite c
Consist of rare earth oxides baked onto a titanium substrate A) Magnesium B) Mixed-metal Oxide C) Galvalum D) Aluminum E) Graphite F) High-Silicon Chromium-Bearing Cast Iron b
______ and _____ alloys have been used as impressed current anodes on reinforced concrete structures. A) Magnetite, Mixed-Metal Oxide B) Copper, Galvalum C) Thermal sprayed zinc, aluminum c
It is used in seawater, brackish water, fresh water, and high-resistivity soil A) Magnesium B) Zinc C) Graphite D) Aluminum E) Galvalum F) Magnetite f
The purpose of anode backfill material is I reduce the resistivity II extend the anode surface area III decrease the amount of current the anode can discharge IV reduce consumption of the anode A) I, II B) I, II, III, IV C) II, III, IV D) I, II, IV d
True or False (t or f) The resistance of carbon backfill is not dependent on how well it is compacted f
In regards to anode backfill: The ____ the degree of compaction, the ____ the resistance A) lower, higher B) higher, higher C) higher, lower D) lower, lower c
In regards to anode backfill: ____ grade coke is often used for ____ anode systems A) larger, hortizonal B) finer, deep C) finer, shallow D) larger, deep b
True or false (t or f) Any exposed metal in an impressed current CP system is part of the anode. t
Types of CP cables: This insulation is commonly used for direct burial cathodic protection installations for both anode and structure wiring A) HMWPE B) Halar C) Kynar a
The primary reactions at the anode surface are: I metal oxidation II oxygen and chlorine evolution III chlorine generation
A) only I B) I, II C) I, II, III c
Gases in a deep anode system should be ____ A) vented B) non vented a
Reactions at the anode produce an excess of ____ ions A) hydroxl B) chlorine C) carbon D) hydrogen d
Hydrogen ions will _____ the environment immediately adjacent to the anode A) acidify B) alkalify a
Anode configurations can be described as ____ or ____ A) distributed, nondistributed B) remote, unified C) distributed, remote c
The anode gradients are ____ within a few feet of the anode. A) largest B) smallest a
The term ____ refers to the point where further distance from the anode produces no further change in voltage gradient. A) distributed B) remote earth C) area of influence D) gradient area b
A _____ configuration uses anodes located at relatively close intervals along the structure. A) distributed B) remote earth C) area of influence D) gradient area a
In regards to distributed anode configuration: "Close" means that the structure being protected will fall within the anode ______, This means that the anodes will cause the electrolyte around the structure to become ____ with respect to remote earth A) current gradient, negative B) voltage gradient, positive C) distributed gradient, positive D) remote earth gradient, positive b
A ____ configuration uses anodes placed at a location considered electrically far from the structure A) distributed B) remote earth C) area of influence D) gradient area b
True or false (t or f) The term electrically remote and geometrically remote are the same thing f
____ anodes are used for coated structures where only holidays in the coating are protected by the CP system and for structures that are electrically isolated from other structures. A) remote B) distributed C) area of influence D) gradient area a
Galvanic anodes are usually installed in a ____manner on offshore platforms A) distributed B) remote a
Impressed current anodes are installed as ____ anodes. A) distributed B) remote C) distributed or remote c
impressed current anodes are used in the remote configuration by installing them in ___ hole drilled from the surface A) deep B) shallow a
In the case of a buried pipeline or elongated structure (e.g., sheet pile wall), anodes can be placed ___ to structure. A) parallel B) perpendicular C) parallel and perpendicular c
Impressed current anodes are installed in a _____manner on offshore structures A) distributed B) remote END OF CHAPTER 3 ...
START OF CHAPTER 4 What is the common type of power supply used for impressed current cathodic protection? A)Solar B) TEG C) rectifier D) Fuel Cell c
A rectifier converts the ___ power supply voltage to the required ___ voltage and then converts it to ___ A) DC, output, AC B) AC, input, DC C) AC, output, DC D) DC, input, DC E) DC, output, DC c
True or false (t or f) Rectifiers are either supplied in ventilated cases or are immersed in transformer oil t
_____ provides protection to the rectifier components from current surges or overload A) circuit breaker B) fuses C) panels D) shunt a
In order to disconnect the AC when working on the face of the panel, the ___ most be off A) meters B) fuses C) panels D) circuit breaker d
These breakers have a bimetallic element that carries current A) magnetic breakers B) thermal breakers C) exothermic breakers D) thermal magnetic breakers b
Circuit breaker is in the tripped position when it is in the ____ position A) up B) down C) left
D) right E) center e
This breaker is considered the most suitable for CP rectifiers A) magnetic breakers B) thermal breakers C) exothermic breakers D) thermal magnetic breakers a
The ______ consists of an iron core surrounded by a coil of wire A) magnetic breakers B) thermal breakers C) exothermic breakers D) thermal magnetic breakers a
It has a magnetic plate attached to the element to increase the speed in tripping the circuit A) magnetic breakers B) thermal breakers C) exothermic breakers D) thermal magnetic breakers d
When it trips it causes the core to pull a trip lever towards it thus causing an open circuit A) exothermic breaker B) thermal breakers C) magnetic breaker D) thermal magnetic breakers c
The purpose of a ____ is to either "step up" or "step down" a(n) ___ supply voltage A) transformer, AC B) circuit breaker, DC C) fuse, DC D) central processing unit, AC E) transformer, DC a
The ratio of the ____ voltage to the induced _____ is in ______ to the windings in each coil A) primary DC voltage, secondary DC voltage, inproportiate B) primary AC voltage, secondary AC voltage, proportion C) primary DC voltage, secondary DC voltage, inproportiate b
In regards to a transformer: The ______ is connected to the ____ supply and the alternating magnetic field ____ a(n) AC voltage in the _____ A) secondary winding, secondary AC voltage, induces, secondary winding B) primary winding, primary AC voltage, conducts, secondary winding C) primary winding, primary AC voltage, induces, secondary winding D) secondary winding, primary AC voltage, induces, secondary winding c
Transformers use _____ A) induction B) conduction a
If a transformer has no losses, what is the secondary voltage of a transformer being supplied with 115 V AC that has 400 turns on the primary and 100 turns on the secondary windings? A) 30Vac B) 28.75Vac C) 22.5Vac D) 32.75Vac b
The _____ tap changes the ____ voltage A) primary, AC B) secondary, AC C) primary, DC D) secondary, AC b
Single phase rectifier that has 4 diodes A) single-phase B) full-wave C) center-tapped b
Single phase rectifier that has has 1 diodes A) single-phase B) full-wave C) center-tapped a
Single phase rectifier that has 2 diodes A) single-phase B) full-wave C) center-tapped c
Which rectifier is the standard most often used A) single-phase B) full-wave C) center-tapped b
Three phase rectifier that has 3 diodes A) single-phase B) wye C) center-tapped D) full-wave b
Three phase rectifier that has 6 diodes A) single-phase B) full-wave C) center-tapped D) wye b
True or False (t or f) In regards to rectifiers:
single-phase units are more efficient than three-phase units f
The theoretical maximum efficiency for a threephase, full-wave bridge rectifier is ___% compared to ___% for a single-phase, fullwave bridge rectifier A) 99.5, 85 B) 81, 96.5 C) 96.5, 81 D) 85, 99.5 c
Modern rectifiers employ either ____ or ____ diodes to provide the rectifying action A) silicon, galanium B) magnesium, cronium C) tituanium, selenium D) selenium, silicon d
True or False (t or f) Diodes are electrical devices that allow current to pass in one direction but block current in the opposite direction t
The two AC input terminals to the rectifying bridge are I1 and I2 The two DC output terminals are O1 and O2
True or False (t or f) The positive potentials always transfer to output terminal O1, and the negative potentials transfer to output terminal O2.
t
In regards to rectifiers: Plates are arranged in "stacks," with the ___ and ____ of plates being determined by the ___ and ____ output capacity of the rectifier. A) weight, size, voltage, current B) number, size, voltage, current C) number, spacing, resistance, conductivity D) spacing, weight, resistance, current b
Which of the diodes in a rectifier is more sensitive to current surges and can be quickly destroyed by any current overload A) silicon B) selenium a
True or False (t or f) Silicon stacks are often called "self-healing" f selenium is "self-healing"
_____ diodes consist of a wafer sliced from a pure single crystal of ____ A) silicon B) selenium ...
_____ stacks can tolerate current overloads up to ten times rated capacity for a few minutes A) silicon B) selenium b
Which is more efficient selenium or silicon diodes A) silicon B) selenium a
Which of the rectifier diodes fail completely rather than slowly A) selenium stacks fail completely rather than slowly like silicon diodes B) silicon diodes fail completely rather than slowly like selenium stacks b
_____ rectification can be achieved with ___ diodes in a ___ tap configuration A) half-wave, four, center B) full-wave, four, center C) half-wave, two, center D) full-wave, two, center d
In regards to rectifiers: In the single phase circuit, ___ diode conducts during each AC cycle and produces a large ripple. A) one B) two C) four D) six a
______ supply current in a cyclic fashion A) Silicon -Controlled Rectifiers B) Pulse Rectifier C) Thermoelectric rectifier D) Switch-mode rectifiers b
______ are sometimes added to provide additional control of the rectification process for some types of cathodic protection rectifiers. A) selenium-controlled rectifiers B) silicon-controlled rectifiers b
Silicon-controlled rectifiers are _____ three-junction PN devices A) 2 B) 3
C) 4 D)6 b
In regards to rectifiers: In order for the SCR to be forward biased and begin conducting, a ___ potential (V AC ) must be applied between ___ (P side) and ___ (N side), and a positive voltage pulse must also be applied between the ___ and the ____ (V GC ) as seen in the center A) negative, anode, cathode, bridge, cathode B) positive, cathode, anode, gate, cathode C) positive, anode, cathode, gate, cathode D) negative, anode, cathode, gate, cathode c
In regards to rectifiers: At the instant the gate pulse is applied, the SCR fires and begins to conduct current from the ____ to the ____ A) anode, cathode B) cathode, anode a
In regards to rectifiers: Regardless of the gate current, the SCR continues to ____ until the applied voltage (V AC ) goes to ____ and the current returns to ___ A) induct, zero, equal B) induct, zero, zero C) conduct, equal, zero D) conduct, zero, zero d
In regards to rectifiers: If the gate pulse is delayed for one quarter of a cycle from the time the applied voltage crosses the zero axis and moves in the positive direction A) none of the half cycle waveform will pass B) one-half of the half cycle (90°) waveform will be allowed to pass
C) the SCR will conduct through a complete half cycle (180°) of the input waveform b
If the gate pulse arrives at the same time the applied voltage crossed the zero axis and begins to move in the positive direction A) none of the half cycle waveform will pass B) one-half of the half cycle (90°) waveform will be allowed to pass C) the SCR will conduct through a complete half cycle (180°) of the input waveform c
In regards to rectifiers: If the gate pulses are applied at the zero crossing of the input waveform (180° conduction angle) A) the output waveform is a fully rectified version of the input waveform B) none of the half cycle waveform will pass C) one-half of the half cycle (90°) waveform will be allowed to pass D) the SCR will conduct through a complete half cycle (180°) of the input waveform a
In regards to rectifiers: If the gate pulse is never applied A) none of the half cycle waveform will pass B) one-half of the half cycle (90°) waveform will be allowed to pass C) the SCR will conduct through a complete half cycle (180°) of the input waveform a
In regards to rectifiers: By controlling the timing of the _____ we can continuously vary the level of the ___ voltage output. A) gate pulses, DC B) bridge pulses, DC C) gate pulses, AC D) shuttle pulses, DC a
In regards to rectifiers: The longer the control circuit delays the gate pulse, the ____ the ripple in the output waveform will be A) shorter B) longer b
This rectifier uses a transformer that is a much smaller, uses a high frequency, ferrite-core transformer A) Silicon -Controlled Rectifiers B) Pulse Rectifier C) Thermoelectric rectifier D) Switch-mode rectifiers d
True or False (t or f) In regards to rectifiers To improve efficiency and reduce ripple, manufacturers normally add filters to the output terminals t
Rather than adjusting the output voltage level using a large, laminated steel core transformer, ______ control the DC output voltage level by producing a series of high frequency (typically 50 to 500 k Hz) DC pulses and adjusting the timing of DC pulses to produce the required output DC voltage level. A) Silicon -Controlled Rectifiers B) Pulse Rectifier C) Thermoelectric rectifier D) Switch-mode rectifiers E) Constant Voltage rectifier d
In regards to a Standard Transformer Rectifier, but the following in order from left to right: Rectifier AC Input Filter (if used) Low Frequency Transformer w/TAPs DC Output
In regards to a Switching Mode Rectifier, put the following in order from left to right DC Output Primary Filter Transformer Secondary Filter Secondary Rectifier Sensing/Switching Circuit Primary Rectifier AC Input Solid State Switch
In regards to a switching mode rectifier: The DC pulses are fed through a high frequency ____ to isolate the output.
A) transformer B) primary filter C) secondary rectifier D) solid state switch a
In regards to a switching mode rectifier: The _______ next converts the DC to high frequency DC pulses A) transformer B) primary filter C) secondary rectifier D) solid state switch d
In regards to a switching mode rectifier: The _______ circuit provides feedback control to the _______ to control the "on" and "off" timing (pulse width) of the switch A) solid state switch, sensing / switch control B) secondary rectifier, primary filter C) solid state switch, secondary rectifier D) sensing/switch control, solid state switch d
The primary advantages of a switching-mode rectifier over a standard transformer/ rectifier are I higher reliability due to number of components II Small size and weight III Prone to higher ripple IV High efficiency at low rated output A) only I B) I, II, IV C) II, IV D) I, II, III E) I, II, III, IV c
In this type of rectifier, the output voltage is adjusted by changing the secondary transformer taps A) Silicon -Controlled Rectifiers B) Pulse Rectifier C) Thermoelectric rectifier
D) Switch-mode rectifiers E) Constant Voltage rectifier F) Constant Current rectifier e
True or false (t or f) In a switching mode rectifier: Repair of individual modules is easy and practical f it is NOT practical
Adjustment of the output is a combination of varying the frequency and adjusting capacitors that in turn set the duty cycle with this type of rectifier A) Silicon -Controlled B) Pulse C) Thermoelectric D) Switch-mode b
The primary use of pulse rectifiers is on _____ A) foreign lines B) mountainous areas C) well casings D) anode beds c
If the external resistance changes, this rectifier output voltage is increased or decreased to maintain the preset value and an external reference electrode is not used in this type of rectifier A) Silicon -Controlled Rectifiers B) Constant Current rectifier C) Thermoelectric rectifier D) Switch-mode rectifiers E) Constant Voltage rectifier F) Pulse Rectifier b
A constant current rectifier can also be achieved using ____-controlled diodes
A) selenium B) silicon b
This ____ uses an external structure-to-electrolyte potential and compares it to the preset value. If the structure-to-electrolyte potential changes from the preset value, the rectifier current either increases or decreases current output to bring the potential back to its preset value A) Silicon -Controlled Rectifiers B) Constant Current rectifier C) Thermoelectric rectifier D) Switch-mode rectifiers E) Constant Potential rectifier F) Pulse Rectifier e
These rectifiers should be manufactured with a current limiting circuit in the event of a loss of reference cell input signal A) Silicon -Controlled Rectifiers B) Constant Current rectifier C) Thermoelectric rectifier D) Switch-mode rectifiers E) Constant Potential rectifier F) Pulse Rectifier e
_____can be supplied with the rectifier to allow cycling the unit on and off for testing purposes A) Filters B) Surge protection C) Interrupters D) Remote Monitoring E) Warning Devices and Signal Lights c
___ is used to protect the rectifier from lightning A) Filters B) Surge protection C) Interrupters D) Remote Monitoring E) Warning Devices and Signal Lights b
Efficiency _____ are used to decrease the AC ripple of the DC output, which decreases the operating cost of the rectifier A) Filters B) Surge protection C) Interrupters D) Remote Monitoring E) Warning Devices and Signal Lights a
____ are used to alert personnel to operating malfunctions of the unit A) Filters B) Surge protection C) Interrupters D) Remote Monitoring E) Warning Devices and Signal Lights e
True or False (t or f) The rectifier MUST be turned off at the breaker before any taps are changed, and changes should be made one at a time t
The _____ rectifiers are usually adjusted by changing the transformer tap settings A) Silicon -Controlled B) Constant Current C) Thermoelectric D) Switch-mode E) Constant Voltage F) Pulse e
In regards to rectifiers: The general procedure to change taps is to turn off rectifier, increase the ____ one setting making certain that the connections are tight, and turn on the rectifier checking ____output voltage A) Coarse tap, DC B) Fine tap, DC
C) Coarse tap, AC D) Fine tap, AC b
In regards to rectifiers: When the Fine taps have reached the _____, lower it to the first setting and increase the ____ one setting. A) minimum, fine tap B) maximum, coarse tap C) maximum, fine tap D) minimum, coarse tap b
Potential control and constant current rectifiers are controlled using a______adjustment found on the controlling circuit board A) multimeter B) ammeter C) potentiometer D) ohm meter E) shunt c
Thermoelectric Generators for CP use the ______ effect to generate potentials across a dissimilar metal junction A) Seebeck B) Hardlock C) Kirkhoff D) Ohms a
In regards to solar energy: The conversion efficiencies for silicon-based photovoltaic cells are in the range of ____% A) 5 to 15 B) 10 to 20 C) 8 to 14 D) 20 to 25 c
In regards to solar energy:
What device ensures the battery bank is properly charged A) solar panels B) charge controller C) monitor D) CP regulator b
Basic rectifier operational data includes I AC input voltage II AC output voltage III DC output voltage and DC output current IV Tap settings V cathode to structure resistance VI anode to structure resistance A) I, III, IV, V B) I, III, V C) I, III, IV, VI D) all c
In regards to standard single-phase, manual adjustment type rectifiers: If there is no input power to the unit or an open circuit within the rectifier is indicated, this is an example of a(n) _______ problem A) Zero Current Output with Unchanged Voltage Output B) Significant Current Change with Unchanged Voltage C) Significant Changes in Both Voltage and Current Outputs D) Significant Changes in Both Voltage and Current Outputs E) Zero Current and Voltage Outputs e
In regards to standard single-phase, manual adjustment type rectifiers: system additions, shorts to other underground structures, or major coating damage are signs of _____ problems A) Zero Current Output with Unchanged Voltage Output B) Significant Current Change with Unchanged Voltage C) Significant Changes in Both Voltage and Current Outputs D) Significant Changes in Both Voltage and Current Outputs b
In regards to standard single-phase, manual adjustment type rectifiers: Open fuse in the output circuit, Faulty connections, An open positive or negative lead cable, Failed anodes A) Zero Current Output with Unchanged Voltage Output B) Significant Current Change with Unchanged Voltage C) Significant Changes in Both Voltage and Current Outputs D) Significant Changes in Both Voltage and Current Outputs a
In regards to standard single-phase, manual adjustment type rectifiers: If AC voltage is present at the ___ terminals, an ___ circuit exists within the ___. A) output, closed, anode B) input, closed, anode C) output, open, anode D) input, open, rectifier d
In regards to standard single-phase, manual adjustment type rectifiers: If it is determined that the input circuit breaker has tripped, a ___ current or ___ has occurred A) low, load B) high, overload C) high, load D) low, underload b
In regards to standard single-phase, manual adjustment type rectifiers: If the circuit has been tripped, proceed to ___ the voltage output tap to a ____ level and reset the circuit breaker. A) reduce, low B) increase, high a
In regards to standard single-phase, manual adjustment type rectifiers: To determine if the short circuit is external to the rectifier I turn off the DC power supply II turn off the AC power supply III disconnect one of the DC output connection leads IV disconnect one of the AC output connection leads V reset the breaker A) II, I, IV, V B) I, II, III, IV, V C) II, III, V D) I, II, III c
In regards to standard single-phase, manual adjustment type rectifiers: If the short circuit is ___ to the rectifier, the circuit breaker will ___ trip. If the short circuit is ___ to the rectifier, the circuit breaker ___ trip A) internal , external, not, will again B) external, not, internal, will again C) external, will, internal, not again D) internal, internal, will again, not b
In regards to standard single-phase, manual adjustment type rectifiers: If the current output significantly ___, a ___circuit resistance is indicated A) increased, higher B) decreased, higher C) increased, lower D) decreased, lower b
In regards to standard single-phase, manual adjustment type rectifiers: Some of the possible causes for this problem might include installation of inline isolators, anode deterioration, discontinuity due to disconnection of system component, or gas blockage
A) Zero Current Output with Unchanged Voltage Output B) Zero Current Output with changed Voltage Output C) Significant Changes in Both Voltage and Current Outputs D) Significant Current Change with Unchanged Voltage d
True or false (t or f) Seasonal variations in soil conditions, such as drying or frost, can also increase the current resistance t
In regards to standard single-phase, manual adjustment type rectifiers: If the voltage and current outputs are approximately one-half of the normal values, the most probable cause is partial failure of ____ , however if the _____ are found to be operating properly, the ____ should be investigated for possible winding to winding shorts A) rectifier case, transformer B) transformer, rectifier stacks, rectifier case C) rectifier stacks, rectifier stacks , transformer c
True or False, in regards to rectifier troubleshooting: If the cathode-to-structure resistance is normal, then the problem is with the rectifier f If the ANODE-to-structure resistance is normal, then the problem is with the rectifier
Which conditions can cause internal short circuits I Failed diodes II contact in transformer windings III Contact between positive circuit and the rectifier cabinet or negative circuit IV Spark-gap type lightning arrestors failed in the shorted condition A) I, II, III B) I, II C) II, III, IV D) all d
True or false: Internal short circuits can occur due to any metallic contact between the positive and negative circuits f EXTERNAL short circuits can occur due to any metallic contact between the positive and negative circuits
True or false: Inadvertent contact between the anode or its low resistivity backfill and the structure is the most common type of external short circuit t
When confronted with a possible short circuit: A) connect all external positive and negative cables at the rectifier before reenergizing the rectifier B) disconnect all external positive and negative cables at the rectifier before reenergizing the rectifier b
If the rectifier operates normally upon re-energizing, then the short is ____ to the unit, providing the short reappears when the cables are _____ A) internal, reconnected B) external, disconnected C) internal, disconnected D) external, reconnected d
If the open circuit is ___, then the voltage will appear across the internal component with open circuit. A) external B) internal b
True or false All rectifiers units can not be operated in the shorted condition when on the lowest AC tap setting f
SOME rectifier units can be operated in the shorted condition when on the lowest AC tap setting
In regards to rectifiers: The open circuit condition is characterized by ____ A) increase current output B) decreased current output C) increased voltage output D) zero current output d
Which of the following is NOT a common cause of internal open circuits I failed diode II broken cables III open connections IV blown fuses A) I, II, IV B) II, III, IV C) I, II, III, IV D) all are a common cause of internal open circuits d
True or false External open circuits generally do not involve broken or corroded cables f
Note that testing, using visual inspection must be performed with the rectifier ___ and ___ power disconnected and locked out. A) on, AC B) off, DC C) off, AC D) on, DC c
The efficiency of a rectifier is calculated with a(n) ___meter A) amp-hour B) watt-hour b
Percent Efficiency = A) DC Power Out/ AC power in x100 B) AC power in/ dc power out x 100 a
calculate the efficiency of a rectifier with a DC output of 10 V 25A DC if the watt meter reads 500 W. A) 40% B) 60% C) 50% D) 70% c
If a watt-hour meter is used to determine the input power, the following formula is used A) AC input power = 3,600K N /T B) AC input power = 2,600 K N /t K = meter constant N = number of revolutions T= time in seconds of observation a
If the efficiency is below what is expected or DC output voltage is about half that expected, the following can be responsible: I input voltage may be lower than it should be II output voltage is too high for the rectifier rating III output voltage is too low for the rectifier rating IV badly aged stacks A) I, III, IV B) II, III, IV C) I, II, III D) only I a
____ are used to improve efficiency and for noise interference control in the rectifiers A) fuses B) resistors C) transformers
D) filters E) diodes d
In regards to rectifiers: If the ___ is blown, replace it and turn on the rectifier. If the ___ blows again, the ____ is defective and should be replaced. A) fuse, transformer, fuse B) transformer, fuse, capacitor C) fuse, fuse, capacitor D) capacitor, capacitor, fuse c
In regards to rectifiers: If AC voltage is present to the primary but not the secondary of a transformer: check to see whether there is an audible hum coming from the transformer, if so, the ____ is operating, but the _____ is probably ____ A) primary, secondary, closed B) secondary, primary, open C) secondary, primary, open D) primary, secondary, open d
In regards to rectifier transformers: The _____ winding should have generally less than one (1) Ω resistance while the ____should have 1 to 10 Ω resistance. A) secondary, primary B) primary, secondary a
True or false when trouble shooting silicon stacks, remove each diode and check individually with a diode checker for forward and reverse bias t
In regards to the transformer in a rectifier:
If there is no output voltage or current, the_____ A) transformer is broken B) fuse is blown C) no AC input voltage b
A functional diode in a stack will typically display a voltage from ___ V to ___ V in the forward bias A) 3, 9 B) 0.5, 1.0 C) 0.3, 0.9 D) 3, 6 E) "OL" (overload or out of limits) c
In regards to a diode in a rectifier: In the reverse bias condition, positive lead to cathode and negative lead to anode, a functional diode will display ____ A) 3V, 9V B) 0.5V, 1.0V C) 0.3V, 0.9V D) 3V, 6V E) "OL" (overload or out of limits) e
True or False (t or f) Diodes can be properly checked while in the circuit or with the power on f CANNOT
How can diodes be tested in a rectifier A) turned off, locked out, disconnect secondary taps and DC cables B) turned off, locked out, disconnect primary taps, and DC cables END OF CHAPTER 4 a
START OF CHAPTER 6 A structure-to-electrolyte potential is a measurement taken with the voltmeter
connected in ____ in the circuit A) parallel B) series a
Structure-to-electrolyte potential profile surveys are used to: I locate cathodic areas II locate anodic areas III locate stray currents IV locate coating holidays A) only II B) I, I, III C) III, IV D) II, III, IV d
When attempting to minimize voltage drops while conducting a pipe to soil measurement _____ A) put the reference electrode in remote earth B) minimize the distance between the reference electrode and the surface of the structure C) measure the potential when the current flow is not interrupted (instant on) D) ensure external CP coupons in the vicinity of the structure to replicate a coating holiday b
One of the disadvantages of structure to electrolyte potentials is that: A) all sources of CP current must be not be interrupted simultaneously, B) stray currents will affect the readings C) locate coating holidays D) is not straightforward b
True or false (t or f) The averaging of the actual structure-to-electrolyte potentials means that surface measurements will detect small corrosion cells that are being cathodically protected f might NOT detect small corrosion cells that are NOT being cathodically protected
In regards to structure to electrolyte: Because the meter circuit is a ____ circuit, the magnitude of the ____ that appears across the meter will be _____ to the ratio of the meter resistance to the total meter circuit resistance A) parallel, current drop, disproportional B) parallel, voltage drop, proportional C) series, voltage drop, proportional D) series, current drop, proportional c
In regards to structure to electrolyte: For the measurement circuit, Kirchhoff's ___ law applies and the true potential difference is equal to the sum of the ____ drops around the ___ circuit. A) voltage, current, parallel B) voltage, voltage, series C) current, voltage, series D) current, current, parallel b
Consider a true potential (E true ) of 1,000 mV, each test lead resistance (R tl ) of 0.01 Ω, a pipe-to-earth resistance (R p,e ) of 10 Ω, a reference electrode resistance to earth (R r,e ) of 100 kΩ, and a meter resistance (R m ) of 1 MΩ. Calculate the voltage that would appear across the voltmeter. A) 1000mV B) 800mV C) 909mV D) 850mV c 1) R t = 3R tl + R p,e + R r,e + R m = 3(0.01) + 10 + 10 5 + 10 6 R t = 1.1 MΩ 2) V m = R m / Rt * E Vm = 1.0Mohms / 1.1Mohsm * 1,000mV = 909mV
The voltage across the voltmeter approaches the true potential as the meter resistance becomes much ___ than the other resistances in the measuring circuit A) greater B) lower a
True or false (t or f) E true is the same as the polarized potential. t
If a potential difference (V l ) of -650 mV cse was measured with an input resistance (R l ) of 1.0 MΩ and a potential difference of -800 mV cse (V h ) was measured with an input resistance (R h ) of 10 MΩ, then the true potential (E true ) is A) -720mVcse B) 1000mVcse C) -821mVcse D) -521mVcse c -800mV(1-0.1) / 1-0.1[-800mV/-650mV] = -821mVcse
What is the total circuit resistance (Rt) given a true potential of -821mVcse, an input resistance (Rh) of 10Mohms A) 10.8Mohms B) 9.3Mohms C) 9.5Mohms D) 10.3Mohms d
What is the resistance in the measuring circuit of a multimeter excluding resistance given Rt is 10.3Mohms and there is an input resistance of 10Mohms A) 0.5Mohms B) 1.0Mohms C) 0.3Mohms D)0.7Mohms
c R circ = R t - R m
In regards to Voltage and current lines around a bare pipeline receiving cathodic protection current (Figure 6.3): The ____ lines denote the ___ paths while the lines _____ to the current lines represent the ______ surfaces created by the current. A) radial, voltage, equipotential, perpendicular B) radial, current, perpendicular, equipotential C) equipotential, current, parallel, radial D) equipotential, current, radial, parallel b
In regards to Voltage and current lines around a bare pipeline receiving cathodic protection current (Figure 6.3): The equipotential surfaces ____ with distance away from the pipe because each successive shell of earth has a ____ surface area and hence a ____ resistance. (figure 6.3) A) decrease, smaller, higher B) increase, smaller, higher C) decrease, larger, higher D) increase, larger, lower d
In regards to Voltage and current lines around a bare pipeline receiving cathodic protection current (Figure 6.3): If the potential difference between adjacent equipotential surfaces is 10 mV, the voltage drop in the soil between the pipe surface and the reference location would be __ lines × __ mV = ___ mV. A) 10, 10, 100 B) 10, 100, 1000 C) 5, 5, 25 D) 100, 10, 1000 a
For well coated pipeline, the equipotential field forms in ________ holidays
A) close proximity to the B) remote proximity to the C) distant proximity to the a
In regards to a well coated pipe: Typically __% of the total voltage drop between the reference and the steel exposed at the holiday is found within about ___ diameters of the holiday A) 50%, 10 B) 80%, 100 C) 95%, 100 D) 95%, 10 d
In regards to a well coated pipe: For a 1 cm diameter holiday, ___% of the voltage occurs within a radius of __ cm from the holiday. A) 50, 10 B) 85, 100 C) 90, 10 D) 95, 100 c
In regards to IR drop error determination and correction: One method to correct for IR drop is to place the reference electrode at ____ to include ____ and then ____ this error from potentials measured with the reference located ____ the structure A) close distance, max IR-drop, add, furthest from B) remote earth, max IR-drop, subtract, nearer C) remote earth, max IR-drop, add, furthest from D) close distance, min IR-drop, subtract, nearer b
In regards to IR drop error determination and correction: One method to correct for IR drop is ____ the current in steps while measuring the change in structure-to-electrolyte potential and the resultant surface voltage gradient.
A) increase B) decrease b
Figure 6.8 The "instant-off" potential should be measured ___ spiking has ________ significant ____ of the structure has occurred. A) before, decayed but before, polarization B) before, decayed but after, depolarization C) after, decayed but after, polarization D) after, decayed but before, depolarization d
Potential Measured (E m ) = A) IR Drop+ Depolarization+ True Potential B) IR Drop- Polarization+ E corr C) E corr Polarization IR Drop D) E corr + Polarization + IR Drop d
Key factors in selecting an interruption cycle include I maintaining depolarization over the duration of the survey project II maximizing depolarization during the OFF period III minimizing depolarization during the day IV Ability to measure accurate OFF potential data after the "spike" has dissipated V maintaining polarization over the duration of the survey project A) I, II, III B) III, IV, V C) II, III, IV D) II, III, IV, V b
True or False (t or f) In regards to current interrupters , the duty cycle is the percentage of ON time to OFF time ...
Maintaining an ___% / ___% or ___% / ____% "duty cycle" is important to minimize ____ during the day and over the duration of the survey project
A) 50/50 , 75/25 , depolarization B) 80/20 , 50/50, polarization C) 80/20 , 75/25, depolarization, polarization D) 80/20 , 75/25, depolarization, depolarization d
True or false (t or f) Current interrupters should be left on during the night f it is important to turn off the current interrupters at night. This will reduce the amount of time the current sources are being cycled and help rebuild any polarization which may have been lost during the day when the current sources were cycling ON and OFF.
Some ____ interrupters will fail in the on position when synchronized if they lose ___ signal and then restart when it comes back, unless there is a _____ monitoring the data A) quartz crystal, head spacing, data logger B) quartz crystal, satellite, meter station C) GPS, satellite, data logger D) GPS, head spacing, meter station c
One method of verifying interruption synchronization and of checking the magnitude and duration of the inductive/capacitive spike is by recording a ____ or "wave print" A) wave scope B) current wave C) data logger D) waveform d
Evidence that cathodic protection is working can be obtained by using ____ , they consist of ____ A) coupons, the same metal as the anode B) coupons, the same metal as the cathode b
Coupons ____ weighed carefully before being electrically connected to the protected structure
A) are B) are not a
True or false (t or f) IR-drop-free potentials can be obtained with coupons without interrupting multiple power sources t
True or false When using coupons there can never be a discrepancy between the polarized potential of the coupon and that of the structure f there CAN be a discrepancy
True or False The coupon is momentarily disconnected from the structure and its potential with respect to the electrolyte is read. This measured value is essentially an IR-drop-free reading of the coupon potential to the reference electrode. t
The IR-drop-free potential of the coupon is similar to ____ potential of the structure A) instant ON B) instant OFF C) depolarization b
In regards to coupons: If corrosion is occurring, the resistance probe will reflect the condition by showing a ____ resistance over time. A) higher B) lower a
_____ are available that will monitor corrosion rate directly without being removed from the environment A) coupons
B) resistance probes C) RMU b
With the reference electrode ____ from the structure, the potential reading includes _____ when the ____ is applied A) is local, the maximum total IR-drop error, current B) is remote, the total resistance error, current C) is remote, the maximum total IR-drop error, current c
Remote earth may be determined by a series of structure-to-electrolyte potential measurements made as one moves ____ from the structure. A) toward B) away b
True or false The distance to remote earth is the same at all points on a structure. f The distance to remote earth is not necessarily the same at all points on a structure.
In _______ soil areas, the distance to remote earth tends to be_____ than in ______ soils A) high-resistivity, greater, low-resistivity soils B) low-resistivity soils, greater, high-resistivity C) high-resistivity, lower, low-resistivity soils a
The ______ involves recording the potential shift in the structure-to-electrolyte potential measurement and a side drain potential measurement as the cathodic protection ________ A) stepwise current reduction technique, current is reduced B) stepwise current reduction technique, current is increased C) stepwise current reduction technique, current is left constant a
In regards to the stepwise current reduction technique: If the potential changes are recorded quickly, this technique can be used in the presence of ____ stray currents
A) steady state B) telluric C) dynamic c
True or False ( t or f) A close interval potential survey can be completed on both cathodically protected and non-cathodically protected structures t
True or False (t or f) If the target CP criteria is the -0.850 V CSE polarized potential criteria, then typically an interrupted CIS is done where the ON and instant off are completed t
For the 100 mV polarization criteria during CIS, the pipe must be ____ for a period of time, and CIS must be conducted at the same location during the initial CIS A) depolarized B) polarized a
If a section of pipe has OFF potentials less negative than -0.850Vcse this indicates A) non adequate levels of CP B) adequate levels of CP a
The graph illustrates what in the first and second half of the picture A) all critiea for CP have been met B) nearly zero IR drop in the ON potential in the second half C) ON and depolarized potentials are the same in the first half of the graph B
Lateral/Side Drain Surface Surveys are completed during CIS projects on ______ protected pipes and are typically ____ and ____ ____ to the pipe A) non-cathodically, 10ft, 25ft, parallel B) cathodically, 15ft, 25ft, parallel C) non-cathodically, 10ft, 25ft perpendicular D) cathodically, 10ft, 20ft, perpendicular c
In regards to Lateral/Side Drain Surface Surveys: anodic locations will only be those areas where the lateral potentials are less ____ than the over-the-pipe potentials A) negative B) positive a
Is it better to have a permanent shunt or use an ammeter to measure current in a circuit? A) ammeter B) permanent shunt b
True or False (t or f) When selecting a shunt, its current rating must exceed the anticipated circuit current and the millivolt drop at the anticipated operating current should be easily measurable on a standard digital multimeter t
To measure very small current accurately, a ____ must be used A) ammeter B) multimeter C) zero resistance ammeter D) ohmmeter c
Which test overcomes odd-sized joints within a pipe span to calculate current on the pipe A) 4 wire B) 2 wire
C) Casing D) 6 wire a
A _____ test point span can be used where a known length of pipeline and the diameter and wall thickness or the weight per foot are known. A) 4 wire B) 2 wire C) Casing D) 6 wire b
If the voltage drop across a 200-ft (61-m) span of 30-in. (762 mm) pipe weighing 118.7 lbs/ft (176.65 kg/m) is 0.17 mV, pipe resistance/ft from Table 6.1 = 2.44 μΩ /ft (8.01 μΩ/m), then the current flow is A) 0.584A B) 0.234A C) 0.348A D) 1.234A c Pipe resistance/ft from Table 6.1 = 2.44 μΩ /ft (8.01 μΩ/m) = 0.00000244 Ω/ft = 200 ft x 0.00000244 Ω/ft = 0.000488 Ω I= E/R .17mV = 0.00017V 0.00017V / 0.000488ohms = 0.348A
In regards to a 4 wire test, the resistance of the pipe section being tested is V 2-3 =+21 mV (before test current applied) V 2-3 =-19 mV (after test current applied) I t = 10 A A) 10m ohms B) 0.4m ohms C) 4m ohms D) .10m ohms c
In regards to a 4 wire test, the resistance of the pipe section being tested is: pipe span resistance is 0.4m ohms, and applied known DC current is 10A Find the calibration factor A) .025A/mV B) 0.25A/mV C) 2.5A/mV D) 25.5A/mV b 10A / 40mV = 0.25A/mV
In regards to a 4 wire test: If the current calibration factor is 0.25A/mV, voltage before test current applied was +21mV, and voltage after test current applied is -19mV, what is the residual magnitude A) .525A B) 1.25A C) 5.25A D) .125A c Voltage before test current (+21mV) * current calibration factor = 5.25A
True or False (t or f) Earth Current Measurements involve two reference electrodes to measure current flow t
On lines that are NOT cathodically protected, corroding areas, or "hot spots," can be found where the potentials are ______ than the nearby potentials. This is ____ of a cathodically protected structures A) more positive, same B) more negative, opposite C) more negative, same D) more positive, opposite b
Illustrates an example of _____ as detected by an over-the-line and lateral pipe-tosoil potential survey A) poor coating B) improper equipment use C) excessive corrosion D) stray current
Illustrates the type of data that would be seen where _______ A) impressed current system is affecting a non-cathodically protected pipe B) impressed current system is affecting a cathodically protected pipe C) galvanic corrosion activity is affecting a non-cathodically protected pipe D) galvanic corrosion activity is affecting a cathodically protected pipe c
Stray current interference is identified when the overthe-line potential becomes ____ in relation to nearby potentials and the lateral potential is more ____ than the over-the-line potentials. A) negative, negative B) positive, positive C) negative, positive D) positive, negate b
A ______ is a method used to detect holidays in a pipe coating after the pipe is buried A) DCVG survey B) Pearson survey
C) coating resistance survey D) pipeline current mapper b
____ is a method for detecting cathodic protection current pickup at coating holidays A) DCVG survey B) Pearson survey C) coating resistance survey D) pipeline current mapper a
In regards to the Pearson survey: As the location of the coating holiday is reached, the radio signal becomes ____ on the receiver A) stronger B) weaker a
It was developed to non-intrusively and accurately measure a near DC current temporarily impressed on the structure and therefore distributed along the pipeline A) DCVG survey B) Pearson survey C) coating resistance survey D) pipeline current mapper d
In regards to the Pearson survey: As the two individuals continue walking, the signal will then ____ and when the back or second person approaches the holiday, the signal will again ___ and the point of the ___ is the location of the coating holiday. A) peak, peak, null B) null, null, peak C) null, null, null D) null, peak, null d
In regards to DCVG: Where there is ___ coating defect, the analog voltmeter needle does ___ register
movement. A) no, not B) definately a, not C) definately, definately D) no, definately a
In regards to DCVG: This technique is accomplished by installing a ____in an existing ____ unit or by using a temporary CP system A) ammeter, rectifier B) current interrupter, rectifier C) voltmeter, rectifier D) resistance meter, rectifier b
True or False ( t or f) In regards to DCVG: the interrupter is set to cycle at a very fast rate with the ON period less than the OFF period, such as a 1/3 second ON and 2/3 second OFF t
True or False (t or f) In regards to DCVG: While walking along the pipeline route the probes are used as walking sticks making sure one electrode tip is in contact with the ground at all times t
In regards to DCVG: ____ is/are always kept near the pipeline centerline ____ A one probe, while the other is held laterally at 1 to 2 m. B) two probes a
True or False (t or f) In regards to DCVG:
Where there is coating defect, the analog voltmeter needle does not register movement f where there is NO coating defect the analog voltmeter needle does not register movement.
In regards to DCVG: The amplitude of the needle swing will ____ as the defect is approached and ____ when passed. A) increase, increase B) decrease, decrease C) decrease, increase D) increase, decrease d
In regards to DCVG: Signal strength at TS A = 200mV Signal strength at TS B =300mV Defect from TS A = 1,372m Defect from TS B = 457m What is the estimated signal strength at defect A) 295mV B) 350mV C) 275mV D) 175mV c 200mV + (1372meters)/ (1372meters + 457 meters) * (300mV-200mV) = 275mV
In regards to DCVG: Centering the defects is achieved by marking the approximate location of the defect at the area where maximum amplitude is indicated A) maximum amplitude B) minimum amplitude a
In regards to DCVG:
Having detected the epicenter of the coating defect, a series of ____ readings are measured moving ____ remote earth. ____ readings near the defect will yield ____ voltage differences where gradients are at a maximum Readings at remote earth will indicate _____ deflections A) perpendicular, away from, lateral, maximum, 10V B) lateral, towards, lateral, maximum, zero to 1mV C) perpendicular, towards, lateral, maximum, zero to 1mV b
In regards to DCVG: calculate the percentage IR of 25, 15, 6, 4, 3, 1, 1, 0 with an estimated signal strength of 275mV A) 15% B) 25% C) 33% D) 20% d Pipe to Remote Earth = 25+15+6+4+3+1+1 mV = 55mV Percentage IR = (Pipe to remote earth) *100 / (signal strength at defect) = (55mV/275mV) * 100 = 20%
The coating resistance is simply the _____ of the structure to the environment ____ by the_____ of the structure. Units are therefore Ω-ft 2 . A) resistance, multiplied, surface area B) resistance, divided, diameter of pipe C) resistance, multiplied, diameter of the pipe D) resistance, multiplied, surface area a
In regards to Coating Resistance Calculations: How long of a pipe section is usually the coating resistance measured out to A) 2 to 5 miles B) 3 to 8 miles C) 1 to 5 miles D) 3 to 5 miles d
In regards to Coating Resistance Calculations: Size of Pipe: 24-in. dia. (610 mm, 61 cm or 0.61 m) Length of Test span: 1 mile = 5,280 ft (1609 m or 1.609 km) What is the total pipe surface area? A) 35,158 ftsq B) 33,158 ftsq C) 31,215 ftsq b (24in / 12inft) 3.14 5,280 ftsq OR metric = 0.61m x π x 1,609 m = 3080 m 2
1) What is the average potential change caused by the current? 2) What is the current on pipe section of interest? 3) What is the pipe-to-earth resistance or the pipe coating resistance? 4) What is the specific coating resistance? 1) 0.975Volts 2) 0.10A 3) 9.75 ohms 4) 323,291 Ω-ft 2
____ is the ____ of resistance A) Conductance, reciprocal B) Inductance, reciprocal a
What is the unit of measure for conductance? A) resistance B) conductors C) capactiance D) siemens d
Current Requirement Tests, given: 1) 2) 3) 4)
Static pipe-to-soil potential = -0.645 V CSE Desired polarized p/s potential = -0.850 V CSE Test current = 50 mA (0.05 Polarized potential due to test current = 0.775 V CSE
A) 100mA B) 200mA C) 78.8mA D) 87.8mA c I req = (Δ E preq * I test) /( Δ E ptest) The value of resistance producing IR drop R = (E ON - E OFF )/I ON I req = [0.850 V - 0.645 V] 0.050 A / (0.775 − 0.645) = 78.8mA
This type of pipe locator uses AC current A) inductive B) conductive b
This type of pipe locator uses frequency AC signal
A) inductive B) conductive a
True or False (t or f) When doing the structure to electrolyte potential for isolation testing the reference electrode must be placed in two different locations f same location
When conducting the DC Line Current to Test Isolation how far apart must the two electrical connection points be A) at least 10 feet apart B) at least 50 feet apart C) at least 100 feet apart D) at least several hundred feet d
In this test, a reference electrode is connected to one lead from a multimeter and placed at a fixed location while the second lead from the multimeter is placed in contact with various parts of the structure A) DC Line Current to Test Isolation B) Fixed Cell to Moving Ground for Continuity Test C) Interrupted Structure-to-Electrolyte Potential to Test Isolation D) Current Response c
Applying a temporary current to one side of an electrical isolation device can determine if the device is functioning properly, with this test ______
A) DC Line Current to Test Isolation B) Fixed Cell to Moving Ground for Continuity Test C) Interrupted Structure-to-Electrolyte Potential to Test Isolation D) Current Response d
With casing shorts the metallic short might attenuate or ____ A) become more positive B) become more negative C) stay the same a
When conducting a structure to electrolyte potential survey on a casing, if the two potentials are less than ___mV, the casing might be shorted to the carrier pipe A) 5 B) 50 C) 100 D) 150 c
When conducting an interrupted structure to electrolyte potential survey, if the casing potentials cycle _____ with the carrier pipe potentials and are _______ , then the casing and carrier pipe are likely shorted A) in unison, shifting the same magnitude B) in unison, shifting dissimilar magnitudes C) not in unison, shifting the same magnitude D) not in unison, shifting dissimilar magnitudes a
The resistance between the pipe and casing can be measured using I ammeter II voltmeter III external DC power supply. IV volt-ohmmeter A) I, II B) I, II, III C) all b
What two factors listed below determine the corrosivity of an electrolyte A) electrolyte temperature and pH B) electrolyte density and resistivity C) electrolyte resistivity and pH c
Wenner involves the use of 4 pins driven into the ground, ____ is applied to the outer pins, and the ___ drop between the ____ pins is measured A) current, voltage, inner B) voltage, current, inner C) voltage, current, outer D) current, voltage, outer a
Wenner 4 pin uses A) Alternating current B) Direct current a
The Nilsson uses a voltage of __ V and a frequency of ___Hz and the Vibroground uses a voltage of __ V and __ Hz A) 24, 97 / 12, 97 B) 12, 97 / 100, 97 C) 24, 47 / 24, 47 D) 12, 127 / 24, 127 b
Resistivity formula in cm is A) p = 4(3.14)aR B) p= 2(3.14)aR C) r = 2(3.14)aR a= spacing in cm , R = resistance , ohms b
True or false (t or f) The resistivity formula for feet is p=191.5aR t
Using the Wenner 4 pin, if the resistance reading from the meter is 8 ohms at a pin spacing of 3.048 meters, then the average resistivity is A) 12,320 ohms-cm B) 18,320 ohms-cm C) 15,320 ohms-cm D) 11,320 ohms-cm c ρ = 2 x π x 304.8 cm x 8 Ω = 15,320 Ω-cm
Using the Wenner 4 pin, if the resistance reading from the meter is 8 ohms at a pin spacing of 10ft, then the average resistivity is A) 12,320 ohms-cm B) 18,320 ohms-cm C) 15,320 ohms-cm D) 11,320 ohms-cm c ρ = 191.5 x 10 ft x 8 Ω = 15,320 Ω -cm
When taking soil resistivity measurements along a structure,it is good practice to place the line of pins _____ to the structure, with the nearest pin no closer than ___ ft from the structure A) parallel, 20 ft B) parallel, 10ft C) perpendicular, 20ft D) perpendicular, 15ft d
Layer Resistivity 1) S 2 layer = 318.2 cm - 159.1 cm =159.1 cm 2) R 2 layer = (R 1 R 2 ) / (R1 - R2 ) = 28.46ohms 3) 2 π x 159.1cm x 28.46 Ω = 28,450ohms-cm
The soil box measures a ____ or resistivity of a relatively small soil sample A) maximum B) minimum b
True or False (t or f) One advantage of the single rod method for measuring resistivity of soil is that it can be employed in confined spaces such as next to tanks and between pipes t
What is the formula for resistivity A) p= (L*A)/(R) B) p = (R*A)/(L) C) p = (X*A)/(R) b
Electrical continuity of concrete rebar structures can be evaluated using ______ a resistance of less than ____ indicates continuity A) DC-resistance measurements, 0.100 ohms B) AC-resistance measurements, 0.100ohms b
In regards to concrete rebar structures and CP The ___ must not come into contact with the rebar or any other metallic component of the structure A) anode B) rectifier C) cathode a
In regards to concrete rebar structures and CP Potentials more positive than ___ mV have a ___ chance of corrosion A) -300, 10% B) -200, 10% C) -150, 5% D) -200, 5% d
In regards to concrete rebar structures and CP Potentials more negative than ___ mV have a ___ chance of corrosion A) -350, 90% B) -350, 95% C) -200, 80% D) -200, 95% b
In regards to leaks vs time It is typical of corrosion that the cumulative frequency increases _____ with time A) straight line fashion B) fast in the beginning , slower C) logarithmically END OF CHAPTER 6 c
START OF CHAPTER 7 ___ stray current is can cause significant corrosion of aluminum, ___ stray current causes signficant corrosion of most metals A) DC , DC B) AC, DC C) DC, AC b
______ allows us to relate the corrosion lost to the amount of current discharged A) Faraday's Law B) Ohm's Law C) Kirchoff's Law a
These currents can be manmade or natural in origin A) Telluric B) Steady State C) Dynamic c
The damaging effect of stray current typically occurs if the current ____ the structure through the electrolyte where corrosion will be accelerated A) remains on B) leaves b
This is an example of stray current using varying voltage gradients with two reference electrodes
_____ stray currents are those currents that vary in amplitude and/or change in the direction of current flow A) Telluric B) Steady State C) Dynamic c
______are defined as those that maintain constant amplitude and constant geographical paths A) Telluric B) Steady State C) Dynamic b
_____ currents are naturally occurring stray currents that are caused by disturbances in the Earth's magnetic field by sun spot activity A) Telluric B) Steady State C) Dynamic a
Varying voltage gradients in the earth can be detected using two reference electrodes spaced ____ to ____ feet apart A) 5 , 10 B) 10, 25
C) 15, 25 D) 25, 50 b
____ uses a long term way of recording stray current magnitude over time A) rectifier timer B) Stripe Anode C) current interrupter D) strip chart recorder d
If stray current is to be successfully drained from the structure of interest to the source, two conditions must be met I The source must tend to pick up stray current at the point where the mitigation bond is to be installed II The source must not pick up stray current at the point where the mitigation bond is to be installed III The structure must tend to discharge stray current at the point where the mitigation bond is to be installed A) I, III B) II, III a
Examples of this stray current include high voltage direct current ground electrodes and CP systems A) Telluric B) Steady State C) Dynamic b
The ____ of the voltage gradients to ____ earth affecting the foreign structure determines the type of interference A) polarity, remote B) resistance, distrubted C) resistance, remote D) polarity, distrubted a
When a voltage gradient overlaps a foreign structure and is ____ with respect to _____, it promotes current discharge from the _____ in the area of influence
A) positive, foreign structure, remote earth B) positive, remote earth, foreign structure C) negative, remote earth, foreign structure D) positive, remote earth, foreign structure c
If current discharges from a structure, then it must pick up current ______, this is cathodic interference A) outside the area of influence B) inside the area of influence a
If a foreign structure crosses a voltage gradient that is with respect to remote earth, then it will promote current pickup on the ____ , ____the area of influence, this is anodic interference A) negative, protected structure, outside B) positive, foreign structure, outside C) positive, foreign structure, within D) negative, protected structure, within c
During anodic interference current will discharge ____ the area of influence A)outside B) inside
a
In a(n) ______ pipeline, the corroding (anodic) areas exhibit a potential that is more _____ when measured against a reference electrode, while the non-corroding (cathodic) areas yield a more ____ potential. A) protected, negative, positive B) protected, positive, positive C) unprotected, positive, negative D) unprotected, negative, positive d
In a(n) ______ pipeline, the corroding (anodic) areas exhibit a potential that is more _____ when measured against a reference electrode, while the non-corroding (cathodic) areas yield a more ____ potential. A) protected, negative, positive B) protected, positive, negative C) unprotected, positive, negative D) unprotected, negative, positive b
In regards to testing for stray current interference with an interrupter installed: Assumption that the ___ potential is the most ____ value must NOT be made A) ON, negative B) ON, positive C) OFF, negative D) OFF, positive a
Which of the following is likely indicating cathodic interference A) X B) Y C) Z b
Which of the following is likely indicating anodic interference A) X B) Y C) Z a
True or False (t or f) Current measurements within a structure such as a pipeline can be used to predict current pickup and discharge areas t
In regards to the installation of metallic bonds to control interference: The resistance of the bond must be ___ than the ___ path through the soil A) lower, perpendicular B) higher, perpendicular C) lower, parallel D) higher, parallel c
In regards to the installation of metallic bonds to control interference: ____ structure must be more ____ than foreign structure at the bond location to return current safely A) protected, positive B) protected, negative C) unprotected, positive D) protected, negative a
A metallic bond may not perform properly in the case of a cathodically protected ______ that is causing interference on a _____ pipeline A) bare pipe, coated B) coated, bare a
True or False (t or f) Resistors or diodes may be needed in metallic bonds t
In regards to installing and adjusting resistors in a bond: The value of resistance is ______ while the structure-to-electrolyte at the most critical location is observed
A) slowly reduced B) slowly increased C) greatly reduced D) greatly increased a
Typically, it is desirable to use a resistance bond instead of a solid bond for the following reasons I The solid bond limits the amount of current for the structure being protected II The resistance bond must be of high enough resistance to ensure that the stray current returns in the metallic path III The resistance bond limits the amount of current for the structure being protected IV Resistance bonds are subject to damage by high current surges A) I, II B) I, II, III C) III, IV D) all c The RESISTANCE BOND limits the amount of current for the structure being protected The resistance bond must be of LOW ENOUGH resistance to ensure that the stray current returns in the metallic path
Stray current is ___ the source when the structure to be protected is discharging current (corroding) and the reverse when the structure is ____ stray current A) away, receiving B) toward, rejecting C) toward, receiving D) away, rejecting c
True or False (t or f) Stray current flow onto the structure is not desirable since it causes a discharge point at some other location(s) t
With ____ stray current sources the direction of current through a bond could reverse causing accelerated corrosion A) dynamic
B) telluric C) steady state a
True or False (t or f) A diode is most useful with dynamic stray current sources because it can react quickly to current changes f A diode can be installed to prevent current changes but it may be slow to respond
True or False (t or f) For dynamic stray current it is best to use a diode and a relay to open or reverse current t
True or False (t or f) Stray current can safely be returned to its source through a cathodic protection system. An example using a sacrificial (galvanic) anode t
In regards to stray current mitigation A) Be sure to coat areas of current discharge B) Do not coat areas of current discharge b
The electromagnetic field created by the alternating current expands and collapses and changes direction ___ times per second A) 60 B) 80 C) 90 D) 120
d
_______ , where the structure acts as the single-turn secondary of an air-core transformer in which the overhead power line is the primary, this type of induction may occur when the structure is _____ A) electrostatic coupling ,abovegrade B) Resistive coupling, below ground C) Electromagnetic induction, above or below ground D) electromagnetic induction, below ground c
_____ is where the structure acts as one side of a capacitor with respect to ground, only corncern when the structure is _____ A) electrostatic coupling ,abovegrade B) Resistive coupling, below ground C) Electromagnetic induction, below ground a
_____ is where AC power is transmitted to ground then flows on and off the underground structure. A) electrostatic coupling B) Resistive coupling C) Electromagnetic induction b
1 A DC discharge results in a loss of approximately ___lbs of steel in one year, while one ampere of AC would consume less than__ lb A) 20, 1 B) 1, 20 C) 10, 5 D) 20, 5 a
Any two materials separated by a dielectric material can be considered as a ____ A) transformer B) conductor C) capacitor D) resistor c
stray current magnitude is ____ proportional to the phase currents (IΦ) and their relative magnitudes and to the length (L) of mutual exposure; it is ____ proportional to the relative distance (d) between the structure and the power line conductors A) directly, directly B) indirectly, directly C) indirectly, indirectly D) directly, indirectly d
In regards to AC Mitigation: The pipe acts as a _______ of an air-core transformer, and the overhead AC power lines are _____ A) primary coil, secondary B) secondary, primary b
In regards to AC Mitigation: The induced voltage (V induced ) appears across the ______. The voltage to ground (V ground ) at each end of the structure is ____ the total induced voltage A) ends of the pipe, 1/3 B) middle of the pipe, 1/3 C) ends of the pipe, 1/2 D) middle of the pipe, 1/2 c
In regards to AC Mitigation: Where a pipeline closely parallels a power line for some distance, induced voltage peaks would be expected where the power line and pipeline ____ A) merge B) seperate b
If an AC voltage is near or is in excess of___ V, the structure is considered hazardous and personnel working on the structure must be advised that a hazardous situation exits A) 5 B) 10
C) 15 D) 20 c
_______ are available that block the low-potential DC cathodic protection current from leaking across an insulating device while still providing instant protection from high-voltage spikes and _____ A) polarization cell, induced AC B) solid state devices, induced AC C) polarization cell, conducted AC D) solid state devices, induced DC b
Which of these devices does not involve caustic liquid electrolytes and is low maintenance A) polarization cell B) SSD c
A polarization cell used as a ___ decoupler that allows ___ current to pass to a ground while blocking the __ current intended for the cathodic protection of the structure A) DC, AC, DC B) AC, DC, DC C) AC, AC, DC D) DC, DC, AC a
True or False ( t or f) Grounding mats are intended to be an electrical ground f They are not intended to be an electrical ground as they are installed close to the surface often in high-resistivity soil or frost
True or False (t or f) If zinc or magnesium ground mats are used as a gradient mat around a test station, then the instant OFF potential is no longer valid as all sources of DC current have not been interrupted. t
In regards to AC Mitigation and AC density: 20 A/m 2 < i ac < 100 A/m 2 A) No corrosion B) Corrosion unpredictable C) corrosion expected b
In regards to AC Mitigation and AC density: i ac > 100 A/m 2 A) No corrosion B) Corrosion unpredictable C) corrosion expected c
In regards to AC Mitigation and AC density: i ac < 20 A/m 2 A) No corrosion B) Corrosion unpredictable C) corrosion expected END OF CHAPTER 7 a
START OF CHAPTER 8 Important question for monitoring: Any part of the structure closely parallel (within ___ ft or so) high-voltage (HVAC or HVDC) electric transmission lines? A) 50 B) 100 C) 200 D) 300
c
A particularly ___ condition could indicate the need for a relatively ___ current density to maintain cathodic protection A) acidic, high B) acidic, low C) alkaline, high D) alkaline, low a
Consumption of _____ at the structure surface _____ the steel at cathodic areas and permits more rapid consumption of the metal by galvanic corrosion cells A) hydroxl, polarizes B) hydrogen, depolarizes C) hydrogen, polarizes D) hydroxl, depolarizes b
True or False (t or f) Most sacrificial (galvanic) anode systems can be routinely inspected by taking reference potential measurements at critical locations throughout the system. t
When another large bare structure is accidentally connected to a structure protected by a galvanic anode, the structure-to-electrolyte potential will naturally become ___ electronegative or ___ electropositive A) less, more B) more, less a
The readings taken to confirm that a DC power source is operating properly should include: I DC Current II DC Voltage III Tap Setting A) I, II B) III C) I, II, III c
Detailed Survey Frequency should be according to DOT A) once per calendar year not to exceed an 15-month interval B) once per calender year C) once per calender year not to exceed an 18-month interval a
Interference Control Drainage Bond inspection frequency should be according to DOT A) once per calender year not to exceed an 15-month interval B) six timer per calender year not to exceed 2.5 month intervals b
Rectifier Inspection Frequency should be according to DOT A) once per calender year not to exceed an 15-month interval B) six timer per calender year not to exceed 2.5 month intervals b
True or False (t or f) weather conditions should be noted in the data sheets t
Measurements must include the accurate recording of the: I Value II Polarity III Units IV Type of reference electrode, where applicable A) I, II, III B) III, IV C) I, II, III, IV c
True or False (t or f) The name and serial numbers of all instruments does not have to be included in the data sheets f The name and serial numbers of all instruments used should be included in the data sheets
Solve the circuit problem -> Answers: R2= 5 ohms It= 3A I1= 1A V1=2V
