Nace CP 1, Course Manual

Page: 530 / 535

TM0101-2001
NACE International 19
11.5.3 Evaluation of Data
11.5.3.1 The potentials taken before the CP
system or groundbed was energized shall be
compared with those taken afterward.
11.5.3.2 Structures that are electrically continuous
with each other display similar negative shifts.
11.6 Invalid Techniques
11.6.1 Techniques utilizing “continuity testers” common
to the electrical trades are not valid for continuity
testing on underground storage tanks in a common
electrolyte. Some equipment in this category includes
the following:
(a) DC ohmmeter
(b) Diode tester
(c) Continuity test light
11.7 Recommended Action
11.7.1 Further investigation may be required to confirm
the presence or lack of continuity, depending on the
original system design. For some systems, correction
of the defect may preclude the installation of additional
cathodic protection measures.
In other instances,
correction of the defect may be necessary in order for
the original system or supplemental protection to be
totally effective.
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Section 12: Piping and Appurtenances
12.1 Cathodic protection for associated piping and
appurtenances shall be tested in accordance with the
recommendations of NACE Standard RP0169
3
and
descriptions in NACE Publication 10A190.
4
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References
1. NACE Standard RP0285 (latest revision), “Corrosion
Control of Underground Storage Tank Systems by Cathodic
Protection” (Houston, TX: NACE).
2. NACE Standard RP0177 (latest revision), “Mitigation of
Alternating Current and Lightning Effects on Metallic
Structures and Corrosion Control Systems” (Houston, TX:
NACE).
3. NACE Standard RP0169 (latest revision), “Control of
External Corrosion on Underground or Submerged Metallic
Piping Systems” (Houston, TX: NACE).
4. NACE Publication 10A190 (withdrawn), “Measurement
Techniques Related to Criteria for Cathodic Protection of
Underground or Submerged Steel Piping Systems (as
defined in NACE Standard RP0169-83)” (Houston, TX:
NACE).
5. NACE Publication 35201 (latest revision), “Technical
Report on the Application and Interpretation of Data from
External Coupons Used in the Evaluation of Cathodically
Protected Metallic Structures” (Houston, TX: NACE).
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Bibliography
Ansuini, F.L., and J.R. Dimond. “Factors Affecting the
Accuracy of Reference Electrodes.” MP 33, 11
(1994): pp. 14-17.
Applegate, L.M. Cathodic Protection. New York, NY:
McGraw-Hill, 1960.
Bushman, J.B., and F.E. Rizzo. “IR Drop in Cathodic
Protection Measurements.” MP 17, 7 (1978): pp.
9-13.
Corrosion Control/System Protection, Book TS-1, Gas
Engineering and Operating Practices Series.
Arlington, VA: American Gas Association, 1986.
Dabkowski, J., and T. Hamilton. “A Review of Instant-Off
Polarized Potential Measurement Errors.”
CORROSION/93, paper no. 561. Houston, TX:
NACE, 1993.
Dearing, B.M. “The 100-mV Polarization Criterion.” MP 33,
9 (1994): pp. 23-27.
DeBethune, A.J. “Fundamental Concepts of Electrode
Potentials.” Corrosion 9, 10 (1953): pp. 336-344.
Escalante, E., ed. Underground Corrosion, ASTM STP 741.
West Conshohocken, PA: ASTM, 1981.