NACE CP2 STUDENT MANUAL CHAPTER 3: FIELD
MEASUREMENTS EXAM ACTUAL QUESTIONS AND ANSWERS
WITH COMPLETE SOLUTIONS VERIFIED GRADED A++
A structure-to-electrolyte potential is a measurement taken with the voltmeter
connected in ____ in the circuit.
A) parallel
B) series
a
A structure-to-electrolyte potential measures the potential difference between
_________.
A) two different structures acting as electrodes
B) the structure and a standard reference electrode
C) the structure and the anode
D) two different points on the structure
b
If 5.0 A of battery current passes through the outside leads of a 4-wire current
span spaced at 30 m (100 ft), resulting in a voltage drop of 5.0 mV with the test
current applied and of 1 mV without the test current, what is a the calibration
factor of the current span?
,A) 0.00025 A/mV
B) 4.0 A/mV
C) 1.25 A/mV
D) 5.0 A/mV
c
K = ΔItest / ΔEtest
ΔItest = 5.0 A
ΔEtest = 5.0 mV - 1 mV
ΔEtest = 4.0 mV
K = 5.0 A / 4.0 mV
K = 1.25 A/mV
Polarized potentials are measured:
A) when the rectifiers are ON
B) just after the rectifiers are turned OFF
C) after the rectifiers are left off for several days
D) just after the rectifiers are turned ON
b
Polarization is determined by ________________.
A) subtracting the ON from the instant OFF potential
,B) measuring the instant OFF potential
C) subtracting the instant OFF from the native (free corroding) potential
D) subtracting the IR drop from the ON potential
c
A 61 cm diameter (24 in) pipe has a current span at each end of a 2 km (1.24
miles) section with the following information determined:
EONts1 = -1200 mVcse ______ EONts2 = -1140 mVcse
EOFFts1 = -1000 mVcse _____ EOFFts2 = -980 mVcse
IONts1 = 3.0 A __________________ IONts2 = 2.8 A
IOFFFts1 = 0.20 A _____________ IOFFts2 = 0.2 A
What is the pipe-to-earth resistance in Ω?
A) 0.9 Ω
B) 9 Ω
C) 66.7 Ω
D) 900 Ω
A
ΔEts1 = EONts1 - EOFFts1 _________ ΔEts2 = EONts2 - EOFFts2
ΔEts1 = -1200 mV - -1000 mV _____ ΔEts2 = -1140 mV - -980 mV
ΔEts1 = -200 mV _______________________ ΔEts2 = -160 mV
, ΔIts1 = IONts1 - IOFFts1 ____________ ΔIts2 = IONts2 - IOFFts2
ΔIts1 = 3.0 A - 0.20 A ________________ ΔIts2 = 2.8 A - 0.2 A
ΔIts1 = 2.8 A ____________________________ ΔIts2 = 2.6 A
Ic = ΔIts1 - ΔIts2
Ic = 0.2 A
ΔEavg = ΔEts1 + ΔEts
ΔEavg = 200 mV + 160 mV / 2
ΔEavg = 360 mV / 2
ΔEavg = 180 mV or .180 V
Rc = ΔEavg / Ic
Rc = .180 / .2
Rc = 0.9 Ω
A 61 cm diameter (24 in) pipe has a current span at each end of a 2 km (1.24
miles) section with the following information determined:
EONts1 = -1200 mVcse ______ EONts2 = -1140 mVcse
EOFFts1 = -1000 mVcse _____ EOFFts2 = -980 mVcse
IONts1 = 3.0 A __________________ IONts2 = 2.8 A
IOFFFts1 = 0.20 A _____________ IOFFts2 = 0.2 A
MEASUREMENTS EXAM ACTUAL QUESTIONS AND ANSWERS
WITH COMPLETE SOLUTIONS VERIFIED GRADED A++
A structure-to-electrolyte potential is a measurement taken with the voltmeter
connected in ____ in the circuit.
A) parallel
B) series
a
A structure-to-electrolyte potential measures the potential difference between
_________.
A) two different structures acting as electrodes
B) the structure and a standard reference electrode
C) the structure and the anode
D) two different points on the structure
b
If 5.0 A of battery current passes through the outside leads of a 4-wire current
span spaced at 30 m (100 ft), resulting in a voltage drop of 5.0 mV with the test
current applied and of 1 mV without the test current, what is a the calibration
factor of the current span?
,A) 0.00025 A/mV
B) 4.0 A/mV
C) 1.25 A/mV
D) 5.0 A/mV
c
K = ΔItest / ΔEtest
ΔItest = 5.0 A
ΔEtest = 5.0 mV - 1 mV
ΔEtest = 4.0 mV
K = 5.0 A / 4.0 mV
K = 1.25 A/mV
Polarized potentials are measured:
A) when the rectifiers are ON
B) just after the rectifiers are turned OFF
C) after the rectifiers are left off for several days
D) just after the rectifiers are turned ON
b
Polarization is determined by ________________.
A) subtracting the ON from the instant OFF potential
,B) measuring the instant OFF potential
C) subtracting the instant OFF from the native (free corroding) potential
D) subtracting the IR drop from the ON potential
c
A 61 cm diameter (24 in) pipe has a current span at each end of a 2 km (1.24
miles) section with the following information determined:
EONts1 = -1200 mVcse ______ EONts2 = -1140 mVcse
EOFFts1 = -1000 mVcse _____ EOFFts2 = -980 mVcse
IONts1 = 3.0 A __________________ IONts2 = 2.8 A
IOFFFts1 = 0.20 A _____________ IOFFts2 = 0.2 A
What is the pipe-to-earth resistance in Ω?
A) 0.9 Ω
B) 9 Ω
C) 66.7 Ω
D) 900 Ω
A
ΔEts1 = EONts1 - EOFFts1 _________ ΔEts2 = EONts2 - EOFFts2
ΔEts1 = -1200 mV - -1000 mV _____ ΔEts2 = -1140 mV - -980 mV
ΔEts1 = -200 mV _______________________ ΔEts2 = -160 mV
, ΔIts1 = IONts1 - IOFFts1 ____________ ΔIts2 = IONts2 - IOFFts2
ΔIts1 = 3.0 A - 0.20 A ________________ ΔIts2 = 2.8 A - 0.2 A
ΔIts1 = 2.8 A ____________________________ ΔIts2 = 2.6 A
Ic = ΔIts1 - ΔIts2
Ic = 0.2 A
ΔEavg = ΔEts1 + ΔEts
ΔEavg = 200 mV + 160 mV / 2
ΔEavg = 360 mV / 2
ΔEavg = 180 mV or .180 V
Rc = ΔEavg / Ic
Rc = .180 / .2
Rc = 0.9 Ω
A 61 cm diameter (24 in) pipe has a current span at each end of a 2 km (1.24
miles) section with the following information determined:
EONts1 = -1200 mVcse ______ EONts2 = -1140 mVcse
EOFFts1 = -1000 mVcse _____ EOFFts2 = -980 mVcse
IONts1 = 3.0 A __________________ IONts2 = 2.8 A
IOFFFts1 = 0.20 A _____________ IOFFts2 = 0.2 A
