MIL-HDBK-1004/10
APPENDIX E (continued)
N 192.465
External corrosion control: Monitoring
(a) Each pipeline that is under cathodic protection must be tested
at least once each calendar year, but with intervals not exceeding 15 months,
to determine whether the cathodic protection meets the requirements of N
192.463. However, if tests at those intervals are impractical for separately
protected short sections of mains or transmission lines, not in excess of 100
feet, or separately protected service lines, these pipelines may be surveyed
on a sampling basis. At least 10 percent of these protected structures,
distributed over the entire system must be surveyed each calendar year, with a
different 10 percent checked each subsequent year, so that the entire system
is tested in each 10-year period.
(b) Each cathodic protection rectifier or other impressed current
power source must be inspected six times each calendar year, but with
intervals not exceeding 2-1/2 months, to insure that it is operating.
(c) Each reverse current switch, each diode, and each interference
bond whose failure would jeopardize structure protection must be electrically
checked for proper performance six times each calendar year, but with
intervals not exceeding 2-1/2 months. Each other interference bond must be
checked at least once each calendar year, but with intervals not exceeding 15
months.
(d) Each operator shall take prompt remedial action to correct any
deficiencies indicated by the monitoring.
(e) After the initial evaluation required by paragraphs (b) and (c)
of N 192.455 and paragraph (b) of 192.457, each operator shall, at intervals
not exceeding 3 years, revaluate its unprotected pipelines and cathodically
protect them in accordance with this subpart in areas in which active
corrosion is found. The operator shall determine the areas of active
corrosion by electrical survey, or where electrical survey is impractical, by
the study of corrosion and leak history records, by leak detection survey, or
by other means.
[Amdt. 192-4, 36 FR 12302, June 30, 1971, as amended by Amdt. 192-33, 43 FR
39390, Sept. 5, 1978; Amdt. 192-35A, 45 FR 23441, Apr. 7, 1980]
---
N 192.467
External corrosion control: Electrical isolation.
(a) Each buried or submerged pipeline must be electrically isolated
from other underground metallic structures, unless the pipeline and the other
structures are electrically interconnected and cathodically protected as a
single unit.
(b) One or more insulating devices must be installed where
electrical isolation of a portion of a pipeline is necessary to facilitate the
application of corrosion control.
275
Previous Page
