structure, measure base (native) structure-to-electrolyte
potentials of the [pipe [and casings]] [structure]. Perform
measurements at anode junction boxes, test stations and other
locations suitable for test purposes (such as service risers or
valves), at intervals not exceeding [30] [120] [_____] meters
[100] [400] [_____] feet [with readings at each end point and the
midpoints as a minimum]. The locations of these measurements shall
be identical to the locations specified for potential measurements
with anodes connected. Use the same measuring equipment that is
specified for measuring protected potential measurements.
[For underground storage tanks, take a minimum of three
measurements with the reference electrode located as follows:
(1) Directly over the longitudinal and transverse centerlines of
the tank at intervals not exceeding the diameter of the tank and
to a distance from the tank of two times the tank diameter.
(2)
At points directly around the circumference of the tank.]
b. Permanent reference electrode calibration: Verify calibration
of the reference electrode by measuring the potential difference
between the permanent reference electrode and an independent
(portable) calibrated reference electrode placed in the soil or
water adjacent to or as close as practicable to the permanent
reference electrode. [Potential differences between the two
electrodes of the same generic type should not exceed [10] [15]
millivolts.] [Zinc permanent reference electrodes should be
within the range of -1000 to -1150 millivolts when calibrated with
a copper-copper sulfate reference electrode.] Permanent reference
electrodes not within these potential differences shall be removed
from the construction site by the end of the day and replaced at
the contractor's expense. The testing provision shall also apply
to replacement reference electrodes as well.
c.
Insulation joint testing: Perform insulation testing at each
insulating joint or fitting [prior to burying the joint or
fitting] before and after the connection of anodes to the pipe at
[anode junction box] [test station]. Before connection, test
using an insulation checker. After connection, test by measuring
the potential shift on both sides of the insulating joint. These
tests shall demonstrate that no metallic contact or short circuit
exists between the two insulated sections of the pipe. Report and
repair defective insulating flanges at the Contractor's expense.
d.
Electrical continuity testing: Perform electrical continuity
testing for joint bonded pipe prior to backfilling of the pipe.
[Circulate current through the pipe and compare the measured
resistance to the theoretical resistance of the pipe and bond
cables. The resistance measured shall not exceed 150 percent of
the theoretical resistance.]
e.
Pipe casing testing: Before final acceptance of the installation,
test the electrical insulation of the carrier pipe from casings
and correct any short circuits.
f.
Anode-to-soil potential and anode output testing: Measure
anode-to-soil potential of each anode with the anode disconnected
[through the anode junction box]. After connecting the anodes to
the pipe, measure current output of each anode [across the shunt
SECTION 13110N
Page 19
Previous Page
